Re: [mpls] Poll to see if we have support to make draft-bryant-mpls-oam-udp-return an mpls working group document

["Nobo Akiya (nobo)" <[e-mail]>]

Hi Stewart,

Clipping out ones with closure.
Please see below.

[...]
> > [snip from Section 4]
> >     If the URO is expected but is not present in Query message and an
> >     MPLS-PLDM Response is requested out-of-band, the Query message
> MUST
> >     NOT be processed further.  If received over a bidirectional LSP, the
> >     control code of the Response message MUST be set to "Error - Missing
> >     TLV" and a Response SHOULD be sent over the reverse LSP.
> >
> > [snip from Section 4.3]
> >     If an Out-of-band response is requested and the Address object or the
> >     URO is missing, the Query SHOULD be dropped in the case of a
> >     unidirectional LSP.  If both these TLVs are missing on a
> >     bidirectional LSP, the control code of Response message should set to
> >     "Invalid Message" and the response SHOULD be sent over the reverse
> >     LSP.
[...]
> > In the second snippet from Section 4.3 above, I believe the condition
> should be && and not ||.
> I don't think so.
> 
> Address only was the original mode and although I have doubts about
> whether there are deployments we need to support it until it is deprecated.
> Thus you might find an address TLV indicating a response over IP is required
> or a URO indicating a response over UDP/IP is required.
> 
> I think we agreed that we needed to support multiple UROs in certain
> circumstances however I am wondering whether we need to support both
> modes (IP and URO) or the same packet.
[...]

I see. I got the impression from the document that having both is not disallowed, thus it's an error if neither are included in the Query (i.e. &&). But you are right, there's no point in keeping around (IP) since (URO) is a superset. Technically I do not see any issue if this document deprecated (IP). Responder implementations will likely need to support both for a while, thus perhaps having a text around the transition period (i.e. what happens when both (IP) and (URO) are in the Query) somewhere in the document (ex: Appendix?) may be beneficial.

Either way, texts in both snippets should be updated.

Thanks!

-Nobo