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New Member

ospf loadbalancing

how can we "loadbalancing" 3 serial links (2 links are 2mbps, and 1 link is 768kbps) in a ospf environment?

  • Other Network Infrastructure Subjects
4 REPLIES
Gold

Re: ospf loadbalancing

You can only load share over equal cost links in OSPF, unless you are using mpls traffic engineering.

Russ

New Member

Re: ospf loadbalancing

Hi,

You could manually assign an equal OSPF cost to each interface. That would force traffic to be shared across the links. I think Cisco's implementation of OSPF supports up to 6 equal cost paths.

example

interface serial 1

ospf cost 100

interface serial 2

ospf cost 100

Hope this helps

Jonathan

Gold

Re: ospf loadbalancing

You can do this, but you need to be careful about overloading the third, lower bandwidth, link. OSPF doesn't have a limit on the number of equal cost paths, but the routing table is limited to 8 equal cost paths, and some platforms limit you to 2 or 6 equal cost paths.

:-)

Russ

Re: ospf loadbalancing

To add on,

By manipulating the cost on all the 3 links, all links will have equal number of packets sent. OSPF wont balance the traffic like EIGRP does with Unequal cost load balancing, where the number of packets sent on two links will be in a ratio x:y where x and y are the bandwidths (metrics) of the links.

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