draft-smack-mpls-rfc4379bis-08.txt   draft-smack-mpls-rfc4379bis-09.txt 
Network Working Group K. Kompella Network Working Group K. Kompella
Internet-Draft Juniper Networks, Inc. Internet-Draft Juniper Networks
Obsoletes: 4379, 6829 (if approved) C. Pignataro Obsoletes: 4379, 6829 (if approved) C. Pignataro
Intended status: Standards Track N. Kumar Intended status: Standards Track N. Kumar
Expires: May 22, 2016 Cisco Expires: June 20, 2016 Cisco
S. Aldrin S. Aldrin
Google Google
M. Chen M. Chen
Huawei Huawei
November 19, 2015 December 18, 2015
Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures
draft-smack-mpls-rfc4379bis-08 draft-smack-mpls-rfc4379bis-09
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.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 22, 2016. This Internet-Draft will expire on June 20, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.1. Return Codes . . . . . . . . . . . . . . . . . . . . . . 13 3.1. Return Codes . . . . . . . . . . . . . . . . . . . . . . 13
3.2. Target FEC Stack . . . . . . . . . . . . . . . . . . . . 13 3.2. Target FEC Stack . . . . . . . . . . . . . . . . . . . . 13
3.2.1. LDP IPv4 Prefix . . . . . . . . . . . . . . . . . . . 15 3.2.1. LDP IPv4 Prefix . . . . . . . . . . . . . . . . . . . 15
3.2.2. LDP IPv6 Prefix . . . . . . . . . . . . . . . . . . . 15 3.2.2. LDP IPv6 Prefix . . . . . . . . . . . . . . . . . . . 15
3.2.3. RSVP IPv4 LSP . . . . . . . . . . . . . . . . . . . . 15 3.2.3. RSVP IPv4 LSP . . . . . . . . . . . . . . . . . . . . 15
3.2.4. RSVP IPv6 LSP . . . . . . . . . . . . . . . . . . . . 16 3.2.4. RSVP IPv6 LSP . . . . . . . . . . . . . . . . . . . . 16
3.2.5. VPN IPv4 Prefix . . . . . . . . . . . . . . . . . . . 16 3.2.5. VPN IPv4 Prefix . . . . . . . . . . . . . . . . . . . 16
3.2.6. VPN IPv6 Prefix . . . . . . . . . . . . . . . . . . . 17 3.2.6. VPN IPv6 Prefix . . . . . . . . . . . . . . . . . . . 17
3.2.7. L2 VPN Endpoint . . . . . . . . . . . . . . . . . . . 18 3.2.7. L2 VPN Endpoint . . . . . . . . . . . . . . . . . . . 18
3.2.8. FEC 128 Pseudowire - IPv4 (Deprecated) . . . . . . . 18 3.2.8. FEC 128 Pseudowire - IPv4 (Deprecated) . . . . . . . 18
3.2.9. FEC 128 Pseudowire - IPv4 (Current) . . . . . . . . . 19 3.2.9. FEC 128 Pseudowire - IPv4 (Current) . . . . . . . . . 18
3.2.10. FEC 129 Pseudowire - IPv4 . . . . . . . . . . . . . . 20 3.2.10. FEC 129 Pseudowire - IPv4 . . . . . . . . . . . . . . 19
3.2.11. BGP Labeled IPv4 Prefix . . . . . . . . . . . . . . . 21 3.2.11. BGP Labeled IPv4 Prefix . . . . . . . . . . . . . . . 20
3.2.12. BGP Labeled IPv6 Prefix . . . . . . . . . . . . . . . 21 3.2.12. BGP Labeled IPv6 Prefix . . . . . . . . . . . . . . . 20
3.2.13. Generic IPv4 Prefix . . . . . . . . . . . . . . . . . 22 3.2.13. Generic IPv4 Prefix . . . . . . . . . . . . . . . . . 21
3.2.14. Generic IPv6 Prefix . . . . . . . . . . . . . . . . . 22 3.2.14. Generic IPv6 Prefix . . . . . . . . . . . . . . . . . 21
3.2.15. Nil FEC . . . . . . . . . . . . . . . . . . . . . . . 23 3.2.15. Nil FEC . . . . . . . . . . . . . . . . . . . . . . . 22
3.2.16. FEC 128 Pseudowire - IPv6 . . . . . . . . . . . . . . 23 3.2.16. FEC 128 Pseudowire - IPv6 . . . . . . . . . . . . . . 22
3.2.17. FEC 129 Pseudowire - IPv6 . . . . . . . . . . . . . . 24 3.2.17. FEC 129 Pseudowire - IPv6 . . . . . . . . . . . . . . 23
3.3. Downstream Mapping . . . . . . . . . . . . . . . . . . . 25 3.3. Downstream Mapping (Deprecated) . . . . . . . . . . . . . 24
3.3.1. Multipath Information Encoding . . . . . . . . . . . 28 3.4. Downstream Detailed Mapping . . . . . . . . . . . . . . . 24
3.3.2. Downstream Router and Interface . . . . . . . . . . . 30 3.4.1. Multipath Information Encoding . . . . . . . . . . . 24
3.4. Pad TLV . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.4.2. Downstream Router and Interface . . . . . . . . . . . 26
3.5. Vendor Enterprise Number . . . . . . . . . . . . . . . . 31 3.5. Pad TLV . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.6. Interface and Label Stack . . . . . . . . . . . . . . . . 32 3.6. Vendor Enterprise Number . . . . . . . . . . . . . . . . 27
3.7. Errored TLVs . . . . . . . . . . . . . . . . . . . . . . 33 3.7. Interface and Label Stack . . . . . . . . . . . . . . . . 27
3.8. Reply TOS Byte TLV . . . . . . . . . . . . . . . . . . . 33 3.8. Errored TLVs . . . . . . . . . . . . . . . . . . . . . . 29
4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 34 3.9. Reply TOS Byte TLV . . . . . . . . . . . . . . . . . . . 29
4.1. Dealing with Equal-Cost Multi-Path (ECMP) . . . . . . . . 34 4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 29
4.2. Testing LSPs That Are Used to Carry MPLS Payloads . . . . 35 4.1. Dealing with Equal-Cost Multi-Path (ECMP) . . . . . . . . 30
4.3. Sending an MPLS Echo Request . . . . . . . . . . . . . . 35 4.2. Testing LSPs That Are Used to Carry MPLS Payloads . . . . 31
4.4. Receiving an MPLS Echo Request . . . . . . . . . . . . . 36 4.3. Sending an MPLS Echo Request . . . . . . . . . . . . . . 31
4.4.1. FEC Validation . . . . . . . . . . . . . . . . . . . 42 4.4. Receiving an MPLS Echo Request . . . . . . . . . . . . . 32
4.5. Sending an MPLS Echo Reply . . . . . . . . . . . . . . . 43 4.4.1. FEC Validation . . . . . . . . . . . . . . . . . . . 38
4.6. Receiving an MPLS Echo Reply . . . . . . . . . . . . . . 44 4.5. Sending an MPLS Echo Reply . . . . . . . . . . . . . . . 39
4.7. Issue with VPN IPv4 and IPv6 Prefixes . . . . . . . . . . 44 4.6. Receiving an MPLS Echo Reply . . . . . . . . . . . . . . 40
4.8. Non-compliant Routers . . . . . . . . . . . . . . . . . . 45 4.7. Issue with VPN IPv4 and IPv6 Prefixes . . . . . . . . . . 40
5. Security Considerations . . . . . . . . . . . . . . . . . . . 45 4.8. Non-compliant Routers . . . . . . . . . . . . . . . . . . 41
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46 5. Security Considerations . . . . . . . . . . . . . . . . . . . 41
6.1. Message Types, Reply Modes, Return Codes . . . . . . . . 47 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42
6.2. TLVs . . . . . . . . . . . . . . . . . . . . . . . . . . 47 6.1. Message Types, Reply Modes, Return Codes . . . . . . . . 43
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 48 6.2. TLVs . . . . . . . . . . . . . . . . . . . . . . . . . . 43
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 49 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 44
8.1. Normative References . . . . . . . . . . . . . . . . . . 49 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.2. Informative References . . . . . . . . . . . . . . . . . 50 8.1. Normative References . . . . . . . . . . . . . . . . . . 45
8.2. Informative References . . . . . . . . . . . . . . . . . 46
Appendix A. Deprecated TLVs . . . . . . . . . . . . . . . . . . 47
A.1. FEC 128 Pseudowire . . . . . . . . . . . . . . . . . . . 47
A.2. Downstream Mapping(DSMAP) . . . . . . . . . . . . . . . . 48
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51
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 Label Switched Paths used to detect data plane failures in MPLS Label Switched Paths
(LSPs). There are two parts to this document: information carried in (LSPs). There are two parts to this document: information carried in
an MPLS "echo request" and "echo reply", and mechanisms for an MPLS "echo request" and "echo reply", and mechanisms for
transporting the echo reply. The first part aims at providing enough transporting the echo reply. The first part aims at providing enough
information to check correct operation of the data plane, as well as information to check correct operation of the data plane, as well as
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. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 4-octet boundary. TLVs may be nested within other TLVs, align to a 4-octet boundary. TLVs may be nested within other TLVs,
in which case the nested TLVs are called sub-TLVs. Sub-TLVs have in which case the nested TLVs are called sub-TLVs. Sub-TLVs have
independent types and MUST also be 4-octet aligned. independent types and MUST also be 4-octet aligned.
Two examples follow. The Label Distribution Protocol (LDP) IPv4 FEC Two examples of how TLV and sub-TLV length are computed, and of how
sub-TLV has the following format: sub-TLVs are padded to be 4-octet aligned as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The Return Subcode contains the point in the label stack where The Return Subcode contains the point in the label stack where
processing was terminated. If the RSC is 0, no labels were processing was terminated. If the RSC is 0, no labels were
processed. Otherwise the packet would have been label switched at processed. Otherwise the packet would have been label switched at
depth RSC. 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 looking at the sub-TLV length fields. determined by 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 LSP 3 20 RSVP IPv4 LSP
4 56 RSVP IPv6 LSP 4 56 RSVP IPv6 LSP
5 Not Assigned 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 - IPv4 (deprecated) 9 10 "FEC 128" Pseudowire - IPv4 (deprecated)
10 14 "FEC 128" Pseudowire - IPv4 10 14 "FEC 128" Pseudowire - IPv4
11 16+ "FEC 129" Pseudowire - IPv4 11 16+ "FEC 129" Pseudowire - IPv4
12 5 BGP labeled IPv4 prefix 12 5 BGP labeled IPv4 prefix
13 17 BGP labeled IPv6 prefix 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 Nil FEC 16 4 Nil FEC
24 38 "FEC 128" Pseudowire - IPv6 24 38 "FEC 128" Pseudowire - IPv6
25 40+ "FEC 129" Pseudowire - IPv6 25 40+ "FEC 129" Pseudowire - IPv6
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
FEC Stack being tested. For example, if an LSR X has an LDP mapping FEC Stack being tested. For example, if an LSR X has an LDP mapping
[RFC5036] for 192.168.1.1 (say, label 1001), then to verify that [RFC5036] for 192.168.1.1 (say, label 1001), then to verify that
label 1001 does indeed reach an egress LSR that announced this prefix label 1001 does indeed reach an egress LSR that announced this prefix
via LDP, X can send an MPLS echo request with an FEC Stack TLV with via LDP, X can send an MPLS echo request with an FEC Stack TLV with
one FEC in it, namely, of type LDP IPv4 prefix, with prefix one FEC in it, namely, of type LDP IPv4 prefix, with prefix
192.168.1.1/32, and send the echo request with a label of 1001. 192.168.1.1/32, and send the echo request with a label of 1001.
Say LSR X wanted to verify that a label stack of <1001, 23456> is the Say LSR X wanted to verify that a label stack of <1001, 23456> is the
right label stack to use to reach a VPN IPv4 prefix [see section right label stack to use to reach a VPN IPv4 prefix [see
3.2.5] of 10/8 in VPN foo. Say further that LSR Y with loopback Section 3.2.5] of 10/8 in VPN foo. Say further that LSR Y with
address 192.168.1.1 announced prefix 10/8 with Route Distinguisher loopback address 192.168.1.1 announced prefix 10/8 with Route
RD-foo-Y (which may in general be different from the Route Distinguisher RD-foo-Y (which may in general be different from the
Distinguisher that LSR X uses in its own advertisements for VPN foo), Route Distinguisher that LSR X uses in its own advertisements for VPN
label 23456 and BGP next hop 192.168.1.1 [RFC4271]. Finally, suppose foo), label 23456 and BGP next hop 192.168.1.1 [RFC4271]. Finally,
that LSR X receives a label binding of 1001 for 192.168.1.1 via LDP. suppose that LSR X receives a label binding of 1001 for 192.168.1.1
X has two choices in sending an MPLS echo request: X can send an MPLS via LDP. X has two choices in sending an MPLS echo request: X can
echo request with an FEC Stack TLV with a single FEC of type VPN IPv4 send an MPLS echo request with an FEC Stack TLV with a single FEC of
prefix with a prefix of 10/8 and a Route Distinguisher of RD-foo-Y. type VPN IPv4 prefix with a prefix of 10/8 and a Route Distinguisher
Alternatively, X can send an FEC Stack TLV with two FECs, the first of RD-foo-Y. Alternatively, X can send an FEC Stack TLV with two
of type LDP IPv4 with a prefix of 192.168.1.1/32 and the second of FECs, the first of type LDP IPv4 with a prefix of 192.168.1.1/32 and
type of IP VPN with a prefix 10/8 with Route Distinguisher of RD-foo- the second of type of IP VPN with a prefix 10/8 with Route
Y. In either case, the MPLS echo request would have a label stack of Distinguisher of RD-foo-Y. In either case, the MPLS echo request
<1001, 23456>. (Note: in this example, 1001 is the "outer" label and would have a label stack of <1001, 23456>. (Note: in this example,
23456 is the "inner" label.) 1001 is the "outer" label and 23456 is the "inner" label.)
3.2.1. LDP IPv4 Prefix 3.2.1. LDP IPv4 Prefix
The IPv4 Prefix FEC is defined in [RFC5036]. When an LDP IPv4 prefix The IPv4 Prefix FEC is defined in [RFC5036]. When an LDP IPv4 prefix
is encoded in a label stack, the following format is used. The value is encoded in a label stack, the following format is used. The value
consists of 4 octets of an IPv4 prefix followed by 1 octet of prefix consists of 4 octets of an IPv4 prefix followed by 1 octet of prefix
length in bits; the format is given below. The IPv4 prefix is in length in bits; the format is given below. The IPv4 prefix is in
network byte order; if the prefix is shorter than 32 bits, trailing network byte order; if the prefix is shorter than 32 bits, trailing
bits SHOULD be set to zero. See [RFC5036] for an example of a bits SHOULD be set to zero. See [RFC5036] for an example of a
Mapping for an IPv4 FEC. Mapping for an IPv4 FEC.
skipping to change at page 18, line 7 skipping to change at page 18, line 7
| IPv6 prefix | | IPv6 prefix |
| | | |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Route Distinguisher is identical to the VPN IPv4 Prefix RD, The Route Distinguisher is identical to the VPN IPv4 Prefix RD,
except that it functions here to allow the creation of distinct except that it functions here to allow the creation of distinct
routes to IPv6 prefixes. See section 3.2.5. When matching this routes to IPv6 prefixes. See Section 3.2.5. When matching this
field to local FEC information, it is treated as an opaque value. field to local FEC information, it is treated as an opaque value.
3.2.7. L2 VPN Endpoint 3.2.7. L2 VPN Endpoint
VPLS stands for Virtual Private LAN Service. The terms VPLS BGP NLRI VPLS stands for Virtual Private LAN Service. The terms VPLS BGP NLRI
and VE ID (VPLS Edge Identifier) are defined in [RFC4761]. This and VE ID (VPLS Edge Identifier) are defined in [RFC4761]. This
document uses the simpler term L2 VPN endpoint when referring to a document uses the simpler term L2 VPN endpoint when referring to a
VPLS BGP NLRI. The Route Distinguisher is an 8-octet identifier used VPLS BGP NLRI. The Route Distinguisher is an 8-octet identifier used
to distinguish information about various L2 VPNs advertised by a to distinguish information about various L2 VPNs advertised by a
node. The VE ID is a 2-octet identifier used to identify a node. The VE ID is a 2-octet identifier used to identify a
skipping to change at page 18, line 43 skipping to change at page 18, line 43
| Route Distinguisher | | Route Distinguisher |
| (8 octets) | | (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender's VE ID | Receiver's VE 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 - IPv4 (Deprecated) 3.2.8. FEC 128 Pseudowire - IPv4 (Deprecated)
FEC 128 (0x80) is defined in [RFC4447], as are the terms PW ID See Appendix A.1 for details
(Pseudowire ID) and PW Type (Pseudowire Type). A PW ID is a non-zero
32-bit connection ID. The PW Type is a 15-bit number indicating the
encapsulation type. It is carried right justified in the field below
termed encapsulation type with the high-order bit set to zero. Both
of these fields are treated in this protocol as opaque values.
When an FEC 128 is encoded in a label stack, the following format is
used. The value field consists of the remote PE IPv4 address (the
destination address of the targeted LDP session), the PW ID, and the
encapsulation type 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote PE IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This FEC is deprecated and is retained only for backward
compatibility. Implementations of LSP ping SHOULD accept and process
this TLV, but SHOULD send LSP ping echo requests with the new TLV
(see next section), unless explicitly configured to use the old TLV.
An LSR receiving this TLV SHOULD use the source IP address of the LSP
echo request to infer the sender's PE address.
3.2.9. FEC 128 Pseudowire - IPv4 (Current) 3.2.9. FEC 128 Pseudowire - IPv4 (Current)
FEC 128 (0x80) is defined in [RFC4447], as are the terms PW ID FEC 128 (0x80) is defined in [RFC4447], as are the terms PW ID
(Pseudowire ID) and PW Type (Pseudowire Type). A PW ID is a non-zero (Pseudowire ID) and PW Type (Pseudowire Type). A PW ID is a non-zero
32-bit connection ID. The PW Type is a 15-bit number indicating the 32-bit connection ID. The PW Type is a 15-bit number indicating the
encapsulation type. It is carried right justified in the field below encapsulation type. It is carried right justified in the field below
termed encapsulation type with the high-order bit set to zero. termed encapsulation type with the high-order bit set to zero.
Both of these fields are treated in this protocol as opaque values. Both of these fields are treated in this protocol as opaque values.
skipping to change at page 25, line 5 skipping to change at page 24, line 5
Sender's PE IPv6 Address: The source IP address of the target IPv6 Sender's PE IPv6 Address: The source IP address of the target IPv6
LDP session. 16 octets. LDP session. 16 octets.
Remote PE IPv6 Address: The destination IP address of the target IPv6 Remote PE IPv6 Address: The destination IP address of the target IPv6
LDP session. 16 octets. LDP session. 16 octets.
The other fields are the same as FEC 129 Pseudowire IPv4 in The other fields are the same as FEC 129 Pseudowire IPv4 in
Section 3.2.10. Section 3.2.10.
3.3. Downstream Mapping 3.3. Downstream Mapping (Deprecated)
The Downstream Mapping object is a TLV that MAY be included in an
echo request message. Only one Downstream Mapping object may appear
in an echo request. The presence of a Downstream Mapping object is a
request that Downstream Mapping objects be included in the echo
reply. If the replying router is the destination of the FEC, then a
Downstream Mapping TLV SHOULD NOT be included in the echo reply.
Otherwise the replying router SHOULD include a Downstream Mapping
object for each interface over which this FEC could be forwarded.
For a more precise definition of the notion of "downstream", see
section 3.3.2, "Downstream Router and Interface".
The Length is K + M + 4*N octets, where M is the Multipath Length,
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
Downstream Mapping 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MTU | Address Type | DS Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream IP Address (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Interface Address (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Multipath Type| Depth Limit | Multipath Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. (Multipath Information) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Label | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Label | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Maximum Transmission Unit (MTU)
The MTU is the size in octets of the largest MPLS frame (including
label stack) that fits on the interface to the Downstream LSR.
Address Type
The Address Type indicates if the interface is numbered or
unnumbered. 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 K Octets
------ ------------ --------
1 IPv4 Numbered 16
2 IPv4 Unnumbered 16
3 IPv6 Numbered 40
4 IPv6 Unnumbered 28
DS Flags
The DS Flags field is a bit vector with the following format:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| Rsvd(MBZ) |I|N|
+-+-+-+-+-+-+-+-+
Two flags are defined currently, I and N. The remaining flags MUST
be set to zero when sending and ignored on receipt.
Flag Name and Meaning
---- ----------------
I Interface and Label Stack Object Request
When this flag is set, it indicates that the replying
router SHOULD include an Interface and Label Stack
Object in the echo reply message.
N Treat as a Non-IP Packet
Echo request messages will be used to diagnose non-IP
flows. However, these messages are carried in IP
packets. For a router that alters its ECMP algorithm
based on the FEC or deep packet examination, this flag
requests that the router treat this as it would if the
determination of an IP payload had failed.
Downstream IP Address and Downstream Interface Address
IPv4 addresses 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 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 of the downstream LSR, and the Downstream
Interface Address MUST be set to the downstream LSR's interface
address.
If the interface to the downstream LSR is unnumbered, the Address
Type MUST be IPv4 Unnumbered or IPv6 Unnumbered, the Downstream IP
Address MUST be the downstream LSR's Router ID, and the Downstream
Interface Address MUST be set to the index assigned by the
upstream 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
Downstream 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 validation, but return Downstream
Mapping TLVs using the information provided.
Multipath Type
The following Multipath Types are defined:
Key Type Multipath Information
--- ---------------- ---------------------
0 no multipath Empty (Multipath Length = 0)
2 IP address IP addresses
4 IP address range low/high address pairs
8 Bit-masked IP IP address prefix and bit mask
address set
9 Bit-masked label set Label prefix and bit mask
Type 0 indicates that all packets will be forwarded out this one
interface.
Types 2, 4, 8, and 9 specify that the supplied Multipath
Information will serve to exercise this path.
Depth Limit
The Depth Limit is applicable only to a label stack and is the
maximum number of labels considered in the hash; this SHOULD be
set to zero if unspecified or unlimited.
Multipath Length
The length in octets of the Multipath Information.
Multipath Information
Address or label values encoded according to the Multipath Type.
See the next section below for encoding details.
Downstream Label(s)
The set of labels in the label stack as it would have appeared if
this router were forwarding the packet through this interface.
Any Implicit Null labels are explicitly included. Labels are
treated as numbers, i.e., they are right justified in the field.
A Downstream Label is 24 bits, in the same format as an MPLS label See Appendix A.2 for more details.
minus the TTL field, i.e., the MSBit of the label is bit 0, the
LSBit is bit 19, the Traffic Class (TC) bits are bits 20-22, and
bit 23 is the S bit. The replying router SHOULD fill in the TC
and S bits; the LSR receiving the echo reply MAY choose to ignore
these bits. Protocol
The Protocol is taken from the following table: 3.4. Downstream Detailed Mapping
Protocol # Signaling Protocol The format of this TLV is defined in section 3.3 of [RFC6424]
---------- ------------------
0 Unknown
1 Static
2 BGP
3 LDP
4 RSVP-TE
3.3.1. Multipath Information Encoding 3.4.1. Multipath Information Encoding
The Multipath Information encodes labels or addresses that will The Multipath Information encodes labels or addresses that will
exercise this path. The Multipath Information depends on the exercise this path. The Multipath Information depends on the
Multipath Type. The contents of the field are shown in the table Multipath Type. The contents of the field are shown in the table
above. IPv4 addresses are drawn from the range 127/8; IPv6 addresses above. IPv4 addresses are drawn from the range 127/8; IPv6 addresses
are drawn from the range 0:0:0:0:0:FFFF:7F00/104. Labels are treated are drawn from the range 0:0:0:0:0:FFFF:7F00/104. Labels are treated
as numbers, i.e., they are right justified in the field. For Type 4, as numbers, i.e., they are right justified in the field. For Type 4,
ranges indicated by Address pairs MUST NOT overlap and MUST be in ranges indicated by Address pairs MUST NOT overlap and MUST be in
ascending sequence. ascending sequence.
skipping to change at page 30, line 35 skipping to change at page 26, line 8
Multipath Information is null (i.e., Multipath Length = 0, or for Multipath Information is null (i.e., Multipath Length = 0, or for
Types 8 and 9, a mask of all zeros), the type MUST be set to 0. Types 8 and 9, a mask of all zeros), the type MUST be set to 0.
For example, suppose LSR X at hop 10 has two downstream LSRs, Y and 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 Multipath Z, for the FEC in question. The received X could return Multipath
Type 4, with low/high IP addresses of 127.1.1.1->127.1.1.255 for Type 4, with low/high IP addresses of 127.1.1.1->127.1.1.255 for
downstream LSR Y and 127.2.1.1->127.2.1.255 for downstream LSR Z. downstream LSR Y and 127.2.1.1->127.2.1.255 for downstream LSR Z.
The head end reflects this information to LSR Y. Y, which has three The head end reflects this information to LSR Y. Y, which has three
downstream LSRs, U, V, and W, computes that 127.1.1.1->127.1.1.127 downstream LSRs, U, V, and W, computes that 127.1.1.1->127.1.1.127
would go to U and 127.1.1.128-> 127.1.1.255 would go to V. Y would would go to U and 127.1.1.128-> 127.1.1.255 would go to V. Y would
then respond with 3 Downstream Mappings: to U, with Multipath Type 4 then respond with 3 "Downstream Detailed Mapping" TLVs: to U, with
(127.1.1.1->127.1.1.127); to V, with Multipath Type 4 Multipath Type 4 (127.1.1.1->127.1.1.127); to V, with Multipath Type
(127.1.1.127->127.1.1.255); and to W, with Multipath Type 0. 4 (127.1.1.127->127.1.1.255); and to W, with Multipath Type 0.
Note that computing Multipath Information may impose a significant Note that computing Multipath 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 Mapping with partial information, SHOULD a reply to a Downstream Detailed Mapping with partial information,
assume that the prefixes missing in the reply were skipped by the SHOULD assume that the prefixes missing in the reply were skipped by
receiver, and MAY re-request information about them in a new echo the receiver, and MAY re-request information about them in a new echo
request. request.
3.3.2. Downstream Router and Interface The encoding of Multipath information in scenarios where few LSRs
apply Entropy label based load balancing while other LSRs are non-EL
(IP based) load balancing will be defined in a different document.
The encoding of multipath information in scenarios where LSR have
Layer 2 ECMP over Link Aggregation Group (LAG) interfaces will be
defined in different document.
3.4.2. 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 and TTL=1 at LSR X, X with TTL n>1 arrived with outermost label L and TTL=1 at LSR X, X
must be able to compute which LSRs could receive the packet if it was must be able to compute which LSRs could receive the packet if it was
originated with TTL=n+1, over which interface the request would originated with TTL=n+1, over which interface the request would
arrive and what label stack those LSRs would see. (It is outside the arrive and what label stack those LSRs would see. (It is outside the
scope of this document to specify how this computation is done.) The scope of this document to specify how this computation is done.) The
set of these LSRs/interfaces consists of the downstream routers/ set of these LSRs/interfaces consists of the downstream routers/
interfaces (and their corresponding labels) for X with respect to L. interfaces (and their corresponding labels) for X with respect to L.
Each pair of downstream router and interface requires a separate Each pair of downstream router and interface requires a separate
Downstream Mapping to be added to the reply. Downstream Detailed Mapping to be added to the reply.
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 discussion below on ECMP) or simultaneous paths (e.g., for MPLS
multicast). In the former case, the Multipath Information is used as multicast). 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 a hint to the sender as to how it may influence the choice of these
alternatives. alternatives.
3.4. Pad TLV 3.5. 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. Vendor Enterprise Number 3.6. Vendor Enterprise Number
SMI Private Enterprise Numbers are maintained by IANA. The Length is SMI Private Enterprise Numbers are maintained by IANA. The Length is
always 4; the value is the SMI Private Enterprise code, in network always 4; the value is the SMI Private Enterprise code, in network
octet order, of the vendor with a Vendor Private extension to any of 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 this TLV 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 the MUST be present. If none of the fields in the fixed part of the
message have Vendor Private extensions, inclusion of this TLV is message have Vendor Private extensions, inclusion of this TLV is
OPTIONAL. Vendor Private ranges for Message Types, Reply Modes, and OPTIONAL. Vendor Private ranges for Message Types, Reply Modes, and
Return Codes have been defined. When any of these are used, the Return Codes have been defined. When any of these are used, the
Vendor Enterprise Number TLV MUST be included in the message. Vendor Enterprise Number TLV MUST be included in the message.
3.6. Interface and Label Stack 3.7. Interface and Label Stack
The Interface and Label Stack TLV MAY be included in a reply message The Interface and Label Stack TLV MAY be included in a reply message
to report the interface on which the request message was received and to report the interface on which the request message was received and
the label stack that was on the packet when it was received. Only the label stack that was on the packet when it was received. Only
one such object may appear. The purpose of the object is to allow one such object may appear. The purpose of the object is to allow
the upstream router to obtain the exact interface and label stack the upstream router to obtain the exact interface and label stack
information as it appears at the replying LSR. information as it appears at the replying LSR.
The Length is K + 4*N octets; N is the number of labels in the label 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 stack. Values for K are found in the description of Address Type
below. The Value field of a Downstream Mapping has the following below. The Value field of this 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Type | Must Be Zero | | Address Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address (4 or 16 octets) | | IP Address (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface (4 or 16 octets) | | Interface (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 33, line 23 skipping to change at page 29, line 10
If the interface is unnumbered, the Address Type MUST be either If the interface is unnumbered, the Address Type MUST be either
IPv4 Unnumbered or IPv6 Unnumbered, the IP Address MUST be the IPv4 Unnumbered or IPv6 Unnumbered, the IP Address MUST be the
LSR's Router ID, and the Interface MUST be set to the index LSR's Router ID, and the Interface MUST be set to the index
assigned to the interface. assigned to the interface.
Label Stack Label Stack
The label stack of the received echo request message. If any TTL The label stack of the received echo request message. If any TTL
values have been changed by this router, they SHOULD be restored. values have been changed by this router, they SHOULD be restored.
3.7. Errored TLVs 3.8. Errored TLVs
The following TLV is a TLV that MAY be included in an echo reply to The following TLV is a TLV that MAY be included in an echo reply to
inform the sender of an echo request 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 that were not understood, encoded The Value field contains the TLVs that were not understood, encoded
as sub-TLVs. 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 |
. . . .
. . . .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.8. Reply TOS Byte TLV 3.9. Reply TOS Byte TLV
This TLV MAY be 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 an echo reply be sent with the IP header TOS byte set to the that an 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. 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 35, line 12 skipping to change at page 30, line 45
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, although desirable, may not be practical, possible paths. This, although desirable, may not be practical,
because the algorithms that a given LSR uses to distribute packets because the algorithms that a given LSR uses to distribute packets
over alternative paths may be proprietary. over 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 latitude 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 latitude is offered by means of the in the case of traceroute, more latitude is offered by means of the
Multipath Information of the Downstream Mapping TLV. This is used as Multipath Information of the Downstream Detailed Mapping TLV. This
follows. An ingress LSR periodically sends an MPLS traceroute is used as follows. An ingress LSR periodically sends an MPLS
message to determine whether there are multipaths for a given LSP. traceroute message to determine whether there are multipaths for a
If so, each hop will provide some information how each of its given LSP. If so, each hop will provide some information how each of
downstream paths can be exercised. The ingress can then send MPLS its downstream paths can be exercised. The ingress can then send
echo requests that exercise these paths. If several transit LSRs MPLS echo requests that exercise these paths. If several transit
have ECMP, the ingress may attempt to compose these to exercise all LSRs have ECMP, the ingress may attempt to compose these to exercise
possible paths. However, full coverage may not be possible. all possible paths. 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
skipping to change at page 36, line 36 skipping to change at page 32, line 21
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 NTP format that the The TimeStamp Sent is set to the time-of-day in NTP format that the
echo request is sent. The TimeStamp Received is set to zero. echo request is sent. The TimeStamp Received is set to zero.
An MPLS echo request MUST have an FEC Stack TLV. Also, the Reply An MPLS echo request MUST have an FEC Stack TLV. Also, the Reply
Mode must be set to the desired reply mode; the Return Code and Mode must be set to the desired reply mode; the Return Code and
Subcode are set to zero. In the "traceroute" mode, the echo request Subcode are set to zero. In the "traceroute" mode, the echo request
SHOULD include a Downstream Mapping TLV. SHOULD include a Downstream Detailed Mapping TLV.
4.4. Receiving an MPLS Echo Request 4.4. Receiving an MPLS Echo Request
Sending an MPLS echo request to the control plane is triggered by one Sending an MPLS echo request to the control plane is triggered by one
of the following packet processing exceptions: Router Alert option, of the following packet processing exceptions: Router Alert option,
IP TTL expiration, MPLS TTL expiration, MPLS Router Alert label, or IP TTL expiration, MPLS TTL expiration, MPLS Router Alert label, or
the destination address in the 127/8 address range. The control the destination address in the 127/8 address range. The control
plane further identifies it by UDP destination port 3503. plane further identifies it by UDP destination port 3503.
For reporting purposes the bottom of stack is considered to be stack- For reporting purposes the bottom of stack is considered to be stack-
skipping to change at page 37, line 31 skipping to change at page 33, line 14
Handle, Sequence Number, and Timestamp Sent are not examined, but Handle, Sequence Number, and Timestamp Sent are not examined, but
are included in the MPLS echo reply message. are included in the MPLS echo reply message.
The algorithm uses the following variables and identifiers: The algorithm uses the following variables and identifiers:
Interface-I: the interface on which the MPLS echo request was Interface-I: the interface on which the MPLS echo request was
received. received.
Stack-R: the label stack on the packet as it was received. Stack-R: the label stack on the packet as it was received.
Stack-D: the label stack carried in the Downstream Mapping Stack-D: the label stack carried in the "Label Stack sub-
TLV (not always present) TLV" in Downstream Detailed Mapping TLV (not
always present)
Label-L: the label from the actual stack currently being Label-L: the label from the actual stack currently being
examined. Requires no initialization. examined. Requires no initialization.
Label-stack-depth: the depth of label being verified. Initialized Label-stack-depth: the depth of label being verified. Initialized
to the number of labels in the received label to the number of labels in the received label
stack S. stack S.
FEC-stack-depth: depth of the FEC in the Target FEC Stack that FEC-stack-depth: depth of the FEC in the Target FEC Stack that
should be used to verify the current actual should be used to verify the current actual
skipping to change at page 39, line 29 skipping to change at page 35, line 16
} }
If the label operation is "Swap or Pop and Switch based on Popped If the label operation is "Swap or Pop and Switch based on Popped
Label" { Label" {
Set Best-return-code to 8 ("Label switched at stack-depth") and Set Best-return-code to 8 ("Label switched at stack-depth") and
Best-rtn-subcode to Label-stack-depth to report transit Best-rtn-subcode to Label-stack-depth to report transit
switching. switching.
If a Downstream Mapping TLV is present in the received echo If a Downstream Detailed Mapping TLV is present in the received
request { echo request {
If the IP address in the TLV is 127.0.0.1 or 0::1 { If the IP address in the TLV is 127.0.0.1 or 0::1 {
Set Best-return-code to 6 ("Upstream Interface Index Set Best-return-code to 6 ("Upstream Interface Index
Unknown"). An Interface and Label Stack TLV SHOULD be Unknown"). An Interface and Label Stack TLV SHOULD be
included in the reply and filled with Interface-I and included in the reply and filled with Interface-I and
Stack-R. Stack-R.
} }
Else { Else {
Verify that the IP address, interface address, and label Verify that the IP address, interface address, and label
stack in the Downstream Mapping TLV match Interface-I and stack in the Downstream Detailed Mapping TLV match
Stack-R. If there is a mismatch, set Best-return-code to Interface-I and Stack-R. If there is a mismatch, set
5, "Downstream Mapping Mismatch". An Interface and Label Best-return-code to 5, "Downstream Mapping Mismatch". An
Stack TLV SHOULD be included in the reply and filled in Interface and Label Stack TLV SHOULD be included in the
based on Interface-I and Stack-R. Go to step 7 (Send reply and filled in based on Interface-I and Stack-R. Go
Reply Packet). to step 7 (Send Reply Packet).
} }
} }
For each available downstream ECMP path { For each available downstream ECMP path {
Retrieve output interface from the NHLFE entry. Retrieve output interface from the NHLFE entry.
/* Note: this return code is set even if Label-stack-depth /* Note: this return code is set even if Label-stack-depth
skipping to change at page 40, line 15 skipping to change at page 36, line 4
} }
For each available downstream ECMP path { For each available downstream ECMP path {
Retrieve output interface from the NHLFE entry. Retrieve output interface from the NHLFE entry.
/* Note: this return code is set even if Label-stack-depth /* Note: this return code is set even if Label-stack-depth
is one */ is one */
If the output interface is not MPLS enabled { If the output interface is not MPLS enabled {
Set Best-return-code to Return Code 9, "Label switched Set Best-return-code to Return Code 9, "Label switched
but no MPLS forwarding at stack-depth" and set Best-rtn- but no MPLS forwarding at stack-depth" and set Best-rtn-
subcode to Label-stack-depth and goto Send_Reply_Packet. subcode to Label-stack-depth and goto Send_Reply_Packet.
} }
If a Downstream Mapping TLV is present { If a Downstream Detailed Mapping TLV is present {
A Downstream Mapping TLV SHOULD be included in the echo A Downstream Detailed Mapping TLV SHOULD be included in
reply (see section 3.3) filled in with information about the echo reply (see Section 3.4) filled in with
the current ECMP path. information about the current ECMP path.
} }
} }
If no Downstream Mapping TLV is present, or the Downstream IP If no Downstream Detailed Mapping TLV is present, or the
Address is set to the ALLROUTERS multicast address, go to step Downstream IP Address is set to the ALLROUTERS multicast
7 (Send Reply Packet). address, go to step 7 (Send Reply Packet).
If the "Validate FEC Stack" flag is not set and the LSR is not If the "Validate FEC Stack" flag is not set and the LSR is not
configured to perform FEC checking by default, go to step 7 configured to perform FEC checking by default, go to step 7
(Send Reply Packet). (Send Reply Packet).
/* Validate the Target FEC Stack in the received echo request. /* Validate the Target FEC Stack in the received echo request.
First determine FEC-stack-depth from the Downstream Mapping First determine FEC-stack-depth from the Downstream Detailed
TLV. This is done by walking through Stack-D (the Downstream Mapping TLV. This is done by walking through Stack-D (the
labels) from the bottom, decrementing the number of labels for Downstream labels) from the bottom, decrementing the number of
each non-Implicit Null label, while incrementing FEC-stack- labels for each non-Implicit Null label, while incrementing
depth for each label. If the Downstream Mapping TLV contains FEC-stack-depth for each label. If the Downstream Detailed
one or more Implicit Null labels, FEC-stack-depth may be Mapping TLV contains one or more Implicit Null labels, FEC-
greater than Label-stack-depth. To be consistent with the stack-depth may be greater than Label-stack-depth. To be
above stack-depths, the bottom is considered to be entry 1. consistent with the above stack-depths, the bottom is
considered to be entry 1.
*/ */
Set FEC-stack-depth to 0. Set i to Label-stack-depth. Set FEC-stack-depth to 0. Set i to Label-stack-depth.
While (i > 0 ) do { While (i > 0 ) do {
++FEC-stack-depth. ++FEC-stack-depth.
if Stack-D[FEC-stack-depth] != 3 (Implicit Null) if Stack-D[FEC-stack-depth] != 3 (Implicit Null)
--i. --i.
} }
skipping to change at page 41, line 32 skipping to change at page 37, line 22
} }
Go to step 7 (Send Reply Packet). Go to step 7 (Send Reply Packet).
} }
5. Egress Processing: 5. Egress Processing:
/* These steps are performed by the LSR that identified itself as /* These steps are performed by the LSR that identified itself as
the tail-end LSR for an LSP. */ the tail-end LSR for an LSP. */
If received echo request contains no Downstream Mapping TLV, or If received echo request contains no Downstream Detailed Mapping
the Downstream IP Address is set to 127.0.0.1 or 0::1 go to step 6 TLV, or the Downstream IP Address is set to 127.0.0.1 or 0::1 go
(Egress FEC Validation). to step 6 (Egress FEC Validation).
Verify that the IP address, interface address, and label stack in Verify that the IP address, interface address, and label stack in
the Downstream Mapping TLV match Interface-I and Stack-R. If not, the Downstream Detailed Mapping TLV match Interface-I and Stack-R.
set Best-return-code to 5, "Downstream Mapping Mis-match". A If not, set Best-return-code to 5, "Downstream Mapping Mis-match".
Received Interface and Label Stack TLV SHOULD be created for the A Received Interface and Label Stack TLV SHOULD be created for the
echo response packet. Go to step 7 (Send Reply Packet). echo response packet. Go to step 7 (Send Reply Packet).
6. Egress FEC Validation: 6. Egress FEC Validation:
/* This is a loop for all entries in the Target FEC Stack starting /* This is a loop for all entries in the Target FEC Stack starting
with FEC-stack-depth. */ with FEC-stack-depth. */
Perform FEC checking by following the algorithm described in Perform FEC checking by following the algorithm described in
subsection 4.4.1 for Label-L and the FEC at FEC-stack-depth. subsection 4.4.1 for Label-L and the FEC at FEC-stack-depth.
skipping to change at page 44, line 9 skipping to change at page 39, line 48
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
Mapping TLVs SHOULD NOT be included in the echo reply. Detailed Mapping TLVs SHOULD NOT be included in the echo reply.
If the echo request contains a Downstream Mapping TLV, and the If the echo request contains a Downstream Detailed Mapping TLV, and
replying router is not the destination of the FEC, the replier SHOULD the replying router is not the destination of the FEC, the replier
compute its downstream routers and corresponding labels for the SHOULD compute its downstream routers and corresponding labels for
incoming label, and add Downstream Mapping TLVs for each one to the the incoming label, and add Downstream Detailed Mapping TLVs for each
echo reply it sends back. one to the echo reply it sends back.
If the Downstream Mapping TLV contains Multipath Information If the Downstream Detailed Mapping TLV contains Multipath Information
requiring more processing than the receiving router is willing to requiring more processing than the receiving router is willing to
perform, the responding router MAY choose to respond with only a perform, the responding router MAY choose to respond with only a
subset of multipaths contained in the echo request Downstream subset of multipaths contained in the echo request Downstream
Mapping. (Note: The originator of the echo request MAY send another Detailed Mapping. (Note: The originator of the echo request MAY send
echo request with the Multipath Information that was not included in another echo request with the Multipath Information that was not
the reply.) included in the reply.)
Except in the case of Reply Mode 4, "Reply via application level Except in the case of Reply Mode 4, "Reply via application level
control channel", echo replies are always sent in the context of the control channel", echo replies are always sent in the context of the
IP/MPLS network. IP/MPLS network.
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 ensure that it is well-formed, reply, X should parse the packet to ensure 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; Handle. If no match is found, then X jettisons the echo reply;
otherwise, it checks the Sequence Number to see if it matches. otherwise, it checks the Sequence Number to see if it matches.
If the echo reply contains Downstream Mappings, and X wishes to If the echo reply contains Downstream Detailed Mappings, and X wishes
traceroute further, it SHOULD copy the Downstream Mapping(s) into its to traceroute further, it SHOULD copy the Downstream Detailed
next echo request(s) (with TTL incremented by one). Mapping(s) into its 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, an LSP ping for a VPN IPv4 prefix or VPN IPv6 prefix is Typically, an LSP ping for a VPN IPv4 prefix or VPN IPv6 prefix is
sent with a label stack of depth greater than 1, with the innermost sent with a 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 label having a TTL of 1. This is to terminate the ping at the egress
PE, before it gets sent to the customer device. However, under PE, before it gets sent to the customer device. However, under
certain circumstances, the label stack can shrink to a single label certain circumstances, the label stack can shrink to a single label
before the ping hits the egress PE; this will result in the ping before the ping hits the egress PE; this will result in the ping
terminating prematurely. One such scenario is a multi-AS Carrier's terminating prematurely. One such scenario is a multi-AS Carrier's
skipping to change at page 45, line 21 skipping to change at page 41, line 14
4.8. Non-compliant Routers 4.8. Non-compliant Routers
If the egress for the FEC Stack being pinged does not support MPLS If the egress for the FEC Stack being pinged does not support MPLS
ping, then no reply will be sent, resulting in possible "false ping, then no reply will be sent, resulting in possible "false
negatives". If in "traceroute" mode, a transit LSR does not support negatives". If in "traceroute" mode, a transit LSR does not support
LSP ping, then no reply will be forthcoming from that LSR for some LSP ping, then no reply will be forthcoming from that LSR for some
TTL, say, n. The LSR originating the echo request SHOULD try sending TTL, 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 the 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 down the path. In such a case, the echo request for TTL > n SHOULD
be sent with Downstream Mapping TLV "Downstream IP Address" field set be sent with Downstream Detailed Mapping TLV "Downstream IP Address"
to the ALLROUTERs multicast address until a reply is received with a field set to the ALLROUTERs multicast address until a reply is
Downstream Mapping TLV. The label stack MAY be omitted from the received with a Downstream Detailed Mapping TLV. The label stack TLV
Downstream Mapping TLV. Furthermore, the "Validate FEC Stack" flag MAY be omitted from the Downstream Detailed Mapping TLV.
SHOULD NOT be set until an echo reply packet with a Downstream Furthermore, the "Validate FEC Stack" flag SHOULD NOT be set until an
Mapping TLV is received. echo reply packet with a Downstream Detailed Mapping TLV is received.
5. Security Considerations 5. Security Considerations
Overall, the security needs for LSP ping are similar to those of ICMP Overall, the security needs for LSP ping are similar to those of ICMP
ping. ping.
There are at least three approaches to attacking LSRs using the There are at least three approaches to attacking LSRs using the
mechanisms defined here. One is a Denial-of-Service attack, by mechanisms defined here. One is a Denial-of-Service attack, by
sending MPLS echo requests/replies to LSRs and thereby increasing sending MPLS echo requests/replies to LSRs and thereby increasing
their workload. The second is obfuscating the state of the MPLS data their workload. The second is obfuscating the state of the MPLS data
skipping to change at page 48, line 14 skipping to change at page 44, line 7
values in the range 31744-32767 and 64512-65535 are for Vendor values in the range 31744-32767 and 64512-65535 are for Vendor
Private Use, and MUST NOT be allocated. 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 Private Enterprise Number, in network octet MUST be that vendor's SMI Private Enterprise Number, in network octet
order. The rest of the Value field is private to the vendor. order. The rest of the Value field is private to the vendor.
TLVs and sub-TLVs defined in this document are the following: TLVs and sub-TLVs defined in this document are the following:
Type Sub-Type Value Field Type Sub-Type Value Field
---- -------- ----------- ---- -------- -----------
1 Target FEC Stack 1 Target FEC Stack
1 LDP IPv4 prefix 1 LDP IPv4 prefix
2 LDP IPv6 prefix 2 LDP IPv6 prefix
3 RSVP IPv4 LSP 3 RSVP IPv4 LSP
4 RSVP IPv6 LSP 4 RSVP IPv6 LSP
5 Not Assigned 5 Not Assigned
6 VPN IPv4 prefix 6 VPN IPv4 prefix
7 VPN IPv6 prefix 7 VPN IPv6 prefix
8 L2 VPN endpoint 8 L2 VPN endpoint
9 "FEC 128" Pseudowire - IPv4 (Deprecated) 9 "FEC 128" Pseudowire - IPv4 (Deprecated)
10 "FEC 128" Pseudowire - IPv4 10 "FEC 128" Pseudowire - IPv4
11 "FEC 129" Pseudowire - IPv4 11 "FEC 129" Pseudowire - IPv4
12 BGP labeled IPv4 prefix 12 BGP labeled IPv4 prefix
13 BGP labeled IPv6 prefix 13 BGP labeled IPv6 prefix
14 Generic IPv4 prefix 14 Generic IPv4 prefix
15 Generic IPv6 prefix 15 Generic IPv6 prefix
16 Nil FEC 16 Nil FEC
24 "FEC 128" Pseudowire - IPv6 24 "FEC 128" Pseudowire - IPv6
25 "FEC 129" Pseudowire - IPv6 25 "FEC 129" Pseudowire - IPv6
2 Downstream Mapping 2 Downstream Mapping
3 Pad 3 Pad
4 Not Assigned 4 Not Assigned
5 Vendor Enterprise Number 5 Vendor Enterprise Number
6 Not Assigned 6 Not Assigned
7 Interface and Label Stack 7 Interface and Label Stack
8 Not Assigned 8 Not Assigned
9 Errored TLVs 9 Errored TLVs
Any value The TLV not understood Any value The TLV not understood
10 Reply TOS Byte 10 Reply TOS Byte
7. Acknowledgements 7. Acknowledgements
The original acknowledgements from RFC 4379 state the following: The original acknowledgements from RFC 4379 state the following:
This document is the outcome of many discussions among many This document is the outcome of many discussions among many
people, including Manoj Leelanivas, Paul Traina, Yakov Rekhter, people, including Manoj Leelanivas, Paul Traina, Yakov Rekhter,
Der-Hwa Gan, Brook Bailey, Eric Rosen, Ina Minei, Shivani Der-Hwa Gan, Brook Bailey, Eric Rosen, Ina Minei, Shivani
Aggarwal, and Vanson Lim. Aggarwal, and Vanson Lim.
The description of the Multipath Information sub-field of the The description of the Multipath Information sub-field of the
Downstream Mapping TLV was adapted from text suggested by Curtis Downstream Mapping TLV was adapted from text suggested by Curtis
Villamizar. Villamizar.
We would like to thank Loa Andersson for motivating the advancement We would like to thank Loa Andersson for motivating the advancement
of this bis specification. We also would like to thank Alexander of this bis specification.
Vainshtein for his review and comments.
We also would like to thank Alexander Vainshtein, Yimin Shen, Curtis
Villamizar, David Allan for their review and comments.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, Communication Layers", STD 3, RFC 1122,
DOI 10.17487/RFC1122, October 1989, DOI 10.17487/RFC1122, October 1989,
<http://www.rfc-editor.org/info/rfc1122>. <http://www.rfc-editor.org/info/rfc1122>.
skipping to change at page 50, line 20 skipping to change at page 46, line 15
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms "Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<http://www.rfc-editor.org/info/rfc5905>. <http://www.rfc-editor.org/info/rfc5905>.
[RFC6424] Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for
Performing Label Switched Path Ping (LSP Ping) over MPLS
Tunnels", RFC 6424, DOI 10.17487/RFC6424, November 2011,
<http://www.rfc-editor.org/info/rfc6424>.
[RFC7506] Raza, K., Akiya, N., and C. Pignataro, "IPv6 Router Alert [RFC7506] Raza, K., Akiya, N., and C. Pignataro, "IPv6 Router Alert
Option for MPLS Operations, Administration, and Option for MPLS Operations, Administration, and
Maintenance (OAM)", RFC 7506, DOI 10.17487/RFC7506, April Maintenance (OAM)", RFC 7506, DOI 10.17487/RFC7506, April
2015, <http://www.rfc-editor.org/info/rfc7506>. 2015, <http://www.rfc-editor.org/info/rfc7506>.
8.2. Informative References 8.2. Informative References
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981, RFC 792, DOI 10.17487/RFC0792, September 1981,
<http://www.rfc-editor.org/info/rfc792>. <http://www.rfc-editor.org/info/rfc792>.
skipping to change at page 51, line 19 skipping to change at page 47, line 19
[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
"LDP Specification", RFC 5036, DOI 10.17487/RFC5036, "LDP Specification", RFC 5036, DOI 10.17487/RFC5036,
October 2007, <http://www.rfc-editor.org/info/rfc5036>. October 2007, <http://www.rfc-editor.org/info/rfc5036>.
[RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual [RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual
Circuit Connectivity Verification (VCCV): A Control Circuit Connectivity Verification (VCCV): A Control
Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085, Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085,
December 2007, <http://www.rfc-editor.org/info/rfc5085>. December 2007, <http://www.rfc-editor.org/info/rfc5085>.
Appendix A. Deprecated TLVs
A.1. FEC 128 Pseudowire
FEC 128 (0x80) is defined in [RFC4447], as are the terms PW ID
(Pseudowire ID) and PW Type (Pseudowire Type). A PW ID is a non-zero
32-bit connection ID. The PW Type is a 15-bit number indicating the
encapsulation type. It is carried right justified in the field below
termed encapsulation type with the high-order bit set to zero. Both
of these fields are treated in this protocol as opaque values.
When an FEC 128 is encoded in a label stack, the following format is
used. The value field consists of the remote PE IPv4 address (the
destination address of the targeted LDP session), the PW ID, and the
encapsulation type 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote PE IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This FEC is deprecated and is retained only for backward
compatibility. Implementations of LSP ping SHOULD accept and process
this TLV, but SHOULD send LSP ping echo requests with the new TLV
(see next section), unless explicitly configured to use the old TLV.
An LSR receiving this TLV SHOULD use the source IP address of the LSP
echo request to infer the sender's PE address.
A.2. Downstream Mapping(DSMAP)
The Downstream Mapping object is a TLV that MAY be included in an
echo request message. Only one Downstream Mapping object may appear
in an echo request. The presence of a Downstream Mapping object is a
request that Downstream Mapping objects be included in the echo
reply. If the replying router is the destination of the FEC, then a
Downstream Mapping TLV SHOULD NOT be included in the echo reply.
Otherwise the replying router SHOULD include a Downstream Mapping
object for each interface over which this FEC could be forwarded.
For a more precise definition of the notion of "downstream", see
section 3.3.2, "Downstream Router and Interface".
The Length is K + M + 4*N octets, where M is the Multipath Length,
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
Downstream Mapping 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MTU | Address Type | DS Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream IP Address (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Interface Address (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Multipath Type| Depth Limit | Multipath Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. (Multipath Information) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Label | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Label | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Maximum Transmission Unit (MTU)
The MTU is the size in octets of the largest MPLS frame (including
label stack) that fits on the interface to the Downstream LSR.
Address Type
The Address Type indicates if the interface is numbered or
unnumbered. 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 K Octets
------ ------------ --------
1 IPv4 Numbered 16
2 IPv4 Unnumbered 16
3 IPv6 Numbered 40
4 IPv6 Unnumbered 28
DS Flags
The DS Flags field is a bit vector with the following format:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| Rsvd(MBZ) |I|N|
+-+-+-+-+-+-+-+-+
Two flags are defined currently, I and N. The remaining flags MUST
be set to zero when sending and ignored on receipt.
Flag Name and Meaning
---- ----------------
I Interface and Label Stack Object Request
When this flag is set, it indicates that the replying
router SHOULD include an Interface and Label Stack
Object in the echo reply message.
N Treat as a Non-IP Packet
Echo request messages will be used to diagnose non-IP
flows. However, these messages are carried in IP
packets. For a router that alters its ECMP algorithm
based on the FEC or deep packet examination, this flag
requests that the router treat this as it would if the
determination of an IP payload had failed.
Downstream IP Address and Downstream Interface Address
IPv4 addresses 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 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 of the downstream LSR, and the Downstream
Interface Address MUST be set to the downstream LSR's interface
address.
If the interface to the downstream LSR is unnumbered, the Address
Type MUST be IPv4 Unnumbered or IPv6 Unnumbered, the Downstream IP
Address MUST be the downstream LSR's Router ID, and the Downstream
Interface Address MUST be set to the index assigned by the
upstream 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
Downstream 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 validation, but return Downstream
Mapping TLVs using the information provided.
Multipath Type
The following Multipath Types are defined:
Key Type Multipath Information
--- ---------------- ---------------------
0 no multipath Empty (Multipath Length = 0)
2 IP address IP addresses
4 IP address range low/high address pairs
8 Bit-masked IP IP address prefix and bit mask
address set
9 Bit-masked label set Label prefix and bit mask
Type 0 indicates that all packets will be forwarded out this one
interface.
Types 2, 4, 8, and 9 specify that the supplied Multipath
Information will serve to exercise this path.
Depth Limit
The Depth Limit is applicable only to a label stack and is the
maximum number of labels considered in the hash; this SHOULD be
set to zero if unspecified or unlimited.
Multipath Length
The length in octets of the Multipath Information.
Multipath Information
Address or label values encoded according to the Multipath Type.
See the next section below for encoding details.
Downstream Label(s)
The set of labels in the label stack as it would have appeared if
this router were forwarding the packet through this interface.
Any Implicit Null labels are explicitly included. Labels are
treated as numbers, i.e., they are right justified in the field.
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 is bit 19, the Traffic Class (TC) bits are bits 20-22, and
bit 23 is the S bit. The replying router SHOULD fill in the TC
and S bits; the LSR receiving the echo reply MAY choose to ignore
these bits. Protocol
The Protocol is taken from the following table:
Protocol # Signaling Protocol
---------- ------------------
0 Unknown
1 Static
2 BGP
3 LDP
4 RSVP-TE
Authors' Addresses Authors' Addresses
Kireeti Kompella Kireeti Kompella
Juniper Networks, Inc. Juniper Networks, Inc.
Email: kireeti.kompella@gmail.com Email: kireeti.kompella@gmail.com
Carlos Pignataro Carlos Pignataro
Cisco Systems, Inc. Cisco Systems, Inc.
Email: cpignata@cisco.com Email: cpignata@cisco.com
Nagendra Kumar Nagendra Kumar
Cisco Systems, Inc. Cisco Systems, Inc.
Email: naikumar@cisco.com Email: naikumar@cisco.com
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