Understanding Cisco Switching Database Manager

--> SDM stands for Switching Database Manager.

--> Multi-Layer Switches provides switching as well as routing functions.

--> SDM is used on Multi-Layer Switches to manage the memory usage ( Memory should be assigned for routing or switching).

--> If you want to use Multi-Layer Switch for routing function there is no need to assign memory for storing MAC addresses.

--> If you want to use Multi-Layer Switch for switching function there is no need to assign memory for storing routing table entries.

--> In simple terms SDM allows managing the size of the tables used by multi-layer switches.

--> There are 4 types of templates used in SDM

1) Default

--> This is the default mode used by all the switches.

--> The default template gives balance to all functions.

--> It supports both routing and switching.

--> No.of Mac Addresses can be created by using the template is 6k.

--> No.of Routes supported by using the template is 8k.

2) VLAN

--> This SDM Template is used when you don't want routing capabilities on the Multi-Layer Switch.

--> Most of the memory is allocated to switching functions.

--> No.of Mac Addresses can be created by using the template is 12k.

--> No.of Routes supported by using the template is 0.

3) Access 

--> The access template is used when you want to create more ACLS on Multi-Layer Switch.

--> Most of the memory is allocated for creating Access Control List.

--> No.of Mac Addresses can be created by using the template is 4k.

--> No.of Routes supported by using the template is 6K.

--> Not commonly used.

4) Routing

--> This access is template is used when you want to use Multi-layer switch mostly for routing functions.

--> Most of the memory is allocated to routing functions.

--> No.of Mac Addresses can be created by using the template is 3k.

--> No.of Routes supported by using the template is 11k.

Configuration:

--> To change the SDM template on the multilayer switch, use the following command.

Switch(config)# sdm prefer routing

Switch(config)# reload

Note: modifying the SDM template on a switch is required to reload the switch in order to use the new SDM template.

Verification:

Switch# show sdm prefer

Reference: Cisco.com

Md.Kareemoddin

CCIE # 54759