User`s guide

Chapter 1: Virtual Local Area Networks
1-4 DIGITAL MultiSwitch 700 Port Based VLAN User’s Guide
group of users assigned to a single VLAN can communicate with one
another freely, but cannot communicate with users on other VLANs
without the services of a Network Layer (OSI Layer 3) routing device to
make the connection between the VLANs. In the “open” mode, this
restriction does not apply.
In order to set up a VLAN, all the network switch devices that are
assigned to the VLAN must support the prestandard IEEE 802.1Q
specification for port based VLANs. Before you attempt to implement a
VLAN strategy, ensure that the switches under consideration support the
IEEE 802.1Q specification.
1.4 VLAN TERMS
To fully understand the operation and configuration of port based
VLANs, it is essential to understand the meanings of several key terms.
VLAN ID
A unique number (between 1 and 4095) that identifies a particular VLAN.
VLAN Name
A 32-character alphanumeric name associated with a VLAN ID. The
VLAN Name is intended to make user-defined VLANs easier to identify
and remember.
Tag Header (VLAN Tag)
A field within a frame that identifies the VLAN the frame has been
classified into. The Tag Header is inserted into the frame directly after the
Source MAC address field. Twelve bits of the Tag Header are the VLAN
ID. The remaining bits are other control information.
Tagged Frame
A data frame that contains a Tag Header. The Tag Header can be added to
the data frame by a VLAN aware switch to any frame received from a port
that is a member of a VLAN.
Untagged Frame
A data frame that does not have a Tag Header inserted into it.