shaffer@operations.dccs.upenn.edu (Earl Shaffer) (06/09/87)
I have put together the following list of "rules" from DEC literature on Ethernet networks. Please send me any comments. ========================================================================= ThinWire Rules 1) Maximum segment length = 185m 2) Stations attach using DESTA and 'T' connector 3) Minimum distance between 'T' connectors = 0.5m 4) Maximum stations on segment regularly = 30 5) Maximum stations on segment with DEMPR = 29 6) Maximum stations on segment with SER and faceplate = 28 Standard Ethernet Cable rules 1) Stations attach using transceiver 2) Maximum segment length regularly = 500m 3) Maximum segment length with DELNI/DEMPR combination = 300m 4) Maximum transceivers on segment = 100 5) Connect DELNI to segment using transceiver, no heartbeat 6) Connect DEMPR to segment using transceiver, <45m of transceiver cable 7) Minimum distance between transceivers = 2.5m DELNI rules 1) DELNI allows 8 devices to share transceiver 2) Stand-alone cascading DELNI network interconnects 8 DELNIs and 64 stations using transceiver cable 3) Connect DELNI to standard Ethernet cable using transceiver 4) DEMPR connects to DELNI using < 45m of transceiver cable 5) Main DELNI in stand-alone cascading DELNI network must be in 'global' mode 6) Non-Main DELNIs in stand-alone cascading DELNI network must be in 'local' mode 7) A DELNI is not a network addressable unit DEMPR rules 1) Connect DEMPR to DELNI using <45m of transceiver cable 2) Connect DEMPR to standard Ethernet cable using transceiver 3) Segments attached to DEMPRs can have 29 stations 4) Main DEMPR in stand-alone cascading DEMPR network uses ThinWire 5) Only one segment attached to main DEMPR in stand-alone cascading DEMPR network can have DEMPRs on it 6) The cascading segment in the stand-alone cascading DEMPR network can have up to 29 DEMPRs on it 7) DEMPRs on cascading segment of a stand-alone cascading DEMPR network are attached using DESTAs 8) A DEMPR grounds an Ethernet segment 9) A DEMPR provides a termination end to a segment 10) A DEMPR is not a network addressable unit General Ethernet Network Rules 1) Maximum cable length between stations = 2800m (all media) 2) All segments must be grounded 3) All segments must be terminated on each of the two ends 4) Maximum stations on a single Ethernet network = 1024 5) A station = network addressable unit 6) Maximum stations on an extended network = 8000 7) Maximum length of low loss transceiver cable = 50m 8) Maximum length of high loss transceiver cable = 12.5m 9) Stand-alone networks cannot be attached to Ethernet networks Repeater Rules 1) Local repeaters join segments < 100m apart 2) Remote repeaters join segments <1000m apart 3) No more than 2 repeaters between any two stations 4) A DEREP cannot be connected to a DELNI Bridge Rules 1) No more than 7 bridges between any 2 stations 2) Local bridges are connected using <100m of transceiver cable 3) Remote bridges are connected using <2000m of fiber cable 4) Each remote bridge half counts as a bridge for the "7 bridge" rule Questions 1) Is a bridge considered to be a station 2) what about the remote bridge/repeater configuration ============================================================================== Earl Shaffer - University of Pennsylvania - Data Communications Department "Time was invented so that everything wouldn't happen at once." Steven Wright ==============================================================================