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EIGRP Load Balancing

Unanswered Question
Aug 5th, 2006
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Dear all,

Now we have 2 connectivity to my HO .I m using EIGRP protocol using redistribute static.As I want to load balance traffic between 2 link but cases are given below

1) when primary link BW become 80% then traffic should be shift to other link

2) Both link works in back up of each others .

How to do load balancing in EIGRP




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devang_etcom Sat, 08/05/2006 - 05:59
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hi SAM...

you can have unequal cost path loadbalancing in EIGRP... as we know we have best path towards the destination in routing table... now if you want to achive the loadbalancing you have to confiugure your EIGRP with VARIANC command... this variance command let you to install multiple path the the same destination... look at this example...

R1 ----cost 5--- R2

----cost 9---


here router1 is connected with router2 with three link... one link is with cost5 other with cost9 and last one is with cost13... now eigrp will have lowest cost path in routing table so your all traffice will travel through the cost5 path... now if you want to configure the loadbalancing then you need mulitple path in routing table so router can load balanc. now u need to use variance command...when you use variance2 then you will have cost5 and cost9 path in routing table...

variance command worklike... n x lowest cost path.

if you use n=2 then in our case 2 x 5=10

so you will have all the path in the routing table whose cost is lowerthen 10... and if you use n=3 then 3 x5=15 then you will have all the path in routing table whose cost is lessthen 15...it means in our case all three path is coverd...

you can have more idea from this link:http://www.cisco.com/warp/public/103/19.html

please rate this post if it helps



zulqurnain Sat, 08/05/2006 - 08:13
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hi sam

for more understanding on load balancing you can refer to


also, You may want to look at LQM which can measure the reliability of a link and take it out of service if it falls below a threshold.


hope this helps

abhayaa123 Sun, 08/06/2006 - 05:05
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As i understand.

Following should be the command on our primar link interface.

int < interface number >

backup interface < interface number >

You just need to add. this command more.

back load 80 60

This command states that whenever load on primar link is 80 % secondar link will be activated and once the load is 60 % the link will again go in standby mode.

Hope this is what our requirement. is.

safe Sun, 08/06/2006 - 08:16
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Dear All,

Thanks for ur replies but this backup interface will also not solve my probs as I have LL on Router-A and Vsat on ROuter-B . How we can achieve Load balance in this case

1) HO ----LL --- Router A ----Router B ---Vsat--- HO

When LL load becomes 80% then i will use Vsat link for traffic sharing.





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