draft-ietf-mpls-lsp-ping-04.txt   draft-ietf-mpls-lsp-ping-05.txt 
Network Working Group K. Kompella (Juniper) Network Working Group K. Kompella (Juniper)
Internet Draft P. Pan (Ciena) Internet Draft P. Pan (Ciena)
draft-ietf-mpls-lsp-ping-04.txt N. Sheth (Juniper) draft-ietf-mpls-lsp-ping-05.txt N. Sheth (Juniper)
Category: Standards Track D. Cooper (Global Crossing) Category: Standards Track D. Cooper (Global Crossing)
Expires: April 2003 G. Swallow (Cisco) Expires: August 2004 G. Swallow (Cisco)
S. Wadhwa (Juniper) S. Wadhwa (Juniper)
R. Bonica (WorldCom) R. Bonica (WorldCom)
October 2003 February 2004
Detecting MPLS Data Plane Failures Detecting MPLS Data Plane Failures
*** DRAFT *** <draft-ietf-mpls-lsp-ping-05.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
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.
skipping to change at page 1, line 38 skipping to change at page 1, line 38
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.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract Abstract
This document describes a simple and efficient mechanism that can be This document describes a simple and efficient mechanism that can be
used to detect data plane failures in Multi-Protocol Label Switching used to detect data plane failures in Multi-Protocol Label Switching
(MPLS) Label Switched Paths (LSPs). There are two parts to this (MPLS) Label Switched Paths (LSPs). There are two parts to this
document: information carried in an MPLS "echo request" and "echo document: information carried in an MPLS "echo request" and "echo
reply" for the purposes of fault detection and isolation; and reply" for the purposes of fault detection and isolation; and
mechanisms for reliably sending the echo reply. mechanisms for reliably sending the echo reply.
Changes since last revision Changes since last revision
(This section to be removed before publication.) (This section to be removed before publication.)
Clarified that an MPLS echo request/reply can be either an IPv4 or an *** Changed the format of an L2 circuit ID FEC. Added a sender's PE
IPv6 packet. address field to uniquely identify the VC ID ***
Expanded on Return Codes (section 3.1). Further clarified that an MPLS echo request/reply can be either an
IPv4 or an IPv6 packet.
Expanded and reformatted the section on Downstream Mapping. Added format pictures for LDP IPv4/IPv6 prefixes.
Expanded the section on Receiving an MPLS Echo Request Clarified the section on Receiving an MPLS Echo Request.
Issues Issues
(This section to be removed before publication.) (This section to be removed before publication.)
Need to fill out Downstream Verification.
Need to address issues with pinging L3VPN FECs. Need to address issues with pinging L3VPN FECs.
Need to add new FEC type for "type 129" L2 circuits.
1. Introduction 1. Introduction
This document describes a simple and efficient mechanism that can be This document describes a simple and efficient mechanism that can be
used to detect data plane failures in MPLS LSPs. There are two parts used to detect data plane failures in MPLS LSPs. There are two parts
to this document: information carried in an MPLS "echo request" and to this document: information carried in an MPLS "echo request" and
"echo reply"; and mechanisms for transporting the echo reply. The "echo reply"; and mechanisms for transporting the echo reply. The
first part aims at providing enough information to check correct first part aims at providing enough information to check correct
operation of the data plane, as well as a mechanism to verify the operation of the data plane, as well as a mechanism to verify the
data plane against the control plane, and thereby localize faults. data plane against the control plane, and thereby localize faults.
The second part suggests two methods of reliable reply channels for The second part suggests two methods of reliable reply channels for
skipping to change at page 5, line 27 skipping to change at page 5, line 29
Value Meaning Value Meaning
----- ------- ----- -------
1 MPLS Echo Request 1 MPLS Echo Request
2 MPLS Echo Reply 2 MPLS Echo Reply
The Reply Mode can take one of the following values: The Reply Mode can take one of the following values:
Value Meaning Value Meaning
----- ------- ----- -------
1 Do not reply 1 Do not reply
2 Reply via an IPv4 UDP packet 2 Reply via an IPv4/IPv6 UDP packet
3 Reply via an IPv4 UDP packet with Router Alert 3 Reply via an IPv4/IPv6 UDP packet with Router Alert
4 Reply via application level control channel 4 Reply via application level control channel
An MPLS echo request with "Do not reply" may be used for one-way An MPLS echo request with "Do not reply" may be used for one-way
connectivity tests; the receiving router may log gaps in the sequence connectivity tests; the receiving router may log gaps in the sequence
numbers and/or maintain delay/jitter statistics. An MPLS echo numbers and/or maintain delay/jitter statistics. An MPLS echo
request would normally have "Reply via an IPv4 UDP packet"; if the request would normally have "Reply via an IPv4/IPv6 UDP packet"; if
normal IPv4 return path is deemed unreliable, one may use "Reply via the normal IP return path is deemed unreliable, one may use "Reply
an IPv4 UDP packet with Router Alert" (note that this requires that via an IPv4/IPv6 UDP packet with Router Alert" (note that this
all intermediate routers understand and know how to forward MPLS echo requires that all intermediate routers understand and know how to
replies). forward MPLS echo replies). The echo reply uses the same IP version
number as the received echo request, i.e., an IPv4 encapsulated echo
reply is sent in response to an IPv4 encapsulated echo request.
Any application which supports an IP control channel between its Any application which supports an IP control channel between its
control entities may set the Reply Mode to 4 to ensure that replies control entities may set the Reply Mode to 4 to ensure that replies
use that same channel. Further definition of this codepoint is use that same channel. Further definition of this codepoint is
application specific and thus beyond the scope of this docuemnt. application specific and thus beyond the scope of this docuemnt.
Return Codes and Subcodes are described in the next section. Return Codes and Subcodes are described in the next section.
The Sender's Handle is filled in by the sender, and returned The Sender's Handle is filled in by the sender, and returned
unchanged by the receiver in the echo reply (if any). There are no unchanged by the receiver in the echo reply (if any). There are no
skipping to change at page 8, line 36 skipping to change at page 8, line 37
Route Distinguisher of RD-foo-Y. Alternatively, X can send a FEC Route Distinguisher of RD-foo-Y. Alternatively, X can send a FEC
Stack TLV with two FECs, the first of type LDP IPv4 with a prefix of Stack TLV with two FECs, the first of type LDP IPv4 with a prefix of
192.168.1.1/32 and the second of type of IP VPN with a prefix 10/8 192.168.1.1/32 and the second of type of IP VPN with a prefix 10/8
with Route Distinguisher of RD-foo-Y. In either case, the MPLS echo with Route Distinguisher of RD-foo-Y. In either case, the MPLS echo
request would have a label stack of <1001, 23456>. (Note: in this request would have a label stack of <1001, 23456>. (Note: in this
example, 1001 is the "outer" label and 23456 is the "inner" label.) example, 1001 is the "outer" label and 23456 is the "inner" label.)
3.2.1. LDP IPv4 Prefix 3.2.1. LDP IPv4 Prefix
The value consists of four octets of an IPv4 prefix followed by one The value consists of four octets of an IPv4 prefix followed by one
octet of prefix length in bits. The IPv4 prefix is in network byte octet of prefix length in bits; the format is given below. The IPv4
order. See [LDP] for an example of a Mapping for an IPv4 FEC. prefix is in network byte order; if the prefix is shorter than 32
bits, trailing bits SHOULD be set to zero. See [LDP] for an example
of a Mapping for an IPv4 FEC.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.2. LDP IPv6 Prefix 3.2.2. LDP IPv6 Prefix
The value consists of sixteen octets of an IPv6 prefix followed by The value consists of sixteen octets of an IPv6 prefix followed by
one octet of prefix length in bits. The IPv6 prefix is in network one octet of prefix length in bits; the format is given below. The
byte order. See [LDP] for an example of a Mapping for an IPv6 FEC. IPv6 prefix is in network byte order; if the prefix is shorter than
128 bits, the trailing bits SHOULD be set to zero. See [LDP] for an
example of a Mapping for an IPv6 FEC.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 prefix |
| (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.3. RSVP IPv4 Session 3.2.3. RSVP IPv4 Session
The value has the format below. The value fields are taken from The value has the format below. The value fields are taken from
[RFC3209, sections 4.6.1.1 and 4.6.2.1]. [RFC3209, sections 4.6.1.1 and 4.6.2.1].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 tunnel end point address | | IPv4 tunnel end point address |
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| Route Distinguisher | | Route Distinguisher |
| (8 octets) | | (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender's CE ID | Receiver's CE ID | | Sender's CE ID | Receiver's CE ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encapsulation Type | Must Be Zero | | Encapsulation Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.8. L2 Circuit ID 3.2.8. L2 Circuit ID
The value field consists of a remote PE address (the address of the The value field consists of the sender's PE address (the source
targetted LDP session), a VC ID and an encapsulation type, as address of the targetted LDP session), the remote PE address (the
follows: destination address of the targetted LDP session), a VC ID and an
encapsulation type, 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender's PE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote PE Address | | Remote PE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VC ID | | VC ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encapsulation Type | Must Be Zero | | Encapsulation Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.3. Downstream Mapping 3.3. Downstream Mapping
The Downstream Mapping object is an optional TLV. Only one The Downstream Mapping object is an optional TLV. Only one
skipping to change at page 18, line 34 skipping to change at page 19, line 6
An LSR X that receives an MPLS echo request first parses the packet An LSR X that receives an MPLS echo request first parses the packet
to ensure that it is a well-formed packet, and that the TLVs that are to ensure that it is a well-formed packet, and that the TLVs that are
not marked "Ignore" are understood. If not, X SHOULD send an MPLS not marked "Ignore" are understood. If not, X SHOULD send an MPLS
echo reply with the Return Code set to "Malformed echo request echo reply with the Return Code set to "Malformed echo request
received" or "TLV not understood" (as appropriate), and the Subcode received" or "TLV not understood" (as appropriate), and the Subcode
set to zero. In the latter case, the misunderstood TLVs (only) are set to zero. In the latter case, the misunderstood TLVs (only) are
included in the reply. included in the reply.
If the echo request is good, X notes the interface I over which the If the echo request is good, X notes the interface I over which the
echo was received, and the label stack with which it came. If the echo was received, and the label stack with which it came.
MPLS echo request contained a Downstream Verification object (TBD),
then X must format this information as a Downstream Verification
object and include it in its MPLS echo reply message.
X matches up the labels in the received label stack with the FECs X matches up the labels in the received label stack with the FECs
contained in the FEC stack. The matching is done beginning at the contained in the FEC stack. The matching is done beginning at the
bottom of both stacks and working up. For reporting purposes the bottom of both stacks, and working up. For reporting purposes the
bottom of stack is consided to be stack-depth of 1. This is to bottom of stack is consided to be stack-depth of 1. This is to
establish an absolute reference for the case where the stack may have establish an absolute reference for the case where the stack may have
more labels than are in the FEC stack and the sender of the ping has more labels than are in the FEC stack.
not requested that a Downstream Verification TLV be sent. If there
are more FECs than labels, the extra FECs are assumed to correspond If there are more FECs than labels, the extra FECs are assumed to
to Implicit Null Labels. correspond to Implicit Null Labels. Thus for the processing below,
there is never the case where there is a FEC with no corresponding
label. Further the label operation associated with an assumed Null
Label is 'pop and continue processing'.
Note: in all the error codes listed in this draft a stack-depth of 0 Note: in all the error codes listed in this draft a stack-depth of 0
means "no value specified". This allows compatibility with existing means "no value specified". This allows compatibility with existing
implementations which do not use the Return Subcode field. implementations which do not use the Return Subcode field.
X sets a variable, call it current-stack-depth, to the number of X sets a variable, call it current-stack-depth, to the number of
labels in the received label stack. Processing now continues with labels in the received label stack. Processing now continues with
the following steps: the following steps:
1. Check if there is a FEC corresponding to the current-stack- 1. Check if there is a FEC corresponding to the current-stack-
depth. If there is, go to step 2. If not, check if the label is depth. If there is, go to step 2. If not, check if the label is
valid on interface I. If it is, continue with step 4. Otherwise valid on interface I. If it is, continue with step 4. Otherwise
X MUST send an MPLS echo reply with a Return Code 11, "No label X MUST send an MPLS echo reply with a Return Code 11, "No label
entry at stack-depth" and a Return Subcode set to current-stack- entry at stack-depth" and a Return Subcode set to current-stack-
depth. depth.
2. Check the FEC at the current-stack-depth to determine what 2. Check the FEC at the current-stack-depth to determine what
protocol was used to advertise it. If X can determine that no protocol would be used to advertise it. If it can determine that
protocol associated with interface I would have advertised a FEC no protocol associated with interface I, would have advertised a
of that FEC-Type, X MUST send an MPLS echo reply with a Return FEC of that FEC-Type, X MUST send an MPLS echo reply with a
Code 12, "Protocol not associated with interface at FEC stack- Return Code 12, "Protocol not associated with interface at FEC
depth" and a Return Subcode set to current-stack-depth. stack-depth" and a Return Subcode set to current-stack-depth.
3. Check that the mapping for the FEC at the current-stack-depth is 3. Check that the mapping for the FEC at the current-stack-depth is
the corresponding label. the corresponding label.
If no mapping for the FEC exists, X MUST send an MPLS echo reply If no mapping for the FEC exists, X MUST send an MPLS echo reply
with a Return Code 4, "Replying router has no mapping for the FEC with a Return Code 4, "Replying router has no mapping for the FEC
at stack-depth" and a Return Subcode set to current- stack-depth. at stack-depth" and a Return Subcode set to current- stack-depth.
If a mapping is found, but the mapping is not the corresponding If a mapping is found, but the mapping is not the corresponding
label, X MUST send an MPLS echo reply with a Return Code 10, label, X MUST send an MPLS echo reply with a Return Code 10,
"Mapping for this FEC is not the given label at stack-depth" and "Mapping for this FEC is not the given label at stack-depth" and
a Return Subcode set to current-stack-depth. a Return Subcode set to current-stack-depth.
4. X determines the label operation. If the operation is to pop and 4. X determines the label operation. If the operation is to pop and
continue processing, X checks the current-stack-depth. If it is continue processing, X checks the current-stack-depth. If it is
one, X MUST send an MPLS echo reply with a Return Code 3, one, X MUST send an MPLS echo reply with a Return Code 3,
"Replying router is an egress for the FEC at stack depth" and a "Replying router is an egress for the FEC at stack depth" and a
Return Subcode set to one. Otherwise, X decrements current- Return Subcode set to one. Otherwise, X decrements current-stack-
stack-depth and goes back to step 1. depth and goes back to step 1.
If the label operation is pop and switch based on the popped If the label operation is pop and switch based on the popped
label, X then checks if it is valid to forward a labelled packet. label, X then checks if it is valid to forward a labelled packet.
If it is not valid to forward a labelled packet, or the current- If it is, X MUST send an MPLS echo reply with a Return Code 8,
stack-depth is one, X MUST send an MPLS echo reply with a Return "Label switched at stack-depth" and a Return Subcode set to
Code 9, "Label switched but no MPLS forwarding at stack-depth" current-stack-depth. If it is not valid to forward a labelled
and a Return Subcode set to current-stack-depth. Otherwise, X packet, X MUST send an MPLS echo reply with a Return Code 9,
MUST send an MPLS echo reply with a Return Code 8, "Label "Label switched but no MPLS forwarding at stack-depth" and a
switched at stack-depth" and a Return Subcode set to current- Return Subcode set to current-stack-depth. This return code is
stack-depth. sent even if current-stack-depth is one.
If the label operation is swap, X MUST send an MPLS echo reply If the label operation is swap, X MUST send an MPLS echo reply
with a Return Code 8, "Label switched at stack-depth" and a with a Return Code 8, "Label switched at stack-depth" and a
Return Subcode set to current-stack-depth. Return Subcode set to current-stack-depth.
If the MPLS echo request contains a downstream mapping TLV, and the If the MPLS echo request contains a downstream mapping TLV, and the
MPLS echo reply has either a Return Code of 8, or a Return Code of 9 MPLS echo reply has either a Return Code of 8, or a Return Code of 9
with a Return Subcode of 1 then Downstream mapping TLVs SHOULD be with a Return Subcode of 1 then Downstream mapping TLVs SHOULD be
included for each multipath. included for each multipath.
If the echo request has a Reply Mode that wants a reply, X uses the X uses the procedure in the next subsection to send the echo reply.
procedure in the next subsection to send the echo reply.
4.4. Sending an MPLS Echo Reply 4.4. Sending an MPLS Echo Reply
An MPLS echo reply is a UDP packet. It MUST ONLY be sent in response An MPLS echo reply is a UDP packet. It MUST ONLY be sent in response
to an MPLS echo request. The source IP address is a routable address to an MPLS echo request. The source IP address is a routable address
of the replier; the source port is the well-known UDP port for MPLS of the replier; the source port is the well-known UDP port for MPLS
ping. The destination IP address and UDP port are copied from the ping. The destination IP address and UDP port are copied from the
source IP address and UDP port of the echo request. The IP TTL is source IP address and UDP port of the echo request. The IP TTL is
set to 255. If the Reply Mode in the echo request is "Reply via an set to 255. If the Reply Mode in the echo request is "Reply via an
IPv4 UDP packet with Router Alert", then the IP header MUST contain IPv4 UDP packet with Router Alert", then the IP header MUST contain
skipping to change at page 24, line 11 skipping to change at page 24, line 16
Private Use, the Length MUST be at least 4, and the first four octets Private Use, the Length MUST be at least 4, and the first four octets
MUST be that vendor's SMI Enterprise Code, in network octet order. MUST be that vendor's SMI Enterprise Code, in network octet order.
The rest of the Value field is private to the vendor. The rest of the Value field is private to the vendor.
Acknowledgments Acknowledgments
This document is the outcome of many discussions among many people, This document is the outcome of many discussions among many people,
that include Manoj Leelanivas, Paul Traina, Yakov Rekhter, Der-Hwa that include Manoj Leelanivas, Paul Traina, Yakov Rekhter, Der-Hwa
Gan, Brook Bailey, Eric Rosen and Ina Minei. Gan, Brook Bailey, Eric Rosen and Ina Minei.
The Multipath Information sub-field of the Downstream Mapping TLV was The description of the Multipath Information sub-field of the
adapted from text suggested by Curtis Villamizar. Downstream Mapping TLV was adapted from text suggested by Curtis
Villamizar.
Appendix Appendix
This appendix specifies non-normative aspects of detecting MPLS data This appendix specifies non-normative aspects of detecting MPLS data
plane liveness. plane liveness.
5.1. CR-LDP FEC 5.1. CR-LDP FEC
This section describes how a CR-LDP FEC can be included in an Echo This section describes how a CR-LDP FEC can be included in an Echo
Request using the following FEC subtype: Request using the following FEC subtype:
skipping to change at page 26, line 29 skipping to change at page 26, line 35
be obtained from the IETF Secretariat. be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive this standard. Please address the information to the IETF Executive
Director. Director.
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2004). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implmentation may be prepared, copied, published and or assist in its implmentation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind, distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
 End of changes. 

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