You can check the port speed on a
Cisco network switch from its
command-line
interface (CLI) by logging into the switch and then issuing the
show interface command. If you want to see the parameters,
including port speed, for all ports on the switch, the command
without any additional command line arguments will display information
for all the ports on the switch. If you are only interested in the rate for
a particular port, then specify it after the command. E.g., show
interface fa0/1.
Hadrian>show interfaces fa0/1
FastEthernet0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0009.e897.d281 (bia 0009.e897.d281)
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 32/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 10Mb/s, media type is 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 72000 bits/sec, 29 packets/sec
5 minute output rate 1286000 bits/sec, 728 packets/sec
686444 packets input, 756803225 bytes, 0 no buffer
Received 6 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
4 input errors, 4 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
1626390 packets output, 293258140 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Hadrian>If you only want to see the port speed and not all of the additional information provided by the command, then you can filter the output so that you only see lines that include "Mb/s" as shown below.
Hadrian>show interfaces fa0/1 | include Mb/s Full-duplex, 10Mb/s, media type is 100BaseTX Hadrian>
In the example above, the
Fast Ethernet port
Fa0/1 is set to 10 Mb/s though it is capable of 100 Mb/s connectivity. In this
case, I know the device connected to the Fa0/1 port is connected to it by
a 100 Mbs
full duplex interface on that device, so I want to set the port on the Cisco
switch to match so that data transmissions via the Fa0/1 port aren't
unncessarily constrained to the slower 10 Mbs data transmission rate. I can
change the rate to 100 Mbs by logging into the Cisco switch, changing
to enable mode, issuing the configure terminal command,
then specifying I want to configure the Fa0/1 port with the
command interface fastethernet 0/1, and then specifying
full-duplex communications and a speed of 100 Mbs as shown below.
I can then exit from configuration mode by hitting the Cntrl
and Z keys simultaneously and if I issue another
show interface fa0/1 | include Mb/s command, I can see
the port speed is now 100 Mb/s rather than 10 Mb/s. The device
connected to the port should now be able to transmit and receive at
100 Mbs; no reboot of the switch is needed for the change to take effect.
User Access Verification Password: Hadrian>enable Password: Hadrian#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Hadrian(config)#interface fastethernet 0/1 Hadrian(config-if)#duplex full Hadrian(config-if)#speed 100 Hadrian(config-if)#^Z Hadrian#show interface fa0/1 | include Mb/s Full-duplex, 100Mb/s, media type is 100BaseTX Hadrian#