Re: [Pals] [EXTERNAL] Re: A question about RFC 6073

Andy,
Lots of thanks for a prompt and very detailed response!

Regards, and best wishes to you and yours,
Sasha

From: Andrew G. Malis <agmalis@gmail.com>
Sent: Tuesday, January 23, 2024 2:49 PM
To: Alexander Vainshtein <Alexander.Vainshtein@rbbn.com>
Cc: Bocci, Matthew (Nokia - GB) <matthew.bocci@nokia.com>; pals@ietf.org; pwe3@ietf.org
Subject: [EXTERNAL] Re: [Pals] A question about RFC 6073

Sasha,

Here's my two cents, but Matthew may disagree ... :-)

1. No.
2. N/A
3. RFC 4447 states in section 5.4.1 "The PW label should not be withdrawn unless the operator administratively configures the pseudowire down (or the PW configuration is deleted entirely)." So the S-PE that detects a local fault should not withdraw labels instead of sending PW status messages.

Cheers,
Andy

On Tue, Jan 23, 2024 at 2:56 AM Alexander Vainshtein <Alexander.Vainshtein@rbbn.com<mailto:Alexander.Vainshtein@rbbn.com>> wrote:
Matthew and all,
I have a couple of questions about what looks to me as an undefined use case in RFC 6073<https://datatracker.ietf.org/doc/html/rfc6073>.

(These questions should be addressed to all the authors of this RFC, but the addresses that appear in the RFC seem to be not relevant anymore).

On one hand, Section 10.4 of this RFC states that “Pseudowire status signaling methodology, defined in [RFC4447], SHOULD be transparent to the switching point”.   This suggests to me that S-PE does not have to be aware of the results of the PW Status negotiation by the T-PEs.

On the other hand, Section 10.1 of this RFC states that  “ When a local fault is detected by the S-PE, a PW status message is sent in both directions along the PW”.  This suggest that PW status messages should be sent even to T-PEs that do not recognize them and, therefore, would simply ignore them.

Now the questions:

1.      Should S-PE really be aware of the results of the PW Status negotiation between the T-PEs?

2.      If the answer to my 1st question is “Yes”, should an S-PE that has detected a local fault still send PW Status messages in both directions of the PW?

3.      If the answer to my 2nd question is “No”, should an S-PE that has detected a local fault withdraw labels it has advertised in both directions of the PW instead of sending PW status messages (probably including appropriate SP-PE TLVs indicating the location of the fault)?

Your timely feedback would be highly appreciated.

Regards, and lots of thanks in advance,
Sasha

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