Path: utzoo!attcan!uunet!lll-winken!ncis.llnl.gov!helios.ee.lbl.gov!pasteur!ucbvax!bloom-beacon!oberon!skat.usc.edu!blarson From: blarson@skat.usc.edu (Bob Larson) Newsgroups: comp.dcom.lans Subject: Re: Ethernet terminal servers Message-ID: <14843@oberon.USC.EDU> Date: 21 Jan 89 09:00:08 GMT References: <6556@fluke.COM> <13718@cup.portal.com> Sender: news@oberon.USC.EDU Reply-To: blarson@skat.usc.edu (Bob Larson) Organization: USC AIS, Los Angeles Lines: 58 In article hedrick@geneva.rutgers.edu (Charles Hedrick) writes: >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.) >1) If you are in a changing environment it's easier to plan. >4) If your primary machine is down, you can go play on another one. >6) In public terminal rooms and for dialups, you get much better >utilization. >7) If you go through a multiuser system, your response time will >be affected by the load on that system. All true of port selectors. >2) There is only one kind of asynch interface to worry about. Terminal - port selector cables are constant. Computer - port selector cables can still be a problem. >5) The telnet implementations on the terminal server is typically better >than the telnet implementation in many hosts. One of the reasons we have terminal server boxes on our port selector. >8) If lots of people telnet from the machine they are wired to to >others, you're using your hosts as terminal servers. They are >probably more expensive per user than a real terminal server, and >probably not as good. And eathernet terminal servers are more expensive per port than port selectors, and rarely have the redundancy. >1) You become critically dependent upon the state of your network. >2) You become critically dependent upon the quality of the software >on your hosts that handles incoming connections. >4) Some "out of band" terminal functions become harder. Not true of port selectors. >3) Every user goes through at minimum two computers: the real one and >the terminal server. Micom 6600 and others have enough built in redundancy and servicability without taking it down I can't remember this ever being a problem. (Power outages and rare firmware upgrades are the only reasons I have seen them down.) Sometimes the connections between the port selectors become bottlenecks, but this is hardly unique to them. -- Bob Larson Arpa: Blarson@Ecla.Usc.Edu blarson@skat.usc.edu Uucp: {sdcrdcf,cit-vax}!oberon!skat!blarson Prime mailing list: info-prime-request%ais1@ecla.usc.edu oberon!ais1!info-prime-request