MavEtJu's Distorted View of the World

Dark Fibre, big troubles

Posted on 2007-03-13 16:13:57, modified on 2007-03-13 19:10:20
Tags: Networking, Adventures

For our network, we are looking at getting a Dark Fibre backbone between our main locations and the data centre. High speed networking, that can only mean one thing: biiiiiiiig trouble.

It started with my absolute zero knowledge about using fibre as a network medium. Yes, I knew that it has to do with sending light through a small plastic tube and that it goes fast, but that is about the amount. Right now I know all pits you can end up in: Been there, done that, got the t-shirt.

First thing, there is single mode and multi mode fibre. Single mode is, as far as I get it, good for long distances, multi mode is, as far as I get it, good for short distances. For weeks and weeks I was told we were getting multi mode, and I was panicking because there so many things to chose from with regarding to multi mode, depending on the distance you cover. At the end, we ended up with single mode and all was good and fine.

Second thing are the connectors on the fibre cable. There are SC connectors, which are big ones, and there are LC connectors, which are small ones. Yes, S for large and L for small. Who could have thought that?

And then, you plug the connectors in a router/switch itself via a GBIC or plug it in a media convertor which converts it to ethernet. Of course, the GBIC needs an LC connector most likely and a media convertor uses an SC connector most likely.

So we have (2+(n-1))*2*2 ways to arrange things. Increase that with my absence of knowledge (which is rapidly decreasing now) plus the idea of using different media convertors halfway the project, that will give you about 3,142 ways to order things.

And yes, we did do them all wrong...

I was told we had ordered multi mode and we have been promised single mode fibre. We ordered LC connectors on the fibre, and then we moved from GBIC to the media convertors, so we had to change put fibre patch leads in between them which were of course male-male instead of female-male so we had to put another bunch of convertors in (it is a good thing that the stuff is passive :-)

To gain bandwidth and redundancy, we have bought special media convertors which can do sending and receiving over one cable. So you can have double the everything! Only problem, the media convertors we got were not the ones we ordered: You need one with frequency A for the local side and one with frequency B for the remote side. And we got two with frequency A. The good news is that we already had ordered another set of media convertors, and we were able to swap them both for frequency B: that way we can shuffle them around and end up with a working set!

But at the end, we got our Dark Fibre backbone up and running! And indeed, it's faaaaaaaast! (Well, 1Gbps between long distances is always fast :-)

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