BMW6957@TAMCHEM.BITNET.UUCP (04/14/87)
I'm a planning to install a thin-wire ethernet to extend our existing baseband ethernet. While reading the network catalog from DEC, I've noticed that it does NOT say that the special H4000-BA transceiver must be used with a DEMPR. It DOES say that the special transceiver is required for a DELNI if a DEMPR is attached to it. An article in the March 9th "Digital Review" states "...the special H4000-BA transceiver that the DEMPR requires...". The network catalog is quite consistent about mentioning an H4000 (no suffix) when talking about attaching a DEMPR directly to the thick ethernet and equally as consistent about mentioning a DELNI/DEMPR combination when talking about the H4000-BA. I will not be using any DELNI and I'm a little confused. Does the DEMPR also require the special H4000-BA, or is Digital Review mistaken? If not, why does a DELNI require the special transceiver only if it's connected to a DEMPR? What have I misread? Anything? Any help will be greatly appreciated. Brad Wilson Chemistry Department Texas A&M University College Station, TX BMW6957@TAMCHEM.BITNET
tedcrane@batcomputer.UUCP (04/14/87)
In article <8704140550.AA29379@ucbvax.Berkeley.EDU> BMW6957@TAMCHEM.BITNET (Brad Wilson) writes: >I'm a planning to install a thin-wire ethernet to extend our existing >baseband ethernet. >.... >I will not be using any DELNI and I'm a little confused. Does the >DEMPR also require the special H4000-BA, ... >If not, why does a DELNI require the special transceiver only if it's >connected to a DEMPR? What have I misread? Anything? Any help will >be greatly appreciated. > Well, you're about to do what we did several weeks ago. We used to have a backbone around our lab with several DELNI's hung off of H4000's. Old H4000's, at that. We took one wing of the backbone and changed it to a single DEMPR with several thinwire segments. The DEMPR is hooked to one of the old H4000's. This works fine. We were worried about the same thing, and just crossed our fingers. There is also another DEMPR hung off our thickwire backbone. This one is also off of an old H4000 and works well. This particular DEMPR came from DEC but has been jury rigged for some special effects. I just mention it to point out that multiple DEMPR's and DELNI's work just fine. One interesting note: During the transition, we hooked the DEMPR up to a DELNI instead of directly to the H4000. It "sort-of-didn't" work. Some of the combinations of thick-to-thin and thin-to-thin couldn't talk to each other, and other combinations worked ok. We could not pin the problem down to any specific "thick"ness of wire, protocol (we have DECnet, TCP/IP, and LAT on the wire), or hardware (we have DEC, HP, and PROnet stuff on the wire). However, since we had several DELNI's, we though to swap the one which the DEMPR was hooked up to with another. Lo, and behold. Everything worked OK! The two DELNI's were listed as the same model, rev, etc. Would anyone care to comment on this wierdness, or shell we chalk it up to causes beyond the other side of nowhere?