Thread View: comp.protocols.misc
2 messages
2 total messages
Started by n2dsy
Mon, 08 Jun 1987 14:25
OSI Protocols
Author: n2dsy
Date: Mon, 08 Jun 1987 14:25
Date: Mon, 08 Jun 1987 14:25
44 lines
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2227 bytes
I have been watching the exchanges between Open Systems and Internet folks and frankly I'm bored with the whole thing. First, let me state that I'm an OSI booster. Second, no way am I going to get imbroiled in the nonsense again...yes I've been there. Third, I am an active Radio Amateur involved in packet radio systems based on the OSI model. We are working on the COSI-Switch which alas, is a bit delayed, not because of technical issues, but the work and school schedule of the main person doing that particular development. Look for it during the early summer. (Vacation time tends to provide time for development !) We'll be putting this stuff on the nets. Fourth, I am interested in finding available implementations of OSI software for small systems such as the MS-DOS based PCs. Portions of the model would be great too ! Special interest is in simple implementations of subsets of FTAM or X.410/420 and basic implementations of the lower layers needed to support them. Implementations in "C" or 8088/Z80 Assembler are of interest. Fifth, (I love lists !) Sixth, I think that we OSI folks are too quiet about what we have done ! I would really like to see OSI code produced and distributed on the same basis as CTRM or Kermit. Look how common this stuff is ! You find Kermit in all kind s of products. Now the caveat is that when you put in public-domain Kermit software in your product, you can't charge for the value-added, but I can assure you that your product (whatever it is) will sell better ! If we're going to have WIDE USE of OSI protocols we will need this approach too ! Any takers ? J. Gordon Beattie, Jr. hou2d!n2dsy 201-615-4772
DEC Ethernet Configuration rules
Author: Earl Shaffer
Date: Tue, 09 Jun 1987 13:23
Date: Tue, 09 Jun 1987 13:23
87 lines
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4281 bytes
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 ==============================================================================
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