Hi,
From my own research/study on BGP i recall that:
Local Preference - preference given to a BGP route to compare it with other routes TO THE SAME destination.
Since this is LOCAL to the AS, it does NOT get passed to EBGP neighbors. You use this..
neighbor x.x.x.x route-map localpref in
and a defined ACL.
MED - is exchanged between AS (unlike the local preference which is not), but what comes into the AS from
an external BGP speaker does not leave the receiving AS (non-transitive).
To influence routing paths or what can/can't be advertised, I've come across several ways:
1. Local Preference
2. MED
3. AS-path filtering
4. network number filtering
5. setting metrics on static routes
6. using a Private AS number and the command "remive-private-AS"
7. using the command "no-export" with COMMUNITY attribute
I've been able to implement most of these on my staging desk using two 2514s, one 2503, and a 4500.
Now I know what and how BGP works somewhat (versus NOTHING) in the previous week, but that's
after several days of studying and tring out different scenarios. And paying a visit to the nearest
Cisco branch office and chatting with their Systems Engineer to verify my configs.
HTH,
Elmer Deloso
