Editing Fast Ethernet (section)

=== 100BaseVG ===
{{Main|100BaseVG}}
Proposed and marketed by [[Hewlett-Packard]], 100BaseVG was an alternative design using category 3 cabling and a token concept instead of CSMA/CD. It was slated for standardization as IEEE 802.12 but it quickly vanished when switched 100BASE-TX became popular. The IEEE standard was later withdrawn.<ref name=vg/>

VG was similar to T4 in that it used more cable pairs combined with a lower carrier frequency to allow it to reach {{nowrap|100 Mbit/s}} on voice-grade cables. It differed in the way those cables were assigned. Whereas T4 would use the two extra pairs in different directions depending on the direction of data exchange, VG instead used two transmission modes. In one,  control, two pairs are used for transmission and reception as in classic Ethernet, while the other two pairs are used for [[Ethernet flow control|flow control]]. In the second mode, transmission, all four are used to transfer data in a single direction. The hubs implemented a [[token passing]] scheme to choose which of the attached nodes were allowed to communicate at any given time, based on signals sent to it from the nodes using control mode. When one node was selected to become active, it would switch to transfer mode, send or receive a packet, and return to control mode.<ref name=vg>{{cite web
|url=https://standards.ieee.org/findstds/standard/802.12-1995.html
|archive-url=https://web.archive.org/web/20140419124102/http://standards.ieee.org/findstds/standard/802.12-1995.html
|url-status=dead
|archive-date=April 19, 2014
|title=ANSI/IEEE 802.12-1995
|publisher=IEEE Standards Association
|access-date=2018-07-31}}</ref>

This concept was intended to solve two problems. The first was that it eliminated the need for collision detection and thereby reduced contention on busy networks. While any particular node may find itself throttled due to heavy traffic, the network as a whole would not end up losing efficiency due to collisions and the resulting rebroadcasts. Under heavy use, the total throughput was increased compared to the other standards. The other was that the hubs could examine the payload types and schedule the nodes based on their bandwidth requirements. For instance, a node sending a video signal may not require much bandwidth but will require it to be predictable in terms of when it is delivered. A VG hub could schedule access on that node to ensure it received the transmission timeslots it needed while opening up the network at all other times to the other nodes. This style of access was known as [[demand priority]].<ref name=vg/>