Re: [Idr] Notification Subcode Squatting (draft-ietf-idr-bgp-open-policy)

["Jeffrey Chiang (jefchian)" <[e-mail]>]

Cisco has implemented https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-multisession-07 many years ago. We are using the subcodes as stated in the draft, but offset by one, because at the time (and now still), subcode 7 was already used. They are
8 - Capability Value Mismatch (was called "No Supported AFI/SAFI" in version 00)
9 - Grouping Conflict
10 - Grouping Required
We would like to resurrect the draft and progress it to RFC.
Are there any other implementations?

Regards,
Jeffrey

-----Original Message-----
From: Idr <[e-mail]> On Behalf Of Susan Hares
Sent: Sunday, December 19, 2021 7:41 AM
To: 'Alvaro Retana' <[e-mail]>; [e-mail]
Cc: [e-mail]; [e-mail]
Subject: Re: [Idr] Notification Subcode Squatting (draft-ietf-idr-bgp-open-policy)

Alvaro: 

Documenting what is out there and pragmatism is the best policy.   

Q1. Something else 

If Cisco has been squatting on the subcode 8, cisco experts should let us know: 1) how widely it is deployed, and 2) how difficult to change.    
If Bird, the same questions apply.  

Pragmatism 

Q2. (b) Deprecating the code and (c) working with pragmatism to get actual implementations to registered code. 


Sue 

PS - +1 to what Jeff Haas says as well. 


-----Original Message-----
From: Idr [mailto:[e-mail]] On Behalf Of Alvaro Retana
Sent: Wednesday, December 15, 2021 3:53 PM
To: [e-mail]
Cc: [e-mail]; [e-mail]; Susan Hares
Subject: [Idr] Notification Subcode Squatting (draft-ietf-idr-bgp-open-policy)

Dear idr WG:

draft-ietf-idr-bgp-open-policy is currently in IETF Last Call.

This document specifies a new Role Mismatch Notification (code 2, subcode 8).  This value was initially allocated by IANA in 2018 [1].

Unfortunately, Alexander (cc'd) just pointed out that BIRD uses the same code and subcode combination for a Notification in the case where an AFI/SAFI is not supported. :-(  As far as I can tell, no such Notification is specified anywhere.  However, a quick search points at cisco potentially implementing the same functionality [2] [3] [4] -- some of these reports go as far back as 2010.


What now?

Given that there seem to be multiple deployed implementations that use this code/subcode combination, we should avoid using it even if they are squatting on it. :-(  Also, BIRD was one of the two reported implementations for draft-ietf-idr-bgp-open-policy.  So I propose that we request IANA to assign a different value for the new Notification specified in this document.

Before moving forward, I want to confirm that the WG agrees with the proposal.  Please take a look at the questions below.  I would like to hear from implementers at BIRD and cisco (and any other that I didn't find that might be in the same situation), and from FRR (the second implementation of draft-ietf-idr-bgp-open-policy).


Q1: Should a new subcode be requested for the Role Mismatch Notification
    specified in draft-ietf-idr-bgp-open-policy?

[ ]: Yes.
[ ]: No, the squatters should update their implementations.
[ ]: Something else.


Q2: What should we do with subcode 8?

[ ]: It should be deprecated (i.e., no one can use it).
[ ]: Write a specification for an "unsupported AFI/SAFI" Notification.
[ ]: Something else.


I will keep this poll open until Jan/5, 2022.


Thanks!

Alvaro.



[1] https://www.iana.org/assignments/bgp-parameters/bgp-parameters.xhtml#bgp-parameters-6

[2] https://community.cisco.com/t5/routing/bgp-3-notification-erro/td-p/1572684

[3] https://www.wireshark.org/lists/wireshark-bugs/201607/msg00164.html

[4] https://bst.cloudapps.cisco.com/bugsearch/bug/CSCsu79206

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