Thursday, June 23, 2011

SDM Mismatch on Cisco Catalyst 3750 switches

Cisco stackable switch - Catalyst 3750 - allows you to stack different models together. For example, you can stack a 12-port SFP fiber switch (Cisco 3750G-12SD) with a 48-port 1000BaseT (Cisco 3750G-48T) switch. However, if you configure the fiber switch as master, you would see the SDM Mismatch error when you perform a "show switch" command. This is described in this Cisco article.

An extract:
The Catalyst 3750-12S switch supports desktop and aggregator Switch Database Management (SDM)templates. All other Catalyst 3750 switches support only the desktop SDM templates. All stack members use the SDM template configured on the stack master. If the stack master is using an aggregator template, only Catalyst 3750-12S switches can be stack members. All other switches attempting to join this switch stack enter SDM-mismatch mode. These switches can join the stack only when the stack master is running a desktop SDM template. We recommend that your stack master use an aggregator template only if you plan to create a switch stack of Catalyst 3750-12S switches. If you plan to have a switch stack with different Catalyst 3750 switch models, configure the stack master to use one of the desktop templates.

To use the desktop template, perform the following commands on the stack master:
  1. For L2 configuration: sdm prefer vlan desktop
  2. For L3 configuration (enabled with ip routing): sdm prefer routing desktop
  3. Do a "show sdm prefer" to verify and reload.

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