Strip AS in BGP peer

Andy Davidson andy at nosignal.org
Fri Nov 20 19:45:03 CST 2009


Sherwin Ang wrote:
> well here it goes.  we'll soon form a new internet exchange and i
> would like to suggest a model in the route-server wherein the
> route-server would strip out it's own AS and give the neighbors/peers
> the AS's of the members.  I have seen this in Any2IX but i have no
> idea on how to implement it as if i am the Any2 route-server.


Hi, Sherwin

Sorry for the late reply.

We (LONAP, London UK) have deployed our route-servers using BIRD and
OpenBGPd on unix servers, rather than traditional big iron hardware for the
following reasons :

 - Availability of the 'stripped asn' feature as you describe.
 - Multiple RIBs per BGP instance, so that route-server participants who
filter (on the route-server) can do so without causing shadowing of prefixes.
 - Don't need the high-capacity forwarding - the route-servers swap
prefixes, not traffic.

As other posters in this thread have described, it's also possible to do
this with the Quagga software, but the current codebase appears to creak
(and then croak !) with scale, when multiple-ribs are enabled.

This email is pretty brief; the exchange community have been discussing
this and publishing talks on the subject since the beginning of the year,
as our understanding of the problems of running the common open-source so I
can point you to some resources that you may find interesting :

Our decisions and introduction to the LONAP service :
http://www.uknof.org.uk/uknof13/Davidson-LONAP_routeservers.pdf

INEX (Dublin, IE) describe the per-peer RIB problem and Quagga problems :
http://www.ripe.net/ripe/meetings/ripe-58/content/presentations/Hilliard-Why_use_Quagga_for_Route_Servers.pdf

LINX (London, UK) also describe the per-peer RIB problem and explain their
efforts to solve the Quagga problems :
http://www.uknof.org.uk/uknof13/Hughes-IXP_routeservers.pdf

EuroIX route server activity report from October :
http://www.ripe.net/ripe/meetings/ripe-59/presentations/hiliard-euroix-update.pdf
(Situation is more evolved now, but I don't know if more recent slides are
public)


The situation is likely to move quickly by the middle of next year, if
there is interest it sounds like a good operational BOF for N'49.

Andy




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