What is a pair status fail on cable-diag tdr mean

markbhiga · ‎03-25-2011

I was running the cable-diagnostics tdr test and show command on a 3560e switch. It returned a pair status of failed. Does anyone know what that staus means? It does not show as a valid status in the Cisco documentation I have found so far. Any hep would be appreciated.

0230_3560e_48_SW1#test cable-diagnostics tdr interface gigabitEthernet 0/48
Link state may be affected during TDR test
TDR test started on interface Gi0/48
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.

0230_3560e_48_SW1#show cable-diagnostics tdr interface gigabitEthernet 0/48
TDR test last run on: March 25 14:00:50

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi0/48    100M Pair A     N/A                Pair B      Fail
                Pair B     N/A                Pair A      Fail
                Pair C     N/A                N/A         Fail
                Pair D     N/A                Pair D      Fail
0230_3560e_48_SW1#

mgoon · ‎03-28-2011

Hi Mark,

Thanks for bringing your question to our attention. To expedite your getting a quicker reply from one of our technical experts, I’ve asked that your post be moved to an appropriate technical forum. I’ll also try to research docs that might contain the description you need. And if appropriate, I’ll be in touch with the doc owner for whichever doc that might need updating.

Regards,

Mary

Leo Laohoo · ‎03-28-2011

Far out. I've never seen a result THIS BAD BEFORE!

On a Gig port, the TDR should be able to test all four pairs ... BUT ...

1. The speed is "detected" at 100 mb. This could mean that the TDR has detected something very far, far away. Most likely beyond 150 meters.

2. Look at the remote pair section. You'll see that you can't find Pair "C"? So which means that something is really wrong.

3. No pair length. Which means that the switch can't really see how far the length is. This could mean that someone's got to re-terminate the link.

markbhiga · ‎03-29-2011

The switch and and router are about 20ft apart, Home run between cabinets and terminated on CAT5e patch panels. Also, the cable-diag is being done the on uplink port between the switch and router, which is running clean.

0230_3560e_48_SW1#sh int gi 0/48
GigabitEthernet0/48 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 0023.5d08.d230 (bia 0023.5d08.d230)
Description: Router Uplink
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/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 00:00:01, output hang never
Last clearing of "show interface" counters 23:39:15
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 3000 bits/sec, 3 packets/sec
5 minute output rate 7000 bits/sec, 6 packets/sec
     1054627 packets input, 102982779 bytes, 0 no buffer
     Received 39805 broadcasts (36934 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 36934 multicast, 0 pause input
     0 input packets with dribble condition detected
     1310399 packets output, 348039622 bytes, 0 underruns
     0 output errors, 0 collisions, 0 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
0230_3560e_48_SW1#

Leo Laohoo · ‎03-29-2011

Fair `nough. The switch is a 3560E and what's on the remote end? What type of router and what type of interface does it have? IT's too bad that the counters were cleared but could you post the result of the command "sh controller ethernet g0/48"?

Can you try to run the TDR test two more times just to verify consistency?

If the distance between the router and the switch is that close, you can try to swap out the cable and re-run the TDR. I can't speak for your network but if I run a TDR and I get a "FAIL" result then the cable is either swapped out or the link is to be tested by a professional Fluke tester. No questions asked.

markbhiga · ‎03-30-2011

The far end is a Cisco 2811 connecting on Fa0/1. Both side are hard code for 100Full. I had reset the counter after finding a duplex mismatch.

0230_3560e_48_SW1#sh controllers ethernet-controller gi 0/48

     Transmit GigabitEthernet0/48             Receive
   3286038574 Bytes                          8229948 Bytes
     88609254 Unicast frames                84513932 Unicast frames
     18638087 Multicast frames               3105879 Multicast frames
      2150730 Broadcast frames                232309 Broadcast frames
            0 Too old frames              3832405662 Unicast bytes
         8599 Deferred frames              242294277 Multicast bytes
            0 MTU exceeded frames           46417654 Broadcast bytes
         7837 1 collision frames                   0 Alignment errors
            0 2 collision frames                   0 FCS errors
            0 3 collision frames                   0 Oversize frames
            0 4 collision frames                   0 Undersize frames
            0 5 collision frames                   0 Collision fragments
            0 6 collision frames
            0 7 collision frames            40772469 Minimum size frames
            0 8 collision frames            33751880 65 to 127 byte frames
            0 9 collision frames             7450463 128 to 255 byte frames
            0 10 collision frames            5803688 256 to 511 byte frames
            0 11 collision frames              45937 512 to 1023 byte frames
            0 12 collision frames              25960 1024 to 1518 byte frames
            0 13 collision frames                  0 Overrun frames
            0 14 collision frames                  0 Pause frames
            0 15 collision frames
            0 Excessive collisions                 0 Symbol error frames
         4565 Late collisions                      0 Invalid frames, too large
            0 VLAN discard frames               1723 Valid frames, too large
            0 Excess defer frames                  0 Invalid frames, too small
      4617359 64 byte frames                       0 Valid frames, too small
     77295083 127 byte frames
     10049930 255 byte frames                      0 Too old frames
      1604744 511 byte frames                      0 Valid oversize frames
      2885583 1023 byte frames                   168 System FCS error frames
      3364515 1518 byte frames                     0 RxPortFifoFull drop frame
      9584290 Too large frames
         7834 Good (1 coll) frames
            0 Good (>1 coll) frames

0230_3560e_48_SW1#

Leo Laohoo · ‎03-30-2011

Both side are hard code for 100Full. I had reset the counter after finding a duplex mismatch.

7837 1 collision frames

4565 Late collisions

I know this is off topic but if you are connecting the router, like the the ISR G1, then you need to let both auto negotiate. This is the reason why you are getting duplex mismatch.

As to the TDR result, all I can tell you is to replace the copper patch cable.

markbhiga · ‎03-31-2011

I have had issues with the router negotiating the correct speed/duplex when set to auto. I usually leave the switch uplink at auto, however this switch negotiated incorrectly. I did try reload the switch, but that had no effect. The original intent of the post was to get more information as to how the cable-diag command works and what a Fail status indicated. As well as possible issues and troubleshooting techniques. Its just strange that the test fails when the uplink passes traffic without issue. Thank you for the help.

mgoon · ‎04-08-2011

Hi Mark,

The Cat 3750-E/3560-E writer has added a description for “failed” for Pair Status in the output for the "show cable-diagnostics tdr" command. Take a look at the description for "failed" in the Catalyst 3750-E and 3560-E Switch Command Reference at:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750e_3560e/software/release/12.2_58_se/command/reference/cli2.html#wp7676076

While Docs can clarify what “failed” means, Docs may not be able to fully troubleshoot a particular technical issue on someone’s system. We hope other customers’ input on this issue will be helpful for troubleshooting.

Good luck,
--Mary