The IEEE 802 committee has reversed its previous decision not to develop the Fast Ethernet Alliance’s proposal for 100Mbps Ethernet within the 802.3 committee. According to 3Com Corp, one of the main supporters of the technology, and the founder of the Fast Ethernet Alliance, the committee voted unanimously that the 802.3 committee should develop the technology, while at a meeting of the IEEE Computer Society LAN MAN Standards Committee last week a task force was established to the undertake development work. The technology is to have the working title of 100Base-T, and is to include two complementary transmission methods to cover different cable types. The 100Base-X specification developed by Grand Junction Networks Inc will be used for two-pair category 5 unshielded twisted pair, shielded twisted pair and fibre optic cabling. This is based on the current draft of the ANSI X3T9.5 Fibre Distributed Data Interface Twisted Pair-Physical Media Dependent working group, onto which is glued the CSMA/CD protocol used in 10Mbps Ethernet. The four-pair voice grade transmission method is to be based on a new proposal known as 4T Plus which is said to extend traditional 10Base-T two-pair signalling to four-pair operation at 100Mbps over voice-grade cabling. The IEEE says it expects draft specifications for both transmission methods to be ready for an interim meeting in January. The next full meeting of the 802.3 committee is to take place in March. News of the IEEE’s change of heart may explain AT&T Electronics’ decision to co-develop 100Base-T products with 3Com (CI No 2,297). AT&T was previously a supporter of the rival 100Base-VG proposal, which is being developed in the newly-established 802.12 committee. Quite where the new decision leaves 100Base-VG, however, remains to be seen: 100Base-T now effectively becomes the only ‘Fast Ethernet’ specification, leaving 100Base-VG out on something of a limb, despite ongoing development work.
