RFC8287 Sub-TLV Length ClarificationCisco Systems, Inc.7200-12 Kit Creek RoadResearch Triangle ParkNC27709USnaikumar@cisco.comCisco Systems, Inc.7200-11 Kit Creek RoadResearch Triangle ParkNC27709UScpignata@cisco.comIndividualCanadafaisal.iqbal@msn.comECI TelecomIsraelvainshtein.alex@gmail.com
Internet
Network Work groupmplsRFC8287 defines the extensions to MPLS LSP Ping and
Traceroute for Segment Routing IGP-Prefix and IGP-Adjacency Segment Identifier (SIDs)
with an MPLS data plane. RFC8287 proposes 3 Target FEC Stack Sub-TLVs. While the standard
defines the format and procedure to handle those Sub-TLVs, it does not sufficiently
clarify how the length of the Segment ID Sub-TLVs should be computed to
include in the Length field of the Sub-TLVs which may result in interoperability
issues.This document updates RFC8287 by clarifying the length of each Segment ID Sub-TLVs
defined in RFC8287.
defines the extensions to MPLS LSP Ping and
Traceroute for Segment Routing IGP-Prefix and IGP-Adjacency Segment Identifier (SIDs)
with an MPLS data plane. proposes 3 Target FEC Stack Sub-TLVs.
While the standard defines the format and procedure to handle those Sub-TLVs, it
does not sufficiently clarify how the length of the Segment ID Sub-TLVs should be computed to
include in the Length field of the Sub-TLVs which may result in interoperability issues.This document updates by clarifying the length of
each Segment ID Sub-TLVs defined in .
This document uses the terminologies defined in
,
,
and so the readers are expected to be familiar with the same.
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 when,
and only when, they appear in all capitals, as shown here.
Section 5 of defines 3 different Segment ID Sub-TLVs that
will be included in Target FEC Stack TLV defined in . The
length of each Sub-TLVs MUST be calculated as defined in this section.
The TLVs representation defined in section 5.1, 5.2 and 5.3 of are updated
to clarify the length calculation as shown in section 4.1, 4.2 and 4.3 respectively.
The updated TLV representation contain explicitly defined length.
The Sub-TLV length for IPv4 IGP-Prefix Segment ID MUST be set to 8 as shown
in the below TLV format:
The Sub-TLV length for IPv6 IGP-Prefix Segment ID MUST be set to 20 as shown
in the below TLV format:
The Sub-TLV length for IGP-Adjacency Segment ID varies depending on the
Adjacency Type and Protocol. In any of the allowed combination of Adjacency Type
and Protocol, the sub-TLV length MUST be calculated by including 2 octets of
Reserved field. Table 1 below list the length for different combinations
of Adj.Type and Protocol.
For example, when the Adj. Type is set to Parallel Adjacency
and the Protocol is set to 0, the Sub-TLV will be as below:
This document does not introduce any IANA consideration.
This document updates and does not introduce
any additional security considerations.
The below individuals contributed to this document:
Zafar Ali, Cisco Systems, Inc.The authors would like to thank Michael Gorokhovsky and Manohar Doppalapudi
for investigating the interop issue during EANTC test.