Fibre issue?

im busy doing quite a big lan upgrade at the moment installing 3560's. The building has two fibre uplinks on opposite sides of the building then on each floor there is another run between the two points on each floor to allow the switches to use one run and then the other for redundancy.

Now when ive been trying to use some of the run's i have been receiving lots of input errors and crc errors on quite a few links. The interface on the switch is up and up however it cannot communicate with the network. The two endpoints of the link are set to auto duplex/speed, if i set the switchport to speed 1000 and full duplex the errors stop however there is still no network communication.

Ive tried swapping spf's, fibre patch cable's etc. i have tried the same switches,cables & gbics on known working ports and they work fine so it looks like an issue with the fibre. Now before i go saying the fibre is faulty is there anything else i can do on the switch to prove it? i think i have already as the same kit works elsewhere but i want to make sure as it will have cost implications.

Also is there anyway to test the fibre run? btw, i dont have access to any highend gear to test the fibre run but would like suggestions no matter how big or small.

From my description do you think im right thinking there is an issue with the fibre?

Here is a display of the port statistics:

GigabitEthernet0/1 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is 001c.58c4.ab01 (bia 001c.58c4.ab01)
  Description: TRUNK PORT
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 235/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseSX SFP
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:28, output 00:00:00, 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 1000 bits/sec, 2 packets/sec
     48 packets input, 9590 bytes, 0 no buffer
     Received 47 broadcasts (0 multicast)
     0 runts, 0 giants, 0 throttles
     66 input errors, 66 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 47 multicast, 0 pause input
     0 input packets with dribble condition detected
     531 packets output, 38942 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 PAUSE output
     0 output buffer failures, 0 output buffers swapped out

This was an output of first connecting the trunk but the input errors and crc increment constantly.

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Comments

JohnDouglas

i'm no hands on engineer but why not start with cleaning the connectors and loop testing?

Mrock4

My initial assumption would be an issue with a strand of fiber, or GBIC. That's obviously hard to test without the right tools. My shop is not a cable-specialty shop, but we carry pen-lights with us that will shoot light through the run, so we can see if there's any breaks. They run about $250-$300. Not a bad investment.

Are you getting the errors only on one switch, or both? Once you set both speed and duplex settings on each sides, you said you're not getting any network connectivity...if you do a show cdp neigh ...do you see the neighboring switch?

redwarrior

Who ran the fiber for you? Most companies that do cabling will come out and test a run if you're having problems with it as long as you ask nicely. The only other thing that came to my mind was perhaps checking the MTU's on both sides to make sure they are correct for whatever kinds of packets you are sending, but that's just conjecture. Let us know how it goes!

nel

Sorry forgot to ask about cleaning. Is there any particular method involved? or anything you can and cant do with it being fibre? Obviously dont want to do anything which can damage it further which is why im asking.

Yeah when i statically define the duplex/speed the errors stop but there are no neighbours etc however the line is still up and up. but there is no network communication at all.

I cant actually inspect the fibre run to see if there's any obvious damage to the cable as i would have to tear the building apart!

Mrock > like i said ive tried all the same equipment - switches, fibre patch cable, gbic etc in other working ports and they work OK.

say one uplink is A and the other is B with there being a run between A and B. i have connected a switch to panel A and it does not work. i have then went across directly to be (to rule out the link between A and

and it still does not work. the only thing i havent done is to patch a cable from a 3560 directly into the 6500 - this to rule out the fibre run between points B and the basement where the 6500's are. Sounds OTT but like i say i dont have any tools to do real testing and dont have the spare cables etc to test the connection from the 3560 to the 6500.

The fibre was ran around 8 years ago and i dont know who the company was as we dont own the building we are leasing it. apparently its our responsibility too

I really want to get these runs working otherwise on this particular floor there will be no redundant link to the 6500's in our basement! its too risky at a large site like ours tbh.

cisco_trooper

Take the fiber into a dark room with a flashlight....shine the light in one end of the fiber and see if you can see it illuminate from the other end. This is not the end all be all test, but if you can't see light you probably have problems.....

nel

cisco_trooper wrote:

Take the fiber into a dark room with a flashlight....shine the light in one end of the fiber and see if you can see it illuminate from the other end. This is not the end all be all test, but if you can't see light you probably have problems.....

The fibre thats ran under the floor and through all the ducts?

can you do that even though the fibre spans several floors?

Remember this is not an issue with the fibre from the switch to the fibre patch panel. Its the runs between floors and comms rooms

JohnDouglas

nel wrote:

Sorry forgot to ask about cleaning. Is there any particular method involved? or anything you can and cant do with it being fibre? Obviously dont want to do anything which can damage it further which is why im asking.

there's a device for cleaning fibres, it's basically a roll of sticky tape. only saw one years ago when i was on a course and TN16X's were cutting edge.

if a third party has run the fibre i'd put money on them screwing it up.

nel

JohnDouglas wrote:

nel wrote:

Sorry forgot to ask about cleaning. Is there any particular method involved? or anything you can and cant do with it being fibre? Obviously dont want to do anything which can damage it further which is why im asking.

there's a device for cleaning fibres, it's basically a roll of sticky tape. only saw one years ago when i was on a course and TN16X's were cutting edge.

if a third party has run the fibre i'd put money on them screwing it up.

yeah a 3rd party ran them thoughout the building. no one even knew the fibre ran like that until i asked them about it. Its not there fault just people have left over the years and took there knowledge with them. so knowone knows if they work or not. but one thing i noticed were many of the faulty links which were attached to the trunk ports were unplugged because apparently there was always causes of looping but i was told no one could figure why so they unplugged em

looks like this maybe the reason why.

how much would it be to buy a device which tested the run? or a rough estimate on someone to test it from an external company?

tiersten

Did the links work before the upgrade?

Mrock4

http://www.lanshack.com/Fiber-Optic-Test-Instruments-C13.aspx

I believe the 850 is like $400.

You'd be surprised how far that light will shoot. We regularly shoot light site-to-site here, although it's not as methodical as using an actual test unit, it gets the job done for a tech with 50 other connectivity issues to troubleshoot

The one thing is, if you don't get a proper seal using a light on the connectors (especially MTRJ), it won't shoot for !*%)!.

nel

tiersten wrote:

Did the links work before the upgrade?

I havent began upgrading that comms room yet so all of the current kit has not been touched. By the sounds of it it hasnt worked for a while as they've had issues but no one knew why. but they didnt know the issue's ive stated could be to do with the fibre before now. they didnt even know it ran like that!

Mrock > thanks for the link. i may have to look into something like that.

Panzer919

When we have to test fiber we use sunrise fiber testers. They are far from cheap but they are great at what they do.

http://www.alltest.us/Sunrise-Telecom-OCx-A-C-F

If you are dealing with 2 strand fiber and the ends are crossed at 1 end you will get an UP UP for the interface but nothing will pass. When we do P2P links and someone is saying that it's not working we turn on ip routing and put ips on both ends and ping across to make sure its passing traffic. You might want to try the same and see if you can get connection.

Also, if this is possible, after hours take the switch from one side and bring it to the other switch. Hook them up with a 1m jumper and see if you get the same result. If you do then you know the issue is not layer 1 related.

nel

Panzer919 wrote:

When we have to test fiber we use sunrise fiber testers. They are far from cheap but they are great at what they do.

http://www.alltest.us/Sunrise-Telecom-OCx-A-C-F

If you are dealing with 2 strand fiber and the ends are crossed at 1 end you will get an UP UP for the interface but nothing will pass. When we do P2P links and someone is saying that it's not working we turn on ip routing and put ips on both ends and ping across to make sure its passing traffic. You might want to try the same and see if you can get connection.

Also, if this is possible, after hours take the switch from one side and bring it to the other switch. Hook them up with a 1m jumper and see if you get the same result. If you do then you know the issue is not layer 1 related.

So if the ends were crossed and you were getting no traffic would you get the constant increments of input errors and crc's?

Panzer919

I'm not 100% sure but you might try swapping the ends and see if the errors stop.