Memory Optimization

Cisco’s 3560 is a multilayer switch, designed to operate well at both layer 2 and layer 3. Due to its dual nature, however, Cisco had to allocate memory in a way that wouldn’t hinder operation in either mode out-of-the-box.

Out of the box, the 3560 has its memory allocated to support learning lots of MAC addresses and lots of unicast IP routes. If you know you’ll be using a 3560 as primarily a L2 or L3 device it makes sense to adjust the memory allocation accordingly. That’s done with a single command:

Switch1# conf t
Switch1(config)# sdm prefer routing
Switch1(config)# end
Switch1# show sdm prefer
 The current template is "desktop default" template.
 The selected template optimizes the resources in
 the switch to support this level of features for
 8 routed interfaces and 1024 VLANs.

  number of unicast mac addresses:             6K
  number of igmp groups + multicast routes:    1K
  number of unicast routes:                    8K
    number of directly connected hosts:        6K
    number of indirect routes:                 2K
  number of policy based routing aces:         0
  number of qos aces:                          512
  number of security aces:                     1K

Look here to see the differences between default, routing, and VLAN mode. Keep in mind that a reload is necessary to apply the changes.

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