Displaying Address Table Entries; Managing The Arp Table - Cisco Catalyst 2950 Software Configuration Manual

Chapter 7 Administering the Switch

Displaying Address Table Entries

You can display the MAC address table by using one or more of the privileged EXEC commands
described in
Table 7-5 Commands for Displaying the MAC Address Table
Command
show mac-address-table address
show mac-address-table aging-time
show mac-address-table count
show mac-address-table dynamic
show mac-address-table interface
show mac-address-table multicast
show mac-address-table static
show mac-address-table vlan

Managing the ARP Table

To communicate with a device (over Ethernet, for example), the software first must determine the 48-bit
MAC or the local data link address of that device. The process of determining the local data link address
from an IP address is called address resolution.
The Address Resolution Protocol (ARP) associates a host IP address with the corresponding media or
MAC addresses and the VLAN ID. Taking an IP address as input, ARP determines the associated MAC
address. Once a MAC address is determined, the IP-MAC address association is stored in an ARP cache
for rapid retrieval. Then the IP datagram is encapsulated in a link-layer frame and sent over the network.
Encapsulation of IP datagrams and ARP requests and replies on IEEE 802 networks other than Ethernet
is specified by the Subnetwork Access Protocol (SNAP). By default, standard Ethernet-style ARP
encapsulation (represented by the arpa keyword) is enabled on the IP interface.
ARP entries added manually to the table do not age and must be manually removed.
For CLI procedures, refer to the Cisco IOS Release 12.1 documentation on Cisco.com.
78-11380-04
Table 7-5:
Description
Displays MAC address table information for the specified MAC address.
Displays the aging time in all VLANs or the specified VLAN.
Displays the number of addresses present in all VLANs or the specified VLAN.
Displays dynamic MAC address table entries only.
Displays the MAC address table information for the specified interface.
Displays the Layer 2 multicast entries for all VLANs or the specified VLAN.
Displays static MAC address table entries only.
Displays the MAC address table information for the specified VLAN.
Catalyst 2950 Desktop Switch Software Configuration Guide
Managing the ARP Table
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