Label Switched Path (LSP) Ping for
Pseudowire Forwarding Equivalence Classes (FECs) Advertised over IPv6Huawei Technologies Co., LtdNo. 3 Xinxi Road, Shang-di, Hai-dian DistrictBeijing100085Chinamach@huawei.comInfineraUSppan@infinera.comCisco Systems7200-12 Kit Creek RoadResearch Triangle Park27709NCUScpignata@cisco.comCisco Systems7025-6 Kit Creek RoadResearch Triangle Park27709NCUSrajiva@cisco.comexampleThe 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.Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Ping
and traceroute are defined in . 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 ). 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
). 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 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 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.This document updates Section 3.2 and Sections 3.2.8 through 3.2.10
of as follows and as indicated in Sections and . 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 list the PW
sub-TLVs and state: "FEC 128" Pseudowire (Deprecated)"FEC 128" Pseudowire"FEC 129" PseudowireThese names and titles are now changed to: "FEC 128" Pseudowire - IPv4 (Deprecated)"FEC 128" Pseudowire - IPv4"FEC 129" Pseudowire - IPv4Additionally, when referring to the PE addresses, Sections 3.2.8
through 3.2.10 of [RFC4379] state: Sender's PE AddressRemote PE Address These are now updated to say: Sender's PE IPv4 AddressRemote PE IPv4 AddressThe 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 . The encoding of the FEC 128 Pseudowire IPv6 sub-TLV is
as follows: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 .PW Type: Same as FEC 128 Pseudowire IPv4 .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 . The encoding of FEC 129 Pseudowire IPv6 is as
follows:FEC 129 PW IPv6 Type: 25. 2 octets.Length: Defines the length in octets of the value field of the
sub-TLV. 2 octetsThe 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 .Section 3.2 of tabulates all the sub-TLVs
for the Target FEC Stack. Per the change described in Sections and , the table would show the
following: This document does not define any new procedures. The process
described in MUST be used.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 ), and the
Reference has been updated to point to this document: Two new entries for the Sub-Type field of the Target FEC TLV (see
) have been created: This document does not introduce any new security issues; the security
mechanisms defined in apply here.The authors gratefully acknowledge the review and comments of Vanson Lim,
Tom Petch, Spike Curtis, Loa Andersson, and Kireeti Kompella.Updates to LDP for IPv6The Label Distribution Protocol (LDP) specification defines procedures to
exchange label bindings over either IPv4, IPv6 or both networks. This document
corrects and clarifies the LDP behavior when IPv6 network is used (with or
without IPv4). This document updates RFC 5036.