Fibre problems

[ictssltd]

Hi All,

 

In the process of upgrading a school's network with new gigabit switches to replace old 10/100 Mbs ones.

 

Existing network had two buildings linked by fibre using 10/100 switches and separate cat5e to fibre media converters (allied Telesis) - Link works

 

Replaced switches with new gigabit switches and fibre modules - Link doesn't work!!

 

Exchanged switches and tested fibre modules/patch cables, all working - Link still doesn't work!!

 

Any ideas as to where the problem may be?

 

Thanks

[FN-GM]

I would try swapping around the connectors on the fibre patch cable itself. Has all sorts of weird messing around with different vendors etc (although in theory it shouldn't be the case!).

[ictssltd]

I've had them replaced with new ones but Link still doesn't work

[FN-GM]

Still worth swapping the connector on the end over. The move the left on the right and the right to the left. Had to do it many times on brand new fibre patch cables.

[paulellam]

Lots of things it could be, a few questions....

 

Do you get a link light when all connected on the fibre modules at both ends?

 

Do you have any spare cores on the fibre to try instead, a link light does not mean a good connection.

 

What fibre, I presume its multimode?

 

What terminations at the fibre panel (presuming there is one) i.e ST LC, then what fibre leads are you using i.e ST to LC.

 

Have you got the same brand/model switches at both ends and same fibre modules? Are they managed switches and configured with IP etc

 

Some switches have an ethernet port that if used will knock out the fibre port or the other way round.

 

Are the fibre ends in good condition, without dust etc.

 

Paul

[ictssltd]

I think I've tried every possible combination but still nothing

[FN-GM]

I think I've tried every possible combination but still nothing

 

What switches do you have?

[ictssltd]

No lights

No spare cores

fibre that was installed by someone else, I think there are four in total but only two each end are terminated, the fibres work when connected to the Allied Telesis converters but otherwise don't

ST LC patch cables

Yes same brand - Netgear, but different models, 28 port in Infants, 52 port in Juniors, fibre modules are the same. Both are managed switches with there own IP

On these models you can use all the ports plus the modules, but just in case, i made sure the last ethernet ports weren't used

Yes as far as I can tell, they work! With the Allied Telesis at least!

 

Thanks

[paulellam]

Can you try a fibre patch lead between the two switches on a desk i.e next to each other to see if the connect then?

[ictssltd]

Yeah tried that already, works fine.

[Oaktech]

is it possible that your modules are wrong for the type of fibre you have - either the patch or the infrastructure cable? What do the allied telesis modules say on them, and what do the new modules say?

 

Do the switches register that modules are present in the sfp slots?

[ictssltd]

I think they're fine for the patch cables, used them before without problems. I am wondering about the link between the buildings though but I don't fancy the idea of having to change that though!!! Lol

[paulellam]

I does sound like something is a mismatch somewhere.

[Sc00by]

It sounds like your new modules are singlemode and your fibre is probably multimode or your modules are for a different type of multimode cable eg 62.5/125, 50/125 etc

 

If this is the case you'll need to get multimode converters to match your cable however we're finding it quite difficult to source multimode Gb modules for our kit. Cisco seem to be the only brand we've had success with but even then it's all from eBay. We're 62.5/125 and officially this only supports GB upto 250metres however we have managed to get a GB at 600metres but not much further than that. To get Gb beyond that you need singlemode cable.

 

If your multimode cable run is quite long and you are trying to get a Gb the connectors inside the splice trays must be absolutely spotless. We have links here that work perfectly fine at 100mb but refuse to run at a Gb. A good clean and they usually work fine.

Edited April 26, 2016 by Sc00by

[twin--turbo]

use your phone camera to confirm there is light on the TX side of the module and that this matches at the far end with the dark RX side of the other module.

[PrimaryNetMan]

See you are in MK. It the cable old MKC installed fibre by any chance? Had a similar issue when my school amalgamated with another due to the OM1 fibre run being too long to support gigabit speeds.

[PotNoodleTech]

I was going to say it could actually be that the fibre cable itself does not support 1GB speed due to being too old/damaged/too long.

[whitte]

Your patch cord is multimode? How about your module? Single-mode or multimode? If your single-mode, you have to use single-mode patch cord.

[synaesthesia]

Necrothread resurrections ahoy! Why can't people read dates before replying?

[Oaktech]

Necrothread resurrections ahoy! Why can't people read dates before replying?

 

Look at the people posting, they are all low rep/low post count/unusual countries, I would not be surprised to find their names popping up next to spam threads.

[PotNoodleTech]

You two get out of bed the wrong side this morning?

[Oaktech]

You two get out of bed the wrong side this morning?

 

I take it in turns to spend the night with my grumpy, insomniac 2 year old. Every other day I don't just get out of the wrong side of the bed, I get out of the wrong bed entirely.

Edited May 24, 2017 by Oaktech