Cisco NM-8B-U - HW ROUTERS L-M User Manual page 123

16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series
Beginning in privileged EXEC mode, follow these steps to prevent the switch from forwarding frames
for stations that it has dynamically learned:
Command
Step 1
configure terminal
Step 2
no bridge bridge-group acquire
Step 3 end
Step 4 show running-config
Step 5
copy running-config startup-config
To cause the switch to forward frames to stations that it has dynamically learned, use the bridge
bridge-group acquire global configuration command.
Configuring the Bridge Table Aging Time
A switch forwards, floods, or drops packets based on the bridge table. The bridge table maintains both
static and dynamic entries. Static entries are entered by you or learned by the switch. Dynamic entries
are entered by the bridge learning process. A dynamic entry is automatically removed after a specified
length of time, known as aging time, from the time the entry was created or last updated.
If you are likely to move hosts on a switched network, decrease the aging-time to enable the switch to
quickly adapt to the change. If hosts on a switched network do not continuously send packets, increase
the aging time to keep the dynamic entries for a longer time and thus reduce the possibility of flooding
when the hosts send again.
Beginning in privileged EXEC mode, follow these steps to configure the aging time:
Command
Step 1 configure terminal
Step 2
bridge bridge-group aging-time seconds
Step 3 end
Step 4
show running-config
Step 5
copy running-config startup-config
Purpose
Enters global configuration mode.
Enables the switch to stop forwarding any frames for stations that it has
dynamically learned through the discovery process and to limit frame
forwarding to statically configured stations.
The switch filters all frames except those whose destined-to addresses
have been statically configured into the forwarding cache. To configure
a static address, use the bridge bridge-group address mac-address
{forward | discard} global configuration command.
For bridge-group, specify the bridge group number. The range is 1
to 255.
Returns to privileged EXEC mode.
Verifies your entry.
(Optional) Saves your entry in the configuration file.
Purpose
Enters global configuration mode.
Specifies the length of time that a dynamic entry remains in the bridge
table from the time the entry was created or last updated.
For bridge-group, specify the bridge group number. The range is 1
•
to 255.
For seconds, enter a number from 0 to 1000000. The default is 300
•
seconds.
Returns to privileged EXEC mode.
Verifies your entry.
(Optional) Saves your entry in the configuration file.
Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ
Configuration Tasks
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