RFC 7110, "Return Path Specified Label Switched Path (LSP) Ping", January 2014

Errata ID: 4195
Status: Verified
Type: Editorial
Publication Format(s) : TEXT
Reported By: tom petch
Date Reported: 2014-12-09
Verifier Name: Adrian Farrel
Date Verified: 2014-12-09

Section 5.4 says:

When an echo reply is received, if the Reply Mode is "Reply via
Specified Path" and the Reply Path return code is "The echo reply was
sent successfully using the specified Reply Path", and if the return
path is an MPLS LSP.  The ingress LSR MUST perform FEC validation
(based on the FEC Stack information of the return path carried in the
Reply Path TLV) as an egress LSR does when receiving an echo request,
the FEC validation process (relevant to "ping" mode) defined in
Section 4.4.1 of [RFC4379] applies here.

When an echo reply is received with return code set to "Malformed
echo request received" and the Subcode set to zero.  It is possible
that the egress LSR may not know the "Reply via Specified Path" Reply
Mode, the operator may choose to re-perform another LSP ping by using
one of the four Reply Modes defined [RFC4379].

It should say:

When an echo reply is received, if the Reply Mode is "Reply via
Specified Path" and the Reply Path return code is "The echo reply was
sent successfully using the specified Reply Path", and if the return
path is an MPLS LSP, the ingress LSR MUST perform FEC validation
(based on the FEC Stack information of the return path carried in the
Reply Path TLV) as an egress LSR does when receiving an echo request,
the FEC validation process (relevant to "ping" mode) defined in
Section 4.4.1 of [RFC4379] applies here.

When an echo reply is received with return code set to "Malformed
echo request received" and the Subcode set to zero, it is possible
that the egress LSR may not know the "Reply via Specified Path" Reply
Mode; the operator may choose to re-perform another LSP ping by using
one of the four Reply Modes defined in [RFC4379].

Notes:

In the first two paragraphs of section 5.4, the conditional clauses and the main clause have been separated by periods, not commas, which creates uncertainty as to whether or not text of the main clause has been elided. This changes the periods into commas.

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