Alcatel Carrier Internetworking Solutions Switch/Router 用户手册

Page 9-25

CAM

 (Content Addressable Memory) on switching modules is used to look up the 

MAC

 

address of endstations attached to the modules. You can use the 

 command to display 

each module’s 

CAM

on the 

 command.

The Omni Switch/Router supports approximately 31.25 K of usable 

CAM

 among all the 

switching modules in a chassis. (A small amount of 

CAM

 memory is reserved by the Omni 

Switch/Router for its processing.)

When each switching module in a 9-slot chassis has 1 K of 

CAM

, the 31.25 K limitation is not 

reached since only 8 K (assuming 8 switching modules) is used. However, when some 
switching modules use 4 K or 8 K of 

CAM

 the 31.25 K limitation could be reached quickly.

For example, if all the switching modules in a fully-loaded 9-slot chassis have 4 K 

CAMs

 you 

would exceed the 31.25 K limit. In this configuration, the Omni Switch/Router would subtract 
256 K of available 

CAM

 memory from the first switching module to initialize and 512 K of 

available 

CAM

 memory from the last switching module to initialize. If you need to configure 

CAM

 usage use the 

 command, which is described below.

♦ Important Note ♦

If you use a configuration file (e.g., 

) from an 

OmniSwitch on an Omni Switch/Router, any 

CAM

 

configuration settings will be ignored.

The 

 command allows you to individually allocate 

CAM

 space to switching modules. 

This command configures the maximum entries a switching module may use, freeing up over-
all 

CAM

 space in the chassis so that some modules can use more of their on-board 

CAM

. 

Follow these two additional rules:

• The 

CAM

 memory size for a switching module must be configured to at least one-half of 

the total memory available on the switching module. For example, if your switching 
module has 2 K of 

CAM

 memory, you must allocate at least 1 K of 

CAM

 to that switching 

module.

• The amount of 

CAM

 memory allocated for a switching module must be a whole-number 

multiple of 1024 (e.g., 1024, 2048, etc.).

Follow these steps to configure the number of 

CAM

 entries used by a switching module:

1. Enter 

 followed by the slot number for the module that you want to configure. You 

can configure the 

CAM

 on switching modules only, not on the 

MPX

. For example, to 

configure 

CAM

 for the module in slot 3, enter

2. The system displays a prompt asking for the number of 

CAM

 entries to use for this 

module.

Enter the number of 

CAM

 entries to use for this module. The current value is listed in 

parentheses. The value you enter must be equal to or less than the total number of entries 
available on board this module. For example, you could not configure 2048 entries for a 
switching module with only 1K of 

CAM

.