Fiber Connections 2

[hosikuma]

Fiber between two Nortel FiberExpress 12 Port (NT7L26A) media converters. The nortel media converters have 12 round push and twist connectors, other than being labelled 1 thru 12 there are no other markings or labels. The swithes at each end of the two media converters A and B are Dlink DES 1024R+ with the Fiber module options. On the switch there are SC connectors, one is marked T for transmit and the other R for receive. How does the link from the switch to the media converter work? Does the T connect to port 1 and the R to port 2?

I was thinking that if the "T" from the switch A is connected to port 1 of Media coverter A then on Media converter B port 1 should hook up with the R of Switch B.
Hence, "R" from Switch A would hook up to port 2 of Media converter A...and fiber cable from Media converter B would go from port 2 to "T".....each cable must have a Transmit or Receive and at each end.

 

[AvayaNovice]

I can't really find any documentation on that nortel product you're describing.

Can you explain your configuration a little bit better?

You're saying that you have fiber between these two nortel units which have 12 connectors on each of the units? numbered 1-12. What exactly does this unit do? Are there any connectors other than Fiber?

Where do these switches come into play in reference to these nortel units?

If these units convert fiber into something else (ie. a different type of cable or something) then yes, you're just using them as a pass through. Always with fiber, you want the transmit on device A to the receive on device B, and likewise the other way.

 

[hosikuma]

AvayaNovice....

Could not find anything on the Web about this product either.
Fiber is running to two rooms (say A and B)in different parts of the building. At each termination of the fiber is a Nortel Media converter...so fiber line goes into each of these units. Each unit has 12 round ports for fiber connections...these are push and turn connectors and not SC connectors, not that it matters.

Now i'm planning to put a switch in each of the rooms to connect the "network" together (there are exisitng punch panels in each room with wiring to different outlets). The switches have a set of fiber connections "T" and "R" that I must connect to the Media converter and back to the other room and then into the other switch.

Thinking about it, I think you are right in that these ports on the media converter are just pass through. All I believe you have to do is make sure that the "T" from the switch of room A goes thru the same port (lets say port 1) of each of the media converters and then into the "R" of switch B....by the same token the "R" from swith A would connect via fiber cable to lets say port 2 of Media converter A thru the fiber link between the two rooms and into Media converter B. From here the signal would come out of Port 2 and via fiber cable into the "T" connection of switch B.

If this is correct, then I have to find fiber patch cable with twist and turn connectors at one end and SC connectors in the other.

 

[dnc16]

FYI, the "twist and turn connectors" are ST connectors and
yes you can get patches with SC on one end and ST on the other.

 

[Bobg1]

If I am understanding this, You have 2 switchs that you want to link with fiber. These switchs have fiber ports on them.

Why do you want to put the media convertors in between?

Sounds to me like all you need are st to sc adaptors to connect your fiber to your switchs.

 

[hosikuma]

Bobg1....The fiber link is existing and is a round cable about 3/4 inches in diameter, they go directly into the two Nortel media converters (they go right into the box...no outside connection here) which are also existing. The only way to connect to the fiber is thru these "ST" connectors(thanks dnc16), 12 ports in total on the exterior of the Media converter box...hence the fiber patch cables with "ST" on one end and "SC" on the other (switch end). I image that there are 12 strands of fiber and they are "hard" connected inside the Media converter.

In any case I will just follow the "T" on switch A thru the media converters to the "R" on the other switch B...with the other cable going from Swith A "R" connection thru to the "T" connection in switch B.

 

[daronwilson]

I wonder if your "media converter" is actually just an LIU (Light Interface Unit) where the fiber terminates on ST fittings, that is what it sounds like you are describing.

If that is the case, the strands (1-12) may be straight through, but often they are reveresed for each pair. If they are reversed, port 1 on one end ends up port 2 on the other end, 3 ends up 4, etc. This is done normally on duplex SC style connectors so that it is easy to patch things and not have to create the twist needed for transmit and receive, however depending on the installation it may have been done on ST's as well.

You are on the right path, I usually don't bother following or tracing, expecially with ST, just plug it in and see if you get link. If you don't, swap the polarity and you should have it, all other things being operational.

Good Luck!

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[AvayaNovice]

DW is probably right.

You're looking at an LIU. That's a fiber termination point, I guess you could think of it as a patch panel.

If you pull it open, you should see the individual fiber strands wrapped up in a loop, and then terminated onto those ST connectors.

That's why I couldn't find any documentation...

Nortel names their products oddly.

That's a passive device, it's actually not even a device... it's a box.

And as far as pairs being reversed. I see that sometimes, but not all the time. If you happen to have a light source and a meter, you could probably trace them out to confirm, but then again you could just swap them until you get a link.

Very easy to do.