mark (10/30/82)
In this month's "Hardcopy", on page 50, it is mentioned that a set of LAN standards is being embraced by a large number of manufacturers, including DEC, HP, Intel, 3Com, Three Rivers, Ungermann-Bass, and Xerox. The article says very little about the protocol, except that it's called CSMA/CD (or ECMA, the article doesn't bother to expand its acronyms and it's pretty hard to tell much from it) and seems to fit at about level 4 of the ISO model (but I'm not even sure of this). The article seems to be mostly concerned with the political issues of whether people will conform. (The answer to that is obvious - they will conform only if they are in the process of designing a new network and can be convinced to go with the standard. Fortunately, LAN's are so new there aren't many existing products with conflicting standards.) Does anyone know anything more about this standard? How is it going to fit in with other standards, such as X.25 and TCP/IP? Is it a standard only for LAN's or for the interconnection of LAN's? Is it a hardware "plug" standard such as RS232, a software protocol standard, or what?
tihor (10/31/82)
#R:cbosgd:-276300:cmcl2:6800001:000:106 cmcl2!tihor Oct 30 21:35:00 1982 ... what is this standard? The answer is the revised Ethernet spec. (q.v.). (As massaged by the IEEE).
george@sri-unix (10/31/82)
The protocols referred to in the "Hardcopy" article presumably are the 10 Mbps Ethernet specifications, worked out by Intel, DEC, and Xerox based on experience with the 3 Mbps experimental Ethernet originally developed by Xerox PARC. This is one of the set of Local Area Network Protocls under discussion by the IEEE 802 LAN standards committee, and is the set nearing consensus. ECMA seems to have helped 802 converge on a standard by supporting a version very similar to the Ethernet spec. CSMA/CD (Carrier Sense Multiple Access/Collision Detect) is a link access protocol to arbitrate use of a shared media (10 Mbps baseband using coax) among a multiplicity of stations without requiring any prior configuartion of slots, tokens, or other transmission order control information. It is part of the Levels 1 and 2 protocol (in ISO terminology) that Ethernet specifies. The are a number of vendors who have anounced products or development efforts using Ethernet, including Xerox, Intel, DEC, Ungermann-Bass, and a number of others. Although I very much doubt that Ethernet will be the only LAN technology to be widely used, it already seems well on its way to being one of the more commonly used ones. George Marshall Ungermann-Bass, Inc.