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Port Channel Load Balancing Protocols Advice Please

Unanswered Question
Jan 16th, 2012
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Hi


What I am attempting to achieve is to aggregate trunk ports out of a VMware server into a single logical connection to give as much bandwidth as possible, the switches are 3750X and are three stacked together with the server connections spread across the stack.


What I am not sure about is if two port channel load balance protocols can happy co-exist on the switch, by default the switch is using MAC address load balancing and Vmware wants to use IP Source load balancing.


As other trunks and channels exist on the switch I don't want to make a change that will affect the other live connections if changing this is a global setting and not local on the channel.


Thanks in advance.


Matt

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Joseph W. Doherty Mon, 01/16/2012 - 05:07
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Years ago, some older Cisco switches used to only support src MAC or dest MAC hashing and it was often optimal to use different hashing algorithms on the two switches connected by an Etherchannel (dest MAC toward end hosts, and src MAC from end host; as GW was only a single MAC).  So, unlikely you'll need to consider what hashing algorithm is being used by the VM server when selecting the optimal algorithm on the Cisco switch.

darren.g Mon, 01/16/2012 - 15:49
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jazzman20014 wrote:




Hi


What I am attempting to achieve is to aggregate trunk ports out of a VMware server into a single logical connection to give as much bandwidth as possible, the switches are 3750X and are three stacked together with the server connections spread across the stack.


What I am not sure about is if two port channel load balance protocols can happy co-exist on the switch, by default the switch is using MAC address load balancing and Vmware wants to use IP Source load balancing.


As other trunks and channels exist on the switch I don't want to make a change that will affect the other live connections if changing this is a global setting and not local on the channel.


Thanks in advance.


Matt


According to this document


http://www.cisco.com/en/US/docs/switches/lan/catalyst3750x_3560x/software/release/12.2_53_se/command/reference/cli1.html#wp1864309


the port-channel load balance setup is a global option - if you're using src-mac (the default) then you can't assign src-ip to an individual port-channel without affecting all of them.


I'm pretty sure that applies to other switches as well - I remember running into this kind of situation when using 4948-10g switches and having to make a choice.


Cheers.

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