SDM templates are used to configure system resources in the switch to optimize support for specific features, depending on how the switch is used in the network. The templates prioritize system resources to optimize support for three types of features:
• Routing—The routing template maximizes system resources for unicast routing, typically required for a router or aggregator in the center of a network.
• VLANs—The VLAN template disables routing and supports the maximum number of unicast MAC addresses. It would typically be selected for a Layer 2 switch.
• Default—The default template gives balance to all functions.
The Cisco Catalyst 3750 series switches use Switch Database Management (SDM) templates to optimize the system resources for specific features dependent on how the switch is used in the network.
There are two versions of the SDM templates: Desktop and Aggregator.
The 3750-12S switch alone supports both templates; it can use the larger ternary content addressable memory (TCAM) size available in the aggregator templates or can use the standard desktop templates. All other model switches of the 3750 series support only the Desktop version.
The default template for desktop switches is the default desktop template; the default template for the Catalyst 3750-12S is the default aggregator template.
CISCO recommends that the stack master is configured with an aggregator template if the stack consists of only Catalyst 3750-12S switches.
When a Cisco Catalyst 3750 switch stack consists of 3750-12S and other models, only the Desktop SDM template should be used.
Use the ‘show sdm prefer’ command to confirm the template being used and then force the desktop template to be used:
show sdm prefer
The current template is “desktop routing” template.
The selected template optimizes the resources in the switch to support this level of features for 8 routed interfaces and 1024 VLANs.
An output from the show switch command when an SDM mismatch exists is shown below