Path: utzoo!attcan!uunet!husc6!bu-cs!kwe From: kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) Newsgroups: comp.dcom.lans Subject: Re: status lights on lan equipment Message-ID: <23457@bu-cs.BU.EDU> Date: 21 Jun 88 15:19:10 GMT References: <5808@dcatla.UUCP> Reply-To: kwe@buit13.bu.edu (Kent England) Followup-To: comp.dcom.lans Organization: Boston Univ. Information Tech. Dept. Lines: 55 In article <5808@dcatla.UUCP> dnwcv@dcatla.UUCP (William C. VerSteeg) writes: >The consensus on lights vs. no lights on lan equipment seems to be >overwhelming in favor having status lights. > >Box status indicators >_____________________ >Power on indicator >Box running/loading indicator > > > >Interface status indicators >___________________________ >Receive Data >Transmit Data >Media Error (i.e. Collisions, no Carrier, etc) I think you also need: SQE (Heartbeat) enabled There is a difference in what is required for bus versus star topology Ethernet. As an example, Cabletron defines 5 status lights for a bus transceiver: Power, Receive, Transmit, Collision, SQE enabled. All of these are very useful for bus transceivers: Power= is this transceiver plugged into anything? Rcv/Xmit= is data flowing both ways? Collision= are there too many collisions (get the analyzer)? SQE= do I have a problem with heartbeat (on a repeater)? For star topology (UTP of fiber) they define two more signals for the point-to-point MAU to concentrator [not IEEE jargon]: Host Link OK Hub Link OK These signals are not data signals. They indicate a good or bad circuit and may eliminate the need for TDRs, special analyzers or breakout boxes. If Link OK not lit, then find the open or crossed circuit. Very, very useful. When forced to eliminate all but two lights on hub concentrators and MAUs, Cabletron chose to keep Link OK and Rcv. Seems reasonable to me. One more thing. It's very very important that vendors implement the IEEE repeater fault protection functionality. Just because they spec 802.3 compatible doesn't mean they implement the fault isolation feature= make sure they implement the fault isolation. Isolation is based on too many consecutive collisions or jamming and provides for automatic recovery. You really need this feature to isolate hardware faults and to allow you to unplug things for debugging. I am not sure of existing vendor compliance, but I think most of the star concentrator equipment will have this feature. Kent England, Boston University