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Layer 3 services module

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Configuring Access List Size in TCAM

The Catalyst 4000 Layer 3 Services module supports TCAM sizes of 32K. The combined size of the

protocol regions and access lists should not exceed your TCAM space. The default size of the access

lists region in a 32K TCAM is 1024 entries. You can use the sdm access-list command to partition the

TCAM space for access lists to overwrite this default.

To partition the TCAM space for access lists, perform the following task in global configuration mode:

Task

Set the name of the protocol region for which you

want to configure the size.

Before you configure the access-list region in TCAM, resize the other regions so that TCAM has enough

space to accommodate the access-list region. Use the show sdm internal all-regions command to find

out how much space is available in TCAM.

In the following example we configure 8192 entries for the access list region in TCAM:

Router# configure terminal

Router(config)# sdm access-list 8192

Router(config)# end

Configuring SDM Autolearn

The SDM autolearn feature applies to longest-match type regions only, not exact-match regions. For a

list of longest-match and exact-match regions, see Table 14.

In the longest-match regions, SDM groups entries into buckets based on their mask lengths. The size of

each bucket in the protocol region depends on the number of same mask length entries SDM has

learned. With autolearn enabled, SDM automatically saves the mask-length distribution (bucket size

distribution). SDM uses this information to set up the bucket partitions after a system reset. If autolearn

is not enabled, the size of each bucket will return to a predefined default size after a system reset. SDM

will then have to reconfigure the bucket size when protocol entries are learned.

The autolearn feature is enabled by default. The no form of the sdm autolearn command disables the

SDM autolearn feature. You can reenable autolearn by entering the sdm autolearn command from

global configuration mode, as shown in this example:

4232-L3# configure terminal

4232-L3(config)# sdm autolearn

4232-L3(config)# Ctrl-Z