Cisco 2911 port gone bad?

[Gian-Luca Casella]

Hi everyone,

I purchased a brand new Cisco 2911 Router and when connecting everything together I noticed an issue with my gi0/1.

When I issue a no shut on both interfaces the port Gi1/0/12 would intermittently blink amber once and then go off, and it would continue to do so and would never connect the interface.

Cisco 2911

interface GigabitEthernet0/2

no ip address

duplex full

speed 1000

end

GigabitEthernet0/1 is down, line protocol is down

  Hardware is CN Gigabit Ethernet, address is 70ca.9b04.5131 (bia 70ca.9b04.5131)

  Description: CNETWORKS INTERNAL NETWORK

  Internet address is 17.2.34.2/24

  MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,

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

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Auto Duplex, Auto Speed, media type is RJ45

  output flow-control is unsupported, input flow-control is unsupported

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input never, output never, 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 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 IP multicasts)

     0 runts, 0 giants, 0 throttles

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

     0 watchdog, 0 multicast, 0 pause input

     0 packets output, 0 bytes, 0 underruns

     0 output errors, 0 collisions, 4 interface resets

     0 unknown protocol drops

     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

Cisco 3750G

interface GigabitEthernet1/0/12

switchport access vlan 801

switchport mode access

speed 1000

duplex full

spanning-tree portfast

end

GigabitEthernet1/0/12 is down, line protocol is down (notconnect)

  Hardware is Gigabit Ethernet, address is 0019.5682.4d0c (bia 0019.5682.4d0c)

  Description: BELL EXTERNAL

  MTU 2000 bytes, BW 10000 Kbit/sec, DLY 1000 usec,

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

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX

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

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input never, output never, 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 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 multicasts)

     0 runts, 0 giants, 0 throttles

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

     0 watchdog, 0 multicast, 0 pause input

     0 input packets with dribble condition detected

     0 packets output, 0 bytes, 0 underruns

     0 output errors, 0 collisions, 1 interface resets

     0 unknown protocol drops

     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

I have yet to see any counters increase. I swapped out the cable several times with new Cat6 cables and still no luck. Any insight would be greatly appreciated. Would be unfortunately for this brand new, never opened device would have a dead port.

Thanks!

[Leo Laohoo]

Try this on the 3750G:

1.  Command:  test cable tdr interface GigabitEthernet1/0/12;

2.  Wait for 5 to 7 seconds;

3.  Command:  sh cable tdr interface GigabitEthernet1/0/12; and

4.  Post the output to #3.

[Gian-Luca Casella]

I always seem to forget about that command;

Here is the output;

Interface Speed Local pair Pair length        Remote pair Pair status

--------- ----- ---------- ------------------ ----------- --------------------

Gi1/0/12  1000M Pair A     0    +/- 4  meters N/A         Short              

                Pair B     0    +/- 4  meters N/A         Normal             

                Pair C     1    +/- 4  meters N/A         Normal             

                Pair D     0    +/- 4  meters N/A         Normal             

[Leo Laohoo]

Gi1/0/12  1000M Pair A     0    +/- 4  meters N/A         Short

And there is your culprit.  The cable coming from the switch is faulty.

[Gian-Luca Casella]

Thank's for the input, however trying over at least 10 Cables, most of them taken out of the original packaging and made by hand will display the same output;

Just plugged in a working cable from my desktop to these two ports;

Interface Speed Local pair Pair length        Remote pair Pair status

--------- ----- ---------- ------------------ ----------- --------------------

Gi1/0/12  1000M Pair A     1    +/- 4  meters N/A         Normal             

                Pair B     3    +/- 4  meters N/A         Short              

                Pair C     2    +/- 4  meters N/A         Normal             

                Pair D     2    +/- 4  meters N/A         Normal

and now another;

This time plugging it into port Gi1/0/9 to show the port won't matter;

Interface Speed Local pair Pair length        Remote pair Pair status

--------- ----- ---------- ------------------ ----------- --------------------

Gi1/0/9   auto  Pair A     0    +/- 4  meters Pair A      Short              

                Pair B     0    +/- 4  meters Pair B      Normal             

                Pair C     0    +/- 4  meters Pair C      Normal             

                Pair D     0    +/- 4  meters Pair D      Normal  

------

One more interesting peice of information -- when leaving everything as auto negotiate for the ports and continuously typing "show int g1/0/9 status" or "show int g1/0/12 status" this kind of thing popped up

Port      Name               Status       Vlan       Duplex  Speed Type

Gi1/0/9   CND005             connected    300        a-half  a-100 10/100/1000BaseTX

Than would disconnect right away

[Leo Laohoo]

How is the router and 3750G connected?  Is it by a single cable or does it go through a series of jacks?

What IOS is your 3750G running?

If I remembered correctly, TDR results on IOS version 15.0(1)SE2 are not to be trusted.   The TDR result on this IOS doesn't get reset when you re-test the port.  You'll need to reboot the appliance just to clear the test result table.

[Gian-Luca Casella]

Directly connected via Straight Through cable;

3750G is running the following;

Switch Ports Model              SW Version            SW Image                

------ ----- -----              ----------            ----------              

*    1 28    WS-C3750G-24PS     15.0(1)SE1            C3750-IPSERVICESK9-M    

it's weird, because all other ports on the Router are connected and working absolutely fine. Gi0/0 and Gi0/2

[Leo Laohoo]

Gian,

If you have a spare 3750G or a 2960S, load 15.0(2)SE2 and try the TDR again on the cables you've tested with the older IOS.

[Gian-Luca Casella]

Sure I have a large lab being build right now.

I'll get one of my 2960's loaded with 15.0(2)SE2, would 15.0(2)SE3 be alright? Just recently downloaded the newest release of the 2960 IOS.

[Leo Laohoo]

would 15.0(2)SE3 be alright?

Holy sh1t!  NO, DO NOT USE IOS version 15.0(2)SE3!

There's a major bug with 15.0(2)SE3 and TACACs.  Read our discussion here. 

[Gian-Luca Casella]

Thanks for the heads up, i'll read that discussion.

I loaded 15.0(2)SE2 and here is the output;

Interface Speed Local pair Pair length        Remote pair Pair status

--------- ----- ---------- ------------------ ----------- --------------------

Fa0/1     auto  Pair A     N/A                N/A         N/A                

                Pair B     N/A                N/A         N/A                

                Pair C     N/A                N/A         Not Supported      

                Pair D     N/A                N/A         Not Supported   

[Leo Laohoo]

Errrr ... Don't use a FastEthernet port, please.

[Gian-Luca Casella]

Sorry about that; here is the output on Gi0/1 on that same switch;

Interface Speed Local pair Pair length        Remote pair Pair status

--------- ----- ---------- ------------------ ----------- --------------------

Gi0/1     auto  Pair A     8    +/- 2  meters N/A         Short              

                Pair B     N/A                N/A         Normal             

                Pair C     N/A                N/A         Normal             

                Pair D     N/A                N/A         Normal     

[Leo Laohoo]

Still calling it a "short" on the most important pair.

Ok, here's one way of testing if this is a faulty test or not.

Connect the same cable to your laptop.  If the laptop's NIC doesn't light up, the test is accurate ... to a certain degree.

[Gian-Luca Casella]

Interface Speed Local pair Pair length        Remote pair Pair status

--------- ----- ---------- ------------------ ----------- --------------------

Gi0/1     1000M Pair A     0    +/- 10 meters Pair A      Normal             

                Pair B     0    +/- 10 meters Pair B      Normal             

                Pair C     0    +/- 10 meters Pair D      Normal             

                Pair D     0    +/- 10 meters Pair C      Normal          

connected to my Laptop from the switch.

and when connected to the router from my laptop

GigabitEthernet0/1 is down, line protocol is down

  Hardware is CN Gigabit Ethernet, address is 70ca.9b04.5131 (bia 70ca.9b04.5131)

  Description: CNETWORKS INTERNAL NETWORK

  Internet address is 17.2.34.2/24

  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,

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