WAN Load balancing

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Dec 20th, 2011
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Hello all,

I'm helping a friend out with a project he has. The setup in place is on yacht that has 4 V-Sats and they are wanting to load balance across all four of these links via a Cisco 2911. My recommendation to him was to just create 4 static default routes to each V-SAT's ip address. Would this accomplish the goal of loadbalancing? My concern is that would it actually load balance amongst the 4 links or just choose one and then move other to another link once the initial primary went down? Also would enabling CEF be an option if its a feature the 2911 can do? I've attached the visio to give a better idea.

Any input is much appreciated!



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Overall Rating: 5 (2 ratings)
cadet alain Tue, 12/20/2011 - 16:01
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CEF is enabled by default and it is doing load-balancing on a per src-dst IP pair.

So configuring 4  static default routes with same default AD of 1 will load balance per src-dst IP and if one route goes down then the other 3 will still load-balance.

But if you do NAT you'll have to use route-maps for the NAT overload config and in the route-map you'll have to match on outgoing interface.



cflory Tue, 12/20/2011 - 16:09
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More on Alain's point, if you wanted to load balance beyond per destination, you could enable 'ip load-sharing per-packet' per each interface to the V-Sats.  This will help load balance further, in case there is only a small number of destinations.

However, I'm not sure about running that command on the 2900's, as I don't have one in front of me, but it is a thought. You'll most likely add more CPU overhead, though.

JFlorian33 Tue, 12/20/2011 - 17:21
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Thanks for the feeback! I deffinetly don't wanna do per-packet load-sharing as I believe they are doing some VOIP services and streaming which could cause some problems. Thanks for the reminder about the NAT'ing portion as I'm not exactly sure if they are using all public addresses or private. I'll certainly have to follow up on that portion.

Marwan ALshawi Wed, 12/21/2011 - 03:47
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You cam follow the logic in this document where you van use pbr fir load sharing the traffic and ip sla to make sure fail over works


Nat cam be used as well if required

Hope this help

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