For more details, please see ourCookie Policy.

Fibre Channel (SAN)

Posts: 0

ISL Trunking, and different ISL Speed

Hi Team,

Good Morning...!!!

We have 2 Fabrics composed of 1 DCX, and 1 Brocade5300 SAN switches each.

There are 2 ISL connections, from the DCX to the BRC5300 in each fabric.

I noticed that, one of ISL Links in one of the Fabrics has speed of 4Gbps and the other is 2Gbps.

I checked both sides of the port are Auto_Neg.

Can anyone please advice me, how do I set it to 4Gbps, and wat impact could we have when we do it.

Also, if anyone can point me to some ISL Trunking related docs, we want to setup the ISL Trunking for these ISL links.


Sarwar J

Former Brocadian
Posts: 445
Registered: ‎04-08-2009

Re: ISL Trunking, and different ISL Speed

Greetings shaikh.sarwar.  Sorry to hear about this minor inconvenience, but we'll get it sorted out.  If I were to guess, I'd start with the cabling.  Its the first thing most people tend to overlook.  At 8 Gigabit Fibre Channel and beyond: Use OM3 or OM4 multimode cables and/or OS1 single-mode cables.  OM1 and OM2 multi-mode cables have very limited distance when used at 8 Gbps and beyond.  After that is sorted, you can hard set the port speeds and shouldn't have any adverse effects. 

Regarding your request for trunking docs, you can start here.  This comes from the FOS Admin Guide and is a trunking overview.  If you need something specific, please specify and I'll see what I can do.

Trunking Requirements:


Mike Eversole
Brocade Community Manager

Join the Broadcom Support Community

Get quick and easy access to valuable resources across the Broadcom Community Network.