draft-ietf-mpls-lsp-ping-08.txt   draft-ietf-mpls-lsp-ping-09.txt 
Network Working Group Kireeti Kompella Network Working Group Kireeti Kompella
Internet Draft Juniper Networks, Inc. Internet Draft Juniper Networks, Inc.
Category: Standards Track Category: Standards Track
Expiration Date: August 2005 Expiration Date: November 2005
George Swallow George Swallow
Cisco Systems, Inc. Cisco Systems, Inc.
February 2005 May 2005
Detecting MPLS Data Plane Failures Detecting MPLS Data Plane Failures
draft-ietf-mpls-lsp-ping-08.txt draft-ietf-mpls-lsp-ping-09.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, the authors certify that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which we are aware have been applicable patent or other IPR claims of which he or she is aware
disclosed, and any of which we become aware will be disclosed, in have been or will be disclosed, and any of which he or she becomes
accordance with RFC 3668. aware will be disclosed, in accordance with Section 6 of BCP 79.
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 5 of RFC3667. Internet-Drafts are working all provisions of Section 5 of RFC3667. Internet-Drafts are working
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Copyright Notice
Copyright (C) The Internet Society (2005).
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.)
o added clarification of TLV lengths, with examples; o fixed the optional vs. mandatory TLV wording
o added a Global Flags field in the header for the o Removed the Error TLV (which never found use and was undefined)
'validate FEC' flag; o Removed an extraneous paragraph from the processing rules and did
o fixed the optional vs. mandatory Types wording; some further word-smithing
o added several new FEC sub-TLVs: o Removed Appendix A on CR-LDP
- 12 BGP labeled IPv4 prefix o Added an Address Type field to the Address and Interface Object;
+ 12 BGP labeled IPv4 prefix combined the IPv4 & IPv6 formats into a single TLV
+ 13 BGP labeled IPv6 prefix (TBD) o Modified example TLV / Sub-TLV to be more instructive on
+ 14 Generic IPv4 prefix determining (Sub-)TLV lengths
+ 15 Generic IPv6 prefix o Removed the BGP Next Hop field from the BGP Labeled IPv4 FEC
+ 16 Nil FEC o Added the BGP Labeled IPv6 FEC
o in Downstream Mapping TLV o Corrected the length calculation for the Downsteam Mapping TLV
+ added an Address Type of IPv6 Unnumbered; o Added two special values for the Downstream Router ID
+ added DS Flags to the DS Map, with 2 defined bits; o Added an error code for upstream Interface Index Unknown
+ renamed Hash key type to multipath type and dropped o Added all requested allocations to the IANA section
codepoints for which no processing rules have been o Spelling and Word-smithing
defined;
o added "Reply TOS byte" TLV;
o updated processing rules to deal fully deal with implicit
null labels
o added text on processing fewer prefixes in DS maps;
o added text on "Testing LSPs That Are Used to Carry MPLS
Payloads";
o fixed text on non-compatible routers.
Contents Contents
1 Introduction .............................................. 5 1 Introduction .............................................. 4
1.1 Conventions ............................................... 5 1.1 Conventions ............................................... 4
1.2 Structure of this document ................................ 5 1.2 Structure of this document ................................ 4
1.3 Contributors .............................................. 5 1.3 Contributors .............................................. 4
2 Motivation ................................................ 6 2 Motivation ................................................ 5
3 Packet Format ............................................. 7 3 Packet Format ............................................. 6
3.1 Return Codes .............................................. 10 3.1 Return Codes .............................................. 10
3.2 Target FEC Stack .......................................... 12 3.2 Target FEC Stack .......................................... 11
3.2.1 LDP IPv4 Prefix ........................................... 13 3.2.1 LDP IPv4 Prefix ........................................... 12
3.2.2 LDP IPv6 Prefix ........................................... 13 3.2.2 LDP IPv6 Prefix ........................................... 12
3.2.3 RSVP IPv4 Session ......................................... 14 3.2.3 RSVP IPv4 LSP ............................................. 13
3.2.4 RSVP IPv6 Session ......................................... 14 3.2.4 RSVP IPv6 LSP ............................................. 13
3.2.5 VPN IPv4 Prefix ........................................... 15 3.2.5 VPN IPv4 Prefix ........................................... 14
3.2.6 VPN IPv6 Prefix ........................................... 15 3.2.6 VPN IPv6 Prefix ........................................... 14
3.2.7 L2 VPN Endpoint ........................................... 15 3.2.7 L2 VPN Endpoint ........................................... 15
3.2.8 FEC 128 Pseudowire (Deprecated) ........................... 16 3.2.8 FEC 128 Pseudowire (Deprecated) ........................... 15
3.2.9 FEC 128 Pseudowire (Current) .............................. 16 3.2.9 FEC 128 Pseudowire (Current) .............................. 16
3.2.10 FEC 129 Pseudowire ........................................ 17 3.2.10 FEC 129 Pseudowire ........................................ 16
3.2.11 BGP Labeled IPv4 Prefix ................................... 17 3.2.11 BGP Labeled IPv4 Prefix ................................... 17
3.2.12 Generic IPv4 Prefix ....................................... 18 3.2.12 BGP Labeled IPv6 Prefix ................................... 17
3.2.13 Generic IPv6 Prefix ....................................... 18 3.2.13 Generic IPv4 Prefix ....................................... 18
3.2.14 Nil FEC ................................................... 19 3.2.14 Generic IPv6 Prefix ....................................... 18
3.3 Downstream Mapping ........................................ 20 3.2.15 Nil FEC ................................................... 19
3.3.1 Multipath Information Encoding ............................ 23 3.3 Downstream Mapping ........................................ 19
3.3.2 Downstream Router and Interface ........................... 24 3.3.1 Multipath Information Encoding ............................ 24
3.4 Pad TLV ................................................... 25 3.3.2 Downstream Router and Interface ........................... 26
3.5 Error Code ................................................ 25 3.4 Pad TLV ................................................... 26
3.6 Vendor Enterprise Code .................................... 25 3.5 Vendor Enterprise Code .................................... 27
3.7 Interface and Label Stack Object .......................... 26 3.6 Interface and Label Stack ................................. 27
3.7.1 IPv4 Interface and Label Stack Object ..................... 26 3.7 Errored TLVs .............................................. 28
3.7.2 IPv6 Interface and Label Stack Object ..................... 27 3.8 Reply TOS Byte TLV ........................................ 29
3.8 Errored TLVs .............................................. 28
3.9 Reply TOS Byte TLV ........................................ 29
4 Theory of Operation ....................................... 29 4 Theory of Operation ....................................... 29
4.1 Dealing with Equal-Cost Multi-Path (ECMP) ................. 29 4.1 Dealing with Equal-Cost Multi-Path (ECMP) ................. 30
4.2 Testing LSPs That Are Used to Carry MPLS Payloads ......... 30 4.2 Testing LSPs That Are Used to Carry MPLS Payloads ......... 31
4.3 Sending an MPLS Echo Request .............................. 31 4.3 Sending an MPLS Echo Request .............................. 31
4.4 Receiving an MPLS Echo Request ............................ 31 4.4 Receiving an MPLS Echo Request ............................ 32
4.5 Sending an MPLS Echo Reply ................................ 35 4.5 Sending an MPLS Echo Reply ................................ 35
4.6 Receiving an MPLS Echo Reply .............................. 36 4.6 Receiving an MPLS Echo Reply .............................. 36
4.7 Issue with VPN IPv4 and IPv6 Prefixes ..................... 36 4.7 Issue with VPN IPv4 and IPv6 Prefixes ..................... 36
4.8 Non-compliant Routers ..................................... 37 4.8 Non-compliant Routers ..................................... 37
5 References ................................................ 37 5 References ................................................ 37
6 Security Considerations ................................... 38 6 Security Considerations ................................... 38
7 IANA Considerations ....................................... 38 7 IANA Considerations ....................................... 38
7.1 Message Types, Reply Modes, Return Codes .................. 39 7.1 Message Types, Reply Modes, Return Codes .................. 39
7.2 TLVs ...................................................... 39 7.2 TLVs ...................................................... 39
8 Acknowledgments ........................................... 39 8 Acknowledgments ........................................... 40
A Appendix .................................................. 40
A.1 CR-LDP FEC ................................................ 40
A.2 Downstream Mapping for CR-LDP ............................. 40
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
the echo request message, for more robust fault isolation. the echo request message, for more robust fault isolation.
An important consideration in this design is that MPLS echo requests An important consideration in this design is that MPLS echo requests
follow the same data path that normal MPLS packets would traverse. follow the same data path that normal MPLS packets would traverse.
MPLS echo requests are meant primarily to validate the data plane, MPLS echo requests are meant primarily to validate the data plane,
and secondarily to verify the data plane against the control plane. and secondarily to verify the data plane against the control plane.
Mechanisms to check the control plane are valuable, but are not cov- Mechanisms to check the control plane are valuable, but are not cov-
ered in this document. ered in this document.
To avoid potential Denial of Service attacks, it is recommended to
regulate the LSP ping traffic going to the control plane. A rate
limiter should be applied to the well-known UDP port defined below.
1.1. Conventions 1.1. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [KEYWORDS]. document are to be interpreted as described in RFC 2119 [KEYWORDS].
1.2. Structure of this document 1.2. Structure of this document
The body of this memo contains four main parts: motivation, MPLS echo The body of this memo contains four main parts: motivation, MPLS echo
request/reply packet format, LSP ping operation, and a reliable request/reply packet format, LSP ping operation, and a reliable
skipping to change at page 7, line 7 skipping to change at page 6, line 7
One way these tools can be used is to periodically ping a FEC to One way these tools can be used is to periodically ping a FEC to
ensure connectivity. If the ping fails, one can then initiate a ensure connectivity. If the ping fails, one can then initiate a
traceroute to determine where the fault lies. One can also periodi- traceroute to determine where the fault lies. One can also periodi-
cally traceroute FECs to verify that forwarding matches the control cally traceroute FECs to verify that forwarding matches the control
plane; however, this places a greater burden on transit LSRs and thus plane; however, this places a greater burden on transit LSRs and thus
should be used with caution. should be used with caution.
3. Packet Format 3. Packet Format
An MPLS echo request is a (possibly labelled) IPv4 or IPv6 UDP An MPLS echo request is a (possibly labeled) IPv4 or IPv6 UDP packet;
packet; the contents of the UDP packet have the following format: the contents of the UDP packet have the following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version Number | Global Flags | | Version Number | Global Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Type | Reply mode | Return Code | Return Subcode| | Message Type | Reply mode | Return Code | Return Subcode|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender's Handle | | Sender's Handle |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 7, line 50 skipping to change at page 6, line 50
changes made to any of the fixed fields, or to any TLV or sub-TLV changes made to any of the fixed fields, or to any TLV or sub-TLV
assignment or format that is defined at a certain version number. assignment or format that is defined at a certain version number.
The Version Number may not need to be changed if an optional TLV or The Version Number may not need to be changed if an optional TLV or
sub-TLV is added.) sub-TLV is added.)
The Global Flags field is a bit vector with the following format: The Global Flags field is a bit vector with the following format:
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SBZ |V| | MBZ |V|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
One flag is defined for now, the V bit; the rest SHOULD be set to One flag is defined for now, the V bit; the rest MUST be set to zero
zero when sending, and ignored on receipt. when sending, and ignored on receipt.
The V (Validate FEC Stack) flag is set to 1 if the sender wants the The V (Validate FEC Stack) flag is set to 1 if the sender wants the
receiver to perform FEC stack validation; if V is 0, the choice is receiver to perform FEC stack validation; if V is 0, the choice is
left to the receiver. left to the receiver.
The Message Type is one of the following: The Message Type is one of the following:
Value Meaning Value Meaning
----- ------- ----- -------
1 MPLS Echo Request 1 MPLS Echo Request
skipping to change at page 8, line 41 skipping to change at page 7, line 41
the normal IP return path is deemed unreliable, one may use "Reply the normal IP return path is deemed unreliable, one may use "Reply
via an IPv4/IPv6 UDP packet with Router Alert" (note that this via an IPv4/IPv6 UDP packet with Router Alert" (note that this
requires that all intermediate routers understand and know how to requires that all intermediate routers understand and know how to
forward MPLS echo replies). The echo reply uses the same IP version forward MPLS echo replies). The echo reply uses the same IP version
number as the received echo request, i.e., an IPv4 encapsulated echo number as the received echo request, i.e., an IPv4 encapsulated echo
reply is sent in response to an IPv4 encapsulated echo request. reply is sent in response to an IPv4 encapsulated echo request.
Any application which supports an IP control channel between its con- Any application which supports an IP control channel between its con-
trol entities may set the Reply Mode to 4 to ensure that replies use trol entities may set the Reply Mode to 4 to ensure that replies use
that same channel. Further definition of this codepoint is applica- that same channel. Further definition of this codepoint is applica-
tion specific and thus beyond the scope of this docuemnt. tion specific and thus beyond the scope of this document.
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
semantics associated with this handle, although a sender may find semantics associated with this handle, although a sender may find
this useful for matching up requests with replies. this useful for matching up requests with replies.
The Sequence Number is assigned by the sender of the MPLS echo The Sequence Number is assigned by the sender of the MPLS echo
request, and can be (for example) used to detect missed replies. request, and can be (for example) used to detect missed replies.
skipping to change at page 9, line 27 skipping to change at page 8, line 27
| Value | | Value |
. . . .
. . . .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Types are defined below; Length is the length of the Value field in Types are defined below; Length is the length of the Value field in
octets. The Value field depends on the Type; it is zero padded to octets. The Value field depends on the Type; it is zero padded to
align to a four-octet boundary. TLVs may be nested within other align to a four-octet boundary. TLVs may be nested within other
TLVs, in which case the nested TLVs are called sub-TLVs. TLVs, in which case the nested TLVs are called sub-TLVs. Sub-TLVs
have independent types and MUST also be four-octet aligned.
Two examples follow. The LDP IPv4 FEC TLV has the following format: Two examples follow. The LDP IPv4 FEC sub-TLV has the following for-
mat:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 1 (LDP IPv4 FEC) | Length = 5 | | Type = 1 (LDP IPv4 FEC) | Length = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 prefix | | IPv4 prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Length for this TLV is 5. A FEC TLV which contains just an LDP The Length for this TLV is 5. A Target FEC Stack TLV which contains
IPv4 FEC sub-TLV has the format: an LDP IPv4 FEC sub-TLV and a VPN IPv4 FEC sub-TLV has the format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 1 (FEC TLV) | Length = 12 | | Type = 1 (FEC TLV) | Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-Type = 1 (LDP IPv4 FEC) | Length = 5 | | sub-Type = 1 (LDP IPv4 FEC) | Length = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 prefix | | IPv4 prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-Type = 6 (VPN IPv4 FEC) | Length = 13 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A description of the Types and Values of the top level TLVs for LSP A description of the Types and Values of the top level TLVs for LSP
ping are given below: ping are given below:
Type # Value Field Type # Value Field
------ ----------- ------ -----------
1 Target FEC Stack 1 Target FEC Stack
2 Downstream Mapping 2 Downstream Mapping
3 Pad 3 Pad
4 Error Code 4 Not Assigned
5 Vendor Enterprise Code 5 Vendor Enterprise Code
6 TBD 6 Not Assigned
7 IPv4 Interface and Label Stack Object 7 Interface and Label Stack
8 IPv6 Interface and Label Stack Object 8 Not Assigned
9 Errored TLVs 9 Errored TLVs
10 Reply TOS Byte 10 Reply TOS Byte
Types less than 32768 (i.e., with the high order bit equal to 0) are Types less than 32768 (i.e., with the high order bit equal to 0) are
mandatory TLVs that MUST either be supported by an implementation or mandatory TLVs that MUST either be supported by an implementation or
result in the return code of 2 ("One or more of the TLVs was not result in the return code of 2 ("One or more of the TLVs was not
understood") being sent in the echo response. understood") being sent in the echo response.
Types greater than or equal to 32768 (i.e., with the high order bit Types greater than or equal to 32768 (i.e., with the high order bit
equal to 1) are optional TLVs that SHOULD be ignored if the implemen- equal to 1) are optional TLVs that SHOULD be ignored if the implemen-
skipping to change at page 11, line 8 skipping to change at page 10, line 16
The Return Code is set to zero by the sender. The receiver can set The Return Code is set to zero by the sender. The receiver can set
it to one of the values listed below. The notation <RSC> refers to it to one of the values listed below. The notation <RSC> refers to
the Return Subcode. This field is filled in with the stack-depth for the Return Subcode. This field is filled in with the stack-depth for
those codes which specify that. For all other codes the Return Sub- those codes which specify that. For all other codes the Return Sub-
code MUST be set to zero. code MUST be set to zero.
Value Meaning Value Meaning
----- ------- ----- -------
0 No return code or return code contained in the Error 0 No return code
Code TLV
1 Malformed echo request received 1 Malformed echo request received
2 One or more of the TLVs was not understood 2 One or more of the TLVs was not understood
3 Replying router is an egress for the FEC at stack 3 Replying router is an egress for the FEC at stack
depth <RSC> depth <RSC>
4 Replying router has no mapping for the FEC at stack 4 Replying router has no mapping for the FEC at stack
depth <RSC> depth <RSC>
5 Downstream Mapping Mismatch (See Note 1) 5 Downstream Mapping Mismatch (See Note 1)
6 Reserved 6 Upstream Interface Index Unknown (See Note 1)
7 Reserved 7 Reserved
8 Label switched at stack-depth <RSC> 8 Label switched at stack-depth <RSC>
9 Label switched but no MPLS forwarding at stack-depth 9 Label switched but no MPLS forwarding at stack-depth
<RSC> <RSC>
10 Mapping for this FEC is not the given label at stack 10 Mapping for this FEC is not the given label at stack
depth <RSC> depth <RSC>
skipping to change at page 11, line 45 skipping to change at page 11, line 7
11 No label entry at stack-depth <RSC> 11 No label entry at stack-depth <RSC>
12 Protocol not associated with interface at FEC stack 12 Protocol not associated with interface at FEC stack
depth <RSC> depth <RSC>
13 Premature termination of ping due to label stack 13 Premature termination of ping due to label stack
shrinking to a single label shrinking to a single label
Note 1 Note 1
The Return Subcode contains the point in the label stack" where pro- The Return Subcode contains the point in the label stack where pro-
cessing was terminated. If the RSC is 0, no labels were processed. cessing was terminated. If the RSC is 0, no labels were processed.
Otherwise the packet would have been label switched at depth RSC. Otherwise the packet would have been label switched at depth RSC.
3.2. Target FEC Stack 3.2. Target FEC Stack
A Target FEC Stack is a list of sub-TLVs. The number of elements is A Target FEC Stack is a list of sub-TLVs. The number of elements is
determined by the looking at the sub-TLV length fields. determined by the looking at the sub-TLV length fields.
Sub-Type # Length Value Field Sub-Type Length Value Field
---------- ------ ----------- -------- ------ -----------
1 5 LDP IPv4 prefix 1 5 LDP IPv4 prefix
2 17 LDP IPv6 prefix 2 17 LDP IPv6 prefix
3 20 RSVP IPv4 Session Query 3 20 RSVP IPv4 LSP
4 56 RSVP IPv6 Session Query 4 56 RSVP IPv6 LSP
5 Reserved; see Appendix 5 Not Assigned
6 13 VPN IPv4 prefix 6 13 VPN IPv4 prefix
7 25 VPN IPv6 prefix 7 25 VPN IPv6 prefix
8 14 L2 VPN endpoint 8 14 L2 VPN endpoint
9 10 "FEC 128" Pseudowire (old) 9 10 "FEC 128" Pseudowire (deprecated)
10 14 "FEC 128" Pseudowire (new) 10 14 "FEC 128" Pseudowire
11 13+ "FEC 129" Pseudowire 11 13+ "FEC 129" Pseudowire
12 9 BGP labeled IPv4 prefix 12 5 BGP labeled IPv4 prefix
13 ?? BGP labeled IPv6 prefix (TBD) 13 17 BGP labeled IPv6 prefix
14 5 Generic IPv4 prefix 14 5 Generic IPv4 prefix
15 17 Generic IPv6 prefix 15 17 Generic IPv6 prefix
16 4*N Nil FEC 16 4*N Nil FEC
Other FEC Types will be defined as needed. Other FEC Types will be defined as needed.
Note that this TLV defines a stack of FECs, the first FEC element Note that this TLV defines a stack of FECs, the first FEC element
corresponding to the top of the label stack, etc. corresponding to the top of the label stack, etc.
An MPLS echo request MUST have a Target FEC Stack that describes the An MPLS echo request MUST have a Target FEC Stack that describes the
skipping to change at page 14, line 5 skipping to change at page 13, line 16
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 prefix | | IPv6 prefix |
| (16 octets) | | (16 octets) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.3. RSVP IPv4 Session 3.2.3. RSVP IPv4 LSP
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Must Be Zero | Tunnel ID | | Must Be Zero | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Tunnel ID | | Extended Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 tunnel sender address | | IPv4 tunnel sender address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Must Be Zero | LSP ID | | Must Be Zero | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.4. RSVP IPv6 Session 3.2.4. RSVP IPv6 LSP
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 4.6.1.2 and 4.6.2.2]. [RFC3209, sections 4.6.1.2 and 4.6.2.2].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 tunnel end point address | | IPv6 tunnel end point address |
| | | |
| | | |
skipping to change at page 15, line 45 skipping to change at page 15, line 22
| | | |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.7. L2 VPN Endpoint 3.2.7. L2 VPN Endpoint
The value field consists of a Route Distinguisher (8 octets), the The value field consists of a Route Distinguisher (8 octets), the
sender (of the ping)'s CE ID (2 octets), the receiver's CE ID (2 sender (of the ping)'s VE ID (2 octets), the receiver's VE ID (2
octets), and an encapsulation type (2 octets), formatted as follows: octets), and an encapsulation type (2 octets), formatted 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher | | Route Distinguisher |
| (8 octets) | | (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender's CE ID | Receiver's CE ID | | Sender's VE ID | Receiver's VE ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encapsulation Type | Must Be Zero | | Encapsulation Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.8. FEC 128 Pseudowire (Deprecated) 3.2.8. FEC 128 Pseudowire (Deprecated)
The value field consists of the remote PE address (the destination The value field consists of the remote PE address (the destination
address of the targetted LDP session), a VC ID and an encapsulation address of the targeted LDP session), a VC ID and an encapsulation
type, as follows: 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote PE Address | | Remote PE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VC ID | | VC ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encapsulation Type | Must Be Zero | | Encapsulation Type | Must Be Zero |
skipping to change at page 16, line 44 skipping to change at page 16, line 27
this TLV, but SHOULD send LSP ping echo requests with the new TLV this TLV, but SHOULD send LSP ping echo requests with the new TLV
(see next section), unless explicitly asked by configuration to use (see next section), unless explicitly asked by configuration to use
the old TLV. the old TLV.
An LSR receiving this TLV SHOULD use the source IP address of the LSP An LSR receiving this TLV SHOULD use the source IP address of the LSP
echo request to infer the Sender's PE Address. echo request to infer the Sender's PE Address.
3.2.9. FEC 128 Pseudowire (Current) 3.2.9. FEC 128 Pseudowire (Current)
The value field consists of the sender's PE address (the source The value field consists of the sender's PE address (the source
address of the targetted LDP session), the remote PE address (the address of the targeted LDP session), the remote PE address (the des-
destination address of the targetted LDP session), a VC ID and an tination address of the targeted LDP session), a VC ID and an encap-
encapsulation type, as follows: sulation 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 | | Sender's PE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote PE Address | | Remote PE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VC ID | | VC ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encapsulation Type | Must Be Zero | | Encapsulation Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.10. FEC 129 Pseudowire 3.2.10. FEC 129 Pseudowire
The Length of this TLV is 13 + AGI length + SAII length + TAII
length. Padding is used to make the total length a multiple of 4;
the length of the padding is not included in the Length field.
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 | | Sender's PE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote PE Address | | Remote PE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW Type | AGI Length | SAII Length | | PW Type | AGI Length | SAII Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TAII Length | AGI Value ... SAII Value ... TAII Value ... | | TAII Length | AGI Value ... SAII Value ... TAII Value ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ... . . ... .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | 0-3 octets of zero padding | | ... | 0-3 octets of zero padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Length of this TLV is 13 + AGI length + SAII length + TAII
length. Padding is used to make the total length a multiple of 4;
the length of the padding is not included in the Length field.
3.2.11. BGP Labeled IPv4 Prefix 3.2.11. BGP Labeled IPv4 Prefix
The value field consists of the BGP Next Hop associated with the NLRI The value field consists the IPv4 prefix (with trailing 0 bits to
advertising the prefix and label, the IPv4 prefix (with trailing 0 make 32 bits in all), and the prefix length, as follows:
bits to make 32 bits in all), and the prefix length, 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BGP Next Hop |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Prefix | | IPv4 Prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.12. Generic IPv4 Prefix 3.2.12. BGP Labeled IPv6 Prefix
The value consists of sixteen octets of an IPv6 prefix followed by
one octet of prefix length in bits; the format is given below. The
IPv6 prefix is in network byte order; if the prefix is shorter than
128 bits, the trailing bits SHOULD be set to zero.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.13. Generic 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 format is given below. The IPv4 octet of prefix length in bits; the format is given below. The IPv4
prefix is in network byte order; if the prefix is shorter than 32 prefix is in network byte order; if the prefix is shorter than 32
bits, trailing bits SHOULD be set to zero. This FEC is used if the bits, trailing bits SHOULD be set to zero. This FEC is used if the
protocol advertising the label is unknown, or may change during the protocol advertising the label is unknown, or may change during the
course of the LSP. An example is an inter-AS LSP that may be sig- course of the LSP. An example is an inter-AS LSP that may be sig-
naled by LDP in one AS, by RSVP-TE in another AS, and by BGP between naled by LDP in one AS, by RSVP-TE in another AS, and by BGP between
the ASes, such as is common for inter-AS VPNs. the ASes, such as is common for inter-AS VPNs.
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 prefix | | IPv4 prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.13. Generic IPv6 Prefix 3.2.14. Generic 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 format is given below. The one octet of prefix length in bits; the format is given below. The
IPv6 prefix is in network byte order; if the prefix is shorter than IPv6 prefix is in network byte order; if the prefix is shorter than
128 bits, the trailing bits SHOULD be set to zero. 128 bits, the trailing bits SHOULD be set to zero.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 prefix | | IPv6 prefix |
| (16 octets) | | (16 octets) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.14. Nil FEC 3.2.15. Nil FEC
At times labels from the reserved range, e.g. Router Alert and At times labels from the reserved range, e.g. Router Alert and
Explicit-null, may be added to the label stack for various diagnostic Explicit-null, may be added to the label stack for various diagnostic
purposes such as influencing load-balancing. These labels may have purposes such as influencing load-balancing. These labels may have
no explicit FEC associated with them. The Nil FEC stack is defined no explicit FEC associated with them. The Nil FEC stack is defined
to allow a Target FEC stack subtlv to be added to the target FEC to allow a Target FEC stack sub-TLV to be added to the target FEC
stack to account for such labels so that proper validation can still stack to account for such labels so that proper validation can still
be performed. be performed.
The Length is 4*N octets, where N is the number of Labels contained The Length is 4. Labels are 20 bit values treated as numbers.
in the Nil FEC stack. stack.
Labels are 20 bit values treated as numbers. The first label speci-
fied correspond with the label nearest the top of the label stack.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label 1 | SBZ | | Label | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label 2 | SBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Label 1, Label 2, ... are the actual labels inserted in the label Label is the actual label value inserted in the label stack; the MBZ
stack; the SBZ fields SHOULD be zero when sent, and ignored on fields MUST be zero when sent, and ignored on receipt.
receipt.
3.3. Downstream Mapping 3.3. Downstream Mapping
The Downstream Mapping object is an optional TLV. Only one Down- The Downstream Mapping object is a TLV which MAY be included in an
stream Mapping request may appear in and echo request. The presence echo request message. Only one Downstream Mapping object may appear
of a Downstream Mapping object is a request that Downstream Mapping in an echo request. The presence of a Downstream Mapping object is a
objects be included in the echo reply. If the replying router is the request that Downstream Mapping objects be included in the echo
destination of the FEC, then a Downstream Mapping TLV SHOULD NOT be reply. If the replying router is the destination of the FEC, then a
included in the echo reply. Otherwise Downstream Mapping objects Downstream Mapping TLV SHOULD NOT be included in the echo reply.
SHOULD include a Downstream Mapping object for each interface over Otherwise the replying router SHOULD include a Downstream Mapping
which this FEC could be forwarded. For a more precise definition of object for each interface over which this FEC could be forwarded.
the notion of "downstream", see the section named "Downstream". For a more precise definition of the notion of "downstream", see the
section named "Downstream".
The Length is 16 + M + 4*N octets, where M is the Multipath Length, The Length is K + M + 4*N octets, where M is the Multipath Length,
and N is the number of Downstream Labels. The Value field of a Down- and N is the number of Downstream Labels. Values for K are found in
the description of Address Type below. The Value field of a Down-
stream Mapping has the following format: stream Mapping has the following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MTU | Address Type | DS Flags | | MTU | Address Type | DS Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream IP Address (4 or 16 octets) | | Downstream IP Address (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Interface Address (4 or 16 octets) | | Downstream Interface Address (4 or 16 octets) |
skipping to change at page 21, line 7 skipping to change at page 20, line 41
| Downstream Label | Protocol | | Downstream Label | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Maximum Transmission Unit (MTU) Maximum Transmission Unit (MTU)
The MTU is the largest MPLS frame (including label stack) that fits The MTU is the largest MPLS frame (including label stack) that fits
on the interface to the Downstream LSR. on the interface to the Downstream LSR.
Address Type Address Type
The Address Type indicates if the interface is numbered or unnumbered The Address Type indicates if the interface is numbered or unnum-
and is set to one of the following values: bered. It also determines the length of the Downstream IP Address
and Downstream Interface fields. The resulting total for the initial
part of the TLV is listed in the table below as "K Octets". The
Address Type is set to one of the following values:
Type # Address Type Type # Address Type K Octets
------ ------------ ------ ------------ --------
1 IPv4 Numbered 1 IPv4 Numbered 16
2 IPv4 Unnumbered 2 IPv4 Unnumbered 16
3 IPv6 Numbered 3 IPv6 Numbered 40
4 IPv6 Unnumbered 4 IPv6 Unnumbered 28
DS Flags DS Flags
The DS Flags field is a bit vector with the following format: The DS Flags field is a bit vector with the following format:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| Rsvd(MBZ) |I|N| | Rsvd(MBZ) |I|N|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Two flags are defined currently, I and N. The remaining flags MUST Two flags are defined currently, I and N. The remaining flags MUST
be set to zero when sending, and ignored on receipt. be set to zero when sending, and ignored on receipt.
Flag Name and Meaning Flag Name and Meaning
---- ---------------- ---- ----------------
I Interface and Label Stack Object Request I Interface and Label Stack Object Request
When this flag is set, it indicates that the replying When this flag is set, it indicates that the replying
router should include an Interface and Label Stack router SHOULD include an Interface and Label Stack
Object in the Echo-Reply message Object in the echo reply message
N Treat as a Non-IP Packet N Treat as a Non-IP Packet
Echo-Request messages will be used to diagnose non-IP Echo request messages will be used to diagnose non-IP
flows. However, these messages are carried in IP flows. However, these messages are carried in IP
packets. For a router which alters its ECMP algorithm packets. For a router which alters its ECMP algorithm
based on the FEC or deep packet examinition, this flag based on the FEC or deep packet examination, this flag
requests that the router treat this as it would if the requests that the router treat this as it would if the
determination of an IP payload had failed. determination of an IP payload had failed.
Downstream IP Address and Downstream Interface Address Downstream IP Address and Downstream Interface Address
IPv4 addresses and and interface indices are encoded in 4 octets,
IPv6 addresses are encoded in 16 octets.
If the interface to the downstream LSR is numbered, then the Address If the interface to the downstream LSR is numbered, then the Address
Type MUST be set to IPv4 or IPv6, the Downstream IP Address MUST be Type MUST be set to IPv4 or IPv6, the Downstream IP Address MUST be
set to either the downstream LSR's Router ID or the interface address set to either the downstream LSR's Router ID or the interface address
of the downstream LSR, and the Downstream Interface Address MUST be of the downstream LSR, and the Downstream Interface Address MUST be
set to the downstream LSR's interface address. set to the downstream LSR's interface address.
If the interface to the downstream LSR is unnumbered, the Address If the interface to the downstream LSR is unnumbered, the Address
Type MUST be Unnumbered, the Downstream IP Address MUST be the down- Type MUST be IPv4 Unnumbered or IPv6 Unnumbered, the Downstream IP
stream LSR's Router ID (4 octets), and the Downstream Interface Address MUST be the downstream LSR's Router ID, and the Downstream
Address MUST be set to the index assigned by the upstream LSR to the Interface Address MUST be set to the index assigned by the upstream
interface. LSR to the interface.
If an LSR does not know the IP address of its neighbor, then it MUST
set the Address Type to either IPv4 Unnumbered or IPv6 Unnumbered.
For IPv4 it must set the Downstream IP Address to 127.0.0.1, for IPv6
the address is set to 0::1. In both cases the interface index MUST
be set to 0. If an LSR receives an Echo Request packet with either
of these addresses in the Downstream IP Address field, this indicates
that it MUST bypass interface verification but continue with label
validation.
If the originator of an Echo Request packet wishes to obtain Down-
stream mapping information but does not know the expected label stack
then it SHOULD set the Address Type to either IPv4 Unnumbered or IPv6
Unnumbered. For IPv4 it MUST set the Downstream IP Address to
224.0.0.2, for IPv6 the address MUST be set to FF02::2. In both
cases the interface index MUST be set to 0. If an LSR receives an
Echo Request packet with the all-routers multicast address, then this
indicates that it MUST bypass both interface and label stack valida-
tion, but return Downstream Mapping TLVs using the information pro-
vided.
Multipath Type Multipath Type
The follow Mutipath Types are defined: The following Mutipath Types are defined:
Key Type Multipath Information Key Type Multipath Information
--- ---------------- --------------------- --- ---------------- ---------------------
0 no multipath (empty; M = 0) 0 no multipath Empty (Multipath Length = 0)
2 IP address IP addresses 2 IP address IP addresses
4 IP address range low/high address pairs 4 IP address range low/high address pairs
8 Bit-masked IPv4 IP address prefix and bit mask 8 Bit-masked IPv4 IP address prefix and bit mask
address set address set
9 Bit-masked label set Label prefix and bit mask 9 Bit-masked label set Label prefix and bit mask
Type 0 indicates that all packets will be forwarded out this one Type 0 indicates that all packets will be forwarded out this one
interface. interface.
Types 2, 4, 8 and 9 specify that the supplied Multipath Information Types 2, 4, 8 and 9 specify that the supplied Multipath Information
will serve to execise this path. will serve to exercise this path.
Depth Limit Depth Limit
The Depth Limit is applicable only to a label stack, and is the maxi- The Depth Limit is applicable only to a label stack, and is the maxi-
mum number of labels considered in the hash; this SHOULD be set to mum number of labels considered in the hash; this SHOULD be set to
zero if unspecified or unlimited. zero if unspecified or unlimited.
Multipath Length Multipath Length
The length in octets of the Multipath Information. The length in octets of the Multipath Information.
Multipath Information Multipath Information
Address or label values encoded according to the Multipath Type. See Address or label values encoded according to the Multipath Type. See
the next section below for encoding details. the next section below for encoding details.
Downstream Label(s) Downstream Label(s)
The set of labels in the label stack as it would have appeared if The set of labels in the label stack as it would have appeared if
this router were forwarding the packet through this interface. Any this router were forwarding the packet through this interface. Any
Implicit Null labels are explicitly inluded. Labels are treated as Implicit Null labels are explicitly included. Labels are treated as
numbers, i.e. they are right justified in the field. numbers, i.e. they are right justified in the field.
A Downstream Label is 24 bits, in the same format as an MPLS label A Downstream Label is 24 bits, in the same format as an MPLS label
minus the TTL field, i.e., the MSBit of the label is bit 0, the LSbit minus the TTL field, i.e., the MSBit of the label is bit 0, the LSbit
is bit 19, the EXP bits are bits 20-22, and bit 23 is the S bit. The is bit 19, the EXP bits are bits 20-22, and bit 23 is the S bit. The
replying router SHOULD fill in the EXP and S bits; the LSR receiving replying router SHOULD fill in the EXP and S bits; the LSR receiving
the echo reply MAY choose to ignore these bits. the echo reply MAY choose to ignore these bits.
Protocol Protocol
The Protocol is taken from the following table: The Protocol is taken from the following table:
Protocol # Signaling Protocol Protocol # Signaling Protocol
---------- ------------------ ---------- ------------------
0 Unknown 0 Unknown
1 Static 1 Static
2 BGP 2 BGP
3 LDP 3 LDP
4 RSVP-TE 4 RSVP-TE
5 Reserved; see Appendix
3.3.1. Multipath Information Encoding 3.3.1. Multipath Information Encoding
The multipath information encodes labels or addresses which will The multipath information encodes labels or addresses which will
exercise this path. The multipath informaiton depends on the multi- exercise this path. The multipath information depends on the multi-
path type. The contents of the field are shown in the table above. path type. The contents of the field are shown in the table above.
IP addresses are drawn from the range 127/8. Labels are treated as IP addresses are drawn from the range 127/8. Labels are treated as
numbers, i.e. they are right justified in the field. Label and numbers, i.e. they are right justified in the field. For Type 4,
Address pairs MUST NOT overlap and MUST be in ascending sequence. ranges indicated by Address pairs MUST NOT overlap and MUST be in
ascending sequence.
Type 8 allows a denser encoding of IP address. The IPv4 prefix is Type 8 allows a denser encoding of IP address. The IPv4 prefix is
formatted as a base IPv4 address with the non-prefix low order bits formatted as a base IPv4 address with the non-prefix low order bits
set to zero. The maximum prefix length is 27. Following the prefix set to zero. The maximum prefix length is 27. Following the prefix
is a mask of length 2^(32-prefix length) bits. Each bit set to one is a mask of length 2^(32-prefix length) bits. Each bit set to one
represents a valid address. The address is the base IPv4 address represents a valid address. The address is the base IPv4 address
plus the position of the bit in the mask where the bits are numbered plus the position of the bit in the mask where the bits are numbered
left to right begining with zero. left to right beginning with zero. For example the IP addresses
127.2.1.0, 127.2.1.5-127.2.1.15, and 127.2.1.20-127.2.1.29 would be
encoded as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 1 1 1 1 1 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 1 1 1 1 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type 9 allows a denser encoding of Labels. The label prefix is for- Type 9 allows a denser encoding of Labels. The label prefix is for-
matted as a base label value with the non-prefix low order bits set matted as a base label value with the non-prefix low order bits set
to zero. The maximum prefix (including leading zeros due to encod- to zero. The maximum prefix (including leading zeros due to encod-
ing) length is 27. Following the prefix is a mask of length ing) length is 27. Following the prefix is a mask of length
2^(32-prefix length) bits. Each bit set to one represents a valid 2^(32-prefix length) bits. Each bit set to one represents a valid
Label. The label is the base label plus the position of the bit in Label. The label is the base label plus the position of the bit in
the mask where the bits are numbered left to right begining with the mask where the bits are numbered left to right beginning with
zero. zero. Label values of all the odd numbers between 1152 and 1279
would be encoded as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
If the received multipath information is non-null, the labels and IP If the received multipath information is non-null, the labels and IP
addresses MUST be picked from the set provided. If none of these addresses MUST be picked from the set provided. If none of these
labels or addresses map to a particular downstream interface, then labels or addresses map to a particular downstream interface, then
for that interface, the type MUST be set to 0. If the received mul- for that interface, the type MUST be set to 0. If the received mul-
tipath information is null, the receiver simply returns null. tipath information is null, (i.e. Multipath Length = 0, or for Types
8 and 9 a mask of all zeroes) the receiver the type MUST be set to 0.
For example, suppose LSR X at hop 10 has two downstream LSRs Y and Z For example, suppose LSR X at hop 10 has two downstream LSRs Y and Z
for the FEC in question. The received X could return Hash Key Type for the FEC in question. The received X could return Multipath Type
4, with low/high IP addresses of 1.1.1.1->1.1.1.255 for downstream 4, with low/high IP addresses of 127.1.1.1->127.1.1.255 for down-
LSR Y and 2.1.1.1->2.1.1.255 for downstream LSR Z. The head end stream LSR Y and 127.2.1.1->127.2.1.255 for downstream LSR Z. The
reflects this information to LSR Y. Y, which has three downstream head end reflects this information to LSR Y. Y, which has three
LSRs U, V and W, computes that 1.1.1.1->1.1.1.127 would go to U and downstream LSRs U, V and W, computes that 127.1.1.1->127.1.1.127
1.1.1.128-> 1.1.1.255 would go to V. Y would then respond with 3 would go to U and 127.1.1.128-> 127.1.1.255 would go to V. Y would
Downstream Mappings: to U, with Hash Key Type 4 (1.1.1.1->1.1.1.127); then respond with 3 Downstream Mappings: to U, with Multipath Type 4
to V, with Hash Key Type 4 (1.1.1.127->1.1.1.255); and to W, with (127.1.1.1->127.1.1.127); to V, with Multipath Type 4
Hash Key Type 7. (127.1.1.127->127.1.1.255); and to W, with Multipath Type 0.
Note that computing multi-path information may impose a significant Note that computing multi-path information may impose a significant
processing burden on the receiver. A receiver MAY thus choose to processing burden on the receiver. A receiver MAY thus choose to
process a subset of the received prefixes. The sender, on receiving process a subset of the received prefixes. The sender, on receiving
a reply to a Downstream Map with partial information, SHOULD assume a reply to a Downstream Map with partial information, SHOULD assume
that the prefixes missing in the reply were skipped by the receiver, that the prefixes missing in the reply were skipped by the receiver,
and MAY re-request information about them in a new echo request. and MAY re-request information about them in a new echo request.
3.3.2. Downstream Router and Interface 3.3.2. Downstream Router and Interface
The notion of "downstream router" and "downstream interface" should The notion of "downstream router" and "downstream interface" should
be explained. Consider an LSR X. If a packet that was originated be explained. Consider an LSR X. If a packet that was originated
with TTL n>1 arrived with outermost label L at LSR X, X must be able with TTL n>1 arrived with outermost label L and TTL=1 at LSR X, X
to compute which LSRs could receive the packet if it was originated must be able to compute which LSRs could receive the packet if it was
with TTL=n+1, over which interface the request would arrive and what originated with TTL=n+1, over which interface the request would
label stack those LSRs would see. (It is outside the scope of this arrive and what label stack those LSRs would see. (It is outside the
document to specify how this computation is done.) The set of these scope of this document to specify how this computation is done.) The
LSRs/interfaces are the downstream routers/interfaces (and their set of these LSRs/interfaces are the downstream routers/interfaces
corresponding labels) for X with respect to L. Each pair of down- (and their corresponding labels) for X with respect to L. Each pair
stream router and interface requires a separate Downstream Mapping to of downstream router and interface requires a separate Downstream
be added to the reply. (Note that there are multiple Downstream Mapping to be added to the reply.
Label fields in each TLV as the incoming label L may be swapped with
a label stack.)
The case where X is the LSR originating the echo request is a special The case where X is the LSR originating the echo request is a special
case. X needs to figure out what LSRs would receive the MPLS echo case. X needs to figure out what LSRs would receive the MPLS echo
request for a given FEC Stack that X originates with TTL=1. request for a given FEC Stack that X originates with TTL=1.
The set of downstream routers at X may be alternative paths (see the The set of downstream routers at X may be alternative paths (see the
discussion below on ECMP) or simultaneous paths (e.g., for MPLS mul- discussion below on ECMP) or simultaneous paths (e.g., for MPLS mul-
ticast). In the former case, the Multipath sub-field is used as a ticast). In the former case, the Multipath Information is used as a
hint to the sender as to how it may influence the choice of these hint to the sender as to how it may influence the choice of these
alternatives. The "No of Multipaths" is the number of IP alternatives.
Address/Next Label fields.
3.4. Pad TLV 3.4. Pad TLV
The value part of the Pad TLV contains a variable number (>= 1) of The value part of the Pad TLV contains a variable number (>= 1) of
octets. The first octet takes values from the following table; all octets. The first octet takes values from the following table; all
the other octets (if any) are ignored. The receiver SHOULD verify the other octets (if any) are ignored. The receiver SHOULD verify
that the TLV is received in its entirety, but otherwise ignores the that the TLV is received in its entirety, but otherwise ignores the
contents of this TLV, apart from the first octet. contents of this TLV, apart from the first octet.
Value Meaning Value Meaning
----- ------- ----- -------
1 Drop Pad TLV from reply 1 Drop Pad TLV from reply
2 Copy Pad TLV to reply 2 Copy Pad TLV to reply
3-255 Reserved for future use 3-255 Reserved for future use
3.5. Error Code 3.5. Vendor Enterprise Code
The Error Code TLV is currently not defined; its purpose is to pro-
vide a mechanism for a more elaborate error reporting structure,
should the reason arise.
3.6. Vendor Enterprise Code
The Length is always 4; the value is the SMI Enterprise code, in net- The Length is always 4; the value is the SMI Enterprise code, in net-
work octet order, of the vendor with a Vendor Private extension to work octet order, of the vendor with a Vendor Private extension to
any of the fields in the fixed part of the message, in which case any of the fields in the fixed part of the message, in which case
this TLV MUST be present. If none of the fields in the fixed part of this TLV MUST be present. If none of the fields in the fixed part of
the message have vendor private extensions, this TLV is OPTIONAL. the message have vendor private extensions, inclusion of this this
TLV in is OPTIONAL. Vendor private ranges for Message Types, Reply
Modes, and Return Codes have been defined. When any of these are
used the Vendor Enterprise Code TLV MUST be included in the message.
3.7. Interface and Label Stack Object 3.6. Interface and Label Stack
The Interface and Label Stack Object is an optional TLV. It is used The Interface and Label Stack TLV MAY be included in a reply message
in a Reply message to report the interface on which the Request Mes- to report the interface on which the request message was received and
sage was received and the label stack which was on the packet when it the label stack which was on the packet when it was received. Only
was received. Only one such object may appear. The purpose of the one such object may appear. The purpose of the object is to allow
object is to allow the upstream router to obtain the exact interface the upstream router to obtain the exact interface and label stack
and label stack information as it appears at the replying LSR. It information as it appears at the replying LSR.
has two formats, type 7 for IPv4 and type 8 for IPv6 (to be assigned
by IANA).
3.7.1. IPv4 Interface and Label Stack Object The Length is K + 4*N octets, N is the number of labels in the Label
Stack. Values for K are found in the description of Address Type
below. The Value field of a Downstream Mapping has the following
format:
The Length is 8 + 4*N octets, N is the number of Downstream Labels.
The value field of a Interface and Label Stack TLV has the following The value field of a Interface and Label Stack TLV has the following
format: format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream IPv4 Address | | Address Type | Must be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Interface Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. Label Stack .
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address (4 or 16 octets) |
Downstream IPv4 Address
If the address type is 'No Address', the address field MUST be
set to zero and ignored on receipt.
If the address type is 'IPv4', the address field MUST either be
set to the downstream LSR's Router ID or the downstream LSR's
interface address.
If the address type is 'unnumbered', the address field MUST be
set to the downstream LSR's Router ID.
Downstream Interface Address
If the address type is 'IPv4', the interface address field MUST
MUST be set to the downstream LSR's interface address.
If the address type is 'unnumbered', interface address field
MUST be set to the index assigned by the downstream LSR to the
interface.
Label Stack
The label stack of the received echo request message. If any
TTL values have been changed by this router, they SHOULD be
restored.
3.7.2. IPv6 Interface and Label Stack Object
The Length is 32 + 4*N octets, N is the number of Downstream Labels.
The value field of a Interface and Label Stack TLV has the following
format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream IPv6 Address | | Interface (4 or 16 octets) |
| Downstream IPv6 Address (Cont.) |
| Downstream IPv6 Address (Cont.) |
| Downstream IPv6 Address (Cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Interface Address | | Downstream Interface Address |
| Downstream Interface Address (Cont.) |
| Downstream Interface Address (Cont.) |
| Downstream Interface Address (Cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. . . .
. Label Stack . . Label Stack .
. . . .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Downstream IPv6 Address Address Type
If the address type is 'No Address', the address field MUST be The Address Type indicates if the interface is numbered or unnum-
set to zero and ignored on receipt. bered. It also determines the length of the Downstream IP Address
and Downstream Interface fields. The resulting total for the initial
part of the TLV is listed in the table below as "K Octets". The
Address Type is set to one of the following values:
If the address type is 'IPv6', the address field MUST either be Type # Address Type K Octets
set to the downstream LSR's Router ID or the downstream LSR's ------ ------------ --------
interface address. 1 IPv4 Numbered 12
2 IPv4 Unnumbered 12
3 IPv6 Numbered 36
4 IPv6 Unnumbered 24
If the address type is 'unnumbered', the address field MUST be IP Address and Interface
set to the downstream LSR's Router ID.
Downstream Interface Address IPv4 addresses and and interface indices are encoded in 4 octets,
IPv6 addresses are encoded in 16 octets.
If the address type is 'IPv6', the interface address field MUST If the interface upon which the echo request message was received is
MUST be set to the downstream LSR's interface address. numbered, then the Address Type MUST be set to IPv4 or IPv6, the IP
Address MUST be set to either the LSR's Router ID or the interface
address, and the Interface MUST be set to the interface address.
If the address type is 'unnumbered', first four octets of If the interface unnumbered, the Address Type MUST be either IPv4
interface address field MUST be set to the index assigned by Unnumbered or IPv6 Unnumbered, the IP Address MUST be the LSR's
the downstream LSR to the interface. The remaining 12 octets Router ID, and the Interface MUST be set to the index assigned to the
MUST be set to zero. interface.
Label Stack Label Stack
The label stack of the received echo request message. If any The label stack of the received echo request message. If any TTL
TTL values have been changed by this router, they SHOULD be values have been changed by this router, they SHOULD be restored.
restored.
3.8. Errored TLVs 3.7. Errored TLVs
The following TLV is an optional TLV defined to be sent back to the The following TLV is a TLV which MAY be included in an echo reply to
sender of an Echo Request to inform it of Mandatory TLVs either not inform the sender of an echo request of Mandatory TLVs either not
supported by an implementation, or parsed and found to be in error. supported by an implementation, or parsed and found to be in error.
The Value field contains the TLVs not understood encoded as subtlvs. The Value field contains the TLVs not understood encoded as sub-TLVs.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 9 | Length | | Type = 9 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value | | Value |
. . . .
. . . .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.9. Reply TOS Byte TLV 3.8. Reply TOS Byte TLV
This TLV is used by the originator of the echo request to request This TLV MAY be used by the originator of the echo request to
request
that a echo reply be sent with the IP header TOS byte set to that a echo reply be sent with the IP header TOS byte set to
the value specified in the TLV. This TLV has a length of 4 with the value specified in the TLV. This TLV has a length of 4 with
the following value field. the following value field.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reply-TOS Byte| Must be zero | | Reply-TOS Byte| Must be zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 29, line 31 skipping to change at page 29, line 44
tested is identified by the "FEC Stack"; for example, if the LSP was tested is identified by the "FEC Stack"; for example, if the LSP was
set up via LDP, and is to an egress IP address of 10.1.1.1, the FEC set up via LDP, and is to an egress IP address of 10.1.1.1, the FEC
stack contains a single element, namely, an LDP IPv4 prefix sub-TLV stack contains a single element, namely, an LDP IPv4 prefix sub-TLV
with value 10.1.1.1/32. If the LSP being tested is an RSVP LSP, the with value 10.1.1.1/32. If the LSP being tested is an RSVP LSP, the
FEC stack consists of a single element that captures the RSVP Session FEC stack consists of a single element that captures the RSVP Session
and Sender Template which uniquely identifies the LSP. and Sender Template which uniquely identifies the LSP.
FEC stacks can be more complex. For example, one may wish to test a FEC stacks can be more complex. For example, one may wish to test a
VPN IPv4 prefix of 10.1/8 that is tunneled over an LDP LSP with VPN IPv4 prefix of 10.1/8 that is tunneled over an LDP LSP with
egress 10.10.1.1. The FEC stack would then contain two sub-TLVs, the egress 10.10.1.1. The FEC stack would then contain two sub-TLVs, the
first being a VPN IPv4 prefix, and the second being an LDP IPv4 pre- bottom being a VPN IPv4 prefix, and the top being an LDP IPv4 prefix.
fix. If the underlying (LDP) tunnel were not known, or was consid- If the underlying (LDP) tunnel were not known, or was considered
ered irrelevant, the FEC stack could be a single element with just irrelevant, the FEC stack could be a single element with just the VPN
the VPN IPv4 sub-TLV. IPv4 sub-TLV.
When an MPLS echo request is received, the receiver is expected to do When an MPLS echo request is received, the receiver is expected to
a number of tests that verify that the control plane and data plane verify that the control plane and data plane are both healthy (for
are both healthy (for the FEC stack being pinged), and that the two the FEC stack being pinged), and that the two planes are in sync.
planes are in sync. The procedures for this are in section 4.4 below.
4.1. Dealing with Equal-Cost Multi-Path (ECMP) 4.1. Dealing with Equal-Cost Multi-Path (ECMP)
LSPs need not be simple point-to-point tunnels. Frequently, a single LSPs need not be simple point-to-point tunnels. Frequently, a single
LSP may originate at several ingresses, and terminate at several LSP may originate at several ingresses, and terminate at several
egresses; this is very common with LDP LSPs. LSPs for a given FEC egresses; this is very common with LDP LSPs. LSPs for a given FEC
may also have multiple "next hops" at transit LSRs. At an ingress, may also have multiple "next hops" at transit LSRs. At an ingress,
there may also be several different LSPs to choose from to get to the there may also be several different LSPs to choose from to get to the
desired endpoint. Finally, LSPs may have backup paths, detour paths desired endpoint. Finally, LSPs may have backup paths, detour paths
and other alternative paths to take should the primary LSP go down. and other alternative paths to take should the primary LSP go down.
skipping to change at page 30, line 19 skipping to change at page 30, line 31
ically not be used for forwarding data unless the primary LSP is down ically not be used for forwarding data unless the primary LSP is down
will not be addressed here. will not be addressed here.
Since the actual LSP and path that a given packet may take may not be Since the actual LSP and path that a given packet may take may not be
known a priori, it is useful if MPLS echo requests can exercise all known a priori, it is useful if MPLS echo requests can exercise all
possible paths. This, while desirable, may not be practical, because possible paths. This, while desirable, may not be practical, because
the algorithms that a given LSR uses to distribute packets over the algorithms that a given LSR uses to distribute packets over
alternative paths may be proprietary. alternative paths may be proprietary.
To achieve some degree of coverage of alternate paths, there is a To achieve some degree of coverage of alternate paths, there is a
certain lattitude in choosing the destination IP address and source certain latitude in choosing the destination IP address and source
UDP port for an MPLS echo request. This is clearly not sufficient; UDP port for an MPLS echo request. This is clearly not sufficient;
in the case of traceroute, more lattitude is offered by means of the in the case of traceroute, more latitude is offered by means of the
"Multipath Exercise" sub-TLV of the Downstream Mapping TLV. This is Multipath Information of the Downstream Mapping TLV. This is used as
used as follows. An ingress LSR periodically sends an MPLS tracer- follows. An ingress LSR periodically sends an MPLS traceroute mes-
oute message to determine whether there are multipaths for a given sage to determine whether there are multipaths for a given LSP. If
LSP. If so, each hop will provide some information how each of its so, each hop will provide some information how each of its downstream
downstreams can be exercised. The ingress can then send MPLS echo paths can be exercised. The ingress can then send MPLS echo requests
requests that exercise these paths. If several transit LSRs have that exercise these paths. If several transit LSRs have ECMP, the
ECMP, the ingress may attempt to compose these to exercise all possi- ingress may attempt to compose these to exercise all possible paths.
ble paths. However, full coverage may not be possible. However, full coverage may not be possible.
4.2. Testing LSPs That Are Used to Carry MPLS Payloads 4.2. Testing LSPs That Are Used to Carry MPLS Payloads
To detect certain LSP breakages, it may be necessary to encapsulate To detect certain LSP breakages, it may be necessary to encapsulate
an MPLS echo request packet with at least one additional label when an MPLS echo request packet with at least one additional label when
testing LSPs that are used to carry MPLS payloads (such as LSPs used testing LSPs that are used to carry MPLS payloads (such as LSPs used
to carry L2VPN and L3VPN traffic. For example, when testing LDP or to carry L2VPN and L3VPN traffic. For example, when testing LDP or
RSVP-TE LSPs, just sending an MPLS echo request packet may not detect RSVP-TE LSPs, just sending an MPLS echo request packet may not detect
instances where the router immediately upstream of the destination of instances where the router immediately upstream of the destination of
the LSP ping may forward the MPLS echo request successfully over an the LSP ping may forward the MPLS echo request successfully over an
interface not configured to carry MPLS payloads because of the use of interface not configured to carry MPLS payloads because of the use of
penultimate hop popping. Since the receiving router has no means to penultimate hop popping. Since the receiving router has no means to
differentiate whether the IP packet was sent unlabeled or implicitly differentiate whether the IP packet was sent unlabeled or implicitly
labeled, the addition of labels shimmed above the MPLS echo request labeled, the addition of labels shimmed above the MPLS echo request
(using the Nil FEC) will prevent a router from forwarding such a (using the Nil FEC) will prevent a router from forwarding such a
packet out unlabeled interfaces. packet out unlabeled interfaces.
4.3. Sending an MPLS Echo Request 4.3. Sending an MPLS Echo Request
An MPLS echo request is a (possibly) labelled UDP packet. The IP An MPLS echo request is a (possibly) labeled UDP packet. The IP
header is set as follows: the source IP address is a routable address header is set as follows: the source IP address is a routable address
of the sender; the destination IP address is a (randomly chosen) of the sender; the destination IP address is a (randomly chosen)
address from 127/8; the IP TTL is set to 1. The source UDP port is address from 127/8; the IP TTL is set to 1. The source UDP port is
chosen by the sender; the destination UDP port is set to 3503 chosen by the sender; the destination UDP port is set to 3503
(assigned by IANA for MPLS echo requests). The Router Alert option (assigned by IANA for MPLS echo requests). The Router Alert option
is set in the IP header. is set in the IP header.
If the echo request is labelled, one may (depending on what is being If the echo request is labeled, one may (depending on what is being
pinged) set the TTL of the innermost label to 1, to prevent the ping pinged) set the TTL of the innermost label to 1, to prevent the ping
request going farther than it should. Examples of this include ping- request going farther than it should. Examples of this include ping-
ing a VPN IPv4 or IPv6 prefix, an L2 VPN end point or a pseudowire. ing a VPN IPv4 or IPv6 prefix, an L2 VPN end point or a pseudowire.
This can also be accomplished by inserting a router alert label above This can also be accomplished by inserting a router alert label above
this label; however, this may lead to the undesired side effect that this label; however, this may lead to the undesired side effect that
MPLS echo requests take a different data path than actual data. MPLS echo requests take a different data path than actual data.
In "ping" mode (end-to-end connectivity check), the TTL in the outer- In "ping" mode (end-to-end connectivity check), the TTL in the outer-
most label is set to 255. In "traceroute" mode (fault isolation most label is set to 255. In "traceroute" mode (fault isolation
mode), the TTL is set successively to 1, 2, .... mode), the TTL is set successively to 1, 2, ....
skipping to change at page 31, line 39 skipping to change at page 32, line 7
the sequence number by 1. However, a sender MAY choose to send a the sequence number by 1. However, a sender MAY choose to send a
group of echo requests with the same sequence number to improve the group of echo requests with the same sequence number to improve the
chance of arrival of at least one packet with that sequence number. chance of arrival of at least one packet with that sequence number.
The TimeStamp Sent is set to the time-of-day (in seconds and The TimeStamp Sent is set to the time-of-day (in seconds and
microseconds) that the echo request is sent. The TimeStamp Received microseconds) that the echo request is sent. The TimeStamp Received
is set to zero. is set to zero.
An MPLS echo request MUST have a FEC Stack TLV. Also, the Reply Mode An MPLS echo request MUST have a FEC Stack TLV. Also, the Reply Mode
must be set to the desired reply mode; the Return Code and Subcode must be set to the desired reply mode; the Return Code and Subcode
are set to zero. In the "traceroute" mode, the echo request SHOULD a are set to zero. In the "traceroute" mode, the echo request SHOULD
Downstream Mapping TLV. include a Downstream Mapping TLV.
4.4. Receiving an MPLS Echo Request 4.4. Receiving an MPLS Echo Request
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. echo was received, and the label stack with which it came.
X matches up the labels in the received label stack with the FECs For reporting purposes the bottom of stack is considered to be stack-
contained in the FEC stack. The matching is done beginning at the depth of 1. This is to establish an absolute reference for the case
bottom of both stacks, and working up. For reporting purposes the where the stack may have more labels than are in the FEC stack. Fur-
bottom of stack is consided to be stack-depth of 1. This is to ther, in all the error codes listed in this document a stack-depth of
establish an absolute reference for the case where the stack may have 0 means "no value specified". This allows compatibility with exist-
more labels than are in the FEC stack. ing implementations which do not use the Return Subcode field.
If there are more FECs than labels, the extra FECs are assumed to
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
means "no value specified". This allows compatibility with existing
implementations which do not use the Return Subcode field.
X sets two variables, called FEC-stack-depth and Label-stack-depth, X employs two variables, called FEC-stack-depth and Label-stack-
to the number of labels in the received label stack. If the label- depth. X sets Label-stack-depth to the number of labels in the
stack-depth is 0, assume there is one implicit null label and set received label stack. If the label-stack-depth is 0, assume there is
label-stack-depth to 1. Processing now continues with the following one implicit null label and set label-stack-depth to 1. FEC-stack-
steps: depth is used later and need not be initialized. Processing now con-
tinues with the following steps:
Label_Validation: Label_Validation:
If the label at Label-stack-depth is valid, goto Label_Operation. If the label at Label-stack-depth is valid, goto Label_Operation.
If not, set Best-return-code to 11, "No label entry at stack-depth" If not, set Best-return-code to 11, "No label entry at stack-depth"
and Best-return-subcode to Label-stack-depth. Goto and Best-return-subcode to Label-stack-depth. Goto
Send_Reply_Packet. Send_Reply_Packet.
Label_Operation: Label_Operation:
skipping to change at page 33, line 15 skipping to change at page 33, line 20
Case: Swap or Pop and Switch based on Popped Label Case: Swap or Pop and Switch based on Popped Label
If the label operation is either swap or pop and switch based on If the label operation is either swap or pop and switch based on
the popped label, Best-return-code to 8, "Label switched at the popped label, Best-return-code to 8, "Label switched at
stack-depth" and Best-return-subcode to Label-stack-depth. stack-depth" and Best-return-subcode to Label-stack-depth.
If a Downstream Mapping TLV is present, a Downstream mapping TLVs If a Downstream Mapping TLV is present, a Downstream mapping TLVs
SHOULD be created for each multipath. SHOULD be created for each multipath.
Determine the output interface. If it is not valid to forward a Determine the output interface. If it is not valid to forward a
labelled packet on this interface, set Best-return-code to Return labeled packet on this interface, set Best-return-code to Return
Code 9, "Label switched but no MPLS forwarding at stack-depth" Code 9, "Label switched but no MPLS forwarding at stack-depth"
and set Best-return-subcode to Label-stack-depth and goto and set Best-return-subcode to Label-stack-depth and goto
Send_Reply_Packet. (Note: this return code is set even if Label- Send_Reply_Packet. (Note: this return code is set even if Label-
stack-depth is one.) stack-depth is one.)
If no Downstream Mapping TLV is present, or the Downstream IP If no Downstream Mapping TLV is present, or the Downstream IP
Address is set to the All-Routers multicast address goto Address is set to the All-Routers multicast address goto
Send_Reply_Packet. Send_Reply_Packet.
Verify that the IP address, interface address and label stack Verify that the IP address, interface address and label stack
match the received interface and label stack. If not, set Best- match the received interface and label stack. If the IP address
return-code to 5, "Downstream Mapping Mis-match". A Received is either 127.0.0.1 or 0::1 bypass the interface check, and set
Interface and Label Stack TLV SHOULD be created. Goto Best-return-code to 6, "Upstream Interface Index Unknown". For
any other error, set Best-return-code to 5, "Downstream Mapping
Mis-match". For either error, an Interface and Label Stack TLV
SHOULD be created. If Best-return-code equals 5, goto
Send_Reply_Packet. Send_Reply_Packet.
If the "Validate FEC Stack" flag is not set, goto If the "Validate FEC Stack" flag is not set, goto
Send_Reply_Packet. Send_Reply_Packet.
Locate the label at Label-stack-depth in the Downstream Labels Locate the label at Label-stack-depth in the Downstream Labels by
and set FEC-stack-depth to that depth. (Note: If the Downstream counting from the bottom of the stack, skipping over, but count-
Labels contain one or more Implicit Null labels, this may be at a ing Implicit Null labels and set FEC-stack-depth to that depth.
depth greater than Label-stack-depth. (Note: If the Downstream Labels contain one or more Implicit Null
labels, this may be at a depth greater than Label-stack-depth.)
If the depth of the FEC stack is greater than or equal to FEC- If the depth of the FEC stack is greater than or equal to FEC-
stack-depth, Perform FEC Checking. If FEC-status is 2, set Best- stack-depth, Perform FEC Checking. If FEC-status is 2, set Best-
return-code to 10, "Mapping for this FEC is not the given label return-code to 10, "Mapping for this FEC is not the given label
at stack-depth". at stack-depth".
If the return code is 1 set Best-return-code to FEC-return-code If the return code is 1 set Best-return-code to FEC-return-code
and Best-return-subcode to FEC-stack-depth. and Best-return-subcode to FEC-stack-depth.
Goto Send_Reply_Packet. Goto Send_Reply_Packet.
Egress_Processing: Egress_Processing:
If no Downstream Mapping TLV is present, goto If no Downstream Mapping TLV is present, goto Egress_FEC_Valida-
Egress_FEC_Validation. tion.
Verify that the IP address, interface address and label stack match Verify that the IP address, interface address and label stack match
the received interface and label stack. If not, set Best-return- the received interface and label stack. If not, set Best-return-
code to 5, "Downstream Mapping Mis-match". A Received Interface code to 5, "Downstream Mapping Mis-match". A Received Interface
and Label Stack TLV SHOULD be created. Goto Send_Reply_Packet. and Label Stack TLV SHOULD be created. Goto Send_Reply_Packet.
Egress_FEC_Validation: Egress_FEC_Validation:
Perform FEC checking. If FEC-status is 1, set Best-return-code Perform FEC checking. If FEC-status is 1, set Best-return-code
to FEC-code and Best-return-subcode to FEC-stack-depth. Goto to FEC-code and Best-return-subcode to FEC-stack-depth. Goto
skipping to change at page 35, line 31 skipping to change at page 35, line 41
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
the Router Alert IP option. If the reply is sent over an LSP, the the Router Alert IP option. If the reply is sent over an LSP, the
topmost label MUST in this case be the Router Alert label (1) (see topmost label MUST in this case be the Router Alert label (1) (see
[LABEL-STACK]). [LABEL-STACK]).
The format of the echo reply is the same as the echo request. The The format of the echo reply is the same as the echo request. The
Sender's Handle, the Sequence Number and TimeStamp Sent are copied Sender's Handle, the Sequence Number and TimeStamp Sent are copied
from the echo request; the TimeStamp Received is set to the time-of- from the echo request; the TimeStamp Received is set to the time-of-
day that the echo request is received (note that this information is day that the echo request is received (note that this information is
most useful if the time-of-day clocks on the requestor and the most useful if the time-of-day clocks on the requester and the
replier are synchronized). The FEC Stack TLV from the echo request replier are synchronized). The FEC Stack TLV from the echo request
MAY be copied to the reply. MAY be copied to the reply.
The replier MUST fill in the Return Code and Subcode, as determined The replier MUST fill in the Return Code and Subcode, as determined
in the previous subsection. in the previous subsection.
If the echo request contains a Pad TLV, the replier MUST interpret If the echo request contains a Pad TLV, the replier MUST interpret
the first octet for instructions regarding how to reply. the first octet for instructions regarding how to reply.
If the replying router is the destination of the FEC, then Downstream If the replying router is the destination of the FEC, then Downstream
skipping to change at page 36, line 8 skipping to change at page 36, line 17
If the echo request contains a Downstream Mapping TLV, and the reply- If the echo request contains a Downstream Mapping TLV, and the reply-
ing router is not the destination of the FEC, the replier SHOULD com- ing router is not the destination of the FEC, the replier SHOULD com-
pute its downstream routers and corresponding labels for the incoming pute its downstream routers and corresponding labels for the incoming
label, and add Downstream Mapping TLVs for each one to the echo reply label, and add Downstream Mapping TLVs for each one to the echo reply
it sends back. it sends back.
If the Downstream Mapping TLV contains multipath information requir- If the Downstream Mapping TLV contains multipath information requir-
ing more processing than the receiving router is willing to perform, ing more processing than the receiving router is willing to perform,
the responding router MAY choose to respond with only a subset of the responding router MAY choose to respond with only a subset of
multipaths contained in the Echo Request Downstream Map. (Note: The multipaths contained in the echo request Downstream Map. (Note: The
originator of the echo request MAY send another echo request with the originator of the echo request MAY send another echo request with the
multipath information that was not included in the reply.) multipath information that was not included in the reply.)
4.6. Receiving an MPLS Echo Reply 4.6. Receiving an MPLS Echo Reply
An LSR X should only receive an MPLS Echo Reply in response to an An LSR X should only receive an MPLS echo reply in response to an
MPLS Echo Request that it sent. Thus, on receipt of an MPLS Echo MPLS echo request that it sent. Thus, on receipt of an MPLS echo
Reply, X should parse the packet to assure that it is well-formed, reply, X should parse the packet to assure that it is well-formed,
then attempt to match up the Echo Reply with an Echo Request that it then attempt to match up the echo reply with an echo request that it
had previously sent, using the destination UDP port and the Sender's had previously sent, using the destination UDP port and the Sender's
Handle. If no match is found, then X jettisons the Echo Reply; oth- Handle. If no match is found, then X jettisons the echo reply; oth-
erwise, it checks the Sequence Number to see if it matches. Gaps in erwise, it checks the Sequence Number to see if it matches. Gaps in
the Sequence Number MAY be logged and SHOULD be counted. Once an the Sequence Number MAY be logged and SHOULD be counted. Once an
Echo Reply is received for a given Sequence Number (for a given UDP echo reply is received for a given Sequence Number (for a given UDP
port and Handle), the Sequence Number for subsequent Echo Requests port and Handle), the Sequence Number for subsequent echo requests
for that UDP port and Handle SHOULD be incremented. for that UDP port and Handle SHOULD be incremented.
If the Echo Reply contains Downstream Mappings, and X wishes to If the echo reply contains Downstream Mappings, and X wishes to
traceroute further, it SHOULD copy the Downstream Mappings into its traceroute further, it SHOULD copy the Downstream Mapping(s) into its
next Echo Request (with TTL incremented by one). next echo request(s) (with TTL incremented by one).
4.7. Issue with VPN IPv4 and IPv6 Prefixes 4.7. Issue with VPN IPv4 and IPv6 Prefixes
Typically, a LSP ping for a VPN IPv4 or IPv6 prefix is sent with a Typically, a LSP ping for a VPN IPv4 or IPv6 prefix is sent with a
label stack of depth greater than 1, with the innermost label having label stack of depth greater than 1, with the innermost label having
a TTL of 1. This is to terminate the ping at the egress PE, before a TTL of 1. This is to terminate the ping at the egress PE, before
it gets sent to the customer device. However, under certain circum- it gets sent to the customer device. However, under certain circum-
stances, the label stack can shrink to a single label before the ping stances, the label stack can shrink to a single label before the ping
hits the egress PE; this will result in the ping terminating prema- hits the egress PE; this will result in the ping terminating prema-
turely. One such scenario is a multi-AS Carrier's Carrier VPN. turely. One such scenario is a multi-AS Carrier's Carrier VPN.
skipping to change at page 37, line 18 skipping to change at page 37, line 22
ping, then no reply will be sent, resulting in possible "false nega- ping, then no reply will be sent, resulting in possible "false nega-
tives". If in "traceroute" mode, a transit LSR does not support LSP tives". If in "traceroute" mode, a transit LSR does not support LSP
ping, then no reply will be forthcoming from that LSR for some TTL, ping, then no reply will be forthcoming from that LSR for some TTL,
say n. The LSR originating the echo request SHOULD try sending the say n. The LSR originating the echo request SHOULD try sending the
echo request with TTL=n+1, n+2, ..., n+k to probe LSRs further down echo request with TTL=n+1, n+2, ..., n+k to probe LSRs further down
the path. In such a case, the echo request for TTL > n SHOULD be the path. In such a case, the echo request for TTL > n SHOULD be
sent with Downstream Mapping TLV "Downstream IP Address" field set to sent with Downstream Mapping TLV "Downstream IP Address" field set to
the ALLROUTERs multicast address until a reply is received with a the ALLROUTERs multicast address until a reply is received with a
Downstream Mapping TLV. The Label Stack MAY be omitted from the Downstream Mapping TLV. The Label Stack MAY be omitted from the
Downstream Mapping TLV. Further the "Validate FEC Stack" flag SHOULD Downstream Mapping TLV. Further the "Validate FEC Stack" flag SHOULD
NOT be set until an ECHO REQUEST packet with a Downstream Mapping TLV NOT be set until an echo reply packet with a Downstream Mapping TLV
is received. is received.
5. References 5. References
Normative References Normative References
[IANA] Narten, T. and H. Alvestrand, "Guidelines for IANA [IANA] Narten, T. and H. Alvestrand, "Guidelines for IANA
Considerations", BCP 26, RFC 2434, October 1998. Considerations", BCP 26, RFC 2434, October 1998.
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate [KEYWORDS] 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.
[LABEL-STACK] Rosen, E., et al, "MPLS Label Stack Encoding", [LABEL-STACK] Rosen, E., et al, "MPLS Label Stack Encoding",
RFC 3032, January 2001. RFC 3032, January 2001.
[RSVP] Braden, R. (Editor), et al, "Resource ReSerVation
Protocol (RSVP) -- Version 1 Functional
Specification," RFC 2205, September 1997.
[RSVP-REFRESH] Berger, L., et al, "RSVP Refresh Overhead Reduction
Extensions", RFC 2961, April 2001.
[RSVP-TE] Awduche, D., et al, "RSVP-TE: Extensions to RSVP for
LSP tunnels", RFC 3209, December 2001.
Informative References Informative References
[ICMP] Postel, J., "Internet Control Message Protocol", [ICMP] Postel, J., "Internet Control Message Protocol",
RFC 792. RFC 792.
[LDP] Andersson, L., et al, "LDP Specification", RFC 3036, [LDP] Andersson, L., et al, "LDP Specification", RFC 3036,
January 2001. January 2001.
6. Security Considerations 6. Security Considerations
There are at least two approaches to attacking LSRs using the mecha- There are at least two approaches to attacking LSRs using the mecha-
nisms defined here. One is a Denial of Service attack, by sending nisms defined here. One is a Denial of Service attack, by sending
MPLS echo requests/replies to LSRs and thereby increasing their work- MPLS echo requests/replies to LSRs and thereby increasing their work-
load. The other is obfuscating the state of the MPLS data plane load. The other is obfuscating the state of the MPLS data plane
liveness by spoofing, hijacking, replaying or otherwise tampering liveness by spoofing, hijacking, replaying or otherwise tampering
with MPLS echo requests and replies. with MPLS echo requests and replies.
Authentication will help reduce the number of seemingly valid MPLS Authentication will help reduce the number of seemingly valid MPLS
echo requests, and thus cut down the Denial of Service attacks; echo requests, and thus cut down the Denial of Service attacks;
beyond that, each LSR must protect itself. beyond that, each LSR must protect itself. To avoid potential Denial
of Service attacks, it is RECOMMENDED that implementations regulate
the LSP ping traffic going to the control plane. A rate limiter
SHOULD be applied to the well-known UDP port defined below.
Authentication sufficiently addresses spoofing, replay and most tam- Authentication sufficiently addresses spoofing, replay and most tam-
pering attacks; one hopes to use some mechanism devised or suggested pering attacks; one hopes to use some mechanism devised or suggested
by the RPSec WG. It is not clear how to prevent hijacking (non- by the RPSec WG. It is not clear how to prevent hijacking (non-
delivery) of echo requests or replies; however, if these messages are delivery) of echo requests or replies; however, if these messages are
indeed hijacked, LSP ping will report that the data plane isn't work- indeed hijacked, LSP ping will report that the data plane isn't work-
ing as it should. ing as it should.
It doesn't seem vital (at this point) to secure the data carried in It doesn't seem vital (at this point) to secure the data carried in
MPLS echo requests and replies, although knowledge of the state of MPLS echo requests and replies, although knowledge of the state of
skipping to change at page 39, line 8 skipping to change at page 39, line 11
however, the message MUST contain an enterprise code as registered however, the message MUST contain an enterprise code as registered
with the IANA SMI Network Management Private Enterprise Codes. For with the IANA SMI Network Management Private Enterprise Codes. For
each name space that has a Vendor Private range, it must be specified each name space that has a Vendor Private range, it must be specified
where exactly the SMI Enterprise Code resides; see below for exam- where exactly the SMI Enterprise Code resides; see below for exam-
ples. In this way, several enterprises (vendors) can use the same ples. In this way, several enterprises (vendors) can use the same
code point without fear of collision. code point without fear of collision.
7.1. Message Types, Reply Modes, Return Codes 7.1. Message Types, Reply Modes, Return Codes
It is requested that IANA maintain registries for Message Types, It is requested that IANA maintain registries for Message Types,
Reply Modes, Return Codes and Return Subcodes. Each of these can Reply Modes, and Return Codes. Each of these can take values in the
take values in the range 0-255. Assignments in the range 0-191 are range 0-255. Assignments in the range 0-191 are via Standards
via Standards Action; assignments in the range 192-251 are made via Action; assignments in the range 192-251 are made via Expert Review;
Expert Review; values in the range 252-255 are for Vendor Private values in the range 252-255 are for Vendor Private Use, and MUST NOT
Use, and MUST NOT be allocated. be allocated.
If any of these fields fall in the Vendor Private range, a top-level If any of these fields fall in the Vendor Private range, a top-level
Vendor Enterprise Code TLV MUST be present in the message. Vendor Enterprise Code TLV MUST be present in the message.
Message Types defined in this document are:
Value Meaning
----- -------
1 MPLS Echo Request
2 MPLS Echo Reply
Reply Modes defined in this document are:
Value Meaning
----- -------
1 Do not reply
2 Reply via an IPv4/IPv6 UDP packet
3 Reply via an IPv4/IPv6 UDP packet with Router Alert
4 Reply via application level control channel
Return Codes defined in this document are listed in section 3.1.
7.2. TLVs 7.2. TLVs
It is requested that IANA maintain registries for the Type field of It is requested that IANA maintain a registry for the Type field of
top-level TLVs as well as for sub-TLVs. The valid range for each of top-level TLVs as well as for any associated sub-TLVs. Note the
these is 0-65535. Assignments in the range 0-16383 and 32768-49161 meaning of a sub-TLV is scoped by the TLV. The valid range for each
are made via Standards Action as defined in [IANA]; assignments in of these is 0-65535. Assignments in the range 0-16383 and
the range 16384-31743 and 49162-64511 are made via Expert Review (see 32768-49161 are made via Standards Action as defined in [IANA];
below); values in the range 31744-32746 and 64512-65535 are for Ven- assignments in the range 16384-31743 and 49162-64511 are made via
dor Private Use, and MUST NOT be allocated. Expert Review (see below); values in the range 31744-32746 and
64512-65535 are for Vendor Private Use, and MUST NOT be allocated.
If a TLV or sub-TLV has a Type that falls in the range for Vendor If a TLV or sub-TLV has a Type that falls in the range for Vendor
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.
TLVs and sub-TLVs defined in this document are:
Type Sub-Type Value Field
---- -------- -----------
1 Target FEC Stack
1 LDP IPv4 prefix
2 LDP IPv6 prefix
3 RSVP IPv4 LSP
4 RSVP IPv6 LSP
5 Not Assigned
6 VPN IPv4 prefix
7 VPN IPv6 prefix
8 L2 VPN endpoint
9 "FEC 128" Pseudowire (Deprecated)
10 "FEC 128" Pseudowire
11 "FEC 129" Pseudowire
12 BGP labeled IPv4 prefix
13 BGP labeled IPv6 prefix
14 Generic IPv4 prefix
15 Generic IPv6 prefix
16 Nil FEC
2 Downstream Mapping
3 Pad
4 Not Assigned
5 Vendor Enterprise Code
6 Not Assigned
7 Interface and Label Stack
8 Not Assigned
9 Errored TLVs
Any value The TLV not understood
10 Reply TOS Byte
8. Acknowledgments 8. 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, Ina Minei, Shivani Aggarwal and Vanson Gan, Brook Bailey, Eric Rosen, Ina Minei, Shivani Aggarwal and Vanson
Lim. Lim.
The description of the Multipath Information sub-field of the Down- The description of the Multipath Information sub-field of the Down-
stream Mapping TLV was adapted from text suggested by Curtis Vil- stream Mapping TLV was adapted from text suggested by Curtis Vil-
lamizar. lamizar.
A. Appendix
This appendix specifies non-normative aspects of detecting MPLS data
plane liveness.
A.1. CR-LDP FEC
This section describes how a CR-LDP FEC can be included in an Echo
Request using the following FEC subtype:
Sub-Type # Length Value Field
---------- ------ -------------
5 6 CR-LDP LSP ID
The value consists of the LSPID of the LSP being pinged. An LSPID is
a four octet IPv4 address (a local address on the ingress LSR, for
example, the Router ID) plus a two octet identifier that is unique
per LSP on a given ingress LSR.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress LSR Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Must Be Zero | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A.2. Downstream Mapping for CR-LDP
If a label in a Downstream Mapping was learned via CR-LDP, the Proto-
col field in the Mapping TLV can use the following entry:
Protocol # Signaling Protocol
---------- ------------------
5 CR-LDP
Authors' Address Authors' Address
Kireeti Kompella Kireeti Kompella
Juniper Networks Juniper Networks
1194 N.Mathilda Ave 1194 N.Mathilda Ave
Sunnyvale, CA 94089 Sunnyvale, CA 94089
Email: kireeti@juniper.net Email: kireeti@juniper.net
George Swallow George Swallow
Cisco Systems Cisco Systems
1414 Massachusetts Ave, 1414 Massachusetts Ave,
Boxborough, MA 01719 Boxborough, MA 01719
Phone: +1 978 936 1398 Phone: +1 978 936 1398
Email: swallow@cisco.com Email: swallow@cisco.com
Full Copyright and Intellectual Property Statements Copyright Notice
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to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Expiration Date
November 2005
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 End of changes. 

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