Re: [mpls] Opsdir last call review of draft-ietf-mpls-bfd-directed-27

[Greg Mirsky <[e-mail]>]

Hi Joe,
I've uploaded the new version that includes updates resulting from our
discussion.
Name:     draft-ietf-mpls-bfd-directed
Revision: 28
Title:    Bidirectional Forwarding Detection (BFD) Directed Return Path for
MPLS Label Switched Paths (LSPs)
Date:     2024-04-16
Group:    mpls
Pages:    11
URL:
https://www.ietf.org/archive/id/draft-ietf-mpls-bfd-directed-28.txt
Status:   https://datatracker.ietf.org/doc/draft-ietf-mpls-bfd-directed/
HTML:
https://www.ietf.org/archive/id/draft-ietf-mpls-bfd-directed-28.html
HTMLized: https://datatracker.ietf.org/doc/html/draft-ietf-mpls-bfd-directed
Diff:
https://author-tools.ietf.org/iddiff?url2=draft-ietf-mpls-bfd-directed-28

Thank you for your help in improving the draft.

Regards,
Greg

On Mon, Apr 15, 2024 at 4:02 PM Greg Mirsky <[e-mail]> wrote:

> Thank you, Joe, for your quick response. I'll upload the updated version
> with the updates addressing the TSVART review.
>
> Regards,
> Greg
>
> On Mon, Apr 15, 2024 at 3:48 PM Joe Clarke (jclarke) <[e-mail]>
> wrote:
>
>> Thanks for the modifications.  They read well to me.  As to the question…
>>
>>
>>
>> Finally, my question.  In the Operational Consideration, what would (or
>> should)
>> happen to the underlying service while the LSP ping is processed in the
>> case of
>> reverse-path FEC failure?  Is there guidance to provide to maintain
>> service
>> while this new session might be established?
>>
>> GIM>> That, in my opinion, is the formative question; thank you for that.
>> It is assumed that the operator controls the network to which the Reverse
>> PAth Control TLV is applied. If theat is the case, the failure of the
>> installed reverse path is a case of the network failure. The operator, I
>> assume that from the ingress BFD peer, is notified, and then can switch the
>> reverse path of the BFD session. I imagine, that there could be other
>> switchover policies, but I believe that it is essential that the ingress
>> BFD peer detects the network failure if the reverse path of the BFD session
>> fails. WDYT?
>>
>>
>>
>> JMC: I read this differently the first time.  Thinking on your figure, I
>> agree with you.  If the tunnel A-B-C-D-G-H is good, but the reverse
>> H-G-D-C-B-A is not (and this is the reverse path requested), then we can
>> assume there isn’t bidirectional forwarding and the ingress peer should be
>> informed.  That likely should warrant a service interruption unless there
>> is another viable failover path.
>>
>>
>>
>> Joe
>>
>