Virtual LAN
<networking> 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 segments 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 addresses used by IP,
IPX, and other network layer protocols to normally identify physical networks.
Administrators assign one subnet address to a number of switch ports (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)
Nearby terms:
virtual disk « Virtual Home Environment « virtual
host «
Virtual LAN » Virtual Loadable Module » Virtual
Local Area Network » Virtual Machine
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