show mac address-table. The addresses are
stored in a table called the bridge forwarding table or
CAM table.
Switch1>show mac address-table
Mac Address Table
-------------------------------------------
Vlan Mac Address Type Ports
---- ----------- -------- -----
All 0009.e897.d280 STATIC CPU
All 0100.0ccc.cccc STATIC CPU
All 0100.0ccc.cccd STATIC CPU
All 0100.0cdd.dddd STATIC CPU
1 0010.db0c.7dd2 DYNAMIC Fa0/1
1 0018.f3a6.018a DYNAMIC Fa0/18
1 00e0.1882.79a4 DYNAMIC Fa0/12
Total Mac Addresses for this criterion: 7Switches maintain a table of both static and dynamically learned
IP addresses. Cisco switches have a number of special built-in
addresses such as the 4 static address above. E.g., in the above case the
first entry 0009.e897.d280 is a static entry reflecting the MAC
address of the switch itself. In the above example, 3 systems are connected to
the switch on ports 1, 12, and 18. Their addresses are reported as dynamic
addresses.
You can view just the static or just the dynamic MAC addresses with the
commands show mac address static and show mac address
dynamic.
You can also view the MAC addresses using the show interfaces
command, but that gives you a lot of extra information as well,
so it isn't as easy to see the MAC addresses for all interfaces at a glance.
Switch1> show interfaces
Vlan1 is up, line protocol is up
Hardware is CPU Interface, address is 0009.e897.d280 (bia 0009.e897.d280)
Internet address is 192.168.0.4/26
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output never, output hang never
Last clearing of "show interface" counters never
A MAC address for the switch can be seen in line 2 of the output of the command. A lot more information is actually output than what is shown.
The show arp command will also show some MAC addresses, but
only those with which the switch has had some communication at the IP
level. The MAC addresses show Ethernet level communications.
Switch1>show arp Protocol Address Age (min) Hardware Addr Type Interface Internet 192.168.0.50 0 00e0.1882.79a4 ARPA Vlan1 Internet 192.168.0.4 - 0009.e897.d280 ARPA Vlan1
In the example above, the 192.168.0.50 address represents
the IP address of the system by which I was logged into the switch. The
switch IP address was 192.168.0.4.
References:
