LSP Ping IPv6 PW FEC: Label Switched Path (LSP) Ping for Pseudowire Forwarding Equivalence Classes (FECs) Advertised over IPv6
Testing pseudowires that use IPv6 addresses with label switched path ping and traceroute
Chen, M., Pan, P., Pignataro, C., and R. Asati, "Label Switched Path (LSP) Ping for Pseudowire Forwarding Equivalence Classes (FECs) Advertised over IPv6", RFC 6829, DOI 10.17487/RFC6829, January 2013, <https://www.rfc-editor.org/info/rfc6829>.
@misc{rfc6829,
series = {Request for Comments},
number = 6829,
howpublished = {RFC 6829},
publisher = {RFC Editor},
doi = {10.17487/RFC6829},
url = {https://www.rfc-editor.org/info/rfc6829},
author = {M. Chen and P. Pan and C. Pignataro and R. Asati},
title = {{Label Switched Path (LSP) Ping for Pseudowire Forwarding Equivalence Classes (FECs) Advertised over IPv6}},
pagetotal = 8,
year = 2013,
month = jan,
} RFC text
Contents
Internet Engineering Task Force (IETF) M. Chen
Request for Comments: 6829 Huawei Technologies Co., Ltd
Updates: 4379 P. Pan
Category: Standards Track Infinera
ISSN: 2070-1721 C. Pignataro
R. Asati
Cisco
January 2013
Label Switched Path (LSP) Ping for
Pseudowire Forwarding Equivalence Classes (FECs) Advertised over IPv6
Abstract
The Multiprotocol Label Switching (MPLS) Label Switched Path (LSP)
Ping and traceroute mechanisms are commonly used to detect and
isolate data-plane failures in all MPLS LSPs, including LSPs used for
each direction of an MPLS Pseudowire (PW). However, the LSP Ping and
traceroute elements used for PWs are not specified for IPv6 address
usage.
This document extends the PW LSP Ping and traceroute mechanisms so
they can be used with PWs that are set up and maintained using IPv6
LDP sessions. This document updates RFC 4379.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6829.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Pseudowire IPv4 Target FEC Stack Sub-TLVs . . . . . . . . . . . 3
3. Pseudowire IPv6 Target FEC Stack Sub-TLVs . . . . . . . . . . . 4
3.1. FEC 128 Pseudowire . . . . . . . . . . . . . . . . . . . . 4
3.2. FEC 129 Pseudowire . . . . . . . . . . . . . . . . . . . . 5
4. Summary of Changes . . . . . . . . . . . . . . . . . . . . . . 6
5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . . 7
1. Introduction
Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Ping
and traceroute are defined in [RFC4379]. These mechanisms can be
used to detect data-plane failures in all MPLS LSPs, including
Pseudowires (PWs). However, the PW LSP Ping and traceroute elements
are not specified for IPv6 address usage.
Specifically, the PW Forwarding Equivalence Class (FEC) sub-TLVs for
the Target FEC Stack in the LSP Ping and traceroute mechanism are
defined only for IPv4 Provider Edge (PE) routers and are not
applicable for the case where PEs use IPv6 addresses. Three PW-
related Target FEC sub-TLVs are currently defined (FEC 128
Pseudowire-Deprecated, FEC 128 Pseudowire-Current, and FEC 129
Pseudowire, see Sections 3.2.8 through 3.2.10 of [RFC4379]). These
sub-TLVs contain the source and destination addresses of the LDP
session, and currently only an IPv4 LDP session is covered. Despite
the fact that the PE IP address family is not explicit in the sub-TLV
definition, this can be inferred indirectly by examining the lengths
of the Sender's/Remote PE Address fields or calculating the length of
the sub-TLVs (see Section 3.2 of [RFC4379]). When an IPv6 LDP
session is used, these existing sub-TLVs cannot be used since the
addresses will not fit. Additionally, all other sub-TLVs are defined
in pairs, one for IPv4 and another for IPv6, but not the PW sub-TLVs.
This document updates [RFC4379] to explicitly constrain the existing
PW FEC sub-TLVs for IPv4 LDP sessions and extends the PW LSP Ping to
IPv6 LDP sessions (i.e., when IPv6 LDP sessions are used to signal
the PW, the Sender's and Receiver's IP addresses are IPv6 addresses).
This is done by renaming the existing PW sub-TLVs to indicate "IPv4"
and also by defining two new Target FEC sub-TLVs (FEC 128 Pseudowire
IPv6 sub-TLV and FEC 129 Pseudowire IPv6 sub-TLV) to extend the
application of PW LSP Ping and traceroute to IPv6 usage when an IPv6
LDP session [MPLS-LDP] is used to signal the Pseudowire. Note that
FEC 128 Pseudowire (Deprecated) is not defined for IPv6 in this
document.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Pseudowire IPv4 Target FEC Stack Sub-TLVs
This document updates Section 3.2 and Sections 3.2.8 through 3.2.10
of [RFC4379] as follows and as indicated in Sections 4 and 6. This
is done to avoid any potential ambiguity and confusion and to clarify
that these TLVs carry only IPv4 addresses. Note that the changes are
limited to the names of fields; there are no semantic changes.
Sections 3.2.8 through 3.2.10 of [RFC4379] list the PW sub-TLVs and
state:
"FEC 128" Pseudowire (Deprecated)
"FEC 128" Pseudowire
"FEC 129" Pseudowire
These names and titles are now changed to:
"FEC 128" Pseudowire - IPv4 (Deprecated)
"FEC 128" Pseudowire - IPv4
"FEC 129" Pseudowire - IPv4
Additionally, when referring to the PE addresses, Sections 3.2.8
through 3.2.10 of [RFC4379] state:
Sender's PE Address
Remote PE Address
These are now updated to say:
Sender's PE IPv4 Address
Remote PE IPv4 Address
3. Pseudowire IPv6 Target FEC Stack Sub-TLVs
3.1. FEC 128 Pseudowire
The FEC 128 Pseudowire IPv6 sub-TLV has a structure consistent with
the FEC 128 Pseudowire sub-TLV as described in Section 3.2.9 of
[RFC4379]. The encoding of the FEC 128 Pseudowire IPv6 sub-TLV is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FEC 128 PW IPv6 Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Sender's PE IPv6 Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Remote PE IPv6 Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: FEC 128 Pseudowire - IPv6
FEC 128 PW IPv6 Type: 24. 2 octets.
Length: Defines the length in octets of the value field of the sub-
TLV and its value is 38. 2 octets.
Sender's PE IPv6 Address: The source IP address of the target IPv6
LDP session. 16 octets.
Remote PE IPv6 Address: The destination IP address of the target IPv6
LDP session. 16 octets.
PW ID: Same as FEC 128 Pseudowire IPv4 [RFC4379].
PW Type: Same as FEC 128 Pseudowire IPv4 [RFC4379].
3.2. FEC 129 Pseudowire
The FEC 129 Pseudowire IPv6 sub-TLV has a structure consistent with
the FEC 129 Pseudowire sub-TLV as described in Section 3.2.10 of
[RFC4379]. The encoding of FEC 129 Pseudowire IPv6 is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FEC 129 PW IPv6 Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Sender's PE IPv6 Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Remote PE IPv6 Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW Type | AGI Type | AGI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ AGI Value ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII Type | SAII Length | SAII Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ SAII Value (continued) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII Type | TAII Length | TAII Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ TAII Value (continued) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TAII (cont.) | 0-3 octets of zero padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: FEC 129 Pseudowire - IPv6
FEC 129 PW IPv6 Type: 25. 2 octets.
Length: Defines the length in octets of the value field of the sub-
TLV. 2 octets
The length of this TLV is 40 + AGI (Attachment Group Identifier)
length + SAII (Source Attachment Individual Identifier) length + TAII
(Target Attachment Individual Identifier) 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.
Sender's PE IPv6 Address: The source IP address of the target IPv6
LDP session. 16 octets.
Remote PE IPv6 Address: The destination IP address of the target IPv6
LDP session. 16 octets.
The other fields are the same as FEC 129 Pseudowire IPv4 [RFC4379].
4. Summary of Changes
Section 3.2 of [RFC4379] tabulates all the sub-TLVs for the Target
FEC Stack. Per the change described in Sections 2 and 3, the table
would show the following:
Sub-Type Length Value Field
-------- ------ -----------
...
9 10 "FEC 128" Pseudowire - IPv4 (Deprecated)
10 14 "FEC 128" Pseudowire - IPv4
11 16+ "FEC 129" Pseudowire - IPv4
...
24 38 "FEC 128" Pseudowire - IPv6
25 40+ "FEC 129" Pseudowire - IPv6
5. Operation
This document does not define any new procedures. The process
described in [RFC4379] MUST be used.
6. IANA Considerations
IANA has made the following assignments in the "Multi-Protocol Label
Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters"
registry.
The following sub-TLV changes, which comprise three updates and two
additions, are made for the TLV Type 1 "Target FEC Stack" in the
"TLVs and sub-TLVs" sub-registry.
The names of the Value fields of these three Sub-TLVs have been
updated to include the "IPv4" qualifier (see Section 2), and the
Reference has been updated to point to this document:
Type Sub-Type Value Field
---- -------- -----------
1 9 "FEC 128" Pseudowire - IPv4 (Deprecated)
1 10 "FEC 128" Pseudowire - IPv4
1 11 "FEC 129" Pseudowire - IPv4
Two new entries for the Sub-Type field of the Target FEC TLV (see
Section 3) have been created:
Type Sub-Type Value Field
---- -------- -----------
1 24 "FEC 128" Pseudowire - IPv6
1 25 "FEC 129" Pseudowire - IPv6
7. Security Considerations
This document does not introduce any new security issues; the
security mechanisms defined in [RFC4379] apply here.
8. Acknowledgements
The authors gratefully acknowledge the review and comments of Vanson
Lim, Tom Petch, Spike Curtis, Loa Andersson, and Kireeti Kompella.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379,
February 2006.
9.2. Informative References
[MPLS-LDP] Asati, R., Manral, V., Papneja, R., and C. Pignataro,
"Updates to LDP for IPv6", Work in Progress, June 2012.
Authors' Addresses
Mach(Guoyi) Chen
Huawei Technologies Co., Ltd
No. 3 Xinxi Road, Shang-di, Hai-dian District
Beijing 100085
China
EMail: mach@huawei.com
Ping Pan
Infinera
US
EMail: ppan@infinera.com
Carlos Pignataro
Cisco Systems
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
US
EMail: cpignata@cisco.com
Rajiv Asati
Cisco Systems
7025-6 Kit Creek Road
Research Triangle Park, NC 27709
US
EMail: rajiva@cisco.com
AI ELI5
On this page
§1The Problem
MPLS Label Switched Path (LSP) Ping and traceroute, defined in RFC 4379, are standard mechanisms for detecting and isolating data-plane failures in MPLS Label Switched Paths (LSPs), including those used for pseudowires.
However, the pseudowire LSP Ping and traceroute mechanisms were not specified for IPv6 address usage. The existing pseudowire Forwarding Equivalence Class (FEC) sub-TLVs could only carry IPv4 addresses. When an IPv6 LDP session is used to set up and maintain a pseudowire, the existing sub-TLVs cannot represent the Sender's and Receiver's PE addresses because they are 16 octets each (IPv6), not 4 octets (IPv4).
A tunnel testing tool was built to work with the old-style IPv4 addresses. When people started using the new IPv6 addresses, the tool did not know what to do.
§2IPv4 and IPv6 FEC Sub-TLVs
RFC 6829 clarifies and extends the pseudowire FEC sub-TLVs. The existing three sub-TLVs from RFC 4379 are renamed to explicitly indicate they carry IPv4 addresses: FEC 128 Pseudowire - IPv4 (Deprecated), FEC 128 Pseudowire - IPv4, and FEC 129 Pseudowire - IPv4. The names change, but the actual structures and semantics do not change; the renaming merely clarifies their use.
Two new sub-TLVs are defined for IPv6: FEC 128 Pseudowire - IPv6 (Type 24) and FEC 129 Pseudowire - IPv6 (Type 25). These have the same structure as their IPv4 counterparts but use 16-octet fields for the Sender's PE IPv6 Address and Remote PE IPv6 Address.
The old tool has two versions: one labeled "IPv4" (the original) and one labeled "IPv6" (the new one). Each version understands the right address style.
| FEC Type | IPv4 Sub-Type | IPv6 Sub-Type | Address Size |
|---|---|---|---|
| FEC 128 Pseudowire (Deprecated) | 9 | N/A | N/A |
| FEC 128 Pseudowire (Current) THIS RFC | 10 | 24 | 4 octets (IPv4) vs 16 octets (IPv6) |
| FEC 129 Pseudowire | 11 | 25 | 4 octets (IPv4) vs 16 octets (IPv6) |
§3FEC 128 Pseudowire IPv6 Structure
The FEC 128 Pseudowire IPv6 sub-TLV (Type 24) contains a 16-octet Sender's PE IPv6 Address, a 16-octet Remote PE IPv6 Address, a 4-octet PW ID, and a 2-octet PW Type field (with a 2-octet Must Be Zero field). The total length is 38 octets.
The Sender's PE IPv6 Address is the source IP address of the target IPv6 LDP session. The Remote PE IPv6 Address is the destination IP address of the target IPv6 LDP session. The PW ID and PW Type are the same as in the IPv4 version.
The IPv6 version of the tunnel identifier packet has two IPv6 addresses (32 octets total) plus information about the tunnel type and ID.
§4FEC 129 Pseudowire IPv6 Structure
The FEC 129 Pseudowire IPv6 sub-TLV (Type 25) is structured similarly to FEC 128 but adds Attachment Group Identifier (AGI), Source Attachment Individual Identifier (SAII), and Target Attachment Individual Identifier (TAII) fields to support virtual circuit identification. It contains 16-octet Sender's PE IPv6 Address and Remote PE IPv6 Address fields, followed by PW Type and the attachment identifiers. The total length is 40 octets plus the variable-length attachment fields, with padding to a multiple of 4 octets.
The FEC 129 version is like FEC 128 but includes extra fields to identify which specific virtual connection the tunnel carries.
§5How It Works
RFC 6829 does not define new procedures; the operation described in RFC 4379 MUST be used. An operator or automated tool runs LSP Ping or traceroute on a pseudowire. If the pseudowire uses IPv6 LDP sessions, the tool uses the new IPv6 FEC sub-TLVs (Type 24 or 25) in the Target FEC Stack to identify the pseudowire. The network devices receiving the ping or traceroute message understand these new types and can process the request.
The technician uses the same testing tool as before, but the tool now knows how to speak about IPv6 tunnels.
§6IANA and Standards
IANA assigned Type values 24 and 25 for the two new IPv6 FEC sub-TLVs in the MPLS Label Switched Paths Ping Parameters registry. The three existing IPv4 sub-TLVs (Types 9, 10, 11) retain their assignments but are now clarified as IPv4-specific.
The IANA registry (the official list of protocol numbers) now lists both the IPv4 versions and the IPv6 versions of the tunnel identifier types.