Redes

Introduction to 100VG AnyLAN and the
IEEE 802.12 Local Area Network
Standard
100VG-AnyLAN provides a 100-Mbit/s data rate with guaranteed bandwidth and maximum access delay for time-critical applications such as multimedia, using existing building wiring. It uses demand priority protocol. Developed by Hewlett-Packard and now supported by over 30 companies ranging from integrated circuit vendors to systems suppliers, demand priority is well on its way to becoming the IEEE 802.12 standard. by Alan R. Albrecht and Patricia A. Thaler

100VG AnyLAN is a new, high speed addition to HP's
AdvanceStack local area network (LAN) product group. It is an economically effective upgrade path for congested
10 Mbit/s 10Base T Ethernet and 4/16 Mbit/s token ring net works. It provides a 100 Mbit/s data rate with guaranteed bandwidth and bounded access delay for time critical appli cations, using existing building wiring. This provides high performance for traditional data transfer applications. It also provides emerging multimedia applications, such as interac tive video, with the low delays they require. It delivers this performance over the most common networking medium,
4 pair unshielded twisted pair (UTP) telephone wire.
100VG AnyLAN uses the demand priority protocol, which was developed as a joint effort by Hewlett Packard Laborato ries in Bristol, England and the HP Roseville Networks Divi sion in California. Now supported by over 30 companies ranging from integrated circuit vendors to systems suppliers, demand priority is well on its way to becoming the IEEE
802.12 standard.
The 100VG AnyLAN articles in this issue look at the develop ment of the demand priority protocol and the 100VG Any
LAN product set.
Local Area Network Technology
Before the initial development of local area networking in the late 1970s, the telephone system was the only generally available data communications option. Bandwidth (3 kHz on a voice grade line) was clearly