Yes, MP_REACH ... sorry for that significant slip :-)

Thanks,
Ketan


On Mon, Aug 25, 2025 at 10:01 PM Robert Raszuk <[email protected]> wrote:

> Hi Ketan,
>
> > A BGP UPDATE message can include those "only few prefixes" in the
> MP_UNREACH
> > attribute and then include the LBW ExtCom (with the desired value) as
> well.
>
> You mean in the MP_REACH_NLRI ?
>
> Including any extended communities with MP_UNREACH_NLRI would seem pretty
> pointless.
>
> Thx,
> R.
>
>
>
>
>
> On Mon, Aug 25, 2025 at 3:28 PM Ketan Talaulikar <[email protected]>
> wrote:
>
>> Hi Saumya,
>>
>> A BGP UPDATE message can include those "only few prefixes" in the
>> MP_UNREACH attribute and then include the LBW ExtCom (with the desired
>> value) as well. That is the way to advertise what you seek. How this is
>> achieved is implementation specific.
>>
>> I hope I am getting your question/point correctly. If not, and if it is
>> specific to BESS use-case that leverages LBW, then perhaps discuss in the
>> BESS WG if it can be included in
>> https://datatracker.ietf.org/doc/draft-ietf-bess-ebgp-dmz/
>>
>> Thanks,
>> Ketan
>>
>>
>> On Mon, Aug 25, 2025 at 5:05 PM Dikshit, Saumya <[email protected]>
>> wrote:
>>
>>> Hi Ketan,
>>>
>>> Thanks for your response.
>>>
>>> *>>> **but this is (or should be) something that every BGP developer is
>>> aware of.*
>>> [saumya] I understand that. But what I was looking for is, that there
>>> could be selective tying of bandwidth with only few prefixes for a specific
>>> next-hop. This is specific to the bandwidth extended community and
>>> applicable to one or more use-cases. Hence, I think needs a placeholder.
>>>
>>> I shall trigger the discussions in bess regarding recursive resolution.
>>>
>>> Thanks,
>>>
>>> Saumya.
>>> *From: *Ketan Talaulikar <[email protected]>
>>> *Date: *Monday, 25 August 2025 at 12:56 PM
>>> *To: *Dikshit, Saumya <[email protected]>
>>> *Cc: *Jeffrey Haas <[email protected]>, BESS <[email protected]>,
>>> [email protected] <[email protected]>
>>> *Subject: *Re: [bess] Re: WGLC for draft-ietf-idr-link-bandwidth
>>> (Ending 1 August, 2025)
>>>
>>> Hi Saumya,
>>>
>>> Pitching in here as I do the AD evaluation for the link-bandwidth draft.
>>> In my opinion, neither of these are directly related to the link bandwidth
>>> draft.
>>>
>>> The first point seems to be about general BGP UPDATE message packing
>>> that is applicable to any attribute and not specific to the LBW ExtCom. I
>>> can't remember off the top of my head if the topic of BGP update packing is
>>> covered by any RFC/draft but you can fork a new thread on IDR for
>>> discussion around it.
>>>
>>> The second point is use of the LBW ExtCom for EVPN and as such it is
>>> better covered in a BESS document. I am not sure
>>> if draft-ietf-bess-ebgp-dmz is that document or if there is another more
>>> appropriate one. I'll request you to start a separate thread on it and the
>>> BESS chairs to guide.
>>>
>>> I hope this helps.
>>>
>>> Thanks,
>>> Ketan
>>>
>>>
>>> On Wed, Aug 20, 2025 at 4:42 PM Dikshit, Saumya <saumya.dikshit=
>>> [email protected]> wrote:
>>>
>>> Please help me with the below email.
>>>
>>> Thanks,
>>>
>>> Saumya.
>>> *From: *Dikshit, Saumya <[email protected]>
>>> *Date: *Monday, 18 August 2025 at 5:00 PM
>>> *To: *Jeffrey Haas <[email protected]>
>>> *Cc: *BESS <[email protected]>, [email protected] <[email protected]>
>>> *Subject: *[bess] Re: WGLC for draft-ietf-idr-link-bandwidth (Ending 1
>>> August, 2025)
>>>
>>> Hi Jeff,
>>>
>>> Please see inline with tag [saumya]
>>>
>>>
>>>
>>> On Wed, Aug 06, 2025 at 07:07:59PM +0000, Dikshit, Saumya wrote:
>>> > I support the progression of this draft. Though I have few
>>> queries/clarifications:
>>> >
>>> > Is the definition of a link restricted to the underlay physical links
>>> or also mapped to logical ones like  TE-links mapping to a tunnel.
>>> > For example, a bandwidth tied to a VPN tunnel stitching two fabrics
>>> over WAN. (like a multisite deployment).
>>> >
>>> > Can we clarify the definition of the “link” if it’s not implicit.
>>>
>>> >From the first part of the draft:
>>> >: The Link Bandwidth Extended Community is defined as a BGP extended
>>> community
>>> >: that carries the bandwidth information of a router, represented by BGP
>>> >: Protocol Next Hop, connecting to remote network.
>>>
>>> >So, while the definition of a "link" is left vague in the specification,
>>> >it's clear in context that it's tied to a BGP next hop.
>>>
>>> [saumya] How I am seeing this is
>>>
>>>    - only one instance of* “*bandwidth extended community “ can be
>>>    carried in one BGP update message.
>>>       - And BGP update message encapsulation procedures are expected to
>>>       bucket as many NRLI’s as possible that share the next hop
>>>    - The choice of NLRI’s to be coupled with this extended community
>>>       - may not be just plain vanilla pointing to same next-hop
>>>       - but also might be driven via other policies as well.
>>>    - This will require a mention of these procedures with MAY clause,
>>>    since this draft is about this new extended community.
>>>
>>>
>>> >In terms of deployment use cases, it's not limited in this
>>> specification.
>>> >One of the discussions overlapping the feature is that the same
>>> community
>>> >can be used in-context for multiple things from underlay, to overlay, to
>>> >load balancing traffic across a provider core for Internet purposes.
>>> The
>>> >draft, covering primarily encoding, doesn't try to restrict the use
>>> cases.
>>>
>>> [saumya] The usage specifically with Overlay Index.
>>>
>>>    - Should this newly attribute be carried with the UPDATE message
>>>    publishing the prefix as NLRI
>>>    - Or with the update message carrying the next-hop-resolution.
>>>    - For example, for EVPN RT-5’s carrying overlay index pointing to
>>>    RT-2’s and RT-1’s.
>>>       - Will this attribute be carried with with RT-5 or RT-2/1 which
>>>       resolve the route and carries the flattened next-hop
>>>
>>>
>>>
>>> >Some of the BESS discussion covering LBW covers these points along with
>>> the
>>> >operational use case for things like accumulation at multipath merge
>>> points.
>>> >I'd suggest familiarizing yourself with those drafts.
>>>
>>> [saumya] I couldn’t get any reference to its usage with Overlay index in
>>> bess or idr.  It will be great to have pointer to the drafts. Else we need
>>> to call out above bullets somewhere.
>>>
>>> I think overlay index usage is very important.
>>>
>>>
>>>
>>> >IDR will be coordinating with BESS to figure out the long term
>>> disposition
>>> >of those drafts now that the protocol component draft is moving
>>> forwarding
>>> >towards publication.
>>>
>>> Thanks,
>>>
>>> Saumya.
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