Re: [mpls] Doubts in allocation of a new G-ACH type for

[Alexander Vainshtein <[e-mail]>]

Dave,

Lots of thanks for a prompt response.



Unfortunately I have to say that it is confusing: interleave of CC and CV packets on the same stream is achieved by using a different G-ACh type for CV messages. This type discriminates between CC and CV messages equally well for any of the two G-ACh types that potentially could be used for carrying CC messages.



Do I miss something fundamental?



Regards,

     Sasha

________________________________
From: David Allan I [[e-mail]]
Sent: Wednesday, July 11, 2012 6:07 PM
To: Alexander Vainshtein; [e-mail]; [e-mail]
Cc: [e-mail]; [e-mail]; [e-mail]; pwe3 ([e-mail]); Rotem Cohen; Andrew Sergeev; Mishael Wexler
Subject: RE: Doubts in allocation of a new G-ACH type for

Hi Sasha:

The reason for this is the overall system behavior implied. A 5885 code point is purely CC operation. A 6428 code point indicates that CV will be interleaved with the stream. We wanted to explicitly disambiguate this.

It further permits misbranching of a 5885 stream into a 6428 path to be detected so the overall network is more robust. If the CC messages in both 5885 and 6428 had a common code point, this would not be possible, and CV operation would not be authoritative.

I hope this helps
Dave

________________________________
From: Alexander Vainshtein [mailto:[e-mail]]
Sent: Wednesday, July 11, 2012 3:51 AM
To: David Allan I; [e-mail]; [e-mail]
Cc: [e-mail]; [e-mail]; [e-mail]; pwe3 ([e-mail]); Rotem Cohen; Andrew Sergeev; Mishael Wexler
Subject: Doubts in allocation of a new G-ACH type for

Hi all,
I have doubts regarding allocation of the G-ACH type for the MPLS-TP CC message in RFC 6428<http://tools.ietf.org/html/rfc6428>.

Looking at both this RFC and RFC 5885<http://tools.ietf.org/html/rfc5885>, it seems that the format of the MPLS-TP CC packet and the format of the raw BFD packet in VCCV is exactly the same. However, two different G-ACH types have been allocated by IANA for these two cases.

IMHO and FWIW such duplication can only create interoperability problems, especially with progress of the new VCCV Type (using GAL) for PWs. The text in Section 3.1 of 6428 that refers to existing capability to run BFD over LSP with the G-ACh using Channel Type 7 only adds to the confusion IMO, since it uses un-capitalized “may” and not one of the IETF reserved requirement level words.

Clarification of intentions by the editors of RFC 6428 (and/or of RFC 5885) would be highly appreciated.

Regards,
     Sasha


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