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LACP load balancing

Hi all, im configuring lacp from my switch to a netapp filer, on th netapp, it gives a load balancing type, mac or IP, as is a layer 2 link, what do I need to use ?

2 REPLIES
Hall of Fame Super Silver

Re: LACP load balancing

Hello Carl,

most cisco switches do IP SA exor IP DA to find an index and decide out what link to send the frame out.

To be noted each side of an etherchannel can use a different load balancing criteria and this info is not exchanged on LACP messages (as far as I know)

Hope to help

Giuseppe

New Member

Re: LACP load balancing

Under most circumstances you would choose IP. The 803.3ad as well as static etherchannels do afford you the option to choose the load-balancing algorithm on each side of the channel. This is because the load-balancing algorithm is used on the transmit side only.

You can determine what your Cisco switch is using by running the following command

show etherchannel load-balance

Most new Cisco switches default to IP but many older switches like that Catalyst 3550 for example and certain legacy chassis based switches will only use MAC based.

Now why you would choose one over the other. If you have clients accessing the NetApp from many different subnets then you would want IP based load-balancing. This is because the source IP and destination IP never changes. MAC on the other hand does change as you traverse router hops. For example All clients accessing your netapp from other subnets would always have the source mac of the local subnets router and the destination mac of the NetApp. This would cause all traffic to be load-balanced to one of the links in the etherchannel, which would likely be bad.

NetApp does an excellent write up of how this works and gives you some great Cisco configuration suggestions for use with their products.

http://communities.netapp.com/blogs/ethernetstorageguy

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