Path: utzoo!attcan!uunet!husc6!bloom-beacon!apple!rutgers!elbereth.rutgers.edu!hardees.rutgers.edu!ron From: ron@hardees.rutgers.edu (Ron Natalie) Newsgroups: comp.dcom.lans Subject: Re: Ethernet terminal servers Message-ID: Date: 22 Jan 89 15:00:40 GMT References: <6556@fluke.COM> <13718@cup.portal.com> <14843@oberon.USC.EDU> Organization: Rutgers Univ., New Brunswick, N.J. Lines: 38 >>Here are some advantages and disadvantages of a terminal server >>compared with directly connected terminals and modems. > > The third alternative, of using a port selector (aka data pbx) > shouldn't be ignored. (We use micoms here at usc, mostly 6600s, > connecting over 4000 terminals and over 100 hosts.) I've lived in both environments. When I started hooking things up at my previous job, the only Ethernet terminal servers on the market were pretty bad. We settled on a Gandalf PACX terminal switch. By and large it worked pretty well. Rutgers had a network of terminal switches as well. We had three INFOTRON switches that are interconnected together and then out to the machines. Port selectors are still a pain. Terminal servers have come a long way. The problem is I've got to run an RS-232 connection to each bloody host port that I want to hook up. I've got to worry about speed problems. Some lines won't autobaud, some will. Adding terminals to the terminal server is about the same level of work as adding them to the port selector, but adding hosts is easy. I don't have to touch the terminal servers. I just plug in the Ethernet interface of the new host and it is accessible to all 20 or so servers we have spread around (there may be more that are run by academic departments that I don't know about) and to all the other hosts on the network through out the state. People on the terminal servers can even get to the supercomputer center in Princeton. Developping an RS-232 switching system to do all this would be a night mare. If a group as a few more terminals to hook up, we can drop in the appropriate sized unit right near the terminals. Rutgers used to be a mess of Short Haul modems and line drivers to bring things back from each building to the switch. > And eathernet terminal servers are more expensive per port than > port selectors, and rarely have the redundancy. Not so. If you buy large terminal servers, you can get the cost per port down to the comparable RS-232 switch. We run 96 lines on a CISCO ASM unit. They're a lot smaller than the equivelent port selector and I don't seem them drop connections or fail as much as our infotrons and I never had to worry about clock jitter like I did with the Gandalfs.