[nsp] Inbound traffic and two BGP paths

TMS tomek@absolut.vinyl.pl
Thu, 26 Sep 2002 08:18:36 +0200


Hello I have question regarding BGP protocol. I have router
with two BGP connections to Tier-1 providers - Sprint and Telia. To
this router I connected also customer which wants two links, first to
Sprint and second for Telia. I created each link using separate BGP
session and separate E1/Serial interface. My question
is about inbound traffic from Sprint and Telia. Is this traffic go to
customer through good interface ? Or router do load-balancing between
Serial2/0 and Serial2/1 (equal BGP paths to customer) ? My idea is:
traffic from Sprint must return via Serial2/0 and traffic
from Telia must return via Serial2/1.

Router configurtion:

!
interface ATM1/0
	no ip address
!
interface ATM1/0.100
	description Sprint (AS1239)
	bandwidth 10000
	ip address 10.10.10.2 255.255.255.252
	pvc 0/100
		enapsulation aal5snap
		vbr-nrt 10000 10000
	!
!
interface ATM1/0.200
	description Telia (AS1299)
	bandwidth 10000
	ip address 20.20.20.2 255.255.255.252
	pvc 0/200
		enapsulation aal5snap
		vbr-nrt 10000 10000
	!
!
interface Serial2/0
	description Customer (AS200) - Sprint
	bandwidth 1000
	ip address 30.30.30.1 255.255.252
!
interface Serial2/1
	description Customer (AS200) - Telia
	bandwidth 1000
	ip address 40.40.40.1 255.255.252
!
router bgp 100
	network 30.30.30.0 mask 255.255.255.0
	network 40.40.40.0 mask 255.255.255.0
	!
	neighbor 10.10.10.1 description Sprint
	neighbor 10.10.10.1 remote-as 1239
	neighbor 10.10.10.1 filter-list 1 out
	!
	neighbor 20.20.20.1 description Telia
	neighbor 20.20.20.1 remote-as 1299
	neighbor 20.20.20.1 filter-list 1 out
	!
	neighbor 30.30.30.2 descripion Customer - Sprint
	neighbor 30.30.30.2 remote-as 200
	neighbor 30.30.30.2 filter-list 30 out
	neighbor 30.30.30.2 route-map SETLOC in
	!
	neighbor 40.40.40.2 descripion Customer - Telia
	neighbor 40.40.40.2 remote-as 200
	neighbor 40.40.40.2 filter-list 40 out
	neighbor 40.40.40.2 route-map SETLOC in
	!
!
ip as-path access-list 1 permit ^$
ip as-path access-list 30 permit ^1239_
ip as-path access-list 40 permit ^1299_
!
route-map SETLOC permit 10
	set local-preference 1000
	set community 100:1
!

best regards,
Tommy