BGP Load Balancing

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Feb 14th, 2008
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Hi,

I have two connections from my ISP, 12mb and a 6mb. Can I load balance the two connections to them using the following command?


conf t

router bgp xxxx

no synchronization

bgp log-neighbor-changes

network 65.xx.xx.0 mask 255.255.255.0

neighbor xxx.xxx.xxx.93 remote-as 1222

neighbor xxx.xxx.xxx.93 desc 12mb

maxium-paths 2

neighbor xxx.xxx.xxx.57 remote-as 1222

neighbor xxx.xxx.xxx.57 desc 6mbBackup

end


My understanding of BGP is by default it only picks one path for each route.

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Overall Rating: 3.8 (3 ratings)
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Rick Morris Thu, 02/14/2008 - 08:47
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You will be able to share the load between the two connections, but you may not get a 50/50 split.


BGP uses various different selection methods. In order to utilize it more effectively you may want to have your provider sent you their full routing tables. This will also help with route selection too.


I assume you are peering with 2 different providers, or at least 2 different peering points?


Routes can make selection on Hops, and it may be faster out one connection over the other.


For more info on BGP go check out:

http://www.cisco.com/en/US/tech/tk365/tk80/tsd_technology_support_sub-protocol_home.html

There are other links in there too.

siskoboy2007 Thu, 02/14/2008 - 08:51
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Thanks for the help. We are peering to the same ISP but to two different peering points.

Rick Morris Thu, 02/14/2008 - 08:52
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Then your config looks fine.

There are a few other things I would do but for the basic set-up you are good.


are you accepting full routes from the provider?

siskoboy2007 Thu, 02/14/2008 - 08:56
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No, we don't. We used them for our default route out to the Internet (0.0.0.0) and they only advertise our public network.

Rick Morris Thu, 02/14/2008 - 09:00
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Thanks for the link...this is a great one!


Mohamed Sobair Thu, 02/14/2008 - 13:09
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Hi,


There is no (load balance) with BGP but rather (Load Share), and could be acheived by spiliting Prefixes & force it tward specific Outbound or inbound directions using BGP (AS-Path Attribute).


HTH

Mohamed

sumedh.rangari@... Fri, 02/15/2008 - 23:56
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Hi,


For example, if i want to Load balance across Multiple E-BGP peers [Different AS] and both are terminating on the same Router at My End.


If i use a combination of "eBGP Multipath" and "bgp bestpath as-path ignore" and also enable CEF, would i get Load Balancing Effect


-Sumedh Rangari

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