draft-ietf-mpls-ldp-p2mp-11.txt   draft-ietf-mpls-ldp-p2mp-12.txt 
Network Working Group I. Minei (Editor) Network Working Group I. Minei, Ed.
Internet-Draft K. Kompella Internet-Draft Juniper Networks
Intended status: Standards Track Juniper Networks Intended status: Standards Track IJ. Wijnands, Ed.
Expires: April 11, 2011 I. Wijnands (Editor) Expires: August 21, 2011 Cisco Systems, Inc.
K. Kompella
Juniper Networks
B. Thomas B. Thomas
Cisco Systems, Inc. Cisco Systems, Inc.
October 8, 2010 February 17, 2011
Label Distribution Protocol Extensions for Point-to-Multipoint and Label Distribution Protocol Extensions for Point-to-Multipoint and
Multipoint-to-Multipoint Label Switched Paths Multipoint-to-Multipoint Label Switched Paths
draft-ietf-mpls-ldp-p2mp-11 draft-ietf-mpls-ldp-p2mp-12
Abstract Abstract
This document describes extensions to the Label Distribution Protocol This document describes extensions to the Label Distribution Protocol
(LDP) for the setup of point to multi-point (P2MP) and multipoint-to- (LDP) for the setup of point to multi-point (P2MP) and multipoint-to-
multipoint (MP2MP) Label Switched Paths (LSPs) in Multi-Protocol multipoint (MP2MP) Label Switched Paths (LSPs) in Multi-Protocol
Label Switching (MPLS) networks. These extensions are also referred Label Switching (MPLS) networks. These extensions are also referred
to as mLDP Multicast LDP. mLDP constructs the P2MP or MP2MP LSPs to as Multicast LDP (mLDP). mLDP constructs the P2MP or MP2MP LSPs
without interacting with or relying upon any other multicast tree without interacting with or relying upon any other multicast tree
construction protocol. Protocol elements and procedures for this construction protocol. Protocol elements and procedures for this
solution are described for building such LSPs in a receiver-initiated solution are described for building such LSPs in a receiver-initiated
manner. There can be various applications for P2MP/MP2MP LSPs, for manner. There can be various applications for P2MP/MP2MP LSPs, for
example IP multicast or support for multicast in BGP/MPLS L3VPNs. example IP multicast or support for multicast in BGP/MPLS L3VPNs.
Specification of how such applications can use a LDP signaled P2MP/ Specification of how such applications can use a LDP signaled P2MP/
MP2MP LSP is outside the scope of this document. MP2MP LSPs is outside the scope of this document.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 11, 2011. This Internet-Draft will expire on August 21, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Conventions used in this document . . . . . . . . . . . . 4 1.1. Conventions used in this document . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Setting up P2MP LSPs with LDP . . . . . . . . . . . . . . . . 5 2. Setting up P2MP LSPs with LDP . . . . . . . . . . . . . . . . 5
2.1. Support for P2MP LSP setup with LDP . . . . . . . . . . . 6 2.1. Support for P2MP LSP setup with LDP . . . . . . . . . . . 5
2.2. The P2MP FEC Element . . . . . . . . . . . . . . . . . . . 6 2.2. The P2MP FEC Element . . . . . . . . . . . . . . . . . . . 6
2.3. The LDP MP Opaque Value Element . . . . . . . . . . . . . 8 2.3. The LDP MP Opaque Value Element . . . . . . . . . . . . . 8
2.3.1. The Generic LSP Identifier . . . . . . . . . . . . . . 8 2.3.1. The Generic LSP Identifier . . . . . . . . . . . . . . 9
2.4. Using the P2MP FEC Element . . . . . . . . . . . . . . . . 9 2.4. Using the P2MP FEC Element . . . . . . . . . . . . . . . . 10
2.4.1. Label Map . . . . . . . . . . . . . . . . . . . . . . 10 2.4.1. Label Map . . . . . . . . . . . . . . . . . . . . . . 10
2.4.2. Label Withdraw . . . . . . . . . . . . . . . . . . . . 12 2.4.2. Label Withdraw . . . . . . . . . . . . . . . . . . . . 12
2.4.3. Upstream LSR change . . . . . . . . . . . . . . . . . 12 2.4.3. Upstream LSR change . . . . . . . . . . . . . . . . . 13
3. Shared Trees . . . . . . . . . . . . . . . . . . . . . . . . . 13 3. Setting up MP2MP LSPs with LDP . . . . . . . . . . . . . . . . 13
4. Setting up MP2MP LSPs with LDP . . . . . . . . . . . . . . . . 13 3.1. Support for MP2MP LSP setup with LDP . . . . . . . . . . . 14
4.1. Support for MP2MP LSP setup with LDP . . . . . . . . . . . 14 3.2. The MP2MP downstream and upstream FEC Elements. . . . . . 15
4.2. The MP2MP downstream and upstream FEC Elements. . . . . . 14 3.3. Using the MP2MP FEC Elements . . . . . . . . . . . . . . . 15
4.3. Using the MP2MP FEC Elements . . . . . . . . . . . . . . . 15 3.3.1. MP2MP Label Map . . . . . . . . . . . . . . . . . . . 16
4.3.1. MP2MP Label Map . . . . . . . . . . . . . . . . . . . 16 3.3.2. MP2MP Label Withdraw . . . . . . . . . . . . . . . . . 20
4.3.2. MP2MP Label Withdraw . . . . . . . . . . . . . . . . . 20 3.3.3. MP2MP Upstream LSR change . . . . . . . . . . . . . . 21
4.3.3. MP2MP Upstream LSR change . . . . . . . . . . . . . . 21 4. Micro-loops in MP LSPs . . . . . . . . . . . . . . . . . . . . 21
5. Micro-loops in MP LSPs . . . . . . . . . . . . . . . . . . . . 21 5. The LDP MP Status TLV . . . . . . . . . . . . . . . . . . . . 21
6. The LDP MP Status TLV . . . . . . . . . . . . . . . . . . . . 21 5.1. The LDP MP Status Value Element . . . . . . . . . . . . . 22
6.1. The LDP MP Status Value Element . . . . . . . . . . . . . 22 5.2. LDP Messages containing LDP MP Status messages . . . . . . 23
6.2. LDP Messages containing LDP MP Status messages . . . . . . 23 5.2.1. LDP MP Status sent in LDP notification messages . . . 23
6.2.1. LDP MP Status sent in LDP notification messages . . . 23 5.2.2. LDP MP Status TLV in Label Mapping Message . . . . . . 23
6.2.2. LDP MP Status TLV in Label Mapping Message . . . . . . 23 6. Upstream label allocation on a LAN . . . . . . . . . . . . . . 24
7. Upstream label allocation on a LAN . . . . . . . . . . . . . . 24 6.1. LDP Multipoint-to-Multipoint on a LAN . . . . . . . . . . 24
7.1. LDP Multipoint-to-Multipoint on a LAN . . . . . . . . . . 24 6.1.1. MP2MP downstream forwarding . . . . . . . . . . . . . 24
7.1.1. MP2MP downstream forwarding . . . . . . . . . . . . . 25 6.1.2. MP2MP upstream forwarding . . . . . . . . . . . . . . 25
7.1.2. MP2MP upstream forwarding . . . . . . . . . . . . . . 25 7. Root node redundancy . . . . . . . . . . . . . . . . . . . . . 25
8. Root node redundancy . . . . . . . . . . . . . . . . . . . . . 25 7.1. Root node redundancy - procedures for P2MP LSPs . . . . . 26
8.1. Root node redundancy - procedures for P2MP LSPs . . . . . 26 7.2. Root node redundancy - procedures for MP2MP LSPs . . . . . 26
8.2. Root node redundancy - procedures for MP2MP LSPs . . . . . 26 8. Make Before Break (MBB) . . . . . . . . . . . . . . . . . . . 27
9. Make Before Break (MBB) . . . . . . . . . . . . . . . . . . . 27 8.1. MBB overview . . . . . . . . . . . . . . . . . . . . . . . 27
9.1. MBB overview . . . . . . . . . . . . . . . . . . . . . . . 27 8.2. The MBB Status code . . . . . . . . . . . . . . . . . . . 28
9.2. The MBB Status code . . . . . . . . . . . . . . . . . . . 28 8.3. The MBB capability . . . . . . . . . . . . . . . . . . . . 29
9.3. The MBB capability . . . . . . . . . . . . . . . . . . . . 29 8.4. The MBB procedures . . . . . . . . . . . . . . . . . . . . 29
9.4. The MBB procedures . . . . . . . . . . . . . . . . . . . . 30 8.4.1. Terminology . . . . . . . . . . . . . . . . . . . . . 29
9.4.1. Terminology . . . . . . . . . . . . . . . . . . . . . 30 8.4.2. Accepting elements . . . . . . . . . . . . . . . . . . 30
9.4.2. Accepting elements . . . . . . . . . . . . . . . . . . 30 8.4.3. Procedures for upstream LSR change . . . . . . . . . . 30
9.4.3. Procedures for upstream LSR change . . . . . . . . . . 31 8.4.4. Receiving a Label Map with MBB status code . . . . . . 31
9.4.4. Receiving a Label Map with MBB status code . . . . . . 31 8.4.5. Receiving a Notification with MBB status code . . . . 31
9.4.5. Receiving a Notification with MBB status code . . . . 32 8.4.6. Node operation for MP2MP LSPs . . . . . . . . . . . . 32
9.4.6. Node operation for MP2MP LSPs . . . . . . . . . . . . 32 9. Typed Wildcard for mLDP FEC Element . . . . . . . . . . . . . 32
10. Typed Wildcard for mLDP FEC Element . . . . . . . . . . . . . 32 10. Security Considerations . . . . . . . . . . . . . . . . . . . 32
11. Security Considerations . . . . . . . . . . . . . . . . . . . 33 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
12. IANA considerations . . . . . . . . . . . . . . . . . . . . . 33 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 34
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 34 13. Contributing authors . . . . . . . . . . . . . . . . . . . . . 34
14. Contributing authors . . . . . . . . . . . . . . . . . . . . . 34 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36
15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36 14.1. Normative References . . . . . . . . . . . . . . . . . . . 36
15.1. Normative References . . . . . . . . . . . . . . . . . . . 36 14.2. Informative References . . . . . . . . . . . . . . . . . . 37
15.2. Informative References . . . . . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 37 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 37
1. Introduction 1. Introduction
The LDP protocol is described in [RFC5036]. It defines mechanisms The LDP protocol is described in [RFC5036]. It defines mechanisms
for setting up point-to-point (P2P) and multipoint-to-point (MP2P) for setting up point-to-point (P2P) and multipoint-to-point (MP2P)
LSPs in the network. This document describes extensions to LDP for LSPs in the network. This document describes extensions to LDP for
setting up point-to-multipoint (P2MP) and multipoint-to-multipoint setting up point-to-multipoint (P2MP) and multipoint-to-multipoint
(MP2MP) LSPs. These are collectively referred to as multipoint LSPs (MP2MP) LSPs. These are collectively referred to as multipoint LSPs
(MP LSPs). A P2MP LSP allows traffic from a single root (or ingress) (MP LSPs). A P2MP LSP allows traffic from a single root (or ingress)
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protocol in the network. There can be several MP LSPs rooted at a protocol in the network. There can be several MP LSPs rooted at a
given ingress node, each with its own identifier. given ingress node, each with its own identifier.
The solution assumes that the leaf nodes of the MP LSP know the root The solution assumes that the leaf nodes of the MP LSP know the root
node and identifier of the MP LSP to which they belong. The node and identifier of the MP LSP to which they belong. The
mechanisms for the distribution of this information are outside the mechanisms for the distribution of this information are outside the
scope of this document. The specification of how an application can scope of this document. The specification of how an application can
use a MP LSP signaled by LDP is also outside the scope of this use a MP LSP signaled by LDP is also outside the scope of this
document. document.
Interested readers may also wish to peruse the requirements draft Related documents that may be of interest include
[I-D.ietf-mpls-mp-ldp-reqs] and other documents [RFC4875] and [I-D.ietf-mpls-mp-ldp-reqs], [I-D.ietf-l3vpn-2547bis-mcast] and
[I-D.ietf-l3vpn-2547bis-mcast]. [RFC4875].
1.1. Conventions used in this document 1.1. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
1.2. Terminology 1.2. Terminology
The following terminology is taken from [I-D.ietf-mpls-mp-ldp-reqs]. Some of the following terminology is taken from
[I-D.ietf-mpls-mp-ldp-reqs].
mLDP: Multicast extensions for LDP.
P2P LSP: An LSP that has one Ingress LSR and one Egress LSR. P2P LSP: An LSP that has one Ingress LSR and one Egress LSR.
P2MP LSP: An LSP that has one Ingress LSR and one or more Egress P2MP LSP: An LSP that has one Ingress LSR and one or more Egress
LSRs. LSRs.
MP2P LSP: An LSP that has one or more Ingress LSRs and one unique MP2P LSP: An LSP that has one or more Ingress LSRs and one unique
Egress LSR. Egress LSR.
MP2MP LSP: An LSP that connects a set of nodes, such that traffic MP2MP LSP: An LSP that connects a set of nodes, such that traffic
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is done is outside the scope of this document. Transit nodes install is done is outside the scope of this document. Transit nodes install
MPLS forwarding state and propagate the P2MP LSP setup (and tear- MPLS forwarding state and propagate the P2MP LSP setup (and tear-
down) toward the root. The root node installs forwarding state to down) toward the root. The root node installs forwarding state to
map traffic into the P2MP LSP; how the root node determines which map traffic into the P2MP LSP; how the root node determines which
traffic should go over the P2MP LSP is outside the scope of this traffic should go over the P2MP LSP is outside the scope of this
document. document.
2.1. Support for P2MP LSP setup with LDP 2.1. Support for P2MP LSP setup with LDP
Support for the setup of P2MP LSPs is advertised using LDP Support for the setup of P2MP LSPs is advertised using LDP
capabilities as defined in [I-D.ietf-mpls-ldp-capabilities]. An capabilities as defined in [RFC5561]. An implementation supporting
implementation supporting the P2MP procedures specified in this the P2MP procedures specified in this document MUST implement the
document MUST implement the procedures for Capability Parameters in procedures for Capability Parameters in Initialization Messages.
Initialization Messages.
A new Capability Parameter TLV is defined, the P2MP Capability. A new Capability Parameter TLV is defined, the P2MP Capability.
Following is the format of the P2MP Capability Parameter. Following is the format of the P2MP Capability Parameter.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0| P2MP Capability (TBD IANA) | Length (= 1) | |1|0| P2MP Capability (TBD IANA)| Length (= 1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Reserved | |1| Reserved |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
The P2MP Capability TLV MUST be supported in the LDP Initialization The P2MP Capability TLV MUST be supported in the LDP Initialization
Message. Advertisement of the P2MP Capability indicates support of Message. Advertisement of the P2MP Capability indicates support of
the procedures for P2MP LSP setup detailed in this document. If the the procedures for P2MP LSP setup detailed in this document. If the
peer has not advertised the corresponding capability, then no label peer has not advertised the corresponding capability, then label
messages using the P2MP FEC Element should be sent to the peer. messages using the P2MP FEC Element SHOULD NOT be sent to the peer.
2.2. The P2MP FEC Element 2.2. The P2MP FEC Element
For the setup of a P2MP LSP with LDP, we define one new protocol For the setup of a P2MP LSP with LDP, we define one new protocol
entity, the P2MP FEC Element to be used as a FEC Element in the FEC entity, the P2MP FEC Element to be used as a FEC Element in the FEC
TLV. Note that the P2MP FEC Element does not necessarily identify TLV. Note that the P2MP FEC Element does not necessarily identify
the traffic that must be mapped to the LSP, so from that point of the traffic that must be mapped to the LSP, so from that point of
view, the use of the term FEC is a misnomer. The description of the view, the use of the term FEC is a misnomer. The description of the
P2MP FEC Element follows. P2MP FEC Element follows.
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| Opaque Length | Opaque Value ... | | Opaque Length | Opaque Value ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
~ ~ ~ ~
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: The type of the P2MP FEC Element is to be assigned by IANA. Type: The type of the P2MP FEC Element is to be assigned by IANA.
Address Family: Two octet quantity containing a value from ADDRESS Address Family: Two octet quantity containing a value from IANA's
FAMILY NUMBERS in [RFC3232] that encodes the address family for "Address Family Numbers" registry that encodes the address family
the Root LSR Address. for the Root LSR Address.
Address Length: Length of the Root LSR Address in octets. Address Length: Length of the Root LSR Address in octets.
Root Node Address: A host address encoded according to the Address Root Node Address: A host address encoded according to the Address
Family field. Family field.
Opaque Length: The length of the Opaque Value, in octets. Opaque Length: The length of the Opaque Value, in octets.
Opaque Value: One or more MP Opaque Value elements, uniquely Opaque Value: One or more MP Opaque Value elements, uniquely
identifying the P2MP LSP in the context of the Root Node. This is identifying the P2MP LSP in the context of the Root Node. This is
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If a FEC TLV contains a P2MP FEC Element, the P2MP FEC Element MUST If a FEC TLV contains a P2MP FEC Element, the P2MP FEC Element MUST
be the only FEC Element in the FEC TLV. be the only FEC Element in the FEC TLV.
2.3. The LDP MP Opaque Value Element 2.3. The LDP MP Opaque Value Element
The LDP MP Opaque Value Element is used in the P2MP and MP2MP FEC The LDP MP Opaque Value Element is used in the P2MP and MP2MP FEC
Elements defined in subsequent sections. It carries information that Elements defined in subsequent sections. It carries information that
is meaningful to Ingress LSRs and Leaf LSRs, but need not be is meaningful to Ingress LSRs and Leaf LSRs, but need not be
interpreted by Transit LSRs. interpreted by Transit LSRs.
The LDP MP Opaque Value Element is encoded as follows: The LDP MP Opaque Value Element basic type is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type(TBD) | Length | Value ... | | Type < 255 | Length | Value ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ ~ ~ ~
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: The Type of the LDP MP Opaque Value Element basic type is to
be assigned by IANA.
Length: The length of the Value field, in octets.
Value: String of Length octets, to be interpreted as specified by
the Type field.
The LDP MP Opaque Value Element extended type is encoded as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 255 | Extended Type | Length (high) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Length (low) | Value |
+-+-+-+-+-+-+-+-+ |
~ ~
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: The type of the LDP MP Opaque Value Element is to be assigned Type: Type = 255.
by IANA.
Extended Type: The Extended Type of the LDP MP Opaque Value Element
extended type is to be assigned by IANA.
Length: The length of the Value field, in octets. Length: The length of the Value field, in octets.
Value: String of Length octets, to be interpreted as specified by Value: String of Length octets, to be interpreted as specified by
the Type field. the Type field.
2.3.1. The Generic LSP Identifier 2.3.1. The Generic LSP Identifier
The generic LSP identifier is a type of Opaque Value Element encoded The generic LSP identifier is a type of Opaque Value Element basic
as follows: type encoded as follows:
Type: 1 (to be assigned by IANA) Type: 1 (to be assigned by IANA)
Length: 4 Length: 4
Value: A 32bit integer, unique in the context of the root, as Value: A 32bit integer, unique in the context of the root, as
identified by the root's address. identified by the root's address.
This type of Opaque Value Element is recommended when mapping of This type of Opaque Value Element is recommended when mapping of
traffic to LSPs is non-algorithmic, and done by means outside LDP. traffic to LSPs is non-algorithmic, and done by means outside LDP.
2.4. Using the P2MP FEC Element 2.4. Using the P2MP FEC Element
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leaf node. leaf node.
2.4.1. Label Map 2.4.1. Label Map
The remainder of this section specifies the procedures for The remainder of this section specifies the procedures for
originating P2MP Label Map messages and for processing received P2MP originating P2MP Label Map messages and for processing received P2MP
label map messages for a particular LSP. The procedures for a label map messages for a particular LSP. The procedures for a
particular LSR depend upon the role that LSR plays in the LSP particular LSR depend upon the role that LSR plays in the LSP
(ingress, transit, or egress). (ingress, transit, or egress).
All labels discussed here are downstream-assigned All labels discussed here are downstream-assigned [RFC5332] except
[I-D.ietf-mpls-multicast-encaps] except those which are assigned those which are assigned using the procedures of Section 6.
using the procedures of Section 7.
2.4.1.1. Determining one's 'upstream LSR' 2.4.1.1. Determining one's 'upstream LSR'
Each node that is either an Leaf or Transit LSR of MP LSP needs to Each node that is either an Leaf or Transit LSR of MP LSP needs to
use the procedures below to select an upstream LSR. A node Z that use the procedures below to select an upstream LSR. A node Z that
wants to join a MP LSP <X, Y> determines the LDP peer U which is Z's wants to join a MP LSP <X, Y> determines the LDP peer U which is Z's
next-hop on the best path from Z to the root node X. If there is more next-hop on the best path from Z to the root node X. If there is more
than one such LDP peer, only one of them is picked. U is Z's than one such LDP peer, only one of them is picked. U is Z's
"Upstream LSR" for <X, Y>. "Upstream LSR" for <X, Y>.
When there are several candidate upstream LSRs, the LSR MAY select When there are several candidate upstream LSRs, the LSR MAY select
one upstream LSR. The algorithm used for the LSR selection is a one upstream LSR. The algorithm used for the LSR selection is a
local matter. If the LSR selection is done over a LAN interface and local matter. If the LSR selection is done over a LAN interface and
the Section 7 procedures are applied, the following procedure SHOULD the Section 6 procedures are applied, the following procedure SHOULD
be applied to ensure that the same upstream LSR is elected amoung a be applied to ensure that the same upstream LSR is elected among a
set of candidate receivers on that LAN. set of candidate receivers on that LAN.
1. The candidate upstream LSRs are numbered from lower to higher IP 1. The candidate upstream LSRs are numbered from lower to higher IP
address address
2. The following hash is performed: H = (CRC32(Opaque value)) modulo 2. The following hash is performed: H = (CRC32(Opaque value)) modulo
N, where N is the number of upstream LSRs. N, where N is the number of upstream LSRs.
3. The selected upstream LSR U is the LSR that has the number H. 3. The selected upstream LSR U is the LSR that has the number H.
skipping to change at page 12, line 34 skipping to change at page 13, line 25
<X, Y, L'> to LSR U. Interface I is determind via the procedures in <X, Y, L'> to LSR U. Interface I is determind via the procedures in
Section 2.4.1.2. Section 2.4.1.2.
If Z already has state for <X, Y>, then Z does not send a Label Map If Z already has state for <X, Y>, then Z does not send a Label Map
message for P2MP LSP <X, Y>. All that Z needs to do in this case is message for P2MP LSP <X, Y>. All that Z needs to do in this case is
check that LSR T is not equal to the upstream LSR of <X, Y> and check that LSR T is not equal to the upstream LSR of <X, Y> and
update its forwarding state. Assuming its old forwarding state was update its forwarding state. Assuming its old forwarding state was
L'-> {<I1, L1> <I2, L2> ..., <In, Ln>}, its new forwarding state L'-> {<I1, L1> <I2, L2> ..., <In, Ln>}, its new forwarding state
becomes L'-> {<I1, L1> <I2, L2> ..., <In, Ln>, <I, L>}. If the LSR T becomes L'-> {<I1, L1> <I2, L2> ..., <In, Ln>, <I, L>}. If the LSR T
is equal to the installed upstream LSR, the Label Map from LSR T MUST is equal to the installed upstream LSR, the Label Map from LSR T MUST
be retained and MUST not update the label forwarding table. be retained and MUST NOT update the label forwarding table.
2.4.1.5. Root Node Operation 2.4.1.5. Root Node Operation
Suppose the root node Z receives a P2MP Label Map <X, Y, L> from LSR Suppose the root node Z receives a P2MP Label Map <X, Y, L> from LSR
T. Z checks whether it already has forwarding state for <X, Y>. If T. Z checks whether it already has forwarding state for <X, Y>. If
not, Z creates forwarding state to push label L onto the traffic that not, Z creates forwarding state to push label L onto the traffic that
Z wants to forward over the P2MP LSP (how this traffic is determined Z wants to forward over the P2MP LSP (how this traffic is determined
is outside the scope of this document). is outside the scope of this document).
If Z already has forwarding state for <X, Y>, then Z adds "push label If Z already has forwarding state for <X, Y>, then Z adds "push label
L, send over interface I" to the nexthop, where I is the interface L, send over interface I" to the nexthop, where I is the interface
associated with LSR T and determined via the procedures in associated with LSR T and determined via the procedures in
Section 2.4.1.2. Section 2.4.1.2.
2.4.2. Label Withdraw 2.4.2. Label Withdraw
The following lists procedures for generating and processing P2MP The following section lists procedures for generating and processing
Label Withdraw messages for nodes that participate in a P2MP LSP. An P2MP Label Withdraw messages for nodes that participate in a P2MP
LSR should apply those procedures that apply to it, based on its role LSP. An LSR should apply those procedures that apply to it, based on
in the P2MP LSP. its role in the P2MP LSP.
2.4.2.1. Leaf Operation 2.4.2.1. Leaf Operation
If a leaf node Z discovers (by means outside the scope of this If a leaf node Z discovers (by means outside the scope of this
document) that it has no downstream neighbors in that LSP, and that document) that it has no downstream neighbors in that LSP, and that
it has no need to be an egress LSR for that LSP, then it SHOULD send it has no need to be an egress LSR for that LSP, then it SHOULD send
a Label Withdraw <X, Y, L> to its upstream LSR U for <X, Y>, where L a Label Withdraw <X, Y, L> to its upstream LSR U for <X, Y>, where L
is the label it had previously advertised to U for <X, Y>. is the label it had previously advertised to U for <X, Y>.
2.4.2.2. Transit Node Operation 2.4.2.2. Transit Node Operation
skipping to change at page 13, line 42 skipping to change at page 14, line 29
2.4.2.3. Root Node Operation 2.4.2.3. Root Node Operation
The procedure when the root node of a P2MP LSP receives a Label The procedure when the root node of a P2MP LSP receives a Label
Withdraw message are the same as for transit nodes, except that it Withdraw message are the same as for transit nodes, except that it
would not propagate the Label Withdraw upstream (as it has no would not propagate the Label Withdraw upstream (as it has no
upstream). upstream).
2.4.3. Upstream LSR change 2.4.3. Upstream LSR change
Suppose that for a given node Z participating in a P2MP LSP <X, Y>, Suppose that for a given node Z participating in a P2MP LSP <X, Y>,
the upstream LSR changes from U to U' as per Section 2.4.1.1. If U' the upstream LSR changes from U to U' as per Section 2.4.1.1. Z MUST
is present in the forwarding table of <X, Y> then it MUST be removed. update its forwarding state as follows. It allocates a new label,
Z MUST also update its forwarding state by deleting the state for L', for <X, Y>. The forwarding state for L' is copied from the
label L, allocating a new label, L', for <X, Y>, and installing the forwarding state for L, with one exception: if U' was present in the
forwarding state for L'. In addition Z MUST send a Label Map <X, Y, forwarding state of L, it MUST NOT be installed in the forwarding
L'> to U' and send a Label Withdraw <X, Y, L> to U. Note, if there state of L'. Then the forwarding state for L is deleted and the
was a downstream mapping from U that was not installed in the forwarding state for L' is installed. In addition Z MUST send a
forwarding due to Section 2.4.1.4 it can now be installed. Label Map <X, Y, L'> to U' and send a Label Withdraw <X, Y, L> to U.
Note, if there was a downstream mapping from U that was not installed
3. Shared Trees in the forwarding due to Section 2.4.1.4 it can now be installed.
The mechanism described above shows how to build a tree with a single
root and multiple leaves, i.e., a P2MP LSP. One can use essentially
the same mechanism to build Shared Trees with LDP. A Shared Tree can
be used by a group of routers that want to multicast traffic among
themselves, i.e., each node is both a root node (when it sources
traffic) and a leaf node (when any other member of the group sources
traffic). A Shared Tree offers similar functionality to a MP2MP LSP,
but the underlying multicasting mechanism uses a P2MP LSP. One
example where a Shared Tree is useful is video-conferencing. Another
is Virtual Private LAN Service (VPLS) [RFC4664], where for some types
of traffic, each device participating in a VPLS must send packets to
every other device in that VPLS.
One way to build a Shared Tree is to build an LDP P2MP LSP rooted at
a common point, the Shared Root (SR), and whose leaves are all the
members of the group. Each member of the Shared Tree unicasts
traffic to the SR (using, for example, the MP2P LSP created by the
unicast LDP FEC advertised by the SR); the SR then splices this
traffic into the LDP P2MP LSP. The SR may be (but need not be) a
member of the multicast group.
A major advantage of this approach is that no further protocol
mechanisms beyond the one already described are needed to set up a
Shared Tree. Furthermore, a Shared Tree is very efficient in terms
of the multicast state in the network, and is reasonably efficient in
terms of the bandwidth required to send traffic.
A property of this approach is that a sender will receive its own While changing the upstream LSR the following must be taken into
packets as part of the multicast; thus a sender must be prepared to consideration. If L' is added before L is removed, there is a
recognize and discard packets that it itself has sent. For a number potential risk of packet duplication, and/or the creation of a
of applications (for example, VPLS), this requirement is easy to transient dataplane forwarding loop. If L is removed before L' is
meet. Another consideration is the various techniques that can be added, packet loss may result.
used to splice unicast LDP MP2P LSPs to the LDP P2MP LSP; these will
be described in a later revision.
4. Setting up MP2MP LSPs with LDP 3. Setting up MP2MP LSPs with LDP
An MP2MP LSP is much like a P2MP LSP in that it consists of a single An MP2MP LSP is much like a P2MP LSP in that it consists of a single
root node, zero or more transit nodes and one or more leaf LSRs root node, zero or more transit nodes and one or more leaf LSRs
acting equally as Ingress or Egress LSR. A leaf node participates in acting equally as Ingress or Egress LSR. A leaf node participates in
the setup of an MP2MP LSP by establishing both a downstream LSP, the setup of an MP2MP LSP by establishing both a downstream LSP,
which is much like a P2MP LSP from the root, and an upstream LSP which is much like a P2MP LSP from the root, and an upstream LSP
which is used to send traffic toward the root and other leaf nodes. which is used to send traffic toward the root and other leaf nodes.
Transit nodes support the setup by propagating the upstream and Transit nodes support the setup by propagating the upstream and
downstream LSP setup toward the root and installing the necessary downstream LSP setup toward the root and installing the necessary
MPLS forwarding state. The transmission of packets from the root MPLS forwarding state. The transmission of packets from the root
skipping to change at page 15, line 18 skipping to change at page 15, line 23
required to reach other leaf nodes. A packet that is received from a required to reach other leaf nodes. A packet that is received from a
downstream node MUST never be forwarded back out to that same node. downstream node MUST never be forwarded back out to that same node.
Mapping traffic to the MP2MP LSP may happen at any leaf node. How Mapping traffic to the MP2MP LSP may happen at any leaf node. How
that mapping is established is outside the scope of this document. that mapping is established is outside the scope of this document.
Due to how a MP2MP LSP is built a leaf LSR that is sending packets on Due to how a MP2MP LSP is built a leaf LSR that is sending packets on
the MP2MP LSP does not receive its own packets. There is also no the MP2MP LSP does not receive its own packets. There is also no
additional mechanism needed on the root or transit LSR to match additional mechanism needed on the root or transit LSR to match
upstream traffic to the downstream forwarding state. Packets that upstream traffic to the downstream forwarding state. Packets that
are forwarded over a MP2MP LSP will not traverse a link more than are forwarded over a MP2MP LSP will not traverse a link more than
once, with the possible exception of LAN links (see Section 4.3.1), once, with the possible exception of LAN links (see Section 3.3.1),
if the procedures of [I-D.ietf-mpls-upstream-label] are not provided. if the procedures of [RFC5331] are not provided.
4.1. Support for MP2MP LSP setup with LDP 3.1. Support for MP2MP LSP setup with LDP
Support for the setup of MP2MP LSPs is advertised using LDP Support for the setup of MP2MP LSPs is advertised using LDP
capabilities as defined in [I-D.ietf-mpls-ldp-capabilities]. An capabilities as defined in [RFC5561]. An implementation supporting
implementation supporting the MP2MP procedures specified in this the MP2MP procedures specified in this document MUST implement the
document MUST implement the procedures for Capability Parameters in procedures for Capability Parameters in Initialization Messages.
Initialization Messages.
A new Capability Parameter TLV is defined, the MP2MP Capability. A new Capability Parameter TLV is defined, the MP2MP Capability.
Following is the format of the MP2MP Capability Parameter. Following is the format of the MP2MP Capability Parameter.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0| MP2MP Capability (TBD IANA) | Length (= 1) | |1|0| MP2MP Capability TBD IANA | Length (= 1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Reserved | |1| Reserved |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
The MP2MP Capability TLV MUST be supported in the LDP Initialization The MP2MP Capability TLV MUST be supported in the LDP Initialization
Message. Advertisement of the MP2MP Capability indicates support of Message. Advertisement of the MP2MP Capability indicates support of
the procedures for MP2MP LSP setup detailed in this document. If the the procedures for MP2MP LSP setup detailed in this document. If the
peer has not advertised the corresponding capability, then no label peer has not advertised the corresponding capability, then label
messages using the MP2MP upstream and downstream FEC Elements should messages using the MP2MP upstream and downstream FEC Elements SHOULD
be sent to the peer. NOT be sent to the peer.
4.2. The MP2MP downstream and upstream FEC Elements. 3.2. The MP2MP downstream and upstream FEC Elements.
For the setup of a MP2MP LSP with LDP we define 2 new protocol For the setup of a MP2MP LSP with LDP we define 2 new protocol
entities, the MP2MP downstream FEC and upstream FEC Element. Both entities, the MP2MP downstream FEC and upstream FEC Element. Both
elements will be used as FEC Elements in the FEC TLV. Note that the elements will be used as FEC Elements in the FEC TLV. Note that the
MP2MP FEC Elements do not necessarily identify the traffic that must MP2MP FEC Elements do not necessarily identify the traffic that must
be mapped to the LSP, so from that point of view, the use of the term be mapped to the LSP, so from that point of view, the use of the term
FEC is a misnomer. The description of the MP2MP FEC Elements follow. FEC is a misnomer. The description of the MP2MP FEC Elements follow.
The structure, encoding and error handling for the MP2MP downstream The structure, encoding and error handling for the MP2MP downstream
and upstream FEC Elements are the same as for the P2MP FEC Element and upstream FEC Elements are the same as for the P2MP FEC Element
described in Section 2.2. The difference is that two new FEC types described in Section 2.2. The difference is that two new FEC types
are used: MP2MP downstream type (TBD) and MP2MP upstream type (TBD). are used: MP2MP downstream type (TBD) and MP2MP upstream type (TBD).
If a FEC TLV contains an MP2MP FEC Element, the MP2MP FEC Element If a FEC TLV contains an MP2MP FEC Element, the MP2MP FEC Element
MUST be the only FEC Element in the FEC TLV. MUST be the only FEC Element in the FEC TLV.
Note, except when using the procedures of Note, except when using the procedures of [RFC5331], the MPLS labels
[I-D.ietf-mpls-upstream-label], the MPLS labels used are "downstream- used are "downstream-assigned" [RFC5332], even if they are bound to
assigned" [I-D.ietf-mpls-multicast-encaps], even if they are bound to
the "upstream FEC element". the "upstream FEC element".
4.3. Using the MP2MP FEC Elements 3.3. Using the MP2MP FEC Elements
This section defines the rules for the processing and propagation of This section defines the rules for the processing and propagation of
the MP2MP FEC Elements. The following notation is used in the the MP2MP FEC Elements. The following notation is used in the
processing rules: processing rules:
1. MP2MP downstream LSP <X, Y> (or simply downstream <X, Y>): an 1. MP2MP downstream LSP <X, Y> (or simply downstream <X, Y>): an
MP2MP LSP downstream path with root node address X and opaque MP2MP LSP downstream path with root node address X and opaque
value Y. value Y.
2. MP2MP upstream LSP <X, Y, D> (or simply upstream <X, Y, D>): a 2. MP2MP upstream LSP <X, Y, D> (or simply upstream <X, Y, D>): a
skipping to change at page 17, line 7 skipping to change at page 17, line 10
address X and opaque value Y used for an upstream MP2MP LSP. address X and opaque value Y used for an upstream MP2MP LSP.
5. MP2MP-D Label Map <X, Y, L>: A Label Map message with a FEC TLV 5. MP2MP-D Label Map <X, Y, L>: A Label Map message with a FEC TLV
with a single MP2MP downstream FEC Element <X, Y> and label TLV with a single MP2MP downstream FEC Element <X, Y> and label TLV
with label L. Label L MUST be allocated from the per-platform with label L. Label L MUST be allocated from the per-platform
label space (see [RFC3031] section 3.14) of the LSR sending the label space (see [RFC3031] section 3.14) of the LSR sending the
Label Map Message. Label Map Message.
6. MP2MP-U Label Map <X, Y, Lu>: A Label Map message with a FEC TLV 6. MP2MP-U Label Map <X, Y, Lu>: A Label Map message with a FEC TLV
with a single MP2MP upstream FEC Element <X, Y> and label TLV with a single MP2MP upstream FEC Element <X, Y> and label TLV
with label Lu. Label L MUST be allocated from the per-platform with label Lu. Label Lu MUST be allocated from the per-platform
label space (see [RFC3031] section 3.14) of the LSR sending the label space (see [RFC3031] section 3.14) of the LSR sending the
Label Map Message. Label Map Message.
7. MP2MP-D Label Withdraw <X, Y, L>: a Label Withdraw message with 7. MP2MP-D Label Withdraw <X, Y, L>: a Label Withdraw message with
a FEC TLV with a single MP2MP downstream FEC Element <X, Y> and a FEC TLV with a single MP2MP downstream FEC Element <X, Y> and
label TLV with label L. label TLV with label L.
8. MP2MP-U Label Withdraw <X, Y, Lu>: a Label Withdraw message with 8. MP2MP-U Label Withdraw <X, Y, Lu>: a Label Withdraw message with
a FEC TLV with a single MP2MP upstream FEC Element <X, Y> and a FEC TLV with a single MP2MP upstream FEC Element <X, Y> and
label TLV with label Lu. label TLV with label Lu.
skipping to change at page 17, line 39 skipping to change at page 17, line 42
process which is outside the scope of this document. During the process which is outside the scope of this document. During the
course of the protocol operation, the root node recognizes its role course of the protocol operation, the root node recognizes its role
because it owns the root node address. A transit node is any node because it owns the root node address. A transit node is any node
(other then the root node) that receives a MP2MP Label Map message (other then the root node) that receives a MP2MP Label Map message
(i.e., one that has leaf nodes downstream of it). (i.e., one that has leaf nodes downstream of it).
Note that a transit node (and indeed the root node) may also be a Note that a transit node (and indeed the root node) may also be a
leaf node and the root node does not have to be an ingress LSR or leaf node and the root node does not have to be an ingress LSR or
leaf of the MP2MP LSP. leaf of the MP2MP LSP.
4.3.1. MP2MP Label Map 3.3.1. MP2MP Label Map
The remainder of this section specifies the procedures for The remainder of this section specifies the procedures for
originating MP2MP Label Map messages and for processing received originating MP2MP Label Map messages and for processing received
MP2MP label map messages for a particular LSP. The procedures for a MP2MP label map messages for a particular LSP. The procedures for a
particular LSR depend upon the role that LSR plays in the LSP particular LSR depend upon the role that LSR plays in the LSP
(ingress, transit, or egress). (ingress, transit, or egress).
All labels discussed here are downstream-assigned All labels discussed here are downstream-assigned [RFC5332] except
[I-D.ietf-mpls-multicast-encaps] except those which are assigned those which are assigned using the procedures of Section 6.
using the procedures of Section 7.
4.3.1.1. Determining one's upstream MP2MP LSR 3.3.1.1. Determining one's upstream MP2MP LSR
Determining the upstream LDP peer U for a MP2MP LSP <X, Y> follows Determining the upstream LDP peer U for a MP2MP LSP <X, Y> follows
the procedure for a P2MP LSP described in Section 2.4.1.1. the procedure for a P2MP LSP described in Section 2.4.1.1.
4.3.1.2. Determining one's downstream MP2MP LSR 3.3.1.2. Determining one's downstream MP2MP LSR
A LDP peer U which receives a MP2MP-D Label Map from a LDP peer D A LDP peer U which receives a MP2MP-D Label Map from a LDP peer D
will treat D as downstream MP2MP LSR. will treat D as downstream MP2MP LSR.
4.3.1.3. Installing the upstream path of a MP2MP LSP 3.3.1.3. Installing the upstream path of a MP2MP LSP
There are two methods for installing the upstream path of a MP2MP LSP There are two methods for installing the upstream path of a MP2MP LSP
to a downstream neighbor. to a downstream neighbor.
1. We can install the upstream MP2MP path (to a downstream neighbor) 1. We can install the upstream MP2MP path (to a downstream neighbor)
based on receiving a MP2MP-D Label Map from the downstream based on receiving a MP2MP-D Label Map from the downstream
neighbor. This will install the upstream path on a per hop by neighbor. This will install the upstream path on a per hop by
hop bases. hop basis.
2. We install the upstream MP2MP path (to a downstream neighbor) 2. We install the upstream MP2MP path (to a downstream neighbor)
based on receiving a MP2MP-U Label Map from the upstream based on receiving a MP2MP-U Label Map from the upstream
neighbor. An LSR does not need to wait for the MP2MP-U Label Map neighbor. An LSR does not need to wait for the MP2MP-U Label Map
if it is the root of the MP2MP LSP or already has received an if it is the root of the MP2MP LSP or already has received an
MP2MP-U Label Map from the upstream neighbor. We call this MP2MP-U Label Map from the upstream neighbor. We call this
method ordered mode. The typical result of this mode is that the method ordered mode. The typical result of this mode is that the
downstream path of the MP2MP is build hop by hop towards the downstream path of the MP2MP is built hop by hop towards the
root. Once the root is reached, the root node will trigger a root. Once the root is reached, the root node will trigger a
MP2MP-U Label Map to the downstream neighbor(s). MP2MP-U Label Map to the downstream neighbor(s).
For setting up the upstream path of a MP2MP LSP ordered mode MUST be For setting up the upstream path of a MP2MP LSP ordered mode MUST be
used. Due to ordered mode the upstream path of the MP2MP LSP is used. Due to ordered mode the upstream path of the MP2MP LSP is
installed at the leaf node once the path to the root is completed. installed at the leaf node once the path to the root is completed.
The advantage is that when a leaf starts sending immediately after The advantage is that when a leaf starts sending immediately after
the upstream path is installed, packets are able to reach the root the upstream path is installed, packets are able to reach the root
node without being dropped due to an incomplete LSP. Method 1 is not node without being dropped due to an incomplete LSP. Method 1 is not
able to guarantee that the upstream path is completed before the leaf able to guarantee that the upstream path is completed before the leaf
starts sending. starts sending.
4.3.1.4. MP2MP leaf node operation 3.3.1.4. MP2MP leaf node operation
A leaf node Z of a MP2MP LSP <X, Y> determines its upstream LSR U for A leaf node Z of a MP2MP LSP <X, Y> determines its upstream LSR U for
<X, Y> as per Section 4.3.1.1, allocates a label L, and sends a <X, Y> as per Section 3.3.1.1, allocates a label L, and sends a
MP2MP-D Label Map <X, Y, L> to U. MP2MP-D Label Map <X, Y, L> to U.
Leaf node Z expects an MP2MP-U Label Map <X, Y, Lu> from node U in Leaf node Z expects an MP2MP-U Label Map <X, Y, Lu> from node U in
response to the MP2MP-D Label Map it sent to node U. Z checks whether response to the MP2MP-D Label Map it sent to node U. Z checks whether
it already has forwarding state for upstream <X, Y>. If not, Z it already has forwarding state for upstream <X, Y>. If not, Z
creates forwarding state to push label Lu onto the traffic that Z creates forwarding state to push label Lu onto the traffic that Z
wants to forward over the MP2MP LSP. How it determines what traffic wants to forward over the MP2MP LSP. How it determines what traffic
to forward on this MP2MP LSP is outside the scope of this document. to forward on this MP2MP LSP is outside the scope of this document.
4.3.1.5. MP2MP transit node operation 3.3.1.5. MP2MP transit node operation
Suppose node Z receives a MP2MP-D Label Map <X, Y, L> from LSR D. Z Suppose node Z receives a MP2MP-D Label Map <X, Y, L> from LSR D. Z
checks whether it has forwarding state for downstream <X, Y>. If checks whether it has forwarding state for downstream <X, Y>. If
not, Z determines its upstream LSR U for <X, Y> as per not, Z determines its upstream LSR U for <X, Y> as per
Section 4.3.1.1. Using this Label Map to update the label forwarding Section 3.3.1.1. Using this Label Map to update the label forwarding
table MUST NOT be done as long as LSR D is equal to LSR U. If LSR U table MUST NOT be done as long as LSR D is equal to LSR U. If LSR U
is different from LSR D, Z will allocate a label L' and install is different from LSR D, Z will allocate a label L' and install
downstream forwarding state to swap label L' with label L over downstream forwarding state to swap label L' with label L over
interface I associated with LSR D and send a MP2MP-D Label Map <X, Y, interface I associated with LSR D and send a MP2MP-D Label Map <X, Y,
L'> to U. Interface I is determined via the procedures in L'> to U. Interface I is determined via the procedures in
Section 2.4.1.2. Section 2.4.1.2.
If Z already has forwarding state for downstream <X, Y>, all that Z If Z already has forwarding state for downstream <X, Y>, all that Z
needs to do in this case is check that LSR D is not equal to the needs to do in this case is check that LSR D is not equal to the
upstream LSR of <X, Y> and update its forwarding state. Assuming its upstream LSR of <X, Y> and update its forwarding state. Assuming its
old forwarding state was L'-> {<I1, L1> <I2, L2> ..., <In, Ln>}, its old forwarding state was L'-> {<I1, L1> <I2, L2> ..., <In, Ln>}, its
new forwarding state becomes L'-> {<I1, L1> <I2, L2> ..., <In, Ln>, new forwarding state becomes L'-> {<I1, L1> <I2, L2> ..., <In, Ln>,
<I, L>}. If the LSR D is equal to the installed upstream LSR, the <I, L>}. If the LSR D is equal to the installed upstream LSR, the
Label Map from LSR D MUST be retained and MUST not update the label Label Map from LSR D MUST be retained and MUST NOT update the label
forwarding table. forwarding table.
Node Z checks if upstream LSR U already assigned a label Lu to <X, Node Z checks if upstream LSR U already assigned a label Lu to <X,
Y>. If not, transit node Z waits until it receives a MP2MP-U Label Y>. If not, transit node Z waits until it receives a MP2MP-U Label
Map <X, Y, Lu> from LSR U. See Section 4.3.1.3. Once the MP2MP-U Map <X, Y, Lu> from LSR U. See Section 3.3.1.3. Once the MP2MP-U
Label Map is received from LSR U, node Z checks whether it already Label Map is received from LSR U, node Z checks whether it already
has forwarding state upstream <X, Y, D>. If it does, then no further has forwarding state upstream <X, Y, D>. If it does, then no further
action needs to happen. If it does not, it allocates a label Lu' and action needs to happen. If it does not, it allocates a label Lu' and
creates a new label swap for Lu' with Label Lu over interface Iu. creates a new label swap for Lu' with Label Lu over interface Iu.
Interface Iu is determined via the procedures in Section 2.4.1.2. In Interface Iu is determined via the procedures in Section 2.4.1.2. In
addition, it also adds the label swap(s) from the forwarding state addition, it also adds the label swap(s) from the forwarding state
downstream <X, Y>, omitting the swap on interface I for node D. The downstream <X, Y>, omitting the swap on interface I for node D. The
swap on interface I for node D is omitted to prevent packet swap on interface I for node D is omitted to prevent packet
originated by D to be forwarded back to D. originated by D to be forwarded back to D.
Node Z determines the downstream MP2MP LSR as per Section 4.3.1.2, Node Z determines the downstream MP2MP LSR as per Section 3.3.1.2,
and sends a MP2MP-U Label Map <X, Y, Lu'> to node D. and sends a MP2MP-U Label Map <X, Y, Lu'> to node D.
4.3.1.6. MP2MP root node operation 3.3.1.6. MP2MP root node operation
4.3.1.6.1. Root node is also a leaf 3.3.1.6.1. Root node is also a leaf
Suppose root/leaf node Z receives a MP2MP-D Label Map <X, Y, L> from Suppose root/leaf node Z receives a MP2MP-D Label Map <X, Y, L> from
node D. Z checks whether it already has forwarding state downstream node D. Z checks whether it already has forwarding state downstream
<X, Y>. If not, Z creates forwarding state for downstream to push <X, Y>. If not, Z creates forwarding state for downstream to push
label L on traffic that Z wants to forward down the MP2MP LSP. How label L on traffic that Z wants to forward down the MP2MP LSP. How
it determines what traffic to forward on this MP2MP LSP is outside it determines what traffic to forward on this MP2MP LSP is outside
the scope of this document. If Z already has forwarding state for the scope of this document. If Z already has forwarding state for
downstream <X, Y>, then Z will add the label push for L over downstream <X, Y>, then Z will add the label push for L over
interface I to it. Interface I is determined via the procedures in interface I to it. Interface I is determined via the procedures in
Section 2.4.1.2. Section 2.4.1.2.
Node Z checks if it has forwarding state for upstream <X, Y, D> If Node Z checks if it has forwarding state for upstream <X, Y, D> If
not, Z allocates a label Lu' and creates upstream forwarding state to not, Z allocates a label Lu' and creates upstream forwarding state to
swap Lu' with the label swap(s) from the forwarding state downstream swap Lu' with the label swap(s) from the forwarding state downstream
<X, Y>, except the swap on interface I for node D. This allows <X, Y>, except the swap on interface I for node D. This allows
upstream traffic to go down the MP2MP to other node(s), except the upstream traffic to go down the MP2MP to other node(s), except the
node from which the traffic was received. Node Z determines the node from which the traffic was received. Node Z determines the
downstream MP2MP LSR as per section Section 4.3.1.2, and sends a downstream MP2MP LSR as per section Section 3.3.1.2, and sends a
MP2MP-U Label Map <X, Y, Lu'> to node D. Since Z is the root of the MP2MP-U Label Map <X, Y, Lu'> to node D. Since Z is the root of the
tree Z will not send a MP2MP-D Label Map and will not receive a tree Z will not send a MP2MP-D Label Map and will not receive a
MP2MP-U Label Map. MP2MP-U Label Map.
4.3.1.6.2. Root node is not a leaf 3.3.1.6.2. Root node is not a leaf
Suppose the root node Z receives a MP2MP-D Label Map <X, Y, L> from Suppose the root node Z receives a MP2MP-D Label Map <X, Y, L> from
node D. Z checks whether it already has forwarding state for node D. Z checks whether it already has forwarding state for
downstream <X, Y>. If not, Z creates downstream forwarding state and downstream <X, Y>. If not, Z creates downstream forwarding state and
installs a outgoing label L over interface I. Interface I is installs a outgoing label L over interface I. Interface I is
determined via the procedures in Section 2.4.1.2. If Z already has determined via the procedures in Section 2.4.1.2. If Z already has
forwarding state for downstream <X, Y>, then Z will add label L over forwarding state for downstream <X, Y>, then Z will add label L over
interface I to the existing state. interface I to the existing state.
Node Z checks if it has forwarding state for upstream <X, Y, D>. If Node Z checks if it has forwarding state for upstream <X, Y, D>. If
not, Z allocates a label Lu' and creates forwarding state to swap Lu' not, Z allocates a label Lu' and creates forwarding state to swap Lu'
with the label swap(s) from the forwarding state downstream <X, Y>, with the label swap(s) from the forwarding state downstream <X, Y>,
except the swap for node D. This allows upstream traffic to go down except the swap for node D. This allows upstream traffic to go down
the MP2MP to other node(s), except the node is was received from. the MP2MP to other node(s), except the node is was received from.
Root node Z determines the downstream MP2MP LSR D as per Root node Z determines the downstream MP2MP LSR D as per
Section 4.3.1.2, and sends a MP2MP-U Label Map <X, Y, Lu'> to it. Section 3.3.1.2, and sends a MP2MP-U Label Map <X, Y, Lu'> to it.
Since Z is the root of the tree Z will not send a MP2MP-D Label Map Since Z is the root of the tree Z will not send a MP2MP-D Label Map
and will not receive a MP2MP-U Label Map. and will not receive a MP2MP-U Label Map.
4.3.2. MP2MP Label Withdraw 3.3.2. MP2MP Label Withdraw
The following lists procedures for generating and processing MP2MP The following section lists procedures for generating and processing
Label Withdraw messages for nodes that participate in a MP2MP LSP. MP2MP Label Withdraw messages for nodes that participate in a MP2MP
An LSR should apply those procedures that apply to it, based on its LSP. An LSR should apply those procedures that apply to it, based on
role in the MP2MP LSP. its role in the MP2MP LSP.
4.3.2.1. MP2MP leaf operation 3.3.2.1. MP2MP leaf operation
If a leaf node Z discovers (by means outside the scope of this If a leaf node Z discovers (by means outside the scope of this
document) that it has no downstream neighbors in that LSP, and that document) that it has no downstream neighbors in that LSP, and that
it has no need to be an egress LSR for that LSP, then it SHOULD send it has no need to be an egress LSR for that LSP, then it SHOULD send
a MP2MP-D Label Withdraw <X, Y, L> to its upstream LSR U for <X, Y>, a MP2MP-D Label Withdraw <X, Y, L> to its upstream LSR U for <X, Y>,
where L is the label it had previously advertised to U for <X,Y>. where L is the label it had previously advertised to U for <X,Y>.
Leaf node Z will also send a unsolicited label release <X, Y, Lu> to Leaf node Z will also send a unsolicited label release <X, Y, Lu> to
U to indicate that the upstream path is no longer used and that Label U to indicate that the upstream path is no longer used and that Label
Lu can be removed. Lu can be removed.
Leaf node Z expects the upstream router U to respond by sending a Leaf node Z expects the upstream router U to respond by sending a
downstream label release for L. downstream label release for L.
4.3.2.2. MP2MP transit node operation 3.3.2.2. MP2MP transit node operation
If a transit node Z receives a MP2MP-D Label Withdraw message <X, Y, If a transit node Z receives a MP2MP-D Label Withdraw message <X, Y,
L> from node D, it deletes label L from its forwarding state L> from node D, it deletes label L from its forwarding state
downstream <X, Y> and from all its upstream states for <X, Y>. Node downstream <X, Y> and from all its upstream states for <X, Y>. Node
Z sends a MP2MP-D Label Release message with label L to D. Since node Z sends a MP2MP-D Label Release message with label L to D. Since node
D is no longer part of the downstream forwarding state, Z cleans up D is no longer part of the downstream forwarding state, Z cleans up
the forwarding state upstream <X, Y, D>. There is no need to send an the forwarding state upstream <X, Y, D>. There is no need to send an
MP2MP-U Label Withdraw <X, Y, Lu> to D because node D already removed MP2MP-U Label Withdraw <X, Y, Lu> to D because node D already removed
Lu and send a label release for Lu to Z. Lu and send a label release for Lu to Z.
If deleting L from Z's forwarding state for downstream <X, Y> results If deleting L from Z's forwarding state for downstream <X, Y> results
in no state remaining for <X, Y>, then Z propagates the MP2MP-D Label in no state remaining for <X, Y>, then Z propagates the MP2MP-D Label
Withdraw <X, Y, L> to its upstream node U for <X,Y> and will also Withdraw <X, Y, L> to its upstream node U for <X,Y> and will also
send a unsolicited MP2MP-U Label Release <X, Y, Lu> to U to indicate send a unsolicited MP2MP-U Label Release <X, Y, Lu> to U to indicate
that the upstream path is no longer used and that Label Lu can be that the upstream path is no longer used and that Label Lu can be
removed. removed.
4.3.2.3. MP2MP root node operation 3.3.2.3. MP2MP root node operation
The procedure when the root node of a MP2MP LSP receives a MP2MP-D The procedure when the root node of a MP2MP LSP receives a MP2MP-D
Label Withdraw message is the same as for transit nodes, except that Label Withdraw message is the same as for transit nodes, except that
the root node would not propagate the Label Withdraw upstream (as it the root node would not propagate the Label Withdraw upstream (as it
has no upstream). has no upstream).
4.3.3. MP2MP Upstream LSR change 3.3.3. MP2MP Upstream LSR change
The procedure for changing the upstream LSR is the same as documented The procedure for changing the upstream LSR is the same as documented
in Section 2.4.3, except it is applied to MP2MP FECs, using the in Section 2.4.3, except it is applied to MP2MP FECs, using the
procedures described in Section 4.3.1 through Section 4.3.2.3. procedures described in Section 3.3.1 through Section 3.3.2.3.
5. Micro-loops in MP LSPs 4. Micro-loops in MP LSPs
Micro-loops created by the unicast routing protocol during Micro-loops created by the unicast routing protocol during
convergence may also effect mLDP MP LSPs. Since the tree building convergence may also effect mLDP MP LSPs. Since the tree building
logic in mLDP is based on unicast routing, a unicast routing loop may logic in mLDP is based on unicast routing, a unicast routing loop may
also result in a micro-loop in the MP LSPs. Micro-loops that involve also result in a micro-loop in the MP LSPs. Micro-loops that involve
2 directly connected routers don't create a loop in mLDP. mLDP is 2 directly connected routers don't create a loop in mLDP. mLDP is
able to prevent this inconsistency by never allowing an upstream LDP able to prevent this inconsistency by never allowing an upstream LDP
neighbor to be added as a downstream LDP neighbor into the LFT for neighbor to be added as a downstream LDP neighbor into the Label
the same FEC. Micro-loops that involve more than 2 LSRs are not Forwarding Table (LFT) for the same FEC. Micro-loops that involve
prevented. more than 2 LSRs are not prevented.
Micro-loops that involve more than 2 LSRs may create a micro-loop in Micro-loops that involve more than 2 LSRs may create a micro-loop in
the downstream path of either a MP2MP LSP or P2MP LSP and the the downstream path of either a MP2MP LSP or P2MP LSP and the
upstream path of the MP2MP LSP. The loops are transient and will upstream path of the MP2MP LSP. The loops are transient and will
disappear as soon as the unicast routing protocol converges. Micro- disappear as soon as the unicast routing protocol converges. Micro-
loops that occur in the upstream path of a MP2MP LSP may be detected loops that occur in the upstream path of a MP2MP LSP may be detected
by including LDP path vector in the MP2MP-U Label Map messages. by including LDP path vector in the MP2MP-U Label Map messages.
These procedures are currently under investigation and are subjected These procedures are currently under investigation and are subjected
to further study. to further study.
6. The LDP MP Status TLV 5. The LDP MP Status TLV
An LDP MP capable router MAY use an LDP MP Status TLV to indicate An LDP MP capable router MAY use an LDP MP Status TLV to indicate
additional status for a MP LSP to its remote peers. This includes additional status for a MP LSP to its remote peers. This includes
signaling to peers that are either upstream or downstream of the LDP signaling to peers that are either upstream or downstream of the LDP
MP capable router. The value of the LDP MP status TLV will remain MP capable router. The value of the LDP MP status TLV will remain
opaque to LDP and MAY encode one or more status elements. opaque to LDP and MAY encode one or more status elements.
The LDP MP Status TLV is encoded as follows: The LDP MP Status TLV is encoded as follows:
0 1 2 3 0 1 2 3
skipping to change at page 23, line 24 skipping to change at page 23, line 24
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
LDP MP Status Type: The LDP MP Status Type to be assigned by IANA. LDP MP Status Type: The LDP MP Status Type to be assigned by IANA.
Length: Length of the LDP MP Status Value in octets. Length: Length of the LDP MP Status Value in octets.
Value: One or more LDP MP Status Value elements. Value: One or more LDP MP Status Value elements.
6.1. The LDP MP Status Value Element 5.1. The LDP MP Status Value Element
The LDP MP Status Value Element that is included in the LDP MP Status The LDP MP Status Value Element that is included in the LDP MP Status
TLV Value has the following encoding. TLV Value has the following encoding.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type(TBD) | Length | Value ... | | Type(TBD) | Length | Value ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ ~ ~ ~
skipping to change at page 24, line 8 skipping to change at page 24, line 8
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: The type of the LDP MP Status Value Element is to be assigned Type: The type of the LDP MP Status Value Element is to be assigned
by IANA. by IANA.
Length: The length of the Value field, in octets. Length: The length of the Value field, in octets.
Value: String of Length octets, to be interpreted as specified by Value: String of Length octets, to be interpreted as specified by
the Type field. the Type field.
6.2. LDP Messages containing LDP MP Status messages 5.2. LDP Messages containing LDP MP Status messages
The LDP MP status message may appear either in a label mapping The LDP MP status message may appear either in a label mapping
message or a LDP notification message. message or a LDP notification message.
6.2.1. LDP MP Status sent in LDP notification messages 5.2.1. LDP MP Status sent in LDP notification messages
An LDP MP status TLV sent in a notification message must be An LDP MP status TLV sent in a notification message must be
accompanied with a Status TLV. The general format of the accompanied with a Status TLV. The general format of the
Notification Message with an LDP MP status TLV is: Notification Message with an LDP MP status TLV is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Notification (0x0001) | Message Length | |0| Notification (0x0001) | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 24, line 36 skipping to change at page 24, line 36
| Status TLV | | Status TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LDP MP Status TLV | | LDP MP Status TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Optional LDP MP FEC TLV | | Optional LDP MP FEC TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Optional Label TLV | | Optional Label TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Status TLV status code is used to indicate that LDP MP status TLV The Status TLV status code is used to indicate that LDP MP status TLV
and an additional information follows in the Notification message's and any additional information follows in the Notification message's
"optional parameter" section. Depending on the actual contents of "optional parameter" section. Depending on the actual contents of
the LDP MP status TLV, an LDP P2MP or MP2MP FEC TLV and Label TLV may the LDP MP status TLV, an LDP P2MP or MP2MP FEC TLV and Label TLV may
also be present to provide context to the LDP MP Status TLV. (NOTE: also be present to provide context to the LDP MP Status TLV. (NOTE:
Status Code is pending IANA assignment). Status Code is pending IANA assignment).
Since the notification does not refer to any particular message, the Since the notification does not refer to any particular message, the
Message Id and Message Type fields are set to 0. Message Id and Message Type fields are set to 0.
6.2.2. LDP MP Status TLV in Label Mapping Message 5.2.2. LDP MP Status TLV in Label Mapping Message
An example of the Label Mapping Message defined in RFC3036 is shown An example of the Label Mapping Message defined in RFC3036 is shown
below to illustrate the message with an Optional LDP MP Status TLV below to illustrate the message with an Optional LDP MP Status TLV
present. present.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Label Mapping (0x0400) | Message Length | |0| Label Mapping (0x0400) | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 25, line 21 skipping to change at page 25, line 21
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FEC TLV | | FEC TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label TLV | | Label TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Optional LDP MP Status TLV | | Optional LDP MP Status TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional Optional Parameters | | Additional Optional Parameters |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7. Upstream label allocation on a LAN 6. Upstream label allocation on a LAN
On a LAN, the procedures so far discussed would require the upstream On a LAN, the procedures so far discussed would require the upstream
LSR to send a copy of the packet to each receiver individually. If LSR to send a copy of the packet to each receiver individually. If
there is more than one receiver on the LAN we don't take full benefit there is more than one receiver on the LAN we don't take full benefit
of the multi-access capability of the network. We may optimize the of the multi-access capability of the network. We may optimize the
bandwidth consumption on the LAN and replication overhead on the bandwidth consumption on the LAN and replication overhead on the
upstream LSR by using upstream label allocation upstream LSR by using upstream label allocation [RFC5331].
[I-D.ietf-mpls-upstream-label]. Procedures on how to distribute Procedures on how to distribute upstream labels using LDP is
upstream labels using LDP is documented in documented in [I-D.ietf-mpls-ldp-upstream].
[I-D.ietf-mpls-ldp-upstream].
7.1. LDP Multipoint-to-Multipoint on a LAN 6.1. LDP Multipoint-to-Multipoint on a LAN
The procedure to allocate a context label on a LAN is defined in The procedure to allocate a context label on a LAN is defined in
[I-D.ietf-mpls-upstream-label]. That procedure results in each LSR [RFC5331]. That procedure results in each LSR on a given LAN having
on a given LAN having a context label which, on that LAN, can be used a context label which, on that LAN, can be used to identify itself
to identify itself uniquely. Each LSR advertises its context label uniquely. Each LSR advertises its context label as an upstream-
as an upstream-assigned label, following the procedures of assigned label, following the procedures of
[I-D.ietf-mpls-ldp-upstream]. Any LSR for which the LAN is a [I-D.ietf-mpls-ldp-upstream]. Any LSR for which the LAN is a
downstream link on some P2MP or MP2MP LSP will allocate an upstream- downstream link on some P2MP or MP2MP LSP will allocate an upstream-
assigned label identifying that LSP. When the LSR forwards a packet assigned label identifying that LSP. When the LSR forwards a packet
downstream on one of those LSPs, the packet's top label must be the downstream on one of those LSPs, the packet's top label must be the
LSR's context label, and the packet's second label is the label LSR's context label, and the packet's second label is the label
identifying the LSP. We will call the top label the "upstream LSR identifying the LSP. We will call the top label the "upstream LSR
label" and the second label the "LSP label". label" and the second label the "LSP label".
7.1.1. MP2MP downstream forwarding 6.1.1. MP2MP downstream forwarding
The downstream path of a MP2MP LSP is much like a normal P2MP LSP, so The downstream path of a MP2MP LSP is much like a normal P2MP LSP, so
we will use the same procedures as defined in we will use the same procedures as defined in
[I-D.ietf-mpls-ldp-upstream]. A label request for a LSP label is [I-D.ietf-mpls-ldp-upstream]. A label request for a LSP label is
send to the upstream LSR. The label mapping that is received from sent to the upstream LSR. The label mapping that is received from
the upstream LSR contains the LSP label for the MP2MP FEC and the the upstream LSR contains the LSP label for the MP2MP FEC and the
upstream LSR context label. The MP2MP downstream path (corresponding upstream LSR context label. The MP2MP downstream path (corresponding
to the LSP label) will be installed the context specific forwarding to the LSP label) will be installed in the context specific
table corresponding to the upstream LSR label. Packets sent by the forwarding table corresponding to the upstream LSR label. Packets
upstream router can be forwarded downstream using this forwarding sent by the upstream router can be forwarded downstream using this
state based on a two label lookup. forwarding state based on a two label lookup.
7.1.2. MP2MP upstream forwarding 6.1.2. MP2MP upstream forwarding
A MP2MP LSP also has an upstream forwarding path. Upstream packets A MP2MP LSP also has an upstream forwarding path. Upstream packets
need to be forwarded in the direction of the root and downstream on need to be forwarded in the direction of the root and downstream on
any node on the LAN that has a downstream interface for the LSP. For any node on the LAN that has a downstream interface for the LSP. For
a given MP2MP LSP on a given LAN, exactly one LSR is considered to be a given MP2MP LSP on a given LAN, exactly one LSR is considered to be
the upstream LSR. If an LSR on the LAN receives a packet from one of the upstream LSR. If an LSR on the LAN receives a packet from one of
its downstream interfaces for the LSP, and if it needs to forward the its downstream interfaces for the LSP, and if it needs to forward the
packet onto the LAN, it ensures that the packet's top label is the packet onto the LAN, it ensures that the packet's top label is the
context label of the upstream LSR, and that its second label is the context label of the upstream LSR, and that its second label is the
LSP label that was assigned by the upstream LSR. LSP label that was assigned by the upstream LSR.
Other LSRs receiving the packet will not be able to tell whether the Other LSRs receiving the packet will not be able to tell whether the
packet really came from the upstream router, but that makes no packet really came from the upstream router, but that makes no
difference in the processing of the packet. The upstream LSR will difference in the processing of the packet. The upstream LSR will
see its own upstream LSR in the label, and this will enable it to see its own upstream LSR in the label, and this will enable it to
determine that the packet is traveling upstream. determine that the packet is traveling upstream.
8. Root node redundancy 7. Root node redundancy
The root node is a single point of failure for an MP LSP, whether The root node is a single point of failure for an MP LSP, whether
this is P2MP or MP2MP. The problem is particularly severe for MP2MP this is P2MP or MP2MP. The problem is particularly severe for MP2MP
LSPs. In the case of MP2MP LSPs, all leaf nodes must use the same LSPs. In the case of MP2MP LSPs, all leaf nodes must use the same
root node to set up the MP2MP LSP, because otherwise the traffic root node to set up the MP2MP LSP, because otherwise the traffic
sourced by some leafs is not received by others. Because the root sourced by some leafs is not received by others. Because the root
node is the single point of failure for an MP LSP, we need a fast and node is the single point of failure for an MP LSP, we need a fast and
efficient mechanism to recover from a root node failure. efficient mechanism to recover from a root node failure.
An MP LSP is uniquely identified in the network by the opaque value An MP LSP is uniquely identified in the network by the opaque value
skipping to change at page 27, line 12 skipping to change at page 27, line 7
on each leaf statically or learned using a dynamic protocol. How on each leaf statically or learned using a dynamic protocol. How
leafs learn about the root node is out of the scope of this document. leafs learn about the root node is out of the scope of this document.
Suppose that for the same opaque value we define two (or more) root Suppose that for the same opaque value we define two (or more) root
node addresses and we build a tree to each root using the same opaque node addresses and we build a tree to each root using the same opaque
value. Effectively these will be treated as different MP LSPs in the value. Effectively these will be treated as different MP LSPs in the
network. Once the trees are built, the procedures differ for P2MP network. Once the trees are built, the procedures differ for P2MP
and MP2MP LSPs. The different procedures are explained in the and MP2MP LSPs. The different procedures are explained in the
sections below. sections below.
8.1. Root node redundancy - procedures for P2MP LSPs 7.1. Root node redundancy - procedures for P2MP LSPs
Since all leafs have set up P2MP LSPs to all the roots, they are Since all leafs have set up P2MP LSPs to all the roots, they are
prepared to receive packets on either one of these LSPs. However, prepared to receive packets on either one of these LSPs. However,
only one of the roots should be forwarding traffic at any given time, only one of the roots should be forwarding traffic at any given time,
for the following reasons: 1) to achieve bandwidth savings in the for the following reasons: 1) to achieve bandwidth savings in the
network and 2) to ensure that the receiving leafs don't receive network and 2) to ensure that the receiving leafs don't receive
duplicate packets (since one cannot assume that the receiving leafs duplicate packets (since one cannot assume that the receiving leafs
are able to discard duplicates). How the roots determine which one are able to discard duplicates). How the roots determine which one
is the active sender is outside the scope of this document. is the active sender is outside the scope of this document.
8.2. Root node redundancy - procedures for MP2MP LSPs 7.2. Root node redundancy - procedures for MP2MP LSPs
Since all leafs have set up an MP2MP LSP to each one of the root Since all leafs have set up an MP2MP LSP to each one of the root
nodes for this opaque value, a sending leaf may pick either of the nodes for this opaque value, a sending leaf may pick either of the
two (or more) MP2MP LSPs to forward a packet on. The leaf nodes two (or more) MP2MP LSPs to forward a packet on. The leaf nodes
receive the packet on one of the MP2MP LSPs. The client of the MP2MP receive the packet on one of the MP2MP LSPs. The client of the MP2MP
LSP does not care on which MP2MP LSP the packet is received, as long LSP does not care on which MP2MP LSP the packet is received, as long
as they are for the same opaque value. The sending leaf MUST only as they are for the same opaque value. The sending leaf MUST only
forward a packet on one MP2MP LSP at a given point in time. The forward a packet on one MP2MP LSP at a given point in time. The
receiving leafs are unable to discard duplicate packets because they receiving leafs are unable to discard duplicate packets because they
accept on all LSPs. Using all the available MP2MP LSPs we can accept on all LSPs. Using all the available MP2MP LSPs we can
skipping to change at page 28, line 11 skipping to change at page 28, line 7
The advantage of pre-building multiple MP2MP LSPs for a single opaque The advantage of pre-building multiple MP2MP LSPs for a single opaque
value is that convergence from a root node failure happens as fast as value is that convergence from a root node failure happens as fast as
the unicast routing protocol is able to notify. There is no need for the unicast routing protocol is able to notify. There is no need for
an additional protocol to advertise to the leaf nodes which root node an additional protocol to advertise to the leaf nodes which root node
is the active root. The root selection is a local leaf policy that is the active root. The root selection is a local leaf policy that
does not need to be coordinated with other leafs. The disadvantage does not need to be coordinated with other leafs. The disadvantage
of pre-building multiple MP2MP LSPs is that more label resources are of pre-building multiple MP2MP LSPs is that more label resources are
used, depending on how many root nodes are defined. used, depending on how many root nodes are defined.
9. Make Before Break (MBB) 8. Make Before Break (MBB)
An LSR selects as its upstream LSR for a MP LSP the LSR that is its An LSR selects as its upstream LSR for a MP LSP the LSR that is its
next hop to the root of the LSP. When the best path to reach the next hop to the root of the LSP. When the best path to reach the
root changes the LSR must choose a new upstream LSR. Sections root changes the LSR must choose a new upstream LSR. Sections
Section 2.4.3 and Section 4.3.3 describe these procedures. Section 2.4.3 and Section 3.3.3 describe these procedures.
When the best path to the root changes the LSP may be broken When the best path to the root changes the LSP may be broken
temporarily resulting in packet loss until the LSP "reconverges" to a temporarily resulting in packet loss until the LSP "reconverges" to a
new upstream LSR. The goal of MBB when this happens is to keep the new upstream LSR. The goal of MBB when this happens is to keep the
duration of packet loss as short as possible. In addition, there are duration of packet loss as short as possible. In addition, there are
scenarios where the best path from the LSR to the root changes but scenarios where the best path from the LSR to the root changes but
the LSP continues to forward packets to the prevous next hop to the the LSP continues to forward packets to the prevous next hop to the
root. That may occur when a link comes up or routing metrics change. root. That may occur when a link comes up or routing metrics change.
In such a case a new LSP should be established before the old LSP is In such a case a new LSP should be established before the old LSP is
removed to limit the duration of packet loss. The procedures removed to limit the duration of packet loss. The procedures
described below deal with both scenarios in a way that an LSR does described below deal with both scenarios in a way that an LSR does
not need to know which of the events described above caused its not need to know which of the events described above caused its
upstream router for an MBB LSP to change. upstream router for an MBB LSP to change.
The MBB procedures are an optional extension to the MP LSP building The MBB procedures are an optional extension to the MP LSP building
procedures described in this draft. The procedures in this section procedures described in this draft. The procedures in this section
offer a make-before-break behavior, except in cases where the new offer a make-before-break behavior, except in cases where the new
path is part of a transient routing loop involving more than 2 LSRs path is part of a transient routing loop involving more than 2 LSRs
(also see Section 5). (also see Section 4).
9.1. MBB overview 8.1. MBB overview
The MBB procedures use additional LDP signaling. The MBB procedures use additional LDP signaling.
Suppose some event causes a downstream LSR-D to select a new upstream Suppose some event causes a downstream LSR-D to select a new upstream
LSR-U for FEC-A. The new LSR-U may already be forwarding packets for LSR-U for FEC-A. The new LSR-U may already be forwarding packets for
FEC-A; that is, to downstream LSRs other than LSR-D. After LSR-U FEC-A; that is, to downstream LSRs other than LSR-D. After LSR-U
receives a label for FEC-A from LSR-D, it will notify LSR-D when it receives a label for FEC-A from LSR-D, it will notify LSR-D when it
knows that the LSP for FEC-A has been established from the root to knows that the LSP for FEC-A has been established from the root to
itself. When LSR-D receives this MBB notification it will change its itself. When LSR-D receives this MBB notification it will change its
next hop for the LSP root to LSR-U. next hop for the LSP root to LSR-U.
skipping to change at page 29, line 28 skipping to change at page 29, line 24
After LSR-U receives LSR-D's Label Mapping message for FEC-A LSR-U After LSR-U receives LSR-D's Label Mapping message for FEC-A LSR-U
MUST NOT reply with an MBB notification to LSR-D until its state for MUST NOT reply with an MBB notification to LSR-D until its state for
the LSP is state #3 above. If the state of the LSP at LSR-U is state the LSP is state #3 above. If the state of the LSP at LSR-U is state
#1 or #2, LSR-U should remember receipt of the Label Mapping message #1 or #2, LSR-U should remember receipt of the Label Mapping message
from LSR-D while waiting for an MBB notification from its upstream from LSR-D while waiting for an MBB notification from its upstream
LSR for the LSP. When LSR-U receives the MBB notification from LSR-U LSR for the LSP. When LSR-U receives the MBB notification from LSR-U
it transitions to LSP state #3 and sends an MBB notification to it transitions to LSP state #3 and sends an MBB notification to
LSR-D. LSR-D.
9.2. The MBB Status code 8.2. The MBB Status code
As noted in Section 9.1, the procedures to establish an MBB MP LSP As noted in Section 8.1, the procedures to establish an MBB MP LSP
are different from those to establish normal MP LSPs. are different from those to establish normal MP LSPs.
When a downstream LSR sends a Label Mapping message for MP LSP to its When a downstream LSR sends a Label Mapping message for MP LSP to its
upstream LSR it MAY include an LDP MP Status TLV that carries a MBB upstream LSR it MAY include an LDP MP Status TLV that carries a MBB
Status Code to indicate MBB procedures apply to the LSP. This new Status Code to indicate MBB procedures apply to the LSP. This new
MBB Status Code MAY also appear in an LDP Notification message used MBB Status Code MAY also appear in an LDP Notification message used
by an upstream LSR to signal LSP state #3 to the downstream LSR; that by an upstream LSR to signal LSP state #3 to the downstream LSR; that
is, that the upstream LSRs state for the LSP exists and that it has is, that the upstream LSRs state for the LSP exists and that it has
received notification from its upstream LSR that the LSP is in state received notification from its upstream LSR that the LSP is in state
#3. #3.
The MBB Status is a type of the LDP MP Status Value Element as The MBB Status is a type of the LDP MP Status Value Element as
described in Section 6.1. It is encoded as follows: described in Section 5.1. It is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBB Type = 1 | Length = 1 | Status code | | MBB Type = 1 | Length = 1 | Status code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MBB Type: Type 1 (to be assigned by IANA) MBB Type: Type 1 (to be assigned by IANA)
Length: 1 Length: 1
Status code: 1 = MBB request Status code: 1 = MBB request
2 = MBB ack 2 = MBB ack
9.3. The MBB capability 8.3. The MBB capability
An LSR MAY advertise that it is capable of handling MBB LSPs using An LSR MAY advertise that it is capable of handling MBB LSPs using
the capability advertisement as defined in the capability advertisement as defined in [RFC5561]. The LDP MP MBB
[I-D.ietf-mpls-ldp-capabilities]. The LDP MP MBB capability has the capability has the following format:
following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0| LDP MP MBB Capability | Length = 1 | |1|0| LDP MP MBB Capability | Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Reserved | |1| Reserved |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Note: LDP MP MBB Capability (Pending IANA assignment) Note: LDP MP MBB Capability (Pending IANA assignment)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0| LDP MP MBB Capability | Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Reserved |
+-+-+-+-+-+-+-+-+
If an LSR has not advertised that it is MBB capable, its LDP peers If an LSR has not advertised that it is MBB capable, its LDP peers
MUST NOT send it messages which include MBB parameters. If an LSR MUST NOT send it messages which include MBB parameters. If an LSR
receives a Label Mapping message with a MBB parameter from downstream receives a Label Mapping message with a MBB parameter from downstream
LSR-D and its upstream LSR-U has not advertised that it is MBB LSR-D and its upstream LSR-U has not advertised that it is MBB
capable, the LSR MUST send an MBB notification immediatly to LSR-U capable, the LSR MUST send an MBB notification immediatly to LSR-U
(see Section 9.4). If this happens an MBB MP LSP will not be (see Section 8.4). If this happens an MBB MP LSP will not be
established, but normal a MP LSP will be the result. established, but normal a MP LSP will be the result.
9.4. The MBB procedures 8.4. The MBB procedures
9.4.1. Terminology 8.4.1. Terminology
1. MBB LSP <X, Y>: A P2MP or MP2MP Make Before Break (MBB) LSP entry 1. MBB LSP <X, Y>: A P2MP or MP2MP Make Before Break (MBB) LSP entry
with Root Node Address X and Opaque Value Y. with Root Node Address X and Opaque Value Y.
2. A(N, L): An Accepting element that consists of an upstream 2. A(N, L): An Accepting element that consists of an upstream
Neighbor N and Local label L. This LSR assigned label L to Neighbor N and Local label L. This LSR assigned label L to
neighbor N for a specific MBB LSP. For an active element the neighbor N for a specific MBB LSP. For an active element the
corresponding Label is stored in the label forwarding database. corresponding Label is stored in the label forwarding database.
3. iA(N, L): An inactive Accepting element that consists of an 3. iA(N, L): An inactive Accepting element that consists of an
skipping to change at page 31, line 37 skipping to change at page 31, line 25
5. F'(N, L): A Forwarding state that has been marked for sending a 5. F'(N, L): A Forwarding state that has been marked for sending a
MBB Notification message to Neighbor N with Label L. MBB Notification message to Neighbor N with Label L.
6. MBB Notification <X, Y, L>: A LDP notification message with a MP 6. MBB Notification <X, Y, L>: A LDP notification message with a MP
LSP <X, Y>, Label L and MBB Status code 2. LSP <X, Y>, Label L and MBB Status code 2.
7. MBB Label Map <X, Y, L>: A P2MP Label Map or MP2MP Label Map 7. MBB Label Map <X, Y, L>: A P2MP Label Map or MP2MP Label Map
downstream with a FEC element <X, Y>, Label L and MBB Status code downstream with a FEC element <X, Y>, Label L and MBB Status code
1. 1.
9.4.2. Accepting elements 8.4.2. Accepting elements
An accepting element represents a specific label value L that has An accepting element represents a specific label value L that has
been advertised to a neighbor N for a MBB LSP <X, Y> and is a been advertised to a neighbor N for a MBB LSP <X, Y> and is a
candidate for accepting labels switched packets on. An LSR can have candidate for accepting labels switched packets on. An LSR can have
two accepting elements for a specific MBB LSP <X, Y> LSP, only one of two accepting elements for a specific MBB LSP <X, Y> LSP, only one of
them MUST be active. An active element is the element for which the them MUST be active. An active element is the element for which the
label value has been installed in the label forwarding database. An label value has been installed in the label forwarding database. An
inactive accepting element is created after a new upstream LSR is inactive accepting element is created after a new upstream LSR is
chosen and is pending to replace the active element in the label chosen and is pending to replace the active element in the label
forwarding database. Inactive elements only exist temporarily while forwarding database. Inactive elements only exist temporarily while
switching to a new upstream LSR. Once the switch has been completed switching to a new upstream LSR. Once the switch has been completed
only one active element remains. During network convergence it is only one active element remains. During network convergence it is
possible that an inactive accepting element is created while an other possible that an inactive accepting element is created while an other
inactive accepting element is pending. If that happens the older inactive accepting element is pending. If that happens the older
inactive accepting element MUST be replaced with an newer inactive inactive accepting element MUST be replaced with an newer inactive
element. If an accepting element is removed a Label Withdraw has to element. If an accepting element is removed a Label Withdraw has to
be send for label L to neighbor N for <X, Y>. be send for label L to neighbor N for <X, Y>.
9.4.3. Procedures for upstream LSR change 8.4.3. Procedures for upstream LSR change
Suppose a node Z has a MBB LSP <X, Y> with an active accepting Suppose a node Z has a MBB LSP <X, Y> with an active accepting
element A(N1, L1). Due to a routing change it detects a new best element A(N1, L1). Due to a routing change it detects a new best
path for root X and selects a new upstream LSR N2. Node Z allocates path for root X and selects a new upstream LSR N2. Node Z allocates
a new local label L2 and creates an inactive accepting element iA(N2, a new local label L2 and creates an inactive accepting element iA(N2,
L2). Node Z sends MBB Label Map <X, Y, L2>to N2 and waits for the L2). Node Z sends MBB Label Map <X, Y, L2>to N2 and waits for the
new upstream LSR N2 to respond with a MBB Notification for <X, Y, new upstream LSR N2 to respond with a MBB Notification for <X, Y,
L2>. During this transition phase there are two accepting elements, L2>. During this transition phase there are two accepting elements,
the element A(N1, L1) still accepting packets from N1 over label L1 the element A(N1, L1) still accepting packets from N1 over label L1
and the new inactive element iA(N2, L2). and the new inactive element iA(N2, L2).
While waiting for the MBB Notification from upstream LSR N2, it is While waiting for the MBB Notification from upstream LSR N2, it is
possible that an other transition occurs due to a routing change. possible that another transition occurs due to a routing change.
Suppose the new upstream LSR is N3. An inactive element iA(N3, L3) Suppose the new upstream LSR is N3. An inactive element iA(N3, L3)
is created and the old inactive element iA(N2, L2) MUST be removed. is created and the old inactive element iA(N2, L2) MUST be removed.
A label withdraw MUST be sent to N2 for <X, Y, L2&gt. The MBB A label withdraw MUST be sent to N2 for <X, Y, L2&gt. The MBB
Notification for <X, Y, L2> from N2 will be ignored because the Notification for <X, Y, L2> from N2 will be ignored because the
inactive element is removed. inactive element is removed.
It is possible that the MBB Notification from upstream LSR is never It is possible that the MBB Notification from upstream LSR is never
received due to link or node failure. To prevent waiting received due to link or node failure. To prevent waiting
indefinitely for the MBB Notification a timeout SHOULD be applied. indefinitely for the MBB Notification a timeout SHOULD be applied.
As soon as the timer expires, the procedures in Section 9.4.5 are As soon as the timer expires, the procedures in Section 8.4.5 are
applied as if a MBB Notification was received for the inactive applied as if a MBB Notification was received for the inactive
element. If a downstream LSR detects that the old upstream LSR went element. If a downstream LSR detects that the old upstream LSR went
down while waiting for the MBB Notification from the new upstream down while waiting for the MBB Notification from the new upstream
LSR, the downstream LSR can immediately proceed without waiting for LSR, the downstream LSR can immediately proceed without waiting for
the timer to expire. the timer to expire.
9.4.4. Receiving a Label Map with MBB status code 8.4.4. Receiving a Label Map with MBB status code
Suppose node Z has state for a MBB LSP <X, Y> and receives a MBB Suppose node Z has state for a MBB LSP <X, Y> and receives a MBB
Label Map <X, Y, L2> from N2. A new forwarding state F(N2, L2) will Label Map <X, Y, L2> from N2. A new forwarding state F(N2, L2) will
be added to the MP LSP if it did not already exist. If this MBB LSP be added to the MP LSP if it did not already exist. If this MBB LSP
has an active accepting element or node Z is the root of the MBB LSP has an active accepting element or node Z is the root of the MBB LSP
a MBB notification <X, Y, L2)> is send to node N2. If node Z has an a MBB notification <X, Y, L2)> is sent to node N2. If node Z has an
inactive accepting element it marks the Forwarding state as <X, Y, inactive accepting element it marks the Forwarding state as <X, Y,
F'(N2, L2)>. If router Z upstream LSR for <X, Y> happens to be N2, F'(N2, L2)>. If router Z upstream LSR for <X, Y> happens to be N2,
then Z MUST not send an MBB notification to N2 at once. Sending the then Z MUST NOT send an MBB notification to N2 at once. Sending the
MBB notification to N2 must be done only after Z upstream for <X, Y> MBB notification to N2 must be done only after Z upstream for <X, Y>
stops being N2. stops being N2.
9.4.5. Receiving a Notification with MBB status code 8.4.5. Receiving a Notification with MBB status code
Suppose node Z receives a MBB Notification <X, Y, L> from N. If node Suppose node Z receives a MBB Notification <X, Y, L> from N. If node
Z has state for MBB LSP <X, Y> and an inactive accepting element Z has state for MBB LSP <X, Y> and an inactive accepting element
iA(N, L) that matches with N and L, we activate this accepting iA(N, L) that matches with N and L, we activate this accepting
element and install label L in the label forwarding database. If an element and install label L in the label forwarding database. If an
other active accepting was present it will be removed from the label other active accepting was present it will be removed from the label
forwarding database. forwarding database.
If this MBB LSP <X, Y> also has Forwarding states marked for sending If this MBB LSP <X, Y> also has Forwarding states marked for sending
MBB Notifications, like <X, Y, F'(N2, L2)>, MBB Notifications are MBB Notifications, like <X, Y, F'(N2, L2)>, MBB Notifications are
send to these downstream LSRs. If node Z receives a MBB Notification sent to these downstream LSRs. If node Z receives a MBB Notification
for an accepting element that is not inactive or does not match the for an accepting element that is not inactive or does not match the
Label value and Neighbor address, the MBB notification is ignored. Label value and Neighbor address, the MBB notification is ignored.
9.4.6. Node operation for MP2MP LSPs 8.4.6. Node operation for MP2MP LSPs
The procedures described above apply to the downstream path of a The procedures described above apply to the downstream path of a
MP2MP LSP. The upstream path of the MP2MP is setup as normal without MP2MP LSP. The upstream path of the MP2MP is setup as normal without
including a MBB Status code. If the MBB procedures apply to a MP2MP including a MBB Status code. If the MBB procedures apply to a MP2MP
downstream FEC element, the upstream path to a node N is only downstream FEC element, the upstream path to a node N is only
installed in the label forwarding database if node N is part of the installed in the label forwarding database if node N is part of the
active accepting element. If node N is part of an inactive accepting active accepting element. If node N is part of an inactive accepting
element, the upstream path is installed when this inactive accepting element, the upstream path is installed when this inactive accepting
element is activated. element is activated.
10. Typed Wildcard for mLDP FEC Element 9. Typed Wildcard for mLDP FEC Element
The format of the mLDP FEC Typed Wildcard FEC is as follows: The format of the mLDP FEC Typed Wildcard FEC is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Typed Wcard | Type = mLDP | Len = 2 | AFI ~ | Typed Wcard | Type = mLDP | Len = 2 | AFI ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ | ~ |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Type Wcard: As specified in [I-D.ietf-mpls-ldp-typed-wildcard] Type Wcard: As specified in [RFC5918]
Type: mLDP FEC Element Type as documented in this draft. Type: mLDP FEC Element Type as documented in this draft.
Len: Len FEC Type Info, two octets (=0x02). Len: Len FEC Type Info, two octets (=0x02).
AFI: Address Family, two octet quantity containing a value from AFI: Address Family, two octet quantity containing a value from
ADDRESS FAMILY NUMBERS in [IANA-AF]. IANA's "Address Family Numbers" registry.
11. Security Considerations 10. Security Considerations
The same security considerations apply as for the base LDP The same security considerations apply as for the base LDP
specification, as described in [RFC5036]. specification, as described in [RFC5036].
12. IANA considerations 11. IANA Considerations
This document creates a new name space (the LDP MP Opaque Value This document creates three new registries to be managed by IANA.
Element type) that is to be managed by IANA, and the allocation of
the value 1 for the type of Generic LSP Identifier.
This document requires allocation of three new LDP FEC Element types: 1. "LDP MP Opaque Value Element basic type"
1. the P2MP FEC type - requested value 0x06 The range is 0-255, with the following values allocated in this
document:
2. the MP2MP-up FEC type - requested value 0x07 1: Generic LSP identifier
3. the MP2MP-down FEC type - requested value 0x08 255: Extended Type field is present in the following two bytes
The allocation policy for this space is 'Standards Action with
Early Allocation'
2. "LDP MP Opaque Value Element extended type"
The range is 0-65335, with the following allocation policies:
0-32767: Standards Action with Early Allocation
32768-65535: First Come, First Served
3. "LDP MP Status Value Element type"
The range is 0-255, with the following value allocated in this
document:
1: MBB Status
The allocation policy for this space is 'Standards Action with
Early Allocation'
This document requires allocation of three new code points from the
IANA managed LDP registry "Forwarding Equivalence Class (FEC) Type
Name Space". The values are:
P2MP FEC type - requested value 0x06
MP2MP-up FEC type - requested value 0x07
MP2MP-down FEC type - requested value 0x08
This document requires the assignment of three new code points for This document requires the assignment of three new code points for
three new Capability Parameter TLVs, corresponding to the three new Capability Parameter TLVs from the IANA managed LDP
advertisement of the P2MP, MP2MP and MBB capabilities. The values registry "TLV Type Name Space", corresponding to the advertisement of
requested are: the P2MP, MP2MP and MBB capabilities. The values requested are:
P2MP Capability Parameter - requested value 0x0508 P2MP Capability Parameter - requested value 0x0508
MP2MP Capability Parameter - requested value 0x0509 MP2MP Capability Parameter - requested value 0x0509
MBB Capability Parameter - requested value 0x050A MBB Capability Parameter - requested value 0x050A
This document requires the assignment of a LDP Status Code to This document requires the assignment of a LDP Status Code to
indicate a LDP MP Status TLV is following in the Notification indicate a LDP MP Status TLV is following in the Notification
message. The value requested from the LDP Status Code Name Space: message. The value requested from the IANA managed LDP registry "LDP
Status Code Name Space" is:
LDP MP status - requested value 0x00000040 LDP MP status - requested value 0x00000040
This document requires the assigment of a new code point for a LDP MP This document requires the assigment of a new code point for a LDP MP
Status TLV. The value requested from the LDP TLV Type Name Space: Status TLV. The value requested from the IANA managed LDP registry
"LDP TLV Type Name Space" is:
LDP MP Status TLV Type - requested value 0x096F LDP MP Status TLV Type - requested value 0x096F
This document creates a new name space (the LDP MP Status Value 12. Acknowledgments
Element type) that is to be managed by IANA, and the allocation of
the value 1 for the type of MBB Status.
This document creates a new name space (the LDP MP Opaque Value
Element type) that is to be managed by IANA.
13. Acknowledgments
The authors would like to thank the following individuals for their The authors would like to thank the following individuals for their
review and contribution: Nischal Sheth, Yakov Rekhter, Rahul review and contribution: Nischal Sheth, Yakov Rekhter, Rahul
Aggarwal, Arjen Boers, Eric Rosen, Nidhi Bhaskar, Toerless Eckert, Aggarwal, Arjen Boers, Eric Rosen, Nidhi Bhaskar, Toerless Eckert,
George Swallow, Jin Lizhong, Vanson Lim, Adrian Farrel and Thomas George Swallow, Jin Lizhong, Vanson Lim, Adrian Farrel, Thomas Morin
Morin. and Ben Niven-Jenkins.
14. Contributing authors 13. Contributing authors
Below is a list of the contributing authors in alphabetical order: Below is a list of the contributing authors in alphabetical order:
Shane Amante Shane Amante
Level 3 Communications, LLC Level 3 Communications, LLC
1025 Eldorado Blvd 1025 Eldorado Blvd
Broomfield, CO 80021 Broomfield, CO 80021
US US
Email: Shane.Amante@Level3.com Email: Shane.Amante@Level3.com
skipping to change at page 36, line 38 skipping to change at page 37, line 4
2, avenue Pierre-Marzin 2, avenue Pierre-Marzin
Lannion, Cedex 22307 Lannion, Cedex 22307
France France
Email: jeanlouis.leroux@francetelecom.com Email: jeanlouis.leroux@francetelecom.com
Bob Thomas Bob Thomas
Cisco Systems, Inc. Cisco Systems, Inc.
300 Beaver Brook Road 300 Beaver Brook Road
Boxborough, MA, 01719 Boxborough, MA, 01719
E-mail: bobthomas@alum.mit.edu E-mail: bobthomas@alum.mit.edu
Lei Wang Lei Wang
Telenor Telenor
Snaroyveien 30 Snaroyveien 30
Fornebu 1331 Fornebu 1331
Norway Norway
Email: lei.wang@telenor.com Email: lei.wang@telenor.com
IJsbrand Wijnands IJsbrand Wijnands
Cisco Systems, Inc. Cisco Systems, Inc.
De kleetlaan 6a De kleetlaan 6a
1831 Diegem 1831 Diegem
Belgium Belgium
E-mail: ice@cisco.com E-mail: ice@cisco.com
15. References 14. References
15.1. Normative References 14.1. Normative References
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007. Specification", RFC 5036, October 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3232] Reynolds, J., "Assigned Numbers: RFC 1700 is Replaced by
an On-line Database", RFC 3232, January 2002.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001. Label Switching Architecture", RFC 3031, January 2001.
[I-D.ietf-mpls-upstream-label] [RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream
Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream
Label Assignment and Context-Specific Label Space", Label Assignment and Context-Specific Label Space",
draft-ietf-mpls-upstream-label-05 (work in progress), RFC 5331, August 2008.
April 2008.
[I-D.ietf-mpls-ldp-upstream] [I-D.ietf-mpls-ldp-upstream]
Aggarwal, R. and J. Roux, "MPLS Upstream Label Assignment Aggarwal, R. and J. Roux, "MPLS Upstream Label Assignment
for LDP", draft-ietf-mpls-ldp-upstream-02 (work in for LDP", draft-ietf-mpls-ldp-upstream-10 (work in
progress), November 2007. progress), February 2011.
[I-D.ietf-mpls-ldp-capabilities] [RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL.
Thomas, B., "LDP Capabilities", Le Roux, "LDP Capabilities", RFC 5561, July 2009.
draft-ietf-mpls-ldp-capabilities-02 (work in progress),
March 2008.
[I-D.ietf-mpls-ldp-typed-wildcard] [RFC5918] Asati, R., Minei, I., and B. Thomas, "Label Distribution
Minei, I., Thomas, B., and R. Asati, "Label Distribution
Protocol (LDP) 'Typed Wildcard' Forward Equivalence Class Protocol (LDP) 'Typed Wildcard' Forward Equivalence Class
(FEC)", draft-ietf-mpls-ldp-typed-wildcard-07 (work in (FEC)", RFC 5918, August 2010.
progress), March 2010.
15.2. Informative References 14.2. Informative References
[RFC4664] Andersson, L. and E. Rosen, "Framework for Layer 2 Virtual [RFC4664] Andersson, L. and E. Rosen, "Framework for Layer 2 Virtual
Private Networks (L2VPNs)", RFC 4664, September 2006. Private Networks (L2VPNs)", RFC 4664, September 2006.
[RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
"Extensions to Resource Reservation Protocol - Traffic "Extensions to Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007. Switched Paths (LSPs)", RFC 4875, May 2007.
[I-D.ietf-mpls-mp-ldp-reqs] [I-D.ietf-mpls-mp-ldp-reqs]
Roux, J., "Requirements for Point-To-Multipoint Extensions Morin, T., "Requirements for Point-To-Multipoint
to the Label Distribution Protocol", Extensions to the Label Distribution Protocol",
draft-ietf-mpls-mp-ldp-reqs-04 (work in progress), draft-ietf-mpls-mp-ldp-reqs-06 (work in progress),
February 2008. December 2010.
[I-D.ietf-l3vpn-2547bis-mcast] [I-D.ietf-l3vpn-2547bis-mcast]
Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y., Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y.,
Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in
MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-06 (work MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-10 (work
in progress), January 2008. in progress), January 2010.
[I-D.ietf-mpls-multicast-encaps] [RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS
Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS Multicast Encapsulations", RFC 5332, August 2008.
Multicast Encapsulations",
draft-ietf-mpls-multicast-encaps-09 (work in progress),
May 2008.
Authors' Addresses Authors' Addresses
Ina Minei Ina Minei (editor)
Juniper Networks Juniper Networks
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, CA 94089 Sunnyvale, CA 94089
US US
Email: ina@juniper.net Email: ina@juniper.net
IJsbrand Wijnands (editor)
Cisco Systems, Inc.
De kleetlaan 6a
Diegem 1831
Belgium
Email: ice@cisco.com
Kireeti Kompella Kireeti Kompella
Juniper Networks Juniper Networks
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, CA 94089 Sunnyvale, CA 94089
US US
Email: kireeti@juniper.net Email: kireeti@juniper.net
IJsbrand Wijnands
Cisco Systems, Inc.
De kleetlaan 6a
Diegem 1831
Belgium
Email: ice@cisco.com
Bob Thomas Bob Thomas
Cisco Systems, Inc. Cisco Systems, Inc.
300 Beaver Brook Road 300 Beaver Brook Road
Boxborough 01719 Boxborough 01719
US US
Email: bobthomas@alum.mit.edu Email: bobthomas@alum.mit.edu
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