MSA Storage

Help needed configuring Inter-Switch Link

Philip Teale

Help needed configuring Inter-Switch Link


I am having problems getting my head round the methodology of trunking FC switches together. I understand the principal in the IP domain but this is the first time I am doing it in the FC domain.

We currently have an EVA4000 connected to various hosts via two 4/16 SAN Switches. Each switch is configured with its own Fabric (Fabric_1 and Fabric_2) and the controllers and hosts are connected to each switch to provide MPIO. This configuration works fine.

We have recently purchased two c7000 Blade Chassis and installed a Brocade (HP) 4Gb SAN switch into each chassis. My problem is that I do not know how to link these new switches into the existing switches.

I suspect I need to use ISL but am not sure if I require a licence for this feature; we did not purchase the power pack, and a command on each switch shows the following:

Web license
Zoning license
Fabric license

Is a license required for ISL on its own, or is it just needed for ISL Trunking? We can survive with just one port linked for the time being, and purchase the Trunking licence at a later date.

Assuming I can do a single port ISL (either witha licence or not). How do I do it? Do I need to set each port on the switch as an Ex-Port and then just connect them with a fibre?

I have read about domain IDs and understand that each switch has to have a unique domain ID. Is this correct? Also, all four switches currently report their SwitchRole as Principal; will the two new switches have a different role?

Also, does the fabric information get shared amongst each switch or does each switch only care about hosts directly connected to it?

As you may be able to tell, I am pretty much in the dark here and a simple step-by-step plan would be very, very much appreciated. I have contacted HP about this but this is apparently a Configuration and Installation question and as such is not covered by our support contract.

Any help much appreciated.


Philip Teale

Re: Help needed configuring Inter-Switch Link

Apologies, after re-reading my post, I think I meant Zone rather then Fabric in the second paragraph and Zone Information rather than Fabric Information in the ninth paragraph; I couldn't see any way of editing my post.
Jorge HP

Re: Help needed configuring Inter-Switch Link

Well, as I know, the most important things you have to do are:

- Make different domain ID in each switch.
- Configure the physical ports for the ISL type. You can use mobile license in the brocade fiber channel switches, so, you can decide which ports of the switch are going to have license, you must to active at least the ones that are going to have the ISL feature.
-Ones you have done it, you are going to see in each switch, all of its zones and all of the zones of the other switch.
-Becareful with the Gbic transceivers... ;-) (distance, etc...)

Juan B.S.R.
Trusted Contributor

Re: Help needed configuring Inter-Switch Link

- License is for Trunking (more than 2 ISL ports), for only one you don´t need a license.
- About Domain ID every switch need an unique Domain ID. You may take a look if the new switch have any configuration.
- Just connect the cable.
- I think that the principal role is assumed by the switch with the lowest WWNN.
- The configuration is shared for all switches in the fabric.


On the new switch.
4)set the domain ID different than existing switch Domain ID.
5)connect the ISL between old switch and new switch.
7)wait till the new switch copies the configuration (cfg and zones) from old switch.
8)confirm the cfg with "cfgshow" command.

Best regards.
Uwe Zessin
Honored Contributor

Re: Help needed configuring Inter-Switch Link

> - License is for Trunking (more than 2 ISL ports), for only one you don't need a license.

You can interconnect two switches with 2 or more ISLs without a Trunking license and both links will be used. Trunking, however enables nice load balancing at the frame level.