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New Member

How to see the duplex mode of an interface ?

The output of show interface fa0/0 is not showing the duplexing mode of that port. Need it very urgently.

Router1#show interfaces fastEthernet 0/0

FastEthernet0/0 is up, line protocol is up (connected)

  Hardware is Lance, address is 0001.96cb.297d (bia 0001.96cb.297d)

  Internet address is 10.11.12.1/24

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 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 00:00:08, output 00:00:05, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0 (size/max/drops); Total output drops: 0

  Queueing strategy: fifo

  Output queue :0/40 (size/max)

  5 minute input rate 0 bits/sec, 0 packets/sec

  5 minute output rate 0 bits/sec, 0 packets/sec

     148 packets input, 6480 bytes, 0 no buffer

     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

     0 input packets with dribble condition detected

     126 packets output, 5398 bytes, 0 underruns

     0 output errors, 0 collisions, 1 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier

     0 output buffer failures, 0 output buffers swapped out

Thanks in advance.

Regards,

Chandu

Regards, Chandu
11 REPLIES
Hall of Fame Super Blue

How to see the duplex mode of an interface ?

Chandu

sh int status | include fa0/0

Jon

New Member

How to see the duplex mode of an interface ?

Jon,

I'm using PT. It wont support include command.

Regards,

Chandu

Regards, Chandu
New Member

How to see the duplex mode of an interface ?

And even it doen't have status option :

switch0#show interfaces ?

  Ethernet         IEEE 802.3

  FastEthernet     FastEthernet IEEE 802.3

  GigabitEthernet  GigabitEthernet IEEE 802.3z

  Vlan             Catalyst Vlans

  etherchannel     Show interface etherchannel information

  switchport       Show interface switchport information

  trunk            Show interface trunk information

 

Regards,

Chandu

Regards, Chandu
Hall of Fame Super Blue

Re: How to see the duplex mode of an interface ?

Your interface output is showing no collisions or later collisions so it's safe to say it is operating in full duplex mode.

Jon

Hall of Fame Super Blue

Re: How to see the duplex mode of an interface ?

Edit - just seen your last reply.

Jon     

New Member

How to see the duplex mode of an interface ?

Jon, actually i configured it to be half-duplex.

That's the reason i want it to confirm with any show command.

Regards,

Chandu

Regards, Chandu
New Member

How to see the duplex mode of an interface ?

Even again i configured it to be half duplex.

Router1(config)#interface fastEthernet 0/0

Router1(config-if)#duplex half

Router1(config-if)#end

Router1#

%SYS-5-CONFIG_I: Configured from console by console

But still the output is not showing the duplexing:

Router1#show interfaces fastEthernet 0/0

FastEthernet0/0 is up, line protocol is up (connected)

  Hardware is Lance, address is 0001.96cb.297d (bia 0001.96cb.297d)

  Internet address is 10.11.12.1/24

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 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 00:00:08, output 00:00:05, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0 (size/max/drops); Total output drops: 0

  Queueing strategy: fifo

  Output queue :0/40 (size/max)

  5 minute input rate 0 bits/sec, 0 packets/sec

  5 minute output rate 0 bits/sec, 0 packets/sec

     0 packets input, 0 bytes, 0 no buffer

     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

     0 input packets with dribble condition detected

     0 packets output, 0 bytes, 0 underruns

     0 output errors, 0 collisions, 1 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier

     0 output buffer failures, 0 output buffers swapped out

Router1#

Regards,

Chandu

Regards, Chandu
Hall of Fame Super Blue

How to see the duplex mode of an interface ?

What is the other end of the link configured as ? If it is also half duplex then you should not see late collisions but you should still see some collisions.

Jon

New Member

How to see the duplex mode of an interface ?

Other end is also half-duplex, other end is a siwtch.

switch0#show cdp neighbors

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID    Local Intrfce   Holdtme    Capability   Platform    Port ID

Router1      Fas 0/3          164            R       C2600       Fas 0/0

Truncated o/p for Fa0/3 on switch:

switch0#show interfaces fastEthernet 0/3

FastEthernet0/3 is up, line protocol is up (connected)

  Hardware is Lance, address is 00d0.ba12.5103 (bia 00d0.ba12.5103)

BW 100000 Kbit, DLY 1000 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Half-duplex, 100Mb/s

  input flow-control is off, output flow-control is off

Regards,

Chandu

Regards, Chandu
Hall of Fame Super Blue

How to see the duplex mode of an interface ?

Then you may well see some collisions at some stage in the interface statistics but not late collisions.

One other point to make. Remember that PT does not always emulate exaxtly what real switches and routers do.

Jon

Hall of Fame Super Gold

How to see the duplex mode of an interface ?

1.  If the other end is half-duplex, then the local end has to be half duplex.  Your link won't go up if one end is half duplex and the other is full duplex.

2.  Your "PT" must be running an old cold.

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