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View Full Version : Any differences between the BGP community "local-as" and "no-export"


Chris
06-17-2009, 01:05 AM
Hey guys .. trying to workout the differences between local-as and no-export communities ….. Is my understanding correct for cases 1 and 2 below?

local-as – do not advertise route outside local-as to any eBGP peer. If this attribute set in sub-as (inside confederations) then it will not be advertised to any other sub-AS’s (eBGP peers).

no-export – do not advertise to any eBGP peers, but if confederations used, then it can be advertised to other sub-AS’s. If no confederations is used then it works like local-as.

Technicaly if we get a question to make sure that the route should not be advertised outside the local-as (no confederations) then we can use either local-as or no-export as they will work the same.

Case 1 - If we are using confederations and need to stop route from been advertised outside our confederation then we must use local-as.

Case 2 - If we are using confederations and need to stop route from been advertised another sub’AS within our confederation then we must use no-export.
Thanks

David.C
06-17-2009, 03:53 AM
http://www.netbraintech.com/share/bgpcommunity_reply.gif

To keep a route INSIDE your confederation, but not to anyone else, use no-export.

http://www.netbraintech.com/share/bgpcommunity_reply2.gif

To keep a route inside YOUR AS, but not even to confederation peers, use local-as.

http://www.netbraintech.com/share/bgpcommunity_reply3.gif

The least to most restrictive well-known communities: Internet --> no-export --> local-as --> no-advertise.

Chris
06-17-2009, 04:52 AM
That really helped, thanks for the quick reply.

xuxxestwwgj
01-24-2011, 08:28 AM
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