资料来源 : Free On-Line Dictionary of Computing
Virtual LAN
Software defined groups of {host} on a {local
area network} (LAN) that communicate as if they were on the
same wire, even though they are physically on different {LAN
segment}s throughout a site. To define a virtual LAN, the
{network administrator} uses a virtual LAN management utility
to establish membersip rules that determine which hostss are
in a specific virtual LAN. Many models may exist but two seem
to dominate:
(1) Vitual Segment (or Port-Group) Virtual LAN. These are
switched at the {data link layer} ({OSI} layer 2). Virtual
segments turn an arbitrary number of physical segments into a
single virtual segment that funtions as a self-contained
traffic domain.
(2) Virtual Subnet Virtual LAN: These are switched at the
{Network Layer} ({OSI} layer 3). Subnet-oriented virtual LANs
are based on {subnet address}es used by {IP}, {IPX}, and other
{network layer} {protocol}s to normally identify physical
networks. Administrators assign one subnet address to a
number of switch {port}s (which may be on different switches
and over a backbone). Once identified as a virtual subnet,
the selected LANs function as a {bridge group} - traffic is
bridged at Layer 2 within the virtual subnet and routed at
Layer 3 between virtual subnets.
["The many faces of virtual LANs", Steven King, Network
World, 1994/5?].
(1995-04-03)