Brocade ISL Trunk configuration

One of the most interesting parts of administrating FC switches is implementing ISL’s (Inter-Switch Links) between 2 datacenters. In this article, we will cover the steps that need to be taken in order to create a fabric. We assume that the physical link (cabling) has already been set up and that the switch is already configured.

On the demonstration below I’m using Brocade SAN switches G62-series running Fabric OS version 8.0.2e.

1. We start off by disabling the switch.

   FOS_STORCOM1:admin> switchdisable

2. Next, we need to configure the port speed of the ports which will be inter-connected.

   FOS_STORCOM1:admin> portcfgspeed -i <port number> -f <port speed>

   

3. Brocade SAN switches can be easily configured using the configure command. Once entered  it will lead you through some important configuration steps.
   
4. Next, we’ll need to calculate the ISL distance. A rule of thumb will be to multiply the real physical distance with 1.5 to get the ISL distance.

   real_distance_km x 1.5 = ISL_logical_distance

   In my case, I have two switches with a physical distance of 146 km. I will use 220 km as ISL distance.

5. To activate the port in LS (Long Distance Dynamic) mode enter the following command

   FOS_STORCOM1:admin> portcfglongdistance <port number> LS 1

   

   A vc_link_init value of 1 uses the ARB fill word (default). A value of 0 uses IDLE. The required value might depend on the link being used. The commands must be repeated for each ISL port.

6. Optionally, you can enable the QOS on the ISL ports by using the following command:

   FOS_STORCOM1:admin> portcfgqos --enable <port number>

7. To check and confirm the port parameters use the following command:

   FOS_STORCOM1:admin> portshow <port number>

8. At this step the port is ready. Enable the switch and the ports using the following commands

   FOS_STORCOM1:admin> switchenable

   FOS_STORCOM1:admin> portcfgpersistantenable <port number>

9. Log on to the second switch and perform the same operations from Step 1 to Step 7
10. Your SAN fabric should be ready now. Verify it using the following commands:

    FOS_STORCOM1:admin> fabricshow

    FOS_STORCOM1:admin> trunkshow

The article Essential troubleshooting command lines every Storage Administrator should know offers interesting stuff related to the switch administration.

A complete command line list and other switch administration can be found on the Brocade Fabric OS Administration Guide.

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