Sup720 load balancing

Unanswered Question
Apr 4th, 2007

Hi.

I have 2 switches 6509 connected by 6 vlans. The traffic must be balanced equally by the six paths, but one of them has the half of traffic than the other 5 paths.

If there are only 5 paths, then the traffic is equal in every path.

If there are only 4 paths, then one path has double traffic (exactly double) than the other three.

The cef shows 6 paths for every route.

The performance is the same in both directions.

I have tried to vary the load-balancing method (mls ip cef load-sharing full), but continues the problem.

It seems that the load-sharing works correctly with an odd number of paths

Any idea?

Thanks and regards.

Jose

I have this problem too.
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cratejockey Wed, 04/04/2007 - 11:06

This might be overly simple of a solution for what you are doing but I'll give it a shot. In all of my Dual Core Chasis enviroents we use HSRP to balance the VLAN load while at the same time keeping our redundancy. For our Even VLANS we set chassis 1 as the HSRP primary ad for the Odd VLANS we set Chassis 2 as the primary. In a failure the VLANS from the failed Chassis roll to the remaining switch. If you set prempt then when the other chassis comes back up you'll go back to load balancing your gateways and their traffic.

Hope this helps.

www.staticnat.com

jyubero Fri, 04/13/2007 - 04:21

Hi.

Our problems is for trafic that goes from one switch to other.

6k5-1 has several parallel links (GE by SDH) with 6k5-2. For every link, we have a vlan like a point-to-point (/30). And we have OSPF in every vlan.

in 6k5-1 we see the route by all the paths. In the cef (mls cef) we have all the paths.

But the traffic is not simetric when we have an even number of links. With an odd number it works correctly.

We cannot use HSRP or portchannel.

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