Cisco Catalyst 2950 Software Guide

6-16
Catalyst 2950 Desktop Switch Software Configuration Guide
78-11380-03
Chapter 6 Configuring the System
Managing the MAC Address Tables
Changing the Address Aging Time
Dynamic addresses are source MAC addresses that the switch learns and then drops when they are not
in use. The aging time parameter defines how long the switch retains unseen addresses in the table. This
parameter applies to all VLANs.
Setting too short an aging time can cause addresses to be prematurely removed from the table. Then
when the switch receives a packet for an unknown destination, it floods the packet to all ports in the same
VLAN as the receiving port. This unnecessary flooding can impact performance. Setting too long an
aging time can cause the address table to be filled with unused addresses; it can cause delays in
establishing connectivity when a workstation is moved to a new port.
Beginning in privileged EXEC mode, follow these steps to configure the dynamic address table aging
time.
Removing Dynamic Address Entries
Beginning in privileged EXEC mode, follow these steps to remove a dynamic address entries:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
mac-address-table aging-time
seconds
Enter the number of seconds that dynamic addresses are to be retained in the
address table. You can enter a number from 10 to 1000000.
Step 3
end Return to privileged EXEC mode.
Step 4
show mac-address-table
aging-time
Verify your entry.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
clear mac-address-table
dynamic [address mac-addr |
interface interface-id | vlan
vlan-id]
(Optional) Enter the address mac-addr to delete the specified MAC
address.
(Optional) Enter the interface interface-id to delete all dynamic
MAC addresses on the specified physical port or port channel.
(Optional) Enter the vlan vlan-id to delete all dynamic MAC
addresses for the specified VLAN. Valid IDs are from 1 to 1005; do
not enter leading zeroes.
Step 3
end Return to privileged EXEC mode.
Step 4
show mac-address-table Verify your entry.

Cisco Catalyst 2950 Specifications

General

Forwarding Bandwidth	8.8 Gbps
Switching Capacity	13.6 Gbps
Forwarding Rate	6.6 Mpps
Weight	3.6 kg
RAM	16 MB
Flash Memory	8 MB
Operating Humidity	10% to 85% non-condensing
Uplink Ports	2 x 10/100/1000Base-T
Dimensions	4.4 cm x 44.5 cm x 24.2 cm
Remote Management Protocol	SNMP, Telnet, HTTP
Features	Quality of Service (QoS), VLAN support
Compliant Standards	IEEE 802.3, IEEE 802.3u, IEEE 802.1D, IEEE 802.1Q, IEEE 802.1p
Status Indicators	system
Operating Temperature	0 to 45°C
Ports	24 x 10/100 Ethernet ports
MAC Address Table Size	8, 192 entries
Power Supply	Internal 100-240V AC, 50-60Hz