[Xorp-hackers] BGP community support
Marko Zec
zec@icir.org
Wed, 3 Aug 2005 17:28:28 +0200
On Wednesday 03 August 2005 03:32, Ratul Mahajan wrote:
> hi -
>
> from the user manual
> "We also have limited support for:
> RFC 1997: BGP Communities Attribute."
>
> could someone briefly tell me what support is currently available?
Hi Ratul,
the current code from CVS includes a more or less functional policy
framework, which among other things allows one to look at the community
attributes. Based on a received community tag, one can decide to
accept or reject the route, or change some of its attributes, including
the communities themselves.
As an example, the following config will match all the inbound routes
that are tagged with both the communities 65000:1 and 65000:2, on such
routes remove the 65000:2 tag, set the localpref value to 1001, and
accept the route.
protocols {
bgp {
...
import: "bgp-in"
}
}
policy {
policy-statement bgp-in {
term a {
from {
community >= "65000:1,65000:2"
}
then {
community-del: "65000:2"
localpref = 1001
accept
}
}
}
}
Another example - unconditionally set community tags to
65001:101,NO_EXPORT on all received routes:
policy {
policy-statement bgp-in {
term a {
then {
community = "65001:101,NO_EXPORT"
accept
}
}
}
}
Hope this helps,
Marko