05-21-2009 11:23 AM - edited 03-04-2019 04:50 AM
What is the quickest easiest way to achieve some degree of load balancing with BGP?
The problem is I have a remote site with 2 T1's from diverse providers. One is ATT MPLS and the other is VB MPLS. It is all eBGP, peering to the interfaces. I have tried peering to the loopbacks across the cloud and it resulted in some mean route flapping.
So the short version is that I need more bandwidth and I need to figure out how to leverage the unused T.
router bgp 65221
no synchronization
no bgp log-neighbor-changes
network 10.60.254.144 mask 255.255.255.255
network 10.75.121.0 mask 255.255.255.0
neighbor 12.117.255.117 remote-as 7018
neighbor 12.117.255.117 prefix-list Local out
neighbor 152.162.109.33 remote-as 65000
neighbor 152.162.109.33 prefix-list Local out
neighbor 152.162.109.33 route-map AddAS in
neighbor 152.162.109.33 route-map AddAS out
no auto-summary
route-map AddAS permit 15
set as-path prepend 65221 65221
05-21-2009 01:01 PM
Okay - first things first. I cringe when anyone talks about "load balancing" BGP. It really is a redundancy protocol foremost with some "load sharing" as an after thought.
Now that the disclaimer is out of the way, lets get down to business. Think of inbound and outbound as completely separate tasks. For inbound load sharing, AS-Path prepending is really your best option (often it is the only option). For outbound load balancing, you need to look at what you are receiving from the providers. Are you taking full or partial routes? Or are you simply taking default routes. If you are taking full or partial routes then you *should* have some kind of load sharing happening. If you are taking default routes, then you might just need to help direct traffic within the network to the closest router or figure out some load sharing scheme.
This is probably something you should be working with your providers on. I've seen some providers that will manipulate BGP attributes w/o your knowledge (like remove your prepends when they get it). At the least they may have some ideas about what you can do.
Jim
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide