morgan@jessica.stanford.edu (RL "Bob" Morgan) (08/10/90)
OK, all you folks with big happy 10Base-T networks, maybe you can help us out. We're looking at doing (finally) our first big 10Base-T installation, and are wondering how to fit it in with our existing telephone wiring plant. I'm aware that 10Base-T standardizes the pinouts when used with an RJ-45 connector, but our plant uses 6-wire RJ-11 exclusively. So, is there a standard for use of RJ-11 pins for 10Base-T? If not, how have others in this situation established their internal standards? Presumably the way you use the pairs for voice or other data connections will have some influence on this. In particular, we'd like to buy off-the-shelf twisted-pair jumper cables to connect between the RJ-45 connector on the computer's 10Base-T adaptor and the RJ-11 on the wall. Are these available from some place? Do they have a standard for how they make them up, or do people just custom-order? Thanks, - RL "Bob" Morgan Networking Systems Stanford morgan@jessica.stanford.edu
kwe@bu-it.bu.edu (Kent England) (08/11/90)
In article <1990Aug9.185455.3488@portia.Stanford.EDU>, morgan@jessica.stanford.edu (RL "Bob" Morgan) writes: > > In particular, we'd like to buy off-the-shelf twisted-pair jumper > cables to connect between the RJ-45 connector on the computer's > 10Base-T adaptor and the RJ-11 on the wall. Are these available from > some place? Do they have a standard for how they make them up, or do > people just custom-order? > Ah, an opportunity to answer a question, rather than ask our RL "Bob" Morgan, the man who has been so helpful to everyone else on the net for years. Let me give some background for the benefit of others. RJ-11 is set-up pairwise like so: 3 2 1 1 2 3 and RJ-45 is set-up pairwise like so: 3 3 2 1 1 2 4 4 We usually number the RJ-45 pins like so; 1 2 3 4 5 6 7 8 and 10BaseT goes like; tx+ tx- rx+ ... ... rx- ... ... Pair numbers are determined by the punchdown sequence on the closet block and not by the jack pin numbers or wire colors. You see right away what the problem is. Only pair 1 and 2 match, but 10BaseT uses pairs 2 and 3 which don't match on the jacks. -------------------------------------------------------------- I would recommend replacing the RJ-11 and using standard patch cords. Assuming you have a single three pair cable to each outlet, you could pull out the single RJ-11 jack and install one or two jacks. You could simply swap the RJ-11 for an RJ-45. The RJ-45 would simply be missing the fourth pair. Terminate the pairs according to RJ-45 sequence. Or you could install a pair of jacks in place of one. The first jack could be RJ-11 with pair 1 installed where pair 1 belongs on a RJ-11. Install tip and ring on this jack for the phone. That jack is a replacement for the one you pulled out. The second jack is an RJ-45. Install pair 2 and pair 3 where they belong on a RJ-45. There will be no pair 1 or pair 4. Or you could jumper pair 1 from the other jack to pair 1 and allow a tip and ring on jack 2 as well as 1. You could use this jack for Ethernet or other data, like LocalTalk or RS-232. Don't jumper tip and ring if you are going to make this a general data outlet. We use straight-thru patch cords from the xcvr to the wall. We use RJ-45 exclusively and four pair circuits. Chuck von Lichtenberg (chuckles@bu-it.bu.edu) is an engineer in my group who has worked with Cabletron on twisted pair Ethernet for years. Chuck convinced Cabletron to offer a 50 pin connector on their concentrators and to do the cross-over inside their system. You can therefore use standard patch cords, standard 25 pair cables, and standard punchdown and jacks with Cabletron and their 50 pin interface. Cabletron listens and designs systems for large installation bases like ours. I believe we have 3-400 10BaseT ports today. If you use Synoptics or other hardware that offer RJ-45 connectors you will have to do your own crossover. We would recommend doing it at the interface to the concentrator, keeping all other hardware standard. --Kent
kwe@bu-it.bu.edu (Kent England) (08/11/90)
In article <1990Aug9.185455.3488@portia.Stanford.EDU>, morgan@jessica.stanford.edu (RL "Bob" Morgan) writes: > > In particular, we'd like to buy off-the-shelf twisted-pair jumper > cables to connect between the RJ-45 connector on the computer's > 10Base-T adaptor and the RJ-11 on the wall. Are these available from > some place? Do they have a standard for how they make them up, or do > people just custom-order? > Ah, an opportunity to answer a question, rather than ask our RL "Bob" Morgan, the man who has been so helpful to everyone else on the net for years. Let me give some background for the benefit of others. RJ-11 is set-up pairwise like so: 3 2 1 1 2 3 and RJ-45 is set-up pairwise like so: 3 3 2 1 1 2 4 4 We usually number the RJ-45 pins like so; 1 2 3 4 5 6 7 8 and 10BaseT goes like; tx+ tx- rx+ ... ... rx- ... ... Pair numbers are determined by the punchdown sequence on the closet block and not by the jack pin numbers or wire colors. You see right away what the problem is. Only pair 1 and 2 match, but 10BaseT uses pairs 2 and 3 which don't match on the jacks. -------------------------------------------------------------- I would recommend replacing the RJ-11 and using standard patch cords. Asceming you have a single three pair cable to each outlet, you could pull out the single RJ-11 jack and install one or two jacks. You could simply swap the RJ-11 for an RJ-45. The RJ-45 would simply be missing the fourth pair. Terminate the pairs according to RJ-45 sequence. Or you could install a pair of jacks in place of one. The first jack could be RJ-11 with pair 1 installed where pair 1 belongs on a RJ-11. Install tip and ring on this jack for the phone. That jack is a replacement for the one you pulled out. The second jack is an RJ-45. Install pair 2 and pair 3 where they belong on a RJ-45. There will be no pair 1 or pair 4. Or you could jumper pair 1 from the other jack to pair 1 and allow a tip and ring on jack 2 as well as 1. You could use this jack for Ethernet or other data, like LocalTalk or RS-232. Don't jumper tip and ring if you are going to make this a general data outlet. We use straight-thru patch cords from the xcvr to the wall. We use RJ-45 exclusively and four pair circuits. Chuck von Lichtenberg (chuckles@bu-it.bu.edu) is an engineer in my group who has worked with Cabletron on twisted pair Ethernet for years. Chuck convinced Cabletron to offer a 50 pin connector on their concentrators and to do the cross-over inside their system. You can therefore use standard patch cords, standard 25 pair cables, and standard punchdown and jacks with Cabletron and their 50 pin interface. Cabletron listens and designs systems for large installation bases like ours. I believe we have 3-400 10BaseT ports today. If you use Synoptics or other hardware that offer RJ-45 connectors you will have to do your own crossover. We would recommend doing it at the interface to the concentrator, keeping all other hardware standard. --Kent
dpz@action.rutgers.edu (David Paul Zimmerman) (08/11/90)
> RJ-11 is set-up pairwise like so: > 3 2 1 1 2 3 > and RJ-45 is set-up pairwise like so: > 3 3 2 1 1 2 4 4 > We usually number the RJ-45 pins like so; > 1 2 3 4 5 6 7 8 Now I'm confused. I've set up my 10baseT environment under the idea that the RJ45 socket was pins 1 2 3 4 5 6 7 8 pairs 2 2 3 1 1 3 4 4 which translates on the closet 110 block to pairs 1 1 2 2 3 3 4 4 "pins" 5 4 1 2 3 6 7 8 and it works. I do believe your RJ-11 breakdown, though. >> In particular, we'd like to buy off-the-shelf twisted-pair jumper >> cables to connect between the RJ-45 connector on the computer's >> 10Base-T adaptor and the RJ-11 on the wall. Are these available from >> some place? Do they have a standard for how they make them up, or do >> people just custom-order? This isn't a cable, but you can get a frob from Brand Rex that you plug between your RJ45 and RJ11 that looks (from the catalog) like it will do the job. It is their part number BR850-MET/RJ25C. It claims to go pin 6 5 4 3 2 1 pair 3 2 1 1 2 3 female || X X male pair 8 7 6 5 4 3 2 1 pin 4 4 3 1 1 3 2 2 and from what I understand of 10baseT it should do the trick, if you do the closet appropriately. They also have a version of that with two female sockets. If neither will do the job, they still might be able to help you, custom or otherwise, esp for a large job. Brand Rex is in Connecticut, 203-456-1706. David -- David Paul Zimmerman dpz@dimacs.rutgers.edu Systems Programmer rutgers!dpz Rutgers Univ Center for Discrete Math and Theoretical Computer Science (DIMACS)
dpz@action.rutgers.edu (David Paul Zimmerman) (08/14/90)
Woop. The Brand Rex connector actually looks like this:
female
pin 6 5 4 3 2 1
pair 3 2 1 1 2 3
||
pair 4 4 3 1 1 3 2 2
pin 8 7 6 5 4 3 2 1
male
Sorry for the confusion. That's what I get for copying verbatim and then
(too) quickly tweaking for clarity.
David
--
David Paul Zimmerman dpz@dimacs.rutgers.edu
Systems Programmer rutgers!dpz
Rutgers Univ Center for Discrete Math and Theoretical Computer Science (DIMACS)autor@sunc1.cs.uiuc.edu (09/26/90)
When I installed a SynOptics system (close enough to 10baseT for this problem) 2 years ago, I also wanted to use the existing RJ11 jacks, since new jacks had been installed <1 before, and they were dual jacks, with a port labeled "voice" and a port labeled "data". After figuring out the transformation from 10BaseT RJ-45 to RJ-11, I had Black Box Corp. make up the cables for me. We made it into a "special part number", and now order them like any other cable. As far as any problems go, I've had none. The only possible problem would be with users plugging the Ethernet cable into the voice outlet.. But my users have always kept away from the computer cables anyway. Since this adaptation was made at the station, the rest of the building wiring is completely standard. ---------------------------------------------------------------------------- Jeff Autor | "Hey Rocky, watch me pull a rabbit out" autor@cs.uiuc.edu | of my hat!" At the University of Illinois | "Again?" | "Nuthin up my sleeve [riiiippppp]! Also affiliated with: | Presto!" Valmont Electric, Danville, IL | [ROAR!] | "No doubt about it, I gotta get me a Opionions expressed are mine! | new hat..." ----------------------------------------------------------------------------