HPE EVA Storage

Cisco MDS PortChannel over long distances, variation in cable length

 
Cmorrall
Frequent Advisor

Cisco MDS PortChannel over long distances, variation in cable length

When designing a new SAN connecting two datacentres over some distance the question came up if we could use multiple dark fibres to create a PortChannel (ISL trunk in Brocade-talk I guess).
The restrictions on a Brocade equivalent came to mind; I can't have too much variation in the cable length in each individual cable in a trunk.
However, I've been unable to find much if there are any such restrictions for Cisco MDS. I found something a bit vague in a marketing flyer for Cisco MDS where they pointed out that a "competing vendor" [duh] has this restriction whereas Cisco does not.

Poring through the manuals, so far no mention of this. I suppose if there weren't any restriction, it wouldn't be mentioned.

Any comments?
2 REPLIES 2
andrewB_1
New Member

Re: Cisco MDS PortChannel over long distances, variation in cable length

Charles - did you get anywhere with this?
Am planning to set this up with my existing MDS9134's

HP, Cisco and EMC have assured me the configuration is supported but I can't find anyone who has actually set this up and can verify that its more than "airware".

Any feedback on your experience so for would be very welcome.
Cmorrall
Frequent Advisor

Re: Cisco MDS PortChannel over long distances, variation in cable length

I used two physical pairs of dark fibre, but I also installed a CWDM solution to split these two pairs into four connections. I connected each switch to both physical fibres, but logicially seperated on different wavelengths. Might sound confusing if you're unfamiliar with CWDM.

The net result was that I had two fabrics with two ISLs in each fabric, and they take two different paths per fabric. So far, I can get link OK, but I've not put any load on the connections yet.