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Bridge Address Learning Limits
19
Bridge Address
Learning Limits
By default, the 36-port 10/100BASE-TX Desktop Switching Modules
(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-wide
limit 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.