[nsp] Load Balancing with BGP over unequal-cost circuits

[Brian Wallingford]

The config you've forwarded indicates only a single bgp neighbor.

BGP will, by default, load balance if all available paths are equal, and
you've specified max-paths.  BGP to multiple upstreams will not
load-balance due to its nature, but to a single AS, it can be very
effective.  IIRC, there is a very intuitive case study on CCO which covers
this nicely.

hth,
brian


On Wed, 2 Oct 2002, Tay Chee Yong wrote:

:Hi all,
:
:My understanding is that BGP doesn't do load balancing because of its nature of
:selection of best path, however load sharing can be achieved.
:
:I have a customer who is doing load balancing over an E1 (2Mbps) and a 1Mbps
:circuit (unequal bandwidth) using BGP, and it seems to work.
:
:Could someone advise how was the load-balancing achieved?
:
:Following is the config :
:
:* Note : Both circuits are terminated to the same router on both ends. *
:
:interface Serial0/1
: description ==> Link 1Mbps
: bandwidth 1024
: ip address 192.168.252.206 255.255.255.252
: no ip redirects
: no ip proxy-arp
: ip load-sharing per-packet
: no fair-queue
: hold-queue 4096 out
:!
:interface Serial0/2
: description ==> Link 2Mbps
: bandwidth 2048
: ip address 192.168.252.202 255.255.255.252
: no ip redirects
: no ip proxy-arp
: ip load-sharing per-packet
: no fair-queue
: hold-queue 1024 out
:!
:
: network 172.16.0.0 mask 255.255.192.0
: network 172.16.64.0 mask 255.255.192.0
: network 172.16.128.0 mask 255.255.192.0
: network 172.16.192.0 mask 255.255.192.0
: neighbor 192.168.255.202 remote-as 65500
: neighbor 192.168.255.202 ebgp-multihop 3
: neighbor 192.168.255.202 update-source Loopback0
: neighbor 192.168.255.202 version 4
: neighbor 192.168.255.202 soft-reconfiguration inbound
: neighbor 192.168.255.202 route-map ksc-in in
: neighbor 192.168.255.202 route-map ksc-out out
:
:ip route 172.16.0.0 255.255.192.0 Null0
:ip route 172.16.64.0 255.255.192.0 Null0
:ip route 172.16.128.0 255.255.192.0 Null0
:ip route 172.16.192.0 255.255.192.0 Null0
:ip route 192.168.255.202 255.255.255.255 Serial0/1
:ip route 192.168.255.202 255.255.255.255 Serial0/2
:
:
:access-list 21 permit any
:access-list 22 permit 172.16.0.0 0.0.255.255
:
:route-map ksc-out permit 10
: match ip address 22
:!
:
:route-map ksc-in permit 10
: match ip address 21
: set local-preference 500