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List:       isp-bgp
Subject:    [isp-bgp] Asymetric Routing with two defaults
From:       Chris Davies <isp () daviesinc ! com>
Date:       2005-04-20 7:06:47
Message-ID: 1113980807.4193.36.camel () tsavo
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I have a 3650 with two connections to two ISPs, I am running BGP and
have both sending me defaults.  I have 2 /22s from one, 1 /22 from the
other.  I would like to send the traffic out the appropriate connection
based on the ultimate owner of the block, i.e. send the traffic from the
2 /22s to provider B, the 1 /22 to provider B.

I have set the weight on one of the providers to 100 temporarily to
prefer them.  Failover works as expected -- shutting down one sends all
traffic to the other and vice versa.

I have a set of route-maps which aspad my blocks from the one provider
on the opposite provider -- thus my /22s from one provider are preferred
inbound to that provider, the /22 from the other provider is preferred
over them.  These do appear to be announcing as expected when I:

sh ip bgp regexp _xxxxx$ 

on several looking glass machines.

However, this sets up an asymetric routing situation.  Traffic comes in
the right connection, but always leaves the 'preferred' connection.
I've temporarily removed those route-maps in favor of stability.

I believe I need a bgp policy map set up to do the mapping, but, no
matter what I try, the cisco decides it doesn't like the policy
route-map.

I set up the following:

route-map from-internap-policy permit 10
 match ip address 60
 set interface GigabitEthernet0/1

Where Internap is connected to GigE 1, and access-list 60 = the internap
IP addresses.

When I try to apply the following to either GigE0/2 or Vlan1, conf t
accepts it, but, does nothing.  It is never saved.

ip policy route-map from-internap-policy

I have also tried entering it outside an interface, but, the system
never seems to accept it.

I've tried many other things, but, the route-maps in bgp don't appear to
be the right answer.  I've checked all of the documentation I can find,
and it appears that a policy is what I need, but, finding enough
documentation to figure out what I am missing is troublesome.  Perhaps
someone has run into this issue before or can point me in the right
direction.

Thank you.


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