3Com 3CB9LF36RL, 3CB9LF36TL, 3CB9LG9MC, 3CB9LF20MM Bridge Address, Learning Limits, Addresses

Bridge Address Learning Limits 19

Bridge Address	By default, the 36-port 10/100BASE-TX Desktop Switching Modules
Learning Limits	(Model Numbers 3CB9LF36RL and 3CB9LF36TL) support two bridging
	addresses (learned plus static) per front-panel port. You can manually
	change this limit to a value from 1 through 36 addresses per port.
	There is also a module-widelimit of 138 address-table entries, which is
	allocated as follows:
	■ 72 learned plus static addresses for the module’s front-panel ports
	■ 36 addresses are a guaranteed allocation of one static address per
	port.
	■ 36 addresses are a pool of free addresses for all ports to use.
	If you use the default limit of two bridging addresses per port, the
	entire module is still restricted to a total of 72 learned and static
	addresses.
	However, for example, if you change the learning limit to 4 addresses
	per port, 1 address is guaranteed per port and 3 addresses come from
	the pool of 36 free addresses that all ports can use. Therefore, if 12
	ports each learn 4 addresses and a 13th port learns 2 addresses, the
	module limit is exceeded because the 36-port pool of free addresses is
	exceeded.
	■ 2 addresses for the module’s CPU
	■ 64 multicast addresses for the IGMP protocol

If a port exceeds its individual address limit, the module:

■Disables the port.

■Sends a trap to the EME.

■Displays limitationsExceeded for the learn status in the bridge port summary and bridge port detail displays.

If an address coming into a port causes the module’s learned address limit to be exceeded, the module:

■Disables the port.

■Sends a trap to the EME.

■Displays moduleLimitationsExceeded for the learn status in the bridge port summary and bridge port detail displays.