/* adding GROW WG as what is being discussed is much more operational topic
then protocol extension */

Hi Jeff,

Minimally, the proposal
> covers an extended community that can be used by policy to say:
>
>   Is my BGP Identifier present in this list of extended communities?
>   If so, I'm interested in it.


I would like to comment on this point. Looks very innocent on the surface.

*Point #1: *

At the target deployment (as per current version of the draft) this means
p2p distribution of information with inherently p2mp protocol. I do not
think this is efficient. This is trying to use BGP as a policy/config push
mechanism only because we do not have a good one yet in IETF.

*Point #2: *

I do have some sympathy (as noted already earlier) that if my extended
community carries a prefix of BGP_ROUTE_IDs this could have potentially
some useful applications**. But not a list of 1:1 mapped BGP_IDs. That list
can get really long and neither processing it at each node now attaching it
to each UPDATE is efficient.

*Point #3: *

As it has been noted already by Gert you can accomplish what you need today
already with just adding a community and applying filtering on it. Of
course modulo filtering on IBGP has its own risks, but those I assume are
well understood.

*Point #4: *

As previously discussed, the draft should discuss handling withdrawals in
all previously described scenarios. Not only in terms of implementation's
ability to do so, but actual protocol correctness (case where UPDATE
carries both MP_REACH and MP_UNREACH and node-target-ext-comm applies to
the former not the latter. Splitting those into different UPDATE messages
may not always be easy.

*Point #5: *

We are starting to get to the point of ingress inline signalling atomic
filtering rules. Nothing wrong with this. But if so I would rather see this
generalized. With that, Wide-Communities provide such ability. Why define
more in encoding which by design is limited in size ? What if next would be
a request to only accept UPDATE by a node which has a client belonging to a
fixed IPv6 prefix ?

Likewise why not enable sender to advertise routes to only a subset of
upstream or peer ASNs ?

We are really walking on the line of protocol inline encoding of policies
vs mgmt driven policy/cfg push (both modulo current RTC like option).

Comments more than welcome (before it's too late :),
Robert
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