Ethernet Switches & Routers

Posts: 54
Registered: ‎01-27-2010

FCX stack-to-stack link aggregation - dynamic or static?

I've seen example configurations for both static and dynamic (LACP) groups, but haven't seen anything about when you would use one or the other. 

Our core will have two FCX stacks interconnected by multiple 10G links.  What would be reasons to choose static or dynamic?  What's a good way to balance the traffic?

Thanks much!

Occasional Contributor
Posts: 11
Registered: ‎11-25-2012

Re: FCX stack-to-stack link aggregation - dynamic or static?

Static LAGs are just a bunch of aggregated links. No signaling takes place between two peers and therefore a misconfiguration on one side can be difficult to troubleshoot.

Dynamic LAGs use LACP packets to establish and negotiate the link which means the chance of misconfiguration is reduced (for example the link won't form if it's only configured on one side).

The important thing to note with LACP is that a node can either be passive (just listening) or active (advertising), but at least one side needs to be active to establish the link.

Example config:

Brocade(config)#interface ethernet 1/1/1 to 1/1/4

Brocade(config-mif-1/1/1-1/1/4)#link-aggregate off

Brocade(config-mif-1/1/1-1/1/4)#link-aggregate configure key 10000

Brocade(config-mif-1/1/1-1/1/4)#link-aggregate active

Brocade(config-mif-1/1/1-1/1/4)#interface ethernet 3/1/5 to 3/1/8

Brocade(config-mif-3/1/5-3/1/8)#link-aggregate off

Brocade(config-mif-3/1/5-3/1/8)#link-aggregate configure key 10000

Brocade(config-mif-3/1/5-3/1/8)#link-aggregate active

This command sequence changes the key for ports 1/1/1 through 1/1/4 and 3/1/5 through 3/1/8 to 10000. Because all ports in an aggregate link must have the same key, this example forms a multi-slot aggregate link for ports 1/1/1 through 1/1/4 and 3/1/5 through 3/1/8.

Check out the config guide, there's a section on LACP.

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