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Etherchannel Load Balancing between two switches

Answered Question
Mar 6th, 2012
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Hi, does anyone know if it is possible to use two different load balancing methods at each end of a port-channel between two switches?


We have a Cisco 6509 at one end of the port-channel and a Cisco blade switch 3020 at the other end.  Right now, we are using "src-dst-ip" at both end of the port-channel.  We would like to change this.  That is, we would like the 3020 switch to use "src-dst-ip" while the 6509 switch should use the "src-dst-port". 


Can this be implemented?  Does it work well?  Are there any potential issues? 


In case someone is wondering why we want to do this, the reason is that we have FWSMs on the 6509.  I've read that by configuring "src-dst-port" on the 6509, one can get a better performace of traffic going through the FWSM.  However, the issue is that the 3020 switch does not support "src-dst-port". 


Thanks for your help

Correct Answer by Peter Paluch about 5 years 5 months ago

Hello,


A very good question! The answer is: you are free to choose whichever load balancing method you want to use at each end, regardless of the method used at the other end - and you are even supposed to do it to achieve maximum traffic spreading. There are no issues related to doing this, as from the viewpoint of an EtherChannel, a particular flow of frames will always be sent over a single link only, and the receiving end of the link bundle does not care why a particular link was used.


Best regards,

Peter

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Correct Answer
Peter Paluch Tue, 03/06/2012 - 01:20
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  • Cisco Employee,

Hello,


A very good question! The answer is: you are free to choose whichever load balancing method you want to use at each end, regardless of the method used at the other end - and you are even supposed to do it to achieve maximum traffic spreading. There are no issues related to doing this, as from the viewpoint of an EtherChannel, a particular flow of frames will always be sent over a single link only, and the receiving end of the link bundle does not care why a particular link was used.


Best regards,

Peter

cosimotodaro Tue, 03/06/2012 - 01:32
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Hi Peater,


Thank you for your reply.  I understand your explanation and it was the answer that I was expecting.  My reasoning also comes to the same conclusion.  Can I ask you if you have implemented this configuration yourself?  Or if you have any Cisco documentation that deals with such configuration.


I cannot find Cisco documentation that clearly deals with such configuration. 


Thank you 

Peter Paluch Tue, 03/06/2012 - 01:39
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  • Cisco Employee,

Hello,


I've implemented it in laboratory environment and also in a multivendor environment when I interconnected Cisco and HP switches, and Cisco switches versus Linux server using ethernet card bonding. Each of these devices may use a different load balancing method, as even with the same basic type of balancing, the hashing function used in each implementation may be different. I have had no issues.


Best regards,

Peter

cosimotodaro Tue, 03/06/2012 - 01:42
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Hi Peter,


Thank you for all your help.  I'm going to go ahead and put forward the change.

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