Cisco NM-8B-U User Guide - Page 123

Configuring the Bridge Table Aging Time, bridge, acquire, con terminal, no bridge, address

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16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Configuration Tasks Beginning in privileged EXEC mode, follow these steps to prevent the switch from forwarding frames for stations that it has dynamically learned: Step 1 Step 2 Command configure terminal no bridge bridge-group acquire Step 3 Step 4 Step 5 end show running-config 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. 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: Step 1 Step 2 Step 3 Step 4 Step 5 Command configure terminal bridge bridge-group aging-time seconds end show running-config copy running-config startup-config 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 123

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16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series
Configuration Tasks
123
Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ
Beginning in privileged EXEC mode, follow these steps to prevent the switch from forwarding frames
for stations that it has dynamically learned:
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
Purpose
Step 1
configure terminal
Enters global configuration mode.
Step 2
no bridge
bridge-group
acquire
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.
Step 3
end
Returns to privileged EXEC mode.
Step 4
show running-config
Verifies your entry.
Step 5
copy running-config startup-config
(Optional) Saves your entry in the configuration file.
Command
Purpose
Step 1
configure terminal
Enters global configuration mode.
Step 2
bridge
bridge-group
aging-time
seconds
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.
Step 3
end
Returns to privileged EXEC mode.
Step 4
show running-config
Verifies your entry.
Step 5
copy running-config startup-config
(Optional) Saves your entry in the configuration file.