Etherchannel Load Balancing

[GRANT3779]

Looking at the attached diagram, would it make sense to have the Load-Balancing Algorithm on the Core to "Destination MAC" and then on the Access Layer Switch Side to "Source Mac" address? Keeping in Mind there would be multiple Servers and also 100s of PC's on the Access Layer side.

Thanks

[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

Yes, that's correct (for using a single MAC hash), but newer devices often offer other choices, so, for example, using src and dest MAC would work on either side.  Using src and dest IP often works well too.

BTW, the servers appear to be on another subnet, so there's only one "core" MAC, the gateway MAC.

[GRANT3779]

OK, so it makes more sense to use destination IP address on the Core switch I would assume. If using Dest MAC, which will always be my SVI, will the physical etherchannel port used, always be the same? 

On the Access Switch however, source MAC or Dest IP probably would work best. 

[Jon Marshall]

If you load balanced on the same mac address yes it would use the same link.

It depends on your switches as to what they can do in terms of load balancing but what you want is a method that will give the greatest variety.

Again, depending on your switches you don't just have to do src or dst you can use both.

Some switches you can show what the switch will do in terms of load balancing ie. you can test it.

See this link for details -

https://supportforums.cisco.com/document/69496/etherchannel-loadbalancing-catalyst-switches

Jon

[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

Yes, on the core side you could use dest IP, because like dest MAC, your destinations should be the various access side hosts.

Dest MAC, on you access side would always be the gateway MAC, which as it's always the same, would use the same Etherchannel linkl.

Dest IP, on access side, unlike dest MAC, should be server IP, so it too would work.