BGP balancing

Unanswered Question
Jul 27th, 2010

I'm a network administrator for an ISP. We are a dual homed BGP shop. We have, in general around 250 Mbps of traffic on each link (2 7206-G2 routers). The problem is, when one link goes down the traffic wouldn't rebalance correctly. We'd end up with about 400 and 100. In order to rebalance it we'd need to reboot the router that was missing traffic, and once it was up, reboot the other router. We've actually moved all of our traffic to the G2 cards from the front cards, which may have fixed the issue. We won't know until we have an outage though.

The main thing I want to know, is there a BGP command that would effect how traffic is balanced after reestablishing the inter link?

Here's my config, minus network statements and changed numbers to protect the innocent. would be the inter link, would be the other ISP

router bgp 12345
no synchronization
bgp log-neighbor-changes

! network entries

neighbor remote-as 12345
neighbor ebgp-multihop 3
neighbor update-source Loopback0
neighbor next-hop-self
neighbor soft-reconfiguration inbound
neighbor remote-as 4321
neighbor password 7 00031E0C055800031B32
neighbor next-hop-self
neighbor soft-reconfiguration inbound
neighbor route-map MAP out
no auto-summary

I have this problem too.
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gatlin007 Tue, 07/27/2010 - 13:27


Can you post a network diagram?  What is your IGP?  Are you using CEF?  You should never have to reboot a router to alter packet forwarding.


the traffic imbalance happens in the incoming direction or outgoing direction?. There are BGP attributes to influence traffic in both direction; when you failed link comes back the BGP can reshaped the traffic back to normal.

Local Preference for outgoing traffic and AS path prepending for incoming traffic.

Share you diagram would further help




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