Xsan: Configuring Emulex switches in a Cascade topology

When you configure Emulex switches for a topology that involves cascading (also known as trunking and inter-switch linking), it is important to configure the switches in a "star" topology with a single "root" switch at the center with "edge" switches connected to the root switch with two fibre channel connections.

Note: For simpler non-cascading configurations, see this article instead.

The steps below refer to Smart Settings. The Smart Settings for each port on Emulex 355 and 375 fiber switches reflect the role that the particular device attached to that port will provide in the fabric topology. The Smart Setting varies according to whether the port will connect to a host (initiator), a storage device (target), or another switch (tree cascade).

The following steps are to be performed in the Emulex Web Manager. To learn more about Web Manager, see the User Guide which is specific to your model Emulex switch. You can download Emulex switch manuals here.

Root Switch Setup

1. Set up Zoning:
   1. Choose Advanced Functions > One step zoning >.
   2. Select the checkbox for Zoning Active.
   3. Click Submit.
   
   
   
2. Set up Smart Settings:
   1. Choose Port > Smart Settings.
   2. Be sure that each of the two ports for every edge switch that you have is set to "tree cascade."
   3. All other ports should be set to target or initiator.
   4. Click Submit.
   
   
   
3. Configure Auto trunking config:
   1. Choose Advanced Functions > Automatic Trunking. You will see each of the Tree Cascade ports listed to the left. Across the top you will see Trunk Groups.
   2. Configure the two ports that are connected to the first edge switch to belong to Trunk Group A.
   3. Set the two ports that are connected to the second edge switch to belong to Trunk Group B, and so forth.
   4. Click Submit.

Edge Switch Setup

Follow the steps below for each edge switch.

1. Set up Zoning:
   1. Choose Advanced Functions > One Step Zoning >.
   2. Select the checkbox for Zoning Active.
   3. Click Submit.
   
   
   
2. Set up Smart settings:
   1. Choose Port > Smart Settings.
   2. Set the ports which are connected to the root switch to "tree cascade." These ports will be connected to two of the ports set to tree cascade on the root switch.
   3. All other ports should be set to target or initiator.
   4. Click Submit.
   
   
   
3. Configure Auto trunking config:
   1. Choose Advanced Functions > Automatic Trunking. You will see each of the two Tree Cascade ports listed to the left. Across the top you will see Trunk Group A.
   2. Configure the ports that are connected to the root switch to belong to Trunk Group A.
   3. Click Submit.
   
   
   
4. Set up Load Balancing:
   1. Choose Advanced Functions > Load Balancing.
   2. For each port that is set to initiator, alternate between Trunk Group A Port a and Trunk Group A Port b. (where a and b are the port numbers that correspond to those which are connected to the root switch)
   3. Click "Submit."

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