Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures
draft-ietf-mpls-lsp-ping-13

It seems to me that the (example) IP addresses used in this document
do not comply with RFC3330 recommended addresses.

Nit from Gen-ART review by David Black:

  Nit: This draft uses "TTL" to refer the MPLS TTL and "IP TTL"
  to refer to the TTL in the IP header.  That convention makes
  sense for an MPLS draft, but it should be stated in the
  conventions section, just in case the reader is not an MPLS
  expert.

- Still need [PW-CONTROL] refernce in section describing FEC 129 (section on FEC 128 has it now).

- The following terms for "FEC 128" and "FEC 129" are more consistent with [PW-CONTROL] (if you search on "128" or "129" in the PW-CONTROL document, you get nothing, because it uses 0x80 and 0x81).

For FEC128: The PWid FEC Element
For FEC129: The Generalized PWid FEC Element

- I know I asked for a normative reference to RFC4026, but it should be Informative given that RFC4026 is informative.

- Something that isn't mentioned in the security considerations section, if the UDP source port is varied when sending an echo request, it is something else an unsophisticated hacker would have to guess correctly for an echo reply.

- IANA Considerations: I believe the return code should be an IANA registry. I think George agreed, and probably just forgot to include it.

>  Value Meaning ----- -------
>  0 No return code
>  1 Malformed echo request received
>  2 One or more of the TLVs was not understood
>  3 Replying router is an egress for the FEC at stack depth <RSC>
>  4 Replying router has no mapping for the FEC at stack depth <RSC>
>  5 Downstream Mapping Mismatch (See Note 1)
>  6 Upstream Interface Index Unknown (See Note 1)
>  7 Reserved
>  8 Label switched at stack-depth <RSC>
>  9 Label switched but no MPLS forwarding at stack-depth <RSC>
>  10 Mapping for this FEC is not the given label at stack depth
>  <RSC>
>  11 No label entry at stack-depth <RSC>
>  12 Protocol not associated with interface at FEC stack depth <RSC>
>  13 Premature termination of ping due to label stack shrinking to a
>  single label

Nit: IPv4 addresses and and interface indices are encoded in 4 octets

General:  I strongly agree with the TTL confusion comment already made.