IEEE 802.3u-1995

1. The CSMA/CD access method of IEEE 802.3 will be retained without change. Therefore, the only change to Clause 4 Media access Control and Clause 6 PLS Service Specifications will be to add a subclause 4.4.2.3 containing the parameterized values for 100 Mb/s operation of the MAC. Management definitions will be provided that build upon the existing set with minimal changes. 2. The link segment phyical layer specification and the multiport repeater specification will be optimized for operation over 100 meter TP links supporting one or more of the horizontal wiring schemes specified in EIA/TIA-568:1991 and TSB-36. The architecture will be sufficiently open that other physical later specifications may be added as future projects. A media independent interface (MII) will be defined which will allow operation of multiple physical later implementations under the MAC. 3. It is recognized that there may be some minor editorial changes required for editorial alignment. For example: "The PLS is found in chapter7" would require correction.l

This standard will provide a higher speed capability for 802.3 LANs at 100 Mb/s, made possible by recent developments in high spped signaling, particularly on unshielded twisted pair and advances in silicon technology. It will afford significant performance improvements with minimal vendor and customer investments by leveraging the infrastructure of 802.3 research, development and market deployment. The design focus for Higher Speed CSMA/CD is better performance for existing applications that are characterized by bursty traffic. This standard is also expected to support emerging applications in the market.

Amendment Standard - Superseded. Superseded by 802.3aa-1998. The ISO/IEC CSMA/CD Media Access Control (MAC) is coupled with a family of new Physical Layer specifications to achieve 100 Mb/s operation. Known collectively as 100BASE-T, this family of Physical Layer specifications includes 100BASE-T4, which uses four pairs of ISO/IEC 11801: 1995 Category 3, 4, or 5 balanced cable; 100BASE-TX, which uses two pairs of Category 5 balanced cable or 150 ohm shielded balanced cable; and 100BASE-FX, which uses two multi-mode fibers. The two 100BASE-X specifications (100BASE-TX and 100BASE-FX) reused portions of the 100 Mb/s physical signaling specifications originally developed for Fibre Distributed Data Interface (FDDI).