ericd@ms.uky.edu (Eric B. Durbin) (07/27/90)
I seem to be getting some conflicting information here... let me
clarify what I need:
Diagram
XXXXXXXXX XXXXXXXXX
============XXX-----------XXXXXXXXX===============XXXXXXXXX===== local ethernet
Ungermann- coax Broadband transceiver Datalink
Bass Modem cable Bridge
Cable
I know this is reasonable, because it has been implemented elsewhere on
campus.
I also know that a Broadband Modem is made by Chipcom Corp. in MA, and
Datalink Bridges are made by DEC (ie LAN Bridge 150). Chipcom also
makes a combined broadband modem and datalink bridge called Ethermodem
III Bridge.
This setup can also be accomplished via an UB Access One box that includes
the modem and a bridge card.
I'm looking for alternatives to the $9K+ Access One setup, ie more vendors
for Broadband Modems and Datalink Bridges. I've heard that Fiber Mux (sp?)
makes the modem but I don't know how to contact them.
Again, many thanks for any directives.
Eric
--
[] Eric B. Durbin (606) 257-4581 [] ericd@ms.uky.edu []
[] University of Kentucky [] ericd@UKMA.BITNET []
[] 165 Markey Cancer Center [] {rutgers, uunet}!ukma!ericd []
[] Lexington, KY 40536-0093 [] eric.durbin@ukwang.uky.edu []eli@spdcc.COM (Steve Elias) (07/27/90)
In article <15721@s.ms.uky.edu> ericd@ms.uky.edu (Eric B. Durbin) writes: > >I also know that a Broadband Modem is made by Chipcom Corp. in MA, and >Datalink Bridges are made by DEC (ie LAN Bridge 150). Chipcom also >makes a combined broadband modem and datalink bridge called Ethermodem >III Bridge. check with Chipcom for an update on their bridges. they also have a new ethernet-to-ethernet bridge called "midnight", with excellent price/performance. they are in southboro mass. 508 460 8900. -- /eli eli@spdcc.com
kwe@bu-it.bu.edu (Kent England) (07/28/90)
In article <15721@s.ms.uky.edu>, ericd@ms.uky.edu (Eric B. Durbin) writes: > I seem to be getting some conflicting information here... let me > clarify what I need: > > Diagram > XXXXXXXXX XXXXXXXXX > ============XXX-----------XXXXXXXXX===============XXXXXXXXX===== local ethernet > Ungermann- coax Broadband transceiver Datalink > Bass Modem cable Bridge > Cable > Ah, now I see what you mean by "Ungermann-Bass". When you say "Ungermann-Bass cable" I see a CATV system. There are a variety of flavors. If you have an Ungermann-Bass set-up, it is probably mid-split, with channel translators that take a single 6 MHz TV channel. U-B uses a 5 Mbps/6 MHz system, that fits conveniently within a single TV channel pair. You can have hi-split and lo-split CATV systems as well. In case you don't understand the split; when you are running data, you have to have one channel for signals sent "up" the cable toward the head-end (root of the CATV system) and another channel for signals sent "down" the cable. The "split" involves picking the frequency location of the guard band between "up" and "down" and the shift between the two channels. A translator takes the signal from "up" and rebroadcasts it "down" the cable, so all stations hear everything. If your CATV system is set-up U-B style, then you only have a 6MHz channel pair (probably mid-split, probably 4A/R channel pair) and a translator already in place. Use a U-B Buffered Repeater in place of the "broadband modem" in the diagram above. > > I also know that a Broadband Modem is made by Chipcom Corp. in MA, and > Datalink Bridges are made by DEC (ie LAN Bridge 150). Chipcom also > makes a combined broadband modem and datalink bridge called Ethermodem > III Bridge. > Chipcom uses the IEEE spec approach. (They may have something proprietary as well.) If you get the Chipcom or other IEEE compliant gear, you get a full 10 Mbps in *three* contiguous channels (18 MHz), one "up" and the other "down". Three channel pairs altogether. A U-B single channel translator won't work with this. You would have to change to a translator from Chipcom or get a translator that shifts bigger chunks of bandwidth. (What do they call those kind of translators?) Also note that the IEEE spec approach has distance limitations, 1800 meters from the head-end max, as I recall. [Check that, I could be wrong.] So, how Ungermann-Bass is your CATV system? Would you be willing to set up new channel assignments, or are you running HBO on those frequencies? Can you replace the U-B translator(s) with whatever the Chipcom gear requires? There's a lot to working with broadband. :-) I hope this explanation helps more than confuses. --Kent