[c-nsp] SoO causing 1-member update groups

Oliver Boehmer (oboehmer) oboehmer at cisco.com
Thu Dec 18 04:00:33 EST 2008

Saku Ytti <> wrote on Thursday, December 18, 2008 08:37:

> On (2008-12-16 13:37 -0800), bill fumerola wrote:
> Hey Bill,
>> why does adding an external community to a route (via a route-map)
>> impact the neighbor itself? i realize in later versions of IOS this
>> command was added to the per-{neighbor,peer-group,peer-policy}
>> stanzas. 
> I'm trying to think how else it could work, and I'm drawing blank.
> Since when neighbour has been set with SoO, you will have to send
> different routes to that neighbour, as you omit sending any routes
> that already have that SoO set.

Well, this is true, but Bill had the same SoO community configured on
all peers, so they all share the same outbound routing policy, and thus
fall all into the same update-group. This was just recently fixed via
CSCso80951 (BGP peers with same policy fall into different update-group
with SOO).

Bill: Not sure if I would use SoO for your purpose due to its dual
semantic: It tags a BGP path (which is what you want to achieve), but it
also implicitly filters those paths outbound on peers setting the same
SoO value inbound (which might or might not be intentional).

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