Hi,
Brocade has a very good Web interface (mainly based on JAVA Applet) for configuring and managing the Switch and all connected ISL switches. Doing it with command line is not a good practice, because you need more time on doing it and might do mistake.
To do an ISL, you have to consider lot of things.
1. Are you trying to do the ISL on Switches which are in long distant. I mean if it is more than 10 KM then you need supported SFP as well as the license for that.
2. Are you doing it with your DR site , then what kind of communication link you are using... I mean are you using dark fibre or iFCP through multiprotocol router.
3. If you are using the Dark Fibre and got the license... first you need to change the Domain ID of the San Switch. Both the switch which will be on ISL can not have same domain IDs.
4. You have to do the trunking if you need more ports to work togather (for higher bandwidth) for ISL
5. You have to do Zoning
Please read the documents that comes with the SAN switch.
For a faster path download the IBM redbook on "SAN16B-2 Implemention"