i have. we have been troubleshooting this 24/7 for a couple days now, so that means things change constantly.

that being said, we traveled to the site containing switch A and plugged Switch C into it's fiber link. Switch C came up on layer 3. that means there is:

1. a problem with the SFPs (unlikely)

2. damaged fiber runs

we shall get our test equipment out tomorrow and being testing strands.

will update this thread with results, but thank you for the response Marvin!

have a great day.

You're welcome.

You might troubleshoot the spans remotely using "show interface transceiver details". Also, turn on UDLD.

so, we have localized the issue to the 6500.

Switch A is currently functioning on fiber port g3/43.

I created a test switch, and programmed the fiber port. i tried several ports on mod 3 (3/27, 3/42, 3/44, etc) as well as mod 4 (4/11). i even tried 6/1, the supervisor module's SFP port.

i then plugged the test switch into g3/43, and it worked. (good layer 3 ping)

we recently upgraded the 6500 from SXI6 to SXI12. i am looking over the release notes but not seeing any bugs like this.

i doubt a "hw-module module X reset" would do anything, since i tried 3 different modules.

thoughts??

also the several ports i tried were all programmed exactly like 3/43, so it is not the config.

When you have fibre SFP in, post the output to the command "sh interface BLAH".

Leo: here ya go

GigabitEthernet3/43 is up, line protocol is up (connected)
  Hardware is C6k 1000Mb 802.3, address is 2894.0f57.437a (bia 2894.0f57.437a)
  Description: FiberTrunk-to-SwitchA
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 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 LH
  input flow-control is off, output flow-control is off
  Clock mode is auto
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:08, output 00:00:24, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 191000 bits/sec, 67 packets/sec
  5 minute output rate 752000 bits/sec, 112 packets/sec
     92584292 packets input, 25411211351 bytes, 0 no buffer
     Received 315527 broadcasts (83158 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
     148923032 packets output, 114663742745 bytes, 0 underruns
     0 output errors, 0 collisions, 6 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
 
GigabitEthernet6/1 is down, line protocol is down (notconnect)
  Hardware is C6k 1000Mb 802.3, address is 001a.a22d.6984 (bia 001a.a22d.6984)
  Description: FiberTestPort
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 0/255, rxload 0/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is LH
  input flow-control is off, output flow-control is off
  Clock mode is auto
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 01:52:33, output 01:51:56, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/2000/0/0 (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
     218 packets input, 26637 bytes, 0 no buffer
     Received 182 broadcasts (63 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
     9476 packets output, 1084062 bytes, 0 underruns
     0 output errors, 0 collisions, 3 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

let me know if you'd like to see anything else.

GigabitEthernet6/1 is down, line protocol is down (notconnect)
  Hardware is C6k 1000Mb 802.3, address is 001a.a22d.6984 (bia 001a.a22d.6984)
  Description: FiberTestPort
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 0/255, rxload 0/255

Your SFP could be faulty.  I have NEVER seen a value like that before.

Can you try putting this SFP in a different port and different slot?

Wait .. there's another thing.  Post a picture of the SFP.  I want to see the front of the SFP where it will have the model number and the serial number. 

Hmmmmm ... Thanks for the pix.  Not what I was hoping. 

Can you do the following:

1.  Plug one of the SFP into 5/1 and plug the other into 6/1.  Test and see if it works.

2.  Plug one SFP into another port other than 5 or 6.  Plug another into 5/1.  Test to see if this works. 

3.  Plug both SFP into 3750 and see if this works.

Note:  Do NOT enable the SFP to go active for very long or you will permanently burn your SFP.