How to avoid traffic being send to a single fully loaded interface of an etherchannel

[dirk.moonens]

Hi,

we're experiencing an issue with the load on an etherchannel between our core and a blade switch.

The hashing on both sides is set correctly to dst-src-ip, and this works fine.

The etherchannel contains 5 ports

A server within this chassis sends sometimes a db dump to a server in another chassis. When this happens the interface of the server goes to full load (1gb) causing 1 of the interfaces in the etherchannel also going to full load. This causes traffic drops to other machines in the chassis due to a fully loaded interface but packets still being send over this interface.

Is there a way to avoid traffic being sent over a fully loaded interface in this channel to avoid drops?

Thanks for your answer/solution!

[marc.groenen]

I believe you can change the outcome of the XOR by changing IP address on servers initiating the session:

https://supportforums.cisco.com/discussion/11165661/lacp-hashing-algorithms

have never tried it myself so good luck :)

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

"Is there a way to avoid traffic being sent over a fully loaded interface in this channel to avoid drops?"

No, that's just the way Etherchannel works.

In a case like yours, the most common solution is to move to a larger bandwidth link, i.e. replace your 5 gig etherchannel, with a 10g link.

PS:

BTW, 5 link etherchannel usually results in suboptimal load balancing of links.