Etherchannel single port utilization high

Unanswered Question
Oct 7th, 2009
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Hello Gentleman all,

I configured 4 ports eth channel bundle between dual core switch 6509 with sup720.

During some of the network server backup time we are getting "High utilization alert" from core switch with single port having more utilization.

The load balance method being used is

'Src-dst IP".

Any workaround to this issue.


Thanks

swami

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glen.grant Thu, 10/08/2009 - 03:56
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If all the traffic is between 2 devices that traffic is all going to go down a single link that's the way etherchannel works . You could try a different load balancing algorithm but if the traffic is between a couple of devices when backing up , not sure there is a way around that.

arumugasamy Sat, 10/10/2009 - 22:08
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Hi,

Thanks for your info.This

ports used in eth channel : 6/22,6/24,2/22,2/23

Total 4 ports being used.

Now the load balanceing method: src-dst-ip.

we are getting high utilization at port 6/22,6/24.This alert is coming frequently 4-5 times a day.All the servers are connected to module 6.

tstandefer Thu, 10/08/2009 - 07:03
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What line card do you have and what ports do you have in the bundle?

arumugasamy Sat, 10/10/2009 - 22:05
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Hi,

Thanks for your info.

The line card model : WS-X6724-SFP\

ports used in eth channel : 6/22,6/24,2/22,2/23

Total 4 ports being used.

Now the load balanceing method: src-dst-ip.

we are getting high utilization at port 6/22,6/24.This alert is coming frequently 4-5 times a day.All the servers are connected to module 6.

Joseph W. Doherty Thu, 10/08/2009 - 08:38
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To expand upon what Glen already notes, if what's being used for the channel hash doesn't change, traffic will use same link. Assuming the backup is running between a pair of hosts, using src-dst IP will always hash to one link. Other hash algorithms (if supported) will have the same result for any single flow. If there were multiple concurrent flows between the hosts, and ports number were also part of the hash, then multiple links might be used.


If concurrent flows with a different hash algorithm isn't an option, as Glen notes there isn't much more you can do with Etherchannel. Other options might include using a higher bandwidth link between the 6509s (e.g. 10 gig) or perhaps splitting the channel into either dual, dual Etherchannels or four individual links and using packet-by-packet routing. (The latter adds the issue of out-of-sequence packets. Shouldn't be a problem across two links between the same two devices, could be a problem with four links.)

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