[c-nsp] route maps and bgp

[james edwards]

> they are telling me i need route maps to filter
> the routes (im advertising my other neighbors routes to them).  im trying 
> to
> advertise two networks out to each neighbor.  my config was basically

> apparently with this simple config, im a transit now - and it is hitting 
> my
> network hard.

Yep, you are sending all best routes to each neighbor, provided you did not 
hear these routes from that neighbor.
You need to filter each neighbor, outgoing, to allow only the routes you 
want advertised.

ip prefix-list neighbor1 seq 5 permit a.b.c.d/24
ip prefix-list neighbor1 seq 10 permit e.f.g.h/20
ip prefix-list neighbor2 seq 5 permit a.b.c.d/24
ip prefix-list neighbor2 seq 10 permit e.f.g.h/20

Apply this way:

router bgp AS#
network a.b.c.d/24
network e.f.g.h/20
neighbor w.x.y.z remote-as ####
neighbor w.x.y.z distribute-list 1 out
neighbor w.x.y.z version 4
neighbor 1.2.3.4 remote-as ####
neighbor 1.2.3.4 distribute-list 2 out
neighbor 1.2.3.4 version 4

If you want to advertise the same prefixes to both neighbors then you can 
use the same list for both.

James
Routing and Security Administrator
At the Santa Fe Office: Cyber Mesa Telecom
jamesh at cybermesa.com  noc at cybermesa.com
http://www.cybermesa.com/ContactCM