The 100VG-AnyLAN/9000 product can communicate at either 10
Mbps using IEEE 802.3/Ethernet or 100 Mbps using IEEE 802.12/Demand
Priority.
802.12 LANs are star-based networks. Demand priority is hub
arbitrated, where the end nodes request permission to transmit and
the hub determines who may do so, depending on the priority of the
traffic. This deterministic access method maximizes network efficiency
by eliminating network collisions.
Each request is labelled with either a normal-priority level
for normal data packets, or a high priority-level for packets supporting
time-critical multimedia applications. High priority requests are
granted access to the network before normal-priority requests, guaranteeing
appropriate service for time-sensitive applications. To guarantee
access for normal-priority requests during an excess of high-priority
traffic, a timer in the hub will automatically raise the normal
priority level to a high-priority level after 200- 300 ms.
100VG-AnyLAN technology supports network design rules and
topologies of Ethernet 10Base-T. Central to the 100VG-AnyLAN network
is the 100VG-AnyLAN hub. All 100 Mbps 100VG-AnyLAN devices connect
to the 100VG hub. All 10 Mbps devices connect to the 10Base-T hub.
100VG-AnyLAN has message-frame compatibility with IEEE 802.3
and Ethernet networks. This frame compatibility allows you to connect
the 100VG-AnyLAN network to existing IEEE 802.3 and Ethernet networks
with a simple-speed matching bridge.
For more detailed information on operation of an HP 100VG
network, refer to Planning and Designing High Speed Networks
Using 100VG-AnyLAN published by Prentice Hall.
At first release 100VG-AnyLAN does not support Token Ring
frames or high-priority requests.
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