Trunk setup for Cisco 6509 and F5 ltm 1600

Posted By rpalacios on 01/27/2010 11:05 AM

 

 

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1. Are there any know issues I need to be aware of when I introduce the trunk?

 

 

 

 

 

Well... You need to be aware that F5 and Cisco people talking need an interpreter between them.

 

 

Cisco Trunks == F5 VLAN Tagging

 

Cisco Etherchannel == F5 Trunks

 

 

Assuming (From the description) you mean cisco trunks/f5 vlan tagging, then no there's no real problems. I usually set the allowed vlans on the cisco however when doing this.

 

 

 

2. What is the best mesh config? Should ltm-A go to 6509-A and ltm-b go to 6509-b?

 

 

 

 

That's the way I doit. Primarily because I also use etherchannels (F5 trunks) to connect for aggregated bandwidth. On cisco's you can't make a channel ACROSS switches.

 

 

 

3. Are there any known issues with looping, spanning tree, etc?

 

 

 

 

Yeah. F5's can be switches. Don't set portfast on the cisco. I usually use STP passthrough on the F5. This is more relevant where you have bridged VLAN's not F5 trunks/etherchannel.

 

 

 

4. What would be the recommended settings for LACP?

 

 

 

 

 

I use

 

 

channel-group mode active

 

 

on each interface.

 

 

 

5. Is there a better method?

 

 

 

 

Well... You could probably come up with a different method each day... Whether they're right would depend on your requirements. I know mine works, and passes all the tests thrown at it.

 

 

H

 

I run a similar setup with 6509's and LTM pairs. LTM-A goes to 6509A and LTM-B goes to 6509B. I use the two fiber modules in an LACP group, and trunk the vlan's to the LACP group.

Thanks for the replies guys.

 

 

Is there any reason why you wouldn't use one interface on each f5 to one 6509 and the other to the second 6509 and configure them as individual trunks?

 

 

I like the one to one relationship, but I would like to explore all possibilities.

 

 

I tried attaching a drawing under 100kb but kept getting an error.

 

 

Thanks again,

 

 

-rp

 

 

Well you won't be able to LACP them, and i think you may run into spanning tree issues there since your A and B switch are probably running different spanning tree priorities, but i am not a network expert. I think if you had one interface to each, you have to set the priority lower on one, to force traffic through one interface when it is up.

Spanning tree will sort itself out, AS LONG AS you have STP passthrough configured (Or if you know networks you could have the F5 do STP as well. But that's not always a simple config. You want to make sure you know exactly what's going to happen with your root bridge in all situations.

 

 

However you WILL get spanning tree reconvergences when doing this. Which means each VLAN (Assuming you're doing VLAN'ed spanning tree), every time you restart an F5. WHich isn't nice (30 second pause in the VLAN).

 

 

I like to avoid spanning tree whenever possible.

 

 

Oh... Don't try to get around the spanning tree by setting portfast... The F5 acts as a bridge. Portfast isn't a good idea through a bridge.

 

 

H