bruce@trigraph.uucp (Bruce Freeman) (01/09/90)
We currently have several computers all connected to a DELNI by nice thick, expensive transceiver cables. We are running out of room on the DELNI and I want to add a cheaper thin wire branch to it. How do I connect this thin wire network to my DELNI? Can I just use a DESTA or do I need to use a repeater such as a DESPR? The DEC Networks Guide is vague (in my opinion) on how you do this saying a DESTA can be used to connect a terminal server to thin wire or that you can connect multiple DESPRs to a DELNI but not explicitly saying if you want to connect thin wire to a DELNI here is what you do. The only reason to use a repeater in my mind would be if the 40m transceiver cable limit applies to the thin wire segment since it would be 50m to 70m long. If we had a shorter segment would a DESTA be feasible? Buying a DESTA at $165 is certainly cheaper than a DEMPR at $2500 (from resellers not DEC!). Thanks for your help Bruce Freeman -- Bruce Freeman Trigraph Inc., Toronto, Canada utzoo!trigraph!bruce
grr@cbmvax.commodore.com (George Robbins) (01/09/90)
In article <1990Jan8.213749.24018@trigraph.uucp> bruce@trigraph.UUCP (Bruce Freeman) writes: > We currently have several computers all connected to a DELNI by nice thick, > expensive transceiver cables. We are running out of room on the DELNI and I > want to add a cheaper thin wire branch to it. How do I connect this thin wire > network to my DELNI? Can I just use a DESTA or do I need to use a repeater > such as a DESPR? The DEC Networks Guide is vague (in my opinion) on how you do > this saying a DESTA can be used to connect a terminal server to thin wire or > that you can connect multiple DESPRs to a DELNI but not explicitly saying if > you want to connect thin wire to a DELNI here is what you do. You don't mention if you are running the DELNI in a stand-alone mode or whether it is connected to a real piece of ethernet... Iff I read the rules correctly: You can use a DESTA to connect the "transceiver port" of the delni to a thin-wire ethernet with no restrictions except the ~600 ft length of the single thin-wire ethernet segment. Additional devices, including more DESTA/DELNI pairs can be connected to the thin-wire segment. You can't plug a DESTA into one of the 8 output ports - this is equivalent to plugging two transceivers together... You can hang a DESPR off the DELNI if the DELNI is not connected to a real ethernet, or if it is and you accept special length restrictions on the real ethernet. You can cascade two DELNI's (for 7 more ports) as long as they aren't connected to a real ethernet. -- George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@uunet.uu.net Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)
ls014ls01@mdcbbs.com (01/09/90)
In article <1990Jan8.213749.24018@trigraph.uucp>, bruce@trigraph.uucp (Bruce Freeman) writes: > How do I connect this thin wire network to my DELNI? Can I just use a DESTA > or do I need to use a repeater such as a DESPR? The DEC Networks Guide is > vague (in my opinion) on how you do this saying a DESTA can be used to > connect a terminal server to thin wire or that you can connect multiple > DESPRs to a DELNI but not explicitly saying if you want to connect thin > wire to a DELNI here is what you do. > > Bruce Freeman Trigraph Inc., Toronto, Canada utzoo!trigraph!bruce When DEC did an analysis of our plant for installing DECnet, they had our thin-wire sub-networks connected to a DEMPR/DESPR and then connected to a DELNI. The DEMPR/DESPR count as repeaters and there is a limit to the number of repeaters, I think 2, that DECnet traffic can pass through. I decided, because of our Fiber-Optic repeaters (DEREP's), to eliminate the thin-wire section in my portion of the network. Ben Loosli LORAL Defense Systems-Arizona
cks@white.toronto.edu (Chris Siebenmann) (01/11/90)
grr@cbmvax.commodore.com (George Robbins) writes: ... | You can cascade two DELNI's (for 7 more ports) as long as they aren't | connected to a real ethernet. While I don't know if it's kosher, we've cascaded two DELNI's and connected them up to the local ethernet with no observed problems. In fact, right now we're cascading two DELNIs behind a LanBridge. Is there a good book on the do's and dont's of Ethernet cabling layout available? -- "I shall clasp my hands together and bow to the corners of the world." Number Ten Ox, "Bridge of Birds" cks@white.toronto.edu ...!{utgpu,utzoo,watmath}!utcsri!white!cks
grr@cbmvax.commodore.com (George Robbins) (01/11/90)
In article <90Jan10.212621est.27312@snow.white.toronto.edu> cks@white.toronto.edu (Chris Siebenmann) writes: > grr@cbmvax.commodore.com (George Robbins) writes: > ... > | You can cascade two DELNI's (for 7 more ports) as long as they aren't > | connected to a real ethernet. > > While I don't know if it's kosher, we've cascaded two DELNI's and > connected them up to the local ethernet with no observed problems. In > fact, right now we're cascading two DELNIs behind a LanBridge. With Ethernet, all kinds of things will "work" as long as long as your network is lightly loaded and/or stays a long way away from the various limits. The day it stops working for no obvious reason will be painful. > Is there a good book on the do's and dont's of Ethernet cabling > layout available? The information presented in the DEC "Networks and Communications Buyer's Guide" is generally reasonable and the names match the toys you're using or can be mapped onto their clones. It's available free from your DEC sales office... There's also comp.dcom.lans where the issue of DELNI cascades has been discussed extensively at least once... -- George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@uunet.uu.net Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)
brodie@fps.mcw.edu (01/13/90)
In article <9289@cbmvax.commodore.com>, grr@cbmvax.commodore.com (George Robbins) writes: > In article <90Jan10.212621est.27312@snow.white.toronto.edu> cks@white.toronto.edu (Chris Siebenmann) writes: >> grr@cbmvax.commodore.com (George Robbins) writes: >> ... >> | You can cascade two DELNI's (for 7 more ports) as long as they aren't >> | connected to a real ethernet. >> >> While I don't know if it's kosher, we've cascaded two DELNI's and >> connected them up to the local ethernet with no observed problems. In >> fact, right now we're cascading two DELNIs behind a LanBridge. > > With Ethernet, all kinds of things will "work" as long as long as your > network is lightly loaded and/or stays a long way away from the various > limits. The day it stops working for no obvious reason will be painful. cascading delni's WORKS, but I wouldn't recommend it. Remember, DELNI's are POWERED, and any unit with power invariable fails. (just ask Bill Hancock on this one, it's one of his favorite pet peeves...) If the "right" delni fails, you lost most of your network..........
macomber@thoreau.nsc.com (Robert Macomber) (01/18/90)
In article <90Jan10.212621est.27312@snow.white.toronto.edu>, cks@white.toronto.edu (Chris Siebenmann) writes: > grr@cbmvax.commodore.com (George Robbins) writes: > ... > > Is there a good book on the do's and dont's of Ethernet cabling > layout available? A book that I've found to be useful is: Keeping the Link (Ethernet Installation & Management) by Martin Nemzow Published by McGraw Hill ISBN 0-07-046302-6 -- Robert L. Macomber National Semiconductor South Portland, Maine macomber@thoreau.nsc.com
jbvb@ftp.COM (James Van Bokkelen) (01/19/90)
In article <29@thoreau.nsc.com>, macomber@thoreau.nsc.com (Robert Macomber) writes: > > A book that I've found to be useful is: > > Keeping the Link (Ethernet Installation & Management) > by Martin Nemzow > Published by McGraw Hill > ISBN 0-07-046302-6 A review in "ConneXions" magazine asserted that this book contained significant factual errors, bad enough that he couldn't recommend it. -- James B. VanBokkelen 26 Princess St., Wakefield, MA 01880 FTP Software Inc. voice: (617) 246-0900 fax: (617) 246-0901