Network - 100BaseVG
100BaseVG is a version of Ethernet developed by Hewlett-Packard (HP) and AT&T Microelectronics, and is currently under consideration by an IEEE 802.12 committee. It is an extension of 10BaseT Ethernet that will support transmissions of up to 100 megabits per second (Mbps) over voicegrade (Category 3) twisted-pair wire. The VG in the name stands for voice-grade. 100BaseVG Ethernet differs from ordinary (10 Mbps) Ethernet in the following ways: n Uses demand priority (rather than CSMA/CD) as the media access method. n Can use ordinary (Category 3) unshielded twisted-pair (UTP) cable, provided that the cable has at least four wire pairs. Ordinary Ethernet needs only two pairs: one to send and one to receive. n Uses quartet signaling to provide four transmission channels (wire pairs) instead of just one. All wire pairs are used in the same direction at a given time. n Uses the more efficient 5B/6B NRZ signal encoding, as opposed to the Differences from 10 Mbps Ethernet Manchester encoding scheme used by ordinary Ethernet. n For category 3 cable, a VG network can be at most 600 meters from end to end-and only 200 meters if all hubs in the network are connected in the same wiring closet. These values increase by 50%-that is, to 900 and 300 meters, respectively-when category 5 cable is used. For VG using fiber-optic cable, the most widely separated network nodes can be up to 5000 meters, or 5 kilometers, apart. 100BaseVG is designed to provide an easy upgrade path from 10 Mbps Ethernet. An upgrade requires two new components: n A 100BaseVG network interface card (NIC) for each node being upgraded. This NIC replaces the 10 Mbps version in the node. n A 100BaseVG hub to replace the 10 Mbps hub. This type of hub is plugcompatible with a 10 Mbps hub, so that the upgrade requires simply unplugging a node from one hub and plugging it into the 100BaseVG hub. This can all take place in the wiring closet. If you are already using twisted-pair Ethernet cabling, you may not need any new wiring, provided that the cable has four wire pairs. Upgrading to 100BaseVG 100BaseVG/AnyLAN is an extension of 100BaseVG, developed as a joint effort between Hewlett-Packard and IBM. This version also supports the Token Ring architecture, and it can be used with either Ethernet or Token Ring cards (but not both at the same time or in the same network). Because the demand priority access method can be deterministic, the 100BaseVG/AnyLAN architecture could handle isochronous data-that is, data (such as voice or video) that requires a constant transmission rate. The 100VG-AnyLAN Forum is the advocacy group for this Ethernet variant. This consortium includes over 20 members, including Apple, Compaq, and IBM. 100Base VG/AnyLAN is also known simply as VG or AnyLAN. BROADER CATEGORY Ethernet SEE ALSO HSLAN (High-Speed Local-Area Network) COMPARE 100BaseT