Fiber DS3

[keefe007]

I was talking to SBC about bringing in additional DS3s to one of our facilities and they mentioned that the local loops are now fiber. How exactly does a copper DS3 compare to a fiber DS3? I always thought that a true DS3 needed to be over copper.

Thanks for the help!

[marchen]

According to my knowledge nowdays most of the DS3 drops are connected by fiber. Am I right?

DS3's are definately copper (Coax w/BNC connectors).

They usually bring it in via a SONET Fibre system (aka. a single channel on an OC3/STS-1).

If you require more than 1 DS3, they'll usually drop an OC3/OC12 SONET MUX/ADM on your premises; and mux the multiple DS3's into a SONET/OC3-OC12 signal for delivery into the Telco Metro Network.

However, "your" interface (i.e. your side of the DEMARC) is always Coax/BNC, one pair of coax (Tx/Rx) per DS3. The fact that the local telos may employ a SONET/Fibre facility is irrelevant to you for all intents and purposes. =)

- R208.

The only Caveat to that, is if you *also* have your own SONET ADM/MUXing equipment. You could request 3 x DS3's, but ask that the Telco bring it in on a channelized OC3 (3 x STS-1's); and you would DEMUX the DS'3s from the SONET signal yourself. (This is what we do - We have a bunch of Nortel OM3500 OC-48 Transport Nodes, and usually request of our carriers to drop any leased DS3's to us on SONET APS 1+1 OC3/OC12 links; which we run protected SONET/Fibre to their equipment.

We then Mux/Demux the DS3's ourselves. However, They *all* still terminate as individual Coax/BNC connections on our own internal DSX-3 termination panel.

_______________________________________
Dir., Network Engineering, for an IXC/CLEC/ISP

[Zitibake]

DS3 hand-off is always done as copper. However, I've never heard of any LEC stringing coax DS3 cables across telephone poles; the coax DS3 is used within the building where the hand-off takes place.

To ride between buildings (e.g. to the CO), DS3 is muxed-up to OC3 or higher. This means that to get a single DS3 into a building with no fiber yet, the LEC will trench fiber into the building and install an OC3 mux... very expensive.