Drew, network statements are for the weak.:)
(I'm kidding of course) but there is a better way.
You should use community tagging in combination with prefix lists and route
maps. The idea is that you announce routes according to a tag and the
behavior of the announcements depends on the specific tag applied. For
example, you could tag routes as peers, transits, global announce, etc and
formulate the type of feeds you give your customers by filtering against
communities so a customer wants peers and customers only you could match the
two appropriate community tags. This also allows you to tag the communities
you globally announce uniquely and make the announcements in a unified way
at your edges. If you accompany this method with the appropriate
redistribute static, redistribute connected, etc and use route maps to
control this behavior you can remove the need for network statements
completely and greatly decrease the things you need to modify and as a
result the possible mistakes. The other upside here is you can mark your
more specifics as do not export and better control traffic internally better
directing the traffic in your example. It also allows you to accept
communities from your customers and have automatic actions taken based on
the tags they apply. Let me know if you need some configuration examples.
----- Original Message -----
From: "Drew Weaver" <drew.wea...@thenap.com>
To: "Cisco-nsp" <cisco-nsp@puck.nether.net>
Sent: Monday, January 04, 2010 12:35 PM
Subject: [c-nsp] BGP - Announcing routes to Internet providers.
Howdy,
I am trying to figure out if there is a different/newer/better(?) way to
announce our public IP ranges to our Internet providers, currently we are
declaring our subnets in 'network statements' in the BGP configuration, we
have static routes setup like ip route x.x.x.x 255.255.224.0 Null0 254 and
then we have a extended access-list applied to each peer with our net
blocks listed in them.
It appears that because of the network statements, the supernet routes
(/18s, /19s, etc) are being distributed via BGP to the rest of the network
which is by design(I assume). This doesn't seem ideal because if traffic
is sent to an IP address that doesn't have a more specific route than say
/18, or /19 it travels all the way through the network to the edge before
stopping. I might be blowing the impact of this out of proportion, but it
just seems like a waste of resources.
Does anyone know of a seemingly more sensible way of doing this?
-Drew
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