draft-ietf-mpls-lsp-ping-relay-reply-04.txt   draft-ietf-mpls-lsp-ping-relay-reply-05.txt 
Network Working Group J. Luo, Ed. Network Working Group J. Luo, Ed.
Internet-Draft ZTE Internet-Draft ZTE
Updates: 4379 (if approved) L. Jin, Ed. Updates: 4379 (if approved) L. Jin, Ed.
Intended status: Standards Track Intended status: Standards Track
Expires: January 31, 2015 T. Nadeau, Ed. Expires: May 18, 2015 T. Nadeau, Ed.
Lucidvision Lucidvision
G. Swallow, Ed. G. Swallow, Ed.
Cisco Cisco
July 30, 2014 November 14, 2014
Relayed Echo Reply mechanism for LSP Ping Relayed Echo Reply mechanism for LSP Ping
draft-ietf-mpls-lsp-ping-relay-reply-04 draft-ietf-mpls-lsp-ping-relay-reply-05
Abstract Abstract
In some inter autonomous system (AS) and inter-area deployment In some inter autonomous system (AS) and inter-area deployment
scenarios for RFC 4379 "Label Switched Path (LSP) Ping and scenarios for RFC 4379 "Label Switched Path (LSP) Ping and
Traceroute", a replying LSR may not have the available route to the Traceroute", a replying LSR may not have the available route to the
initiator, and the Echo Reply message sent to the initiator would be initiator, and the Echo Reply message sent to the initiator would be
discarded resulting in false negatives or complete failure of discarded resulting in false negatives or complete failure of
operation of LSP Ping and Traceroute. This document describes operation of LSP Ping and Traceroute. This document describes
extensions to LSP Ping mechanism to enable the replying Label extensions to LSP Ping mechanism to enable the replying Label
skipping to change at page 1, line 44 skipping to change at page 1, line 44
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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."
This Internet-Draft will expire on January 31, 2015. This Internet-Draft will expire on May 18, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 38 skipping to change at page 2, line 38
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 . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions Used in This Document . . . . . . . . . . . . 3 1.1. Conventions Used in This Document . . . . . . . . . . . . 3
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Relayed Echo Reply message . . . . . . . . . . . . . . . 5 3.1. Relayed Echo Reply message . . . . . . . . . . . . . . . 6
3.2. Relay Node Address Stack . . . . . . . . . . . . . . . . 6 3.2. Relay Node Address Stack . . . . . . . . . . . . . . . . 6
3.3. New Return Code . . . . . . . . . . . . . . . . . . . . . 7 3.3. New Return Code . . . . . . . . . . . . . . . . . . . . . 8
4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Sending an Echo Request . . . . . . . . . . . . . . . . . 8 4.1. Sending an Echo Request . . . . . . . . . . . . . . . . . 8
4.2. Receiving an Echo Request . . . . . . . . . . . . . . . . 8 4.2. Receiving an Echo Request . . . . . . . . . . . . . . . . 8
4.3. Originating an Relayed Echo Reply . . . . . . . . . . . . 9 4.3. Originating an Relayed Echo Reply . . . . . . . . . . . . 9
4.4. Relaying an Relayed Echo Reply . . . . . . . . . . . . . 9 4.4. Relaying an Relayed Echo Reply . . . . . . . . . . . . . 9
4.5. Sending an Echo Reply . . . . . . . . . . . . . . . . . . 10 4.5. Sending an Echo Reply . . . . . . . . . . . . . . . . . . 10
4.6. Receiving an Echo Reply . . . . . . . . . . . . . . . . . 10 4.6. Receiving an Echo Reply . . . . . . . . . . . . . . . . . 10
4.7. Impact to Traceroute . . . . . . . . . . . . . . . . . . 10 4.7. Impact to Traceroute . . . . . . . . . . . . . . . . . . 10
5. LSP Ping Relayed Echo Reply Example . . . . . . . . . . . . . 10 5. LSP Ping Relayed Echo Reply Example . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. Backward Compatibility . . . . . . . . . . . . . . . . . . . 12 7. Backward Compatibility . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8.1. New Message Type . . . . . . . . . . . . . . . . . . . . 13 8.1. New Message Type . . . . . . . . . . . . . . . . . . . . 13
8.2. New TLV . . . . . . . . . . . . . . . . . . . . . . . . . 13 8.2. New TLV . . . . . . . . . . . . . . . . . . . . . . . . . 14
8.3. New Return Code . . . . . . . . . . . . . . . . . . . . . 13 8.3. New Return Code . . . . . . . . . . . . . . . . . . . . . 14
9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 14 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 14
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
11.1. Normative References . . . . . . . . . . . . . . . . . . 14 11.1. Normative References . . . . . . . . . . . . . . . . . . 15
11.2. Informative References . . . . . . . . . . . . . . . . . 14 11.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
This document describes the extensions to the Label Switched Path This document describes the extensions to the Label Switched Path
(LSP) Ping as specified in [RFC4379], by adding a relayed echo reply (LSP) Ping as specified in [RFC4379], by adding a relayed echo reply
mechanism which could be used to detect data plane failures for the mechanism which could be used to detect data plane failures for the
inter autonomous system (AS) and inter-area LSPs. The extensions are inter autonomous system (AS) and inter-area LSPs. The extensions are
to update the [RFC4379]. Without these extensions, the ping to update the [RFC4379]. Without these extensions, the ping
functionality provided by [RFC4379] would fail in many deployed functionality provided by [RFC4379] would fail in many deployed
inter-AS scenarios, since the replying LSR in one AS may not have the inter-AS scenarios, since the replying LSR in one AS may not have the
available route to the initiator in the other AS. The mechanism in available route to the initiator in the other AS. The mechanism in
this document defines a new message type referred as "Relayed Echo this document defines a new message type referred as "Relayed Echo
Reply message", and a new TLV referred as "Relay Node Address Stack Reply message", and a new TLV referred as "Relay Node Address Stack
TLV". TLV".
This document is also to update [RFC4379], include updating of Echo
Request sending procedure in section 4.3 of [RFC4379], Echo Request
receiving procedure in section 4.4 of [RFC4379], Echo Reply sending
procedure in Section 4.5 of [RFC4379], Echo Reply receiving procedure
in section 4.6 of [RFC4379].
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 [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Motivation 2. Motivation
LSP Ping [RFC4379] defines a mechanism to detect the data plane LSP Ping [RFC4379] defines a mechanism to detect the data plane
failures and localize faults. The mechanism specifies that the Echo failures and localize faults. The mechanism specifies that the Echo
skipping to change at page 3, line 50 skipping to change at page 4, line 8
administrative domains where IP addresses reachability are allowed administrative domains where IP addresses reachability are allowed
among LSRs, and every LSR is able to route back to the originating among LSRs, and every LSR is able to route back to the originating
LSR. However, in practice, this is often not the case due to intra- LSR. However, in practice, this is often not the case due to intra-
provider routing policy, route hiding, and network address provider routing policy, route hiding, and network address
translation at autonomous system border routers (ASBR). In fact, it translation at autonomous system border routers (ASBR). In fact, it
is almost uniformly the case that in inter-AS scenarios, it is not is almost uniformly the case that in inter-AS scenarios, it is not
allowed the distribution or direct routing to the IP addresses of any allowed the distribution or direct routing to the IP addresses of any
of the nodes other than the ASBR in another AS. of the nodes other than the ASBR in another AS.
Figure 1 demonstrates a case where one LSP is set up between PE1 and Figure 1 demonstrates a case where one LSP is set up between PE1 and
PE2. If private addresses were in use within AS1, a traceroute from PE2. If PE1's IP address is not distributed to AS2, a traceroute
PE1 directed to PE2 could fail if the fault exists somewhere between from PE1 directed to PE2 could fail if the fault exists somewhere
ASBR2 and PE2. Because P2 cannot forward packets back to PE1 given between ASBR2 and PE2. Because P2 cannot forward packets back to PE1
that it is a private address within AS1. In this case, PE1 would given that it is an routable IP address in AS1 but not routable in
detect a path break, as the Echo Reply messages would not be AS2. In this case, PE1 would detect a path break, as the Echo Reply
received. Then localization of the actual fault would not be messages would not be received. Then localization of the actual
possible. fault would not be possible.
Note that throughout the document, routable address means that it is
possible to route an IP packet to this address using the normal
information exchanged by the IGP operating in the AS
+-------+ +-------+ +------+ +------+ +------+ +------+ +-------+ +-------+ +------+ +------+ +------+ +------+
| | | | | | | | | | | | | | | | | | | | | | | |
| PE1 +---+ P1 +---+ ASBR1+---+ ASBR2+---+ P2 +---+ PE2 | | PE1 +---+ P1 +---+ ASBR1+---+ ASBR2+---+ P2 +---+ PE2 |
| | | | | | | | | | | | | | | | | | | | | | | |
+-------+ +-------+ +------+ +------+ +------+ +------+ +-------+ +-------+ +------+ +------+ +------+ +------+
<---------------AS1-------------><---------------AS2------------> <---------------AS1-------------><---------------AS2------------>
<---------------------------- LSP ------------------------------> <---------------------------- LSP ------------------------------>
Figure 1: Simple Inter-AS LSP Configuration Figure 1: Simple Inter-AS LSP Configuration
skipping to change at page 4, line 45 skipping to change at page 5, line 22
\ | | | | | | \| | \ | | | | | | \| |
+--+ AGN12 +---+ AGN22 +---+ ABR2 +---+ LSR2 +--> to AGN +--+ AGN12 +---+ AGN22 +---+ ABR2 +---+ LSR2 +--> to AGN
| | | | | | | | | | | | | | | |
+-------+ +-------+ +------+ +------+ +-------+ +-------+ +------+ +------+
static route ISIS L1 LDP ISIS L2 LDP static route ISIS L1 LDP ISIS L2 LDP
<-Access-><--Aggregation Domain--><---------Core---------> <-Access-><--Aggregation Domain--><---------Core--------->
Figure 2: Seamless MPLS Architecture Figure 2: Seamless MPLS Architecture
This document describes extensions to the LSP Ping mechanism to This document describes extensions to the LSP Ping mechanism to
facilitate a response from the replying LSR, by defining a simple facilitate a response from the replying LSR, by defining a mechanism
mechanism that uses a relay node (e.g, ASBR) to relay the message that uses a relay node (e.g, ASBR) to relay the message back to the
back to the initiator. Every designated or learned relay node must initiator. Every designated or learned relay node must be reachable
have an IP route to the next relay node or to the initiator. Using a to the next relay node or to the initiator. Using a recursive
recursive approach, relay node could relay the message to the next approach, relay node could relay the message to the next relay node
relay node until the initiator is reached. until the initiator is reached.
The LSP Ping relay mechanism in this document is defined for unicast The LSP Ping relay mechanism in this document is defined for unicast
case. How to apply the LSP Ping relay mechanism in multicast case is case. How to apply the LSP Ping relay mechanism in multicast case is
out of the scope. out of the scope.
3. Extensions 3. Extensions
[RFC4379] describes the basic MPLS LSP Ping mechanism, which defines [RFC4379] describes the basic MPLS LSP Ping mechanism, which defines
two message types, Echo Request and Echo Reply message. This two message types, Echo Request and Echo Reply message. This
document defines a new message, Relayed Echo Reply message. This new document defines a new message, Relayed Echo Reply message. This new
skipping to change at page 6, line 35 skipping to change at page 7, line 7
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Relay Node Address Stack TLV Figure 3: Relay Node Address Stack TLV
- Type: to be assigned by IANA. A value should be assigned from - Type: to be assigned by IANA. A value should be assigned from
32768-49161 as suggested by [RFC4379] Section 3. 32768-49161 as suggested by [RFC4379] Section 3.
- Length: the length of the value field in octets. - Length: the length of the value field in octets.
- Initiator Source Port: the source UDP port that the initiator - Initiator Source Port: the source UDP port that the initiator uses
sends the Echo Request message, and also the port that is expected in the Echo Request message, and also the port that is expected to
to receive the Echo Reply message. receive the Echo Reply message.
- Number of Relayed Addresses: an integer indicating the number of - Number of Relayed Addresses: an integer indicating the number of
relayed addresses in the stack. relayed addresses in the stack.
- Stack of Relayed Addresses: a list of relay node addresses. - Stack of Relayed Addresses: a list of relay node addresses.
The format of each relay node address is as below: The format of each relay node address is as below:
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
skipping to change at page 7, line 26 skipping to change at page 7, line 39
1 IPv4 4 1 IPv4 4
2 IPv6 16 2 IPv6 16
Reserved: This field is reserved and MUST be set to zero. Reserved: This field is reserved and MUST be set to zero.
K bit: if the K bit is set to 1, then this sub-TLV MUST be kept in K bit: if the K bit is set to 1, then this sub-TLV MUST be kept in
Relay Node Address Stack during TLV compress process described in Relay Node Address Stack during TLV compress process described in
section 4.2. The entry with Unspecified Address Type SHOULD NOT set section 4.2. The entry with Unspecified Address Type SHOULD NOT set
K bit. K bit.
Having the K bit set on the relay node address entry causes that Having the K bit set in the relay node address entry causes that
entry to be preserved in the Relay Node Address Stack TLV for the entry to be preserved in the Relay Node Address Stack TLV for the
entire traceroute operation. A responder node MAY set the K bit to entire traceroute operation. A responder node MAY set the K bit to
ensure its relay node address entry remains as one of the relay nodes ensure its relay node address entry remains as one of the relay nodes
in the Relay Node Address Stack TLV. Some nodes could be configured in the Relay Node Address Stack TLV. The address with K bit set will
to always set the K bit, or the module handling MPLS echo requests always be a relay node address for the Relayed Echo Reply, see
could discover its K bit use through topology awareness. How a node section 4.3. Some nodes could be configured to always set the K bit,
determines to set the K bit is outside the scope of this document. or the module handling MPLS echo requests could discover its K bit
use through topology awareness. One application scenario of K bit is
given out in section 5.
Relayed Address: this field specifies the node address, either IPv4 Relayed Address: this field specifies the node address, either IPv4
or IPv6. or IPv6.
3.3. New Return Code 3.3. New Return Code
A new Return Code is used by the replying LSR to notify the initiator A new Return Code is used by the replying LSR to notify the initiator
that the packet length is exceeded unexpected by the Relay Node that the packet length is exceeded unexpected by the Relay Node
Address Stack TLV. Address Stack TLV.
skipping to change at page 8, line 30 skipping to change at page 8, line 42
message. message.
4.2. Receiving an Echo Request 4.2. Receiving an Echo Request
In addition to the processes in section 4.4 of [RFC4379], the In addition to the processes in section 4.4 of [RFC4379], the
procedures of the Relay Node Address Stack TLV are defined here. procedures of the Relay Node Address Stack TLV are defined here.
Upon receiving a Relay Node Address Stack TLV of the Echo Request Upon receiving a Relay Node Address Stack TLV of the Echo Request
message, the receiver MUST check the addresses of the stack in message, the receiver MUST check the addresses of the stack in
sequence from top to bottom (the first address in the stack will be sequence from top to bottom (the first address in the stack will be
the first one to be checked), to find out the first public routable the first one to be checked), to find out the first routable IP
IP address. Those address entries behind of the first routable IP address. Those address entries behind of the first routable IP
address in the address list with K bit set to 0 MUST be deleted, and address in the address list with K bit set to 0 MUST be deleted, and
the address entry of the replying LSR MUST be added at the bottom of the address entry of the replying LSR MUST be added at the bottom of
the stack. The address entry added by the replying LSR MUST be same the stack. The address entry added by the replying LSR MUST be same
as the source IP address of Relay Echo Reply (section 4.3) or Echo as the source IP address of Relay Echo Reply (section 4.3) or Echo
Reply message (section 4.5) being sent. Those address entries with K Reply message (section 4.5) being sent. A second or more address
bit set to 1 MUST be kept in the stack. The updated Relay Node entries could also be added if necessary, which depends on
Address Stack TLV MUST be carried in the response message. implementation. Those address entries with K bit set to 1 MUST be
kept in the stack. The updated Relay Node Address Stack TLV MUST be
carried in the response message.
If the replying LSR is configured to hide its routable address If the replying LSR is configured to hide its routable address
information, the address entry added in the stack SHOULD be a blank information, the address entry added in the stack SHOULD be a blank
entry with Address Type set to unspecified. The blank address entry entry with Address Type set to unspecified. The blank address entry
in the receiving Echo Request SHOULD be treated as an unroutable in the receiving Echo Request SHOULD be treated as an unroutable
address entry. address entry.
If the packet length was exceeded unexpectedly by the Relay Node If the packet length was exceeded unexpectedly by the Relay Node
Address Stack TLV, the TLV SHOULD be returned back unchanged in the Address Stack TLV, the TLV SHOULD be returned back unchanged in the
Echo Reply message. And the new return code in section 3.3 SHOULD be Echo Reply message. And the new return code in section 3.3 SHOULD be
used to notify the initiator of the situation. used to notify the initiator of the situation.
If the first routable IP address is the first address in the stack,
the replying LSR SHOULD respond an Echo Reply message to the
initiator.
If the first routable IP address is an intermediate node, other than
the first address in the stack, the replying LSR SHOULD send a
Relayed Echo Reply instead of an Echo Reply as a response.
An LSR not recognize the Relay Node Address Stack TLV, SHOULD ignore An LSR not recognize the Relay Node Address Stack TLV, SHOULD ignore
it according to section 3 of [RFC4379]. it according to section 3 of [RFC4379].
4.3. Originating an Relayed Echo Reply 4.3. Originating an Relayed Echo Reply
When the replying LSR receives an Echo Request with the first IP To find out the next relay node address, the node SHOULD check the
address in the Relay Node Address Stack TLV is IP unroutable, the address items in Relay Node Address Stack TLV in sequence from top to
replying LSR SHOULD send a Relayed Echo Reply message to the first down, and find the first IP routable address, e.g., A, and the last
routable intermediate node. The processing of Relayed Echo Reply is address with K bit set, e.g., B. If address A is before address B in
the same with the procedure of the Echo Reply described in Relay Node Address Stack TLV, then use address B as the next relay
node address. Otherwise, use address A as the next relay node
address. If there is no B existed, then use A as the next relay node
address.
When the replying LSR receives an Echo Request, and the first IP
address in the Relay Node Address Stack TLV is not the next relay
node address, the replying LSR SHOULD send a Relayed Echo Reply
message to the next relay node. The processing of Relayed Echo Reply
is the same with the procedure of the Echo Reply described in
Section 4.5 of [RFC4379], except the destination IP address and the Section 4.5 of [RFC4379], except the destination IP address and the
destination UDP port. The destination IP address of the Relayed Echo destination UDP port. The destination IP address of the Relayed Echo
Reply is set to the first routable IP address from the Relay Node Reply is set to the next relay node address from the Relay Node
Address Stack TLV, and both the source and destination UDP port is Address Stack TLV, and both the source and destination UDP port is
set to 3503. set to 3503. The updated Relay Node Address Stack TLV described in
section 4.2 MUST be carried in the Relayed Echo Reply message.
4.4. Relaying an Relayed Echo Reply 4.4. Relaying an Relayed Echo Reply
Upon receiving an Relayed Echo Reply message with its own address as Upon receiving an Relayed Echo Reply message with its own address as
the destination address in the IP header, the relay node SHOULD check the destination address in the IP header, the relay node SHOULD find
the address items in Relay Node Address Stack TLV in sequence from out the next relay node address as described in section 4.3.
top to down, and find the first routable node address.
If the first routable address is the top one of the address list,
e.g, the initiator address, the relay node SHOULD send an Echo Reply
message to the initiator containing the same payload with the Relayed
Echo Reply message received. See section 4.5 for detail.
If the first routable address is not the top one of the address list, If the next relay node address is not the first one in the address
e.g, another intermediate relay node, the relay node SHOULD send an list, e.g, another intermediate relay node, the relay node SHOULD
Relayed Echo Reply message to this relay node with the payload send an Relayed Echo Reply message to this next relay node with the
unchanged. The TTL of the Relayed Echo Reply SHOULD be copied from payload unchanged. The TTL of the Relayed Echo Reply SHOULD be
the received Relay Echo Reply and decremented by 1. copied from the received Relay Echo Reply and decremented by 1.
Note, the replying LSR SHOULD send a Relayed Echo Reply message to Note, the next relay node address MUST be located before the source
the first relay node found in Relay Node Address Stack TLV that is IP IP address of the received Relayed Echo Reply which MUST be also in
routable. The routable address MUST be located before the source IP the stack, otherwise the Relayed Echo Reply SHOULD NOT be sent, so as
address of the received Relayed Echo Reply which must be also in the to avoid potential loop.
stack, otherwise the Relayed Echo Reply SHOULD not be sent, so as to
avoid potential loop.
4.5. Sending an Echo Reply 4.5. Sending an Echo Reply
The Echo Reply is sent in two cases: The Echo Reply is sent in two cases:
1. When the replying LSR receives an Echo Request with the first IP 1. When the replying LSR receives an Echo Request, and the first IP
address in the Relay Node Address Stack TLV IP routable, the replying address in the Relay Node Address Stack TLV is the next relay node
LSR would send an Echo Reply to the initiator. In addition to the address (section 4.3), the replying LSR would send an Echo Reply to
procedure of the Echo Reply described in Section 4.5 of [RFC4379], the initiator. In addition to the procedure of the Echo Reply
the Relay Node Address Stack TLV would be carried in the Echo Reply. described in Section 4.5 of [RFC4379], the updated Relay Node Address
Stack TLV described in section 4.2 MUST be carried in the Echo Reply.
2. When the intermediate relay node receives a Relayed Echo Reply 2. When the intermediate relay node receives a Relayed Echo Reply,
with the first IP address in the Relay Node Address Stack TLV IP and the first IP address in the Relay Node Address Stack TLV is the
routable, the intermediate relay node would send the Echo Reply to next relay node address (section 4.3), the intermediate relay node
the initiator with the UDP payload unchanged other than the Message would send the Echo Reply to the initiator with the UDP payload
Type field (change from type of Relayed Echo Reply to Echo Reply). unchanged other than the Message Type field (change from type of
The destination IP address of the Echo Reply is set to the first IP Relayed Echo Reply to Echo Reply). The destination IP address of the
address in the stack, and the destination UDP port would be copied Echo Reply is set to the first IP address in the stack, and the
from the Initiator Source Port field of the Relay Node Address Stack destination UDP port would be copied from the Initiator Source Port
TLV. The source UDP port should be 3503. The TTL of the Echo Reply field of the Relay Node Address Stack TLV. The source UDP port
SHOULD be copied from the received Relay Echo Reply and decremented should be 3503. The TTL of the Echo Reply SHOULD be copied from the
by 1. received Relay Echo Reply and decremented by 1.
4.6. Receiving an Echo Reply 4.6. Receiving an Echo Reply
In addition to the processes in Section 4.6 of [RFC4379], the In addition to the processes in Section 4.6 of [RFC4379], the
initiator would copy the Relay Node Address Stack TLV received in the initiator would copy the Relay Node Address Stack TLV received in the
Echo Reply to the next Echo Request. Echo Reply to the next Echo Request.
4.7. Impact to Traceroute 4.7. Impact to Traceroute
Source IP address in Echo Reply and Relay Echo Reply are to be of the Source IP address in Echo Reply and Relay Echo Reply is to be of the
address of the node sending those packets, not the original address of the node sending those packets, not the original
responding node. Then the traceroute address output module will responding node. Then the traceroute address output module will
print the source IP address as below: print the source IP address as below:
if (Relay Node Address Stack TLV exists) { if (Relay Node Address Stack TLV exists) {
Print the last address in the stack; Print the last address in the stack;
} else { } else {
Print the source IP address of Echo Reply message; Print the source IP address of Echo Reply message;
} }
skipping to change at page 11, line 40 skipping to change at page 12, line 4
address following PE1 address. As a result, there would be PE1's address following PE1 address. As a result, there would be PE1's
address followed by ASBR1's address in the Relay Node Address Stack address followed by ASBR1's address in the Relay Node Address Stack
TLV of the Echo Reply sent by ASBR1. TLV of the Echo Reply sent by ASBR1.
PE1 then sends an Echo Request with outer-most label TTL=3, PE1 then sends an Echo Request with outer-most label TTL=3,
containing the Relay Node Address Stack TLV copied from the received containing the Relay Node Address Stack TLV copied from the received
Echo Reply message. Upon receiving the Echo Request message, ASBR2 Echo Reply message. Upon receiving the Echo Request message, ASBR2
checks the address list in the Relay Node Address Stack TLV in checks the address list in the Relay Node Address Stack TLV in
sequence, and finds out that PE1's address is IP route unreachable, sequence, and finds out that PE1's address is IP route unreachable,
and ASBR1's address is the first routable one in the Relay Node and ASBR1's address is the first routable one in the Relay Node
Address Stack TLV. ASBR2 adds its address as the last address item Address Stack TLV. So ASBR1 is the next relay node. ASBR2 adds its
following ASBR1's address in Relay Node Address Stack TLV, sets address as the last address item following ASBR1's address in Relay
ASBR1's address as the destination address of the Relayed Echo Reply, Node Address Stack TLV, sets ASBR1's address as the destination
and sends the Relayed Echo Reply to ASBR1. address of the Relayed Echo Reply, and sends the Relayed Echo Reply
to ASBR1.
Upon receiving the Relayed Echo Reply from ASBR2, ASBR1 checks the Upon receiving the Relayed Echo Reply from ASBR2, ASBR1 checks the
address list in the Relay Node Address Stack TLV in sequence, and address list in the Relay Node Address Stack TLV in sequence, and
finds out that PE1's address is first routable one in the address finds out that PE1's address is first routable one in the address
list. Then ASBR1 sends an Echo Reply to PE1 with the payload of the list. So PE1 is the next relay node. Then ASBR1 sends an Echo Reply
received Relayed Echo Reply no changes other than the Message Type to PE1 with the payload of the received Relayed Echo Reply unchanged
field. other than the Message Type field.
For the Echo Request with outer-most label TTL=4, P2 checks the For the Echo Request with outer-most label TTL=4, P2 checks the
address list in the Relay Node Address Stack TLV in sequence, and address list in the Relay Node Address Stack TLV in sequence, and
finds out that both PE1's and ASBR1's addresses are not IP routable, finds out that both PE1's and ASBR1's addresses are not IP routable,
and ASBR2's address is the first routable address. Then P2 sends an and ASBR2's address is the first routable address. Then P2 sends an
Relayed Echo Reply to ASBR2 with the Relay Node Address Stack TLV Relayed Echo Reply to ASBR2 with the Relay Node Address Stack TLV
containing four addresses, PE1's, ASBR1's, ASBR2's and P2's address containing four addresses, PE1's, ASBR1's, ASBR2's and P2's address
in sequence. in sequence.
Then according to the process described in section 4.4, ASBR2 sends Then according to the process described in section 4.4, ASBR2 sends
the Relayed Echo Reply to ASBR1. Upon receiving the Relayed Echo the Relayed Echo Reply to ASBR1. Upon receiving the Relayed Echo
Reply, ASBR1 sends an Echo Reply to PE1 which is routable. And as Reply, ASBR1 sends an Echo Reply to PE1 which is IP routable. And as
relayed by ASBR2 and ASBR1, the Echo Reply would finally be sent to relayed by ASBR2 and ASBR1, the Echo Reply would finally be sent to
the initiator PE1. the initiator PE1.
For the Echo Request with outer-most label TTL=5, the Echo Reply For the Echo Request with outer-most label TTL=5, the Echo Reply
would relayed to PE1 by ASBR2 and ASBR1, similar to the case of would relayed to PE1 by ASBR2 and ASBR1, similar to the case of
TTL=4. TTL=4.
The Echo Reply from the replying node which has no IP reachable route The Echo Reply from the replying node which has no IP reachable route
to the initiator is finally transmitted to the initiator by multiple to the initiator is finally transmitted to the initiator by multiple
relay nodes. relay nodes.
In the case that the interface address of ASBR1 to P1 is IP1 which
maybe an IPv4 private address and not IP routable for AS2, and the
loopback address on ASRB1 is IP2 which is routable for AS2. Then
when ASBR1 sends a Relayed Echo Reply, it will firstly add IP1
without K bit set in the Relay Node Address Stack TLV, and then add
IP2 with K bit set in the stack TLV. Then ASBR2/P2 could relay the
Relayed Echo Reply back first to IP2 which is routable for ASBR2/P2,
then ASBR1 will send Echo Reply to PE1. Thanks for the K bit, the
ASBR1 will not be skipped for message relay.
6. Security Considerations 6. Security Considerations
The Relayed Echo Reply mechanism for LSP Ping creates an increased The Relayed Echo Reply mechanism for LSP Ping creates an increased
risk of DoS by putting the IP address of a target router in the Relay risk of DoS by putting the IP address of a target router in the Relay
Node Address Stack. These messages then could be used to attack the Node Address Stack. These messages then could be used to attack the
control plane of an LSR by overwhelming it with these packets. A control plane of an LSR by overwhelming it with these packets. A
rate limiter SHOULD be applied to the well-known UDP port on the rate limiter SHOULD be applied to the well-known UDP port on the
relay node as suggested in [RFC4379]. The node which acts as a relay relay node as suggested in [RFC4379]. The node which acts as a relay
node SHOULD validate the relay reply against a set of valid source node SHOULD validate the relay reply against a set of valid source
addresses and discard packets from untrusted border router addresses. addresses and discard packets from untrusted border router addresses.
skipping to change at page 14, line 17 skipping to change at page 14, line 40
TBD Response Packet length was exceeded unexpected by the Relay TBD Response Packet length was exceeded unexpected by the Relay
Node Address Stack TLV unexpected Node Address Stack TLV unexpected
The value should be assigned from the "Standards Action" range The value should be assigned from the "Standards Action" range
(0-191), and using the lowest free value within this range. (0-191), and using the lowest free value within this range.
9. Acknowledgement 9. Acknowledgement
The authors would like to thank Carlos Pignataro, Xinwen Jiao, Manuel The authors would like to thank Carlos Pignataro, Xinwen Jiao, Manuel
Paul, Loa Andersson, Wim Henderickx, Mach Chen, Thomas Morin, Gregory Paul, Loa Andersson, Wim Henderickx, Mach Chen, Thomas Morin, Gregory
Mirsky, and Nobo Akiya for their valuable comments and suggestions. Mirsky, Nobo Akiya and Joel M. Halpern for their valuable comments
and suggestions.
10. Contributors 10. Contributors
Ryan Zheng Ryan Zheng
JSPTPD JSPTPD
371, Zhongshan South Road 371, Zhongshan South Road
Nanjing, 210006, China Nanjing, 210006, China
Email: ryan.zhi.zheng@gmail.com Email: ryan.zhi.zheng@gmail.com
11. References 11. References
11.1. Normative References 11.1. Normative References
[I-D.ietf-mpls-proxy-lsp-ping]
Swallow, G., Lim, V., and S. Aldrin, "Proxy MPLS Echo
Request", draft-ietf-mpls-proxy-lsp-ping-02 (work in
progress), July 2014.
[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.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379, Label Switched (MPLS) Data Plane Failures", RFC 4379,
February 2006. February 2006.
11.2. Informative References 11.2. Informative References
[I-D.ietf-mpls-seamless-mpls] [I-D.ietf-mpls-seamless-mpls]
 End of changes. 33 change blocks. 
105 lines changed or deleted 121 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/