--- 1/draft-ietf-mpls-mldp-hsmp-01.txt 2013-10-12 09:14:27.062042215 -0700 +++ 2/draft-ietf-mpls-mldp-hsmp-02.txt 2013-10-12 09:14:27.094043036 -0700 @@ -1,35 +1,36 @@ Network Working Group L. Jin Internet-Draft Intended status: Standards Track F. Jounay -Expires: October 20, 2013 France Telecom +Expires: April 14, 2014 France Telecom I. Wijnands - Cisco Systems, Inc + Cisco Systems N. Leymann - Deutsche Telekom AG - April 18, 2013 + Deutsche Telekom + October 11, 2013 LDP Extensions for Hub & Spoke Multipoint Label Switched Path - draft-ietf-mpls-mldp-hsmp-01.txt + draft-ietf-mpls-mldp-hsmp-02.txt Abstract - This draft introduces a hub & spoke multipoint LSP (short for HSMP - LSP), which allows traffic both from root to leaf through P2MP LSP + This draft introduces a hub & spoke multipoint LSP (or HSMP LSP for + short), which allows traffic both from root to leaf through P2MP LSP and also leaf to root along the co-routed reverse path. That means traffic entering the HSMP LSP from application/customer at the root - node travels downstream, exactly as if it was traveling downstream - along a P2MP LSP to each leaf node, and traffic entering the HSMP LSP - at any leaf node travels upstream along the tree to the root as if it - is unicast to the root, except that it follows the path of the tree - rather than ordinary unicast to the root. + node travels downstream to each leaf node, exactly as if it is + travelling downstream along a P2MP LSP to each leaf node. Upstream + traffic entering the HSMP LSP at any leaf node travels upstream along + the tree to the root, as if it is unicast to the root, and strictly + follows the downstream path of the tree rather than routing protocol + based unicast path to the root. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119 [RFC2119]. Status of this Memo This Internet-Draft is submitted in full conformance with the @@ -37,426 +38,452 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - - This Internet-Draft will expire on October 20, 2013. + This Internet-Draft will expire on April 14, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3.1. Time synchronization scenario . . . . . . . . . . . . . . 4 - 3.2. VPMS scenario . . . . . . . . . . . . . . . . . . . . . . 4 - 3.3. IPTV scenario . . . . . . . . . . . . . . . . . . . . . . 4 - 4. Setting up HSMP LSP with LDP . . . . . . . . . . . . . . . . . 5 - 4.1. Support for HSMP LSP setup with LDP . . . . . . . . . . . 5 - 4.2. HSMP FEC Elements . . . . . . . . . . . . . . . . . . . . 6 - 4.3. Using the HSMP FEC Elements . . . . . . . . . . . . . . . 6 - 4.3.1. HSMP LSP Label Map . . . . . . . . . . . . . . . . . . 6 - 4.3.2. HSMP LSP Label Withdraw . . . . . . . . . . . . . . . 8 - 4.3.3. HSMP LSP upstream LSR change . . . . . . . . . . . . . 9 - 5. HSMP LSP on a LAN . . . . . . . . . . . . . . . . . . . . . . 9 - 6. Redundancy considerations . . . . . . . . . . . . . . . . . . 9 - 7. Co-routed path exceptions . . . . . . . . . . . . . . . . . . 9 - 8. Failure Detection of HSMP LSP . . . . . . . . . . . . . . . . 10 - 9. Security Considerations . . . . . . . . . . . . . . . . . . . 10 - 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 - 11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11 - 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 12.1. Normative references . . . . . . . . . . . . . . . . . . . 11 - 12.2. Informative References . . . . . . . . . . . . . . . . . . 12 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 3. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 3.1. Time Synchronization Scenario . . . . . . . . . . . . . . 5 + 3.2. Virtual Private Multicast Service Scenario . . . . . . . . 5 + 3.3. IPTV Scenario . . . . . . . . . . . . . . . . . . . . . . 5 + 4. Setting up HSMP LSP with LDP . . . . . . . . . . . . . . . . . 6 + 4.1. Support for HSMP LSP Setup with LDP . . . . . . . . . . . 6 + 4.2. HSMP FEC Elements . . . . . . . . . . . . . . . . . . . . 7 + 4.3. Using the HSMP FEC Elements . . . . . . . . . . . . . . . 7 + 4.3.1. HSMP LSP Label Map . . . . . . . . . . . . . . . . . . 8 + 4.3.2. HSMP LSP Label Withdraw . . . . . . . . . . . . . . . 10 + 4.3.3. HSMP LSP Upstream LSR Change . . . . . . . . . . . . . 10 + 5. HSMP LSP on a LAN . . . . . . . . . . . . . . . . . . . . . . 10 + 6. Redundancy Considerations . . . . . . . . . . . . . . . . . . 11 + 7. Co-routed Path Exceptions . . . . . . . . . . . . . . . . . . 11 + 8. Failure Detection of HSMP LSP . . . . . . . . . . . . . . . . 11 + 9. Security Considerations . . . . . . . . . . . . . . . . . . . 12 + 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 + 11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 13 + 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 + 12.1. Normative references . . . . . . . . . . . . . . . . . . . 13 + 12.2. Informative References . . . . . . . . . . . . . . . . . . 13 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 1. Introduction The point-to-multipoint LSP defined in [RFC6388] allows traffic to transmit from root to several leaf nodes, and multipoint-to- multipoint LSP allows traffic from every node to transmit to every - other node. This draft introduces a hub & spoke multipoint LSP - (short for HSMP LSP), which allows traffic both from root to leaf + other node. This draft introduces a hub & spoke multipoint LSP (or + HSMP LSP for short), which allows traffic both from root to leaf through P2MP LSP and also leaf to root along the co-routed reverse path. That means traffic entering the HSMP LSP at the root node - travels downstream, exactly as if it was traveling downstream along a + travels downstream, exactly as if it is travelling downstream along a P2MP LSP, and traffic entering the HSMP LSP at any other node travels - upstream along the tree to the root. A packet traveling upstream + upstream along the tree to the root. A packet travelling upstream should be thought of as being unicast to the root, except that it - follows the path of the tree rather than ordinary unicast to the - root. + follows the path of the tree rather than routing protocol based + unicast path to the root. The combination of upstream LSPs initiated + from all leaf nodes forms a multipoint-to-point LSP. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. This document uses some terms and acronyms as follows: - mLDP: Multipoint extensions for LDP + HSMP LSP: hub & spoke multipoint LSP. An LSP allows traffic both + from root to leaf through P2MP LSP and also leaf to root along the + co-routed reverse path. - P2MP LSP: An LSP that has one Ingress LSR and one or more Egress - LSRs. + mLDP: Multipoint extensions for LDP MP2MP LSP: An LSP that connects a set of nodes, such that traffic sent by any node in the LSP is delivered to all others. - HSMP LSP: hub & spoke multipoint LSP. An LSP allows traffic both - from root to leaf through P2MP LSP and also leaf to root along the - co-routed reverse path. - PTP: The timing and synchronization protocol used by IEEE1588 + P2MP LSP: An LSP that has one Ingress LSR and one or more Egress + LSRs. + 3. Applications - In some cases, the P2MP LSP may not have a reply path for the OAM - message (e.g, LSP Ping). If P2MP LSP is provided by HSMP LSP, then - the upstream path could be exactly used as the OAM message reply - path. This is especially useful in the case of P2MP LSP fault - detection, performance measurement, root node redundancy and etc. - There are several other applications that could take advantage of - such kind of LDP based HSMP LSP as described below. + In some cases, the P2MP LSP may not have a reply path for OAM + messages (e.g, LSP Ping Echo Request). If P2MP LSP is provided by + HSMP LSP instead, then the upstream path could be used as the OAM + message reply path. This is especially useful in the case of P2MP + LSP fault detection, performance measurement, root node redundancy + and etc. There are several other applications that could take + advantage of a LDP based HSMP LSP as described below. -3.1. Time synchronization scenario +3.1. Time Synchronization Scenario [IEEE1588] over MPLS is defined in [I-D.ietf-tictoc-1588overmpls]. It is required that the LSP used to transport PTP event message between a Master Clock and a Slave Clock, and the LSP between the - same Slave Clock and Master Clock must be co-routed. By using point- - to-multipoint technology to transmit PTP event messages from Master + same Slave Clock and Master Clock must be co-routed. Using point-to- + multipoint technology to transmit PTP event messages from Master Clock at root side to Slave Clock at leaf side will greatly improve the bandwidth usage. Unfortunately current point-to-multipoint LSP only provides unidirectional path from root to leaf, which cannot - provide a co-routed reverse path for the PTP event messages. LDP + provides a co-routed reverse path for the PTP event messages. LDP based HSMP LSP described in this draft provides unidirectional point- - to-multipoint LSP from root to leaf and co-routed reverse path from + to-multipoint LSP from root to leaf and co-routed reverse LSP from leaf to root. -3.2. VPMS scenario +3.2. Virtual Private Multicast Service Scenario Point to multipoint PW described in [I-D.ietf-pwe3-p2mp-pw] requires to setup reverse path from leaf node (referred as egress PE) to root node (referred as ingress PE), if HSMP LSP is used to multiplex P2MP PW, the reverse path can also be multiplexed to HSMP upstream path to avoid setup independent reverse path. In that case, the operational cost will be reduced for maintaining only one HSMP LSP, instead of P2MP LSP and n (number of leaf nodes) P2P reverse LSPs. The VPMS defined in [I-D.ietf-l2vpn-vpms-frmwk-requirements] requires reverse path from leaf to root node. The P2MP PW multiplexed to HSMP LSP can provide VPMS with reverse path, without introducing independent reverse path from each leaf to root. -3.3. IPTV scenario +3.3. IPTV Scenario The mLDP based HSMP LSP can also be applied in a typical IPTV scenario. There is usually only one location with senders but there - are many receiver locations. If IGMP is used for signaling between - senders as IGMP querier and receivers, the IGMP messages from the - receivers are travelling only from the leaves to the root (and from - root towards leaves) but not from leaf to leaf. In addition traffic - from the root is only replicated towards the leaves. Then leaf node - receiving IGMP message (for SSM case) will join HSMP LSP, and then - send IGMP message upstream to root along HSMP LSP. Note that in - above case, there is no node redundancy for IGMP querier. And the - node redundancy for IGMP querier could be provided by two independent - VPMS instances with HSMP applied. + are many receiver locations. If IGMP is used for signalling between + senders as IGMP querier [RFC3376] and receivers, the IGMP messages + from the receivers are travelling only from the leaves to the root + (and from root towards leaves) but not from leaf to leaf. In + addition traffic from the root is only replicated towards the leaves. + Then leaf node receiving IGMP report message (for source specific + multicast case) will join HSMP LSP(use similar mechanism in [RFC6826] + section 2), and then send IGMP report message upstream to root along + HSMP upstream LSP. Note that in above case, there is no node + redundancy for IGMP querier. And the node redundancy for IGMP + querier[RFC3376] could be provided by two independent VPMS instances + with HSMP applied. 4. Setting up HSMP LSP with LDP HSMP LSP is similar with MP2MP LSP described in [RFC6388], with the difference that the leaf LSRs can only send traffic to root node along the same path of traffic from root node to leaf node. HSMP LSP consists of a downstream path and upstream path. The downstream path is same as MP2MP LSP, while the upstream path is only from leaf to root node, without communication between leaf and leaf - nodes. The transmission of packets from the root node of a HSMP LSP + nodes. The transmission of packets from the root node of an HSMP LSP to the receivers is identical to that of a P2MP LSP. Traffic from a - leaf node follows the upstream path toward the root node, along the - identical path of downstream path. + leaf node follows the upstream path toward the root node, along a + path that traverse the same nodes as the downstream node, but in + reverse order. - For setting up the upstream path of a HSMP LSP, ordered mode MUST be + For setting up the upstream path of an HSMP LSP, ordered mode MUST be used which is same as MP2MP. Ordered mode can guarantee a leaf to start sending packets to root immediately after the upstream path is installed, without being dropped due to an incomplete LSP. - Due to much of same behavior between HSMP LSP and MP2MP LSP, the + Due to much of similar behaviors between HSMP LSP and MP2MP LSP, the following sections only describe the difference between the two entities. -4.1. Support for HSMP LSP setup with LDP +4.1. Support for HSMP LSP Setup with LDP - HSMP LSP also needs the LDP capabilities [RFC5561] to indicate the - supporting for the setup of HSMP LSPs. An implementation supporting - the HSMP LSP procedures specified in this document MUST implement the - procedures for Capability Parameters in Initialization Messages. - Advertisement of the HSMP LSP Capability indicates support of the - procedures for HSMP LSP setup. + HSMP LSP requires the LDP capabilities [RFC5561] for nodes to + indicate that they support setup of HSMP LSPs. An implementation + supporting the HSMP LSP procedures specified in this document MUST + implement the procedures for Capability Parameters in Initialization + Messages. Advertisement of the HSMP LSP Capability indicates support + of the procedures for HSMP LSP setup. - A new Capability Parameter TLV is defined, the HSMP LSP Capability. - Following is the format of the HSMP LSP Capability Parameter. + A new Capability Parameter TLV is defined, the HSMP LSP Capability + Parameter. Following is the format of the HSMP LSP Capability + Parameter. 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| HSMP LSP Cap(TBD IANA) | Length (= 1) | + |1|0| HSMP LSP Cap(TBD IANA) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |1| Reserved | + |S| Reserved | +-+-+-+-+-+-+-+-+ Figure 1. HSMP LSP Capability Parameter encoding - The HSMP LSP capability type is to be assigned by IANA. + The length SHOULD be 1, and the S bit and reserved bits are defined + in [RFC5561] section 3. + + The HSMP LSP Capability Parameter type is to be assigned by IANA. 4.2. HSMP FEC Elements Similar as MP2MP LSP, we define two new protocol entities, the HSMP - downstream FEC and upstream FEC Element. If a FEC TLV contains an - HSMP FEC Element, the HSMP FEC Element MUST be the only FEC Element - in the FEC TLV. The structure, encoding and error handling for the - HSMP downstream and upstream FEC Elements are the same as for the - MP2MP FEC Element described in [RFC6388] Section 4.2. The difference - is that two additional new FEC types are used: HSMP downstream type - (TBD, IANA) and HSMP upstream type (TBD, IANA). + Downstream FEC Element and Upstream FEC Element. If a FEC TLV + contains one of the HSMP FEC Elements, the HSMP FEC Element MUST be + the only FEC Element in the FEC TLV. The structure, encoding and + error handling for the HSMP Downstream FEC Element and Upstream FEC + Element are the same as for the MP2MP FEC Element described in + [RFC6388] Section 3.2. The difference is that two additional new FEC + types are defined: HSMP Downstream FEC (TBD, IANA) and HSMP Upstream + FEC(TBD, IANA). 4.3. Using the HSMP FEC Elements - In order to describe the message processing clearly, following - defines the processing of the HSMP FEC Elements, which is inherited - from [RFC6388] section 4.3. + In order to describe the message processing clearly, the entries in + the list below define the processing of the HSMP FEC Elements. + Additionally, the entries defined in [RFC6388] section 3.3 are also + reused in the following sections. - 1. HSMP downstream LSP (or simply downstream ): a HSMP + 1. HSMP downstream LSP (or simply downstream ): an HSMP LSP downstream path with root node address X and opaque value Y. - 2. HSMP upstream LSP (or simply upstream ): a HSMP LSP + 2. HSMP upstream LSP (or simply upstream ): an HSMP LSP upstream path for root node address X and opaque value Y which will be used by any of downstream node to send traffic upstream to root node. 3. HSMP downstream FEC Element : a FEC Element with root node address X and opaque value Y used for a downstream HSMP LSP. 4. HSMP upstream FEC Element : a FEC Element with root node address X and opaque value Y used for an upstream HSMP LSP. - 5. HSMP-D Label Map : A Label Map message with a single - HSMP downstream FEC Element and label TLV with label L. Label - L MUST be allocated from the per-platform label space of the LSR - sending the Label Map Message. + 5. HSMP-D Label Mapping : A Label Mapping message with a + single HSMP downstream FEC Element and label TLV with label L. + Label L MUST be allocated from the per-platform label space of the + LSR sending the Label Mapping Message. - 6. HSMP-U Label Map : A Label Map message with a single - HSMP upstream FEC Element and label TLV with label Lu. Label - Lu MUST be allocated from the per-platform label space of the LSR - sending the Label Map Message. + 6. HSMP-U Label Mapping : A Label Mapping message with a + single HSMP upstream FEC Element and label TLV with label Lu. + Label Lu MUST be allocated from the per-platform label space of the + LSR sending the Label Mapping Message. 4.3.1. HSMP LSP Label Map - This section specifies the procedures for originating HSMP Label Map - messages and processing received HSMP label map messages for a - particular HSMP LSP. The procedure of downstream HSMP LSP is same as - that of downstream MP2MP LSP described in [RFC6388]. Under the - operation of ordered mode, the upstream LSP will be setup by sending - HSMP LSP mapping message with label which is allocated by upstream - LSR to its downstream LSR one by one from root to leaf node, - installing the upstream forwarding table by every node along the LSP. - Detail procedure of upstream HSMP LSP is different with that of + This section specifies the procedures for originating HSMP Label + Mapping messages and processing received HSMP Label Mapping messages + for a particular HSMP LSP. The procedure of downstream HSMP LSP is + same as that of downstream MP2MP LSP described in [RFC6388]. When + LDP operates in Ordered Label Distribution Control mode [RFC5036], + the upstream LSP will be set up by sending HSMP LSP LDP Label Mapping + message with a label which is allocated by upstream LSR to its + downstream LSR hop by hop from root to leaf node, installing the + upstream forwarding table by every node along the LSP. The detail + procedure of setting up upstream HSMP LSP is different with that of upstream MP2MP LSP, and is specified in below section. All labels discussed here are downstream-assigned [RFC5332] except those which are assigned using the procedures described in section 5. - Determining the upstream LSR for a HSMP LSP follows the - procedure for a MP2MP LSP described in [RFC6388] Section 4.3.1.1. + Determining the upstream LSR for the HSMP LSP follows the + procedure for a MP2MP LSP described in [RFC6388] Section 3.3.1.1. - Determining one's downstream HSMP LSR procedure is much same as - defined in [RFC6388] section 4.3.1.2. A LDP peer U which receives a - HSMP-D Label Map from a LDP peer D will treat D as downstream HSMP - LSR. + Determining one's HSMP downstream LSR follows the procedure defined + in [RFC6388] section 3.3.1.2. That is, an upstream LDP peer which + receives a Label Mapping with HSMP downstream FEC Element from an LDP + peer D will treat D as HSMP downstream LDP peer. - Determining the forwarding interface to an LSR has same procedure as - defined in [RFC6388] section 2.4.1.2. + Determining the forwarding interface to an LSR follows the procedure + as defined in [RFC6388] section 2.4.1.2. -4.3.1.1. HSMP LSP leaf node operation +4.3.1.1. HSMP LSP Leaf Node Operation The leaf node operation is same as the operation of MP2MP LSP defined - in [RFC6388] section 4.3.1.4, only with different FEC element - processing and specified below. + in [RFC6388] section 3.3.1.4. The only difference is the FEC + elements as specified below. - A leaf node Z will send a HSMP-D Label Map to U, instead of - MP2MP-D Label Map . and expects a HSMP-U Label Map from node U and checks whether it already has forwarding state - for upstream . The created forwarding state on leaf node Z is - same as the leaf node of MP2MP LSP. Z will push label Lu onto the - traffic that Z wants to forward over the HSMP LSP. + A leaf node Z will send an HSMP-D Label Mapping to U, + instead of MP2MP-D Label Mapping , and expects an HSMP-U + Label Mapping from node U and checks whether it already + has forwarding state for upstream . The created forwarding + state on leaf node Z is same as the leaf node of MP2MP LSP. Z will + push label Lu onto the traffic that Z wants to forward over the HSMP + LSP. -4.3.1.2. HSMP LSP transit node operation +4.3.1.2. HSMP LSP Transit Node Operation - Suppose node Z receives a HSMP-D Label Map from LSR D, the - procedure is same as processing MP2MP-D Label Mapping message defined - in [RFC6388] section 4.3.1.5, and the processing protocol entity is - HSMP-D label mapping message. The different procedure is specified - below. + Suppose node Z receives an HSMP-D Label Mapping from LSR D, + the procedure is much the same as processing MP2MP-D Label Mapping + message defined in [RFC6388] section 3.3.1.5, and the processing + protocol entity is HSMP-D Label Mapping message. The only difference + is specified below. - Node Z checks if upstream LSR U already assigned a label Lu to - upstream . If not, transit node Z waits until it receives a - HSMP-U Label Map from LSR U. Once the HSMP-U Label Map is - received from LSR U, node Z checks whether it already has forwarding - state upstream with incoming label Lu' and outgoing label Lu. - If it does, Z sends a HSMP-U Label Map to downstream - node. If it does not, it allocates a label Lu' and creates a new - label swap for Lu' with Label Lu over interface Iu. Interface Iu is - determined via the procedures in Section 4.3.1. Node Z determines - the downstream HSMP LSR as per Section 4.3.1, and sends a HSMP-U - Label Map to node D. + Node Z checks if upstream LSR U already has assigned a label Lu to + upstream . If not, transit node Z waits until it receives an + HSMP-U Label Mapping from LSR U. Once the HSMP-U Label + Mapping is received from LSR U, node Z checks whether it already has + forwarding state upstream with incoming label Lu' and outgoing + label Lu. If it does, Z sends an HSMP-U Label Mapping to + downstream node. If it does not, it allocates a label Lu' and + creates a new label swap for Lu' with Label Lu over interface Iu. + Interface Iu is determined via the procedures in section 4.3.1. Node + Z determines the downstream HSMP LSR as per section 4.3.1, and sends + an HSMP-U Label Mapping to node D. Since a packet from any downstream node is forwarded only to the - upstream node, the same label (representing the upstream path) can be - distributed to all downstream nodes. This differs from the - procedures for MPMP LSPs [RFC6388], where a distinct label must be + upstream node, the same label (representing the upstream path) SHOULD + be distributed to all downstream nodes. This differs from the + procedures for MP2MP LSPs [RFC6388], where a distinct label must be distributed to each downstream node. The forwarding state upstream on node Z will be like this {, }. Iu means the upstream interface over which Z receives HSMP-U Label Map - from LSR U. Packets from any downstream interface over which Z send + from LSR U. Packets from any downstream interface over which Z sends HSMP-U Label Map with label Lu' will be forwarded to Iu with label Lu' swap to Lu. -4.3.1.3. HSMP LSP root node operation +4.3.1.3. HSMP LSP Root Node Operation - Suppose root node Z receives a HSMP-D Label Map from node - D, the procedure is much same as processing MP2MP-D Label Mapping - message defined in [RFC6388] section 4.3.1.6, and the processing - protocol entity is HSMP-D label mapping message. The different - procedure is specified below. + Suppose root node Z receives an HSMP-D Label Mapping from + node D, the procedure is much the same as processing MP2MP-D Label + Mapping message defined in [RFC6388] section 3.3.1.6, and the + processing protocol entity is HSMP-D Label Mapping message. The only + difference is specified below. Node Z checks if it has forwarding state for upstream . If not, Z creates a forwarding state for incoming label Lu' that indicates that Z is the LSP egress. E.g., the forwarding state might specify that the label stack is popped and the packet passed to some specific application. Node Z determines the downstream HSMP LSR as - per section 4.3.1, and sends a HSMP-U Label Map to node + per section 4.3.1, and sends an HSMP-U Label Map to node D. - Since Z is the root of the tree, Z will not send a HSMP-D Label Map - and will not receive a HSMP-U Label Map. + Since Z is the root of the tree, Z will not send an HSMP-D Label Map + and will not receive an HSMP-U Label Mapping. 4.3.2. HSMP LSP Label Withdraw - The HSMP Label Withdraw procedure is much same as MP2MP leaf - operation defined in [RFC6388] section 4.3.2, and the processing - protocol entities are HSMP FECs. The only difference is process of - HSMP-U label release message, which is specified below. + The HSMP Label Withdraw procedure is much the same as MP2MP leaf + operation defined in [RFC6388] section 3.3.2, and the processing FEC + Elements are HSMP FEC Elements. The only difference is the process + of HSMP-U Label Release message, which is specified below. - When a transit node Z receives a HSMP-U label release message from + When a transit node Z receives an HSMP-U Label Release message from downstream node D, Z should check if there are any incoming interface in forwarding state upstream . If all downstream nodes are released and there is no incoming interface, Z should delete the - forwarding state upstream and send HSMP-U label release - message to its upstream node. + forwarding state upstream and send HSMP-U Label Release + message to its upstream node. Otherwise, no HSMP-U Label Release + message will be sent to the upstream node. -4.3.3. HSMP LSP upstream LSR change +4.3.3. HSMP LSP Upstream LSR Change The procedure for changing the upstream LSR is the same as defined in - [RFC6388] section 4.3.3, except it is applied to HSMP FECs. + [RFC6388] section 3.3.3, only with different processing FEC Element, + the HSMP FEC Element. 5. HSMP LSP on a LAN - The procedure to process P2MP LSP on a LAN has been described in - [RFC6388]. When the LSR forwards a packet downstream on one of those - LSPs, the packet's top label must be the "upstream LSR label", and - the packet's second label is "LSP label". + The procedure to process the downstream HSMP LSP on a LAN is much the + same as downstream MP2MP LSP described in [RFC6388] section 6.1.1. - When establishing the downstream path of a HSMP LSP, as defined in - [RFC6389], a label request for a LSP label is send to the upstream - LSR. The upstream LSR should send label mapping that contains the - LSP label for the downstream HSMP FEC and the upstream LSR context - label. At the same time, it must also send label mapping for - upstream HSMP FEC to downstream node. Packets sent by the upstream - router can be forwarded downstream using this forwarding state based - on a two label lookup. Packets traveling upstream need to be - forwarded in the direction of the root by using the label allocated - by upstream LSR. + When establishing the downstream path of an HSMP LSP, as defined in + [RFC6389], a Label Request message for an LSP label is sent to the + upstream LSR. The upstream LSR should send Label Mapping message + that contains the LSP label for the downstream HSMP FEC and the + upstream LSR context label defined in [RFC5331]. When the LSR + forwards a packet downstream on one of those LSPs, the packet's top + label must be the "upstream LSR context label", and the packet's + second label is "LSP label". The HSMP downstream path will be + installed in the context-specific forwarding table corresponding to + the upstream LSR label. Packets sent by the upstream LSR can be + forwarded downstream using this forwarding state based on a two-label + lookup. -6. Redundancy considerations + The upstream path of an HSMP LSP on a LAN is the same as the one on + other kind of links. That is, the upstream LSR must send Label + Mapping message that contains the LSP label for upstream HSMP FEC to + downstream node. Packets travelling upstream need to be forwarded in + the direction of the root by using the label allocated for upstream + HSMP FEC. + +6. Redundancy Considerations In some scenario, it is necessary to provide two root nodes for redundancy purpose. One way to implement this is to use two independent HSMP LSPs acting as active/standby. At one time, only one HSMP LSP will be active, and the other will be standby. After detecting the failure of active HSMP LSP, the root and leaf nodes - will switch the traffic to the new active HSMP LSP which is switched - from former standby LSP. The detail of redundancy mechanism will be - for future study. + will switch the traffic to the standby HSMP LSP which takes on the + role as active HSMP LSP. The detail of redundancy mechanism is out + of the scope. -7. Co-routed path exceptions +7. Co-routed Path Exceptions - There are some exceptional cases that mLDP based HSMP LSP could not + There are some exceptional cases when mLDP based HSMP LSP could not achieve co-routed path. One possible case is using static routing between LDP neighbors; another possible case is IGP cost asymmetric generated by physical link cost asymmetric, or TE-Tunnels used - between LDP neighbors. The LSR/LER in HSMP LSP could detect if the - path is co-routed or not, if not co-routed, an indication could be - generated to the management system. + between LDP neighbors. The LSR/LER in HSMP LSP should detect if the + path is co-routed or not. If not co-routed, an alarm indication + should be generated to the management system. 8. Failure Detection of HSMP LSP The idea of LSP ping for HSMP LSPs could be expressed as an intention - to test the packets that enter at the root along a particular - downstream path of HSMP LSP, and end their MPLS path on the leaf. - The leaf node then sends the LSP ping response along the co-routed - upstream path of HSMP LSP, and end on the root that are the - (intended) root node. + to test the LSP Ping Echo Request packets that enter at the root + along a particular downstream path of HSMP LSP, and end their MPLS + path on the leaf. The leaf node then sends the LSP Ping Echo Reply + along the co-routed upstream path of HSMP LSP, and end on the root + that are the (intended) root node. New sub-TLVs are required to be assigned by IANA in Target FEC Stack TLV to define the corresponding HSMP-upstream FEC type and HSMP- downstream FEC type. In order to ensure the leaf node to send the - LSP ping response along the HSMP upstream path, the R bit (Validate + LSP Ping Echo Reply along the HSMP upstream path, the R bit (Validate Reverse Path) in Global Flags Field defined in [RFC6426] is reused here. - The node processing mechanism of LSP ping for HSMP LSP is inherited - from [RFC6425] and [RFC6426] section 3.4, except the following: + The node processing mechanism of LSP Ping Echo Request and Echo Reply + for HSMP LSP is inherited from [RFC6425] and [RFC6426] section 3.4, + except the following: - 1. The root node sending LSP ping message for HSMP LSP MUST attach - Target FEC Stack with HSMP downstream FEC, and set R bit to '1' in - Global Flags Field. + 1. The root node sending LSP Ping Echo Request message for HSMP LSP + MUST attach Target FEC Stack with HSMP downstream FEC, and set R bit + to '1' in Global Flags Field. - 2. When the leaf node receiving the LSP ping, it MUST send the LSP - ping response to the associated HSMP upstream path. The Reverse-path - Target FEC Stack TLV attached by leaf node in reply message SHOULD - contain the sub-TLV of associated HSMP upstream FEC. + 2. When the leaf node receiving the LSP Ping Echo Request, it MUST + send the LSP Ping Echo Reply to the associated HSMP upstream path. + The Reverse-path Target FEC Stack TLV attached by leaf node in Echo + Reply message SHOULD contain the sub-TLV of associated HSMP upstream + FEC. 9. Security Considerations The same security considerations apply as for the MP2MP LSP described in [RFC6388] and [RFC6425]. + Although this document introduces new FEC Elements and corresponding + procedures, the protocol does not bring any new security issues + compared to [RFC6388] and [RFC6425]. + 10. IANA Considerations This document requires allocation of two new LDP FEC Element types from the "Label Distribution Protocol (LDP) Parameters registry" the "Forwarding Equivalence Class (FEC) Type Name Space": 1. the HSMP-upstream FEC type - requested value TBD 2. the HSMP-downstream FEC type - requested value TBD @@ -470,29 +497,34 @@ inclusion within the LSP ping [RFC4379] Target FEC Stack TLV (TLV type 1). 1. the HSMP-upstream LDP FEC Stack - requested value TBD 2. the HSMP-downstream LDP FEC Stack - requested value TBD 11. Acknowledgement The author would like to thank Eric Rosen, Sebastien Jobert, Fei Su, - Edward, Mach Chen, Thomas Morin for their valuable comments. + Edward, Mach Chen, Thomas Morin, Loa Andersson for their valuable + comments. 12. References 12.1. Normative references [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. + [RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream + Label Assignment and Context-Specific Label Space", + RFC 5331, August 2008. + [RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS Multicast Encapsulations", RFC 5332, August 2008. [RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL. Le Roux, "LDP Capabilities", RFC 5561, July 2009. [RFC6388] Wijnands, IJ., Minei, I., Kompella, K., and B. Thomas, "Label Distribution Protocol Extensions for Point-to- Multipoint and Multipoint-to-Multipoint Label Switched Paths", RFC 6388, November 2011. @@ -519,45 +551,58 @@ progress), October 2012. [I-D.ietf-pwe3-p2mp-pw] Sivabalan, S., Boutros, S., and L. Martini, "Signaling Root-Initiated Point-to-Multipoint Pseudowire using LDP", draft-ietf-pwe3-p2mp-pw-04 (work in progress), March 2012. [I-D.ietf-tictoc-1588overmpls] Davari, S., Oren, A., Bhatia, M., Roberts, P., and L. Montini, "Transporting Timing messages over MPLS - Networks", draft-ietf-tictoc-1588overmpls-04 (work in - progress), February 2013. + Networks", draft-ietf-tictoc-1588overmpls-05 (work in + progress), June 2013. [IEEE1588] "IEEE standard for a precision clock synchronization protocol for networked measurement and control systems", IEEE1588v2 , March 2008. + [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. + Thyagarajan, "Internet Group Management Protocol, Version + 3", RFC 3376, October 2002. + [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", RFC 4379, February 2006. [RFC4762] Lasserre, M. and V. Kompella, "Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling", RFC 4762, January 2007. + [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP + Specification", RFC 5036, October 2007. + [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay Measurement for MPLS Networks", RFC 6374, September 2011. + [RFC6826] Wijnands, IJ., Eckert, T., Leymann, N., and M. Napierala, + "Multipoint LDP In-Band Signaling for Point-to-Multipoint + and Multipoint-to-Multipoint Label Switched Paths", + RFC 6826, January 2013. + Authors' Addresses Lizhong Jin Shanghai, China Email: lizho.jin@gmail.com + Frederic Jounay France Telecom 2, avenue Pierre-Marzin 22307 Lannion Cedex, FRANCE Email: frederic.jounay@orange.ch IJsbrand Wijnands Cisco Systems, Inc De kleetlaan 6a