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Command to show if ports are full/half duplex?

Andy White
Level 3
Level 3

Hello,

Is there a summary command to show whether the ports on a switch are in half or full duplex and in 10/100/1000?

Thanks

6 Replies 6

cadet alain
VIP Alumni
VIP Alumni

Hi,

sh interface status

Regards.

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.

hobbe
Level 7
Level 7

Hi

And you can also use the mode button on the switch.

That will most of the time tell you the information also.

Good luck

HTH

singhaam007
Level 3
Level 3

Hi Andy,

use

Network-Test#sh int status | inc Fa0/1

Port        Name               Status       Vlan       Duplex    Speed    Type

Fa0/1                        notconnect     108          auto         auto    10/100BaseTX

and also you can use sh interface f0/1

thanks

RKT
Level 1
Level 1

Hi Andy

            # show interface status

or          # show int fa0/1

Thanks

show controller if available. if not check show log

sw4#show contr g0/3 | i ull
Device status = full-duplex, link up

showing output from only relevant section

sw4#show controllers g0/3

..

Register decodes:
Status : 0x80080783, FD, UP, 1000Mbps, Auto1000Mbps, PCI
Control register : 0x00000040, HD, SetLinkUP, 10Mbs
Control register ext: 0x00000000, Copper

Rxdescriptor addr=09594E00 len=00000000, stat=00000000
Txdescriptor addr=06CC5B87 cmd/len=0B00003C, stat=00000001
RX is enabled, TX is enabled
Device status = full-duplex, link up
PCI width = 32, PCI66=0, PCIX=0, PCIXSPD is 50-66MHz Device Speed = 1000Mbps

...

show interface status just says auto which is uselsss...

carlosacosta234
Level 1
Level 1

Hi all,

Nice answers. Another way to find out whether the ports on a switch are in half or full duplex is using CDP with the command show cdp neighbors detail

Please find below the output. It shows the neighbor duplex operation.

  • Duplex: full  //Neighbor connected to that port is operating in full duplex.
  • Duplex: half  //Neighbor connected to that port is operating in half duplex.
  • Duplex: half (Mismatch) //Neighbor connected to that port is in half duplex but the local port is in full duplex.
  • Duplex: full (Mismatch) //Neighbor connected to that port is in full duplex but the local port is in half duplex.

SW-L3-02#show cdp nei det
-------------------------
<output omitted>
Native VLAN: 1
Duplex: full  //shows the neighbor duplex operation.
Management address(es):
IP address: 192.168.1.10

Hope it helps.

Kind regards,

Carlos Acosta

Review Cisco Networking products for a $25 gift card