Enterasys Networks 802.1Q - Manual (Page 18)

Configuration Process
2-2 VLAN Operation
2.3 CONFIGURATION PROCESS
Before a VLAN can operate, steps must be performed to configure the switch to establish and
configure a VLAN. Enterasys Networks VLAN aware SmartSwitches default to operate in the
802.1Q VLAN mode. However, further configuration is necessary to establish multiple logical
networks.
2.3.1 Defining a VLAN
A VLAN must exist and have a unique identity before any ports or rules can be assigned to it. The
Administrator defines a VLAN by assigning it a unique identification number (the VLAN ID), a
filter database association, and an optional name. The VLAN ID is the number that will identify
data frames originating from, and intended for, the ports that will belong to this new VLAN.
2.3.2 Classifying Frames to a VLAN
Now that a VLAN has been created, rules are defined to classify all frames in a VLAN. This is
accomplished through management by associating a VLAN ID with each port on the switch.
Optionally, frames can be classified according to a protocol identifier contained within the frame.
The order of frame classification priority is by VLAN Tag, a protocol match, and lastly the PVID.
This combination of the switch port’s identification and the VLAN ID becomes the Port VLAN ID
(PVID).
At the same time, the Administrator configures the trunk ports that need to consider themselves
members of every VLAN. The configuration of trunk ports is very important in multiswitch VLAN
configurations where a frame’s VLAN membership needs to be maintained across several
switches.
2.3.3 Customizing the VLAN Forwarding List
Each port on a VLAN aware switch has a VLAN forwarding list that contains, as a minimum, the
PVID of the VLAN configured. Additionally, the Port VLAN Forwarding List of each port can be
configured to allow any number of VLANs to be added to its list. In the case of GMRP (dynamic
VLANs), the list can have VLANs added and deleted by the switch as directed by the protocol.
NOTE: The actual steps involved in VLAN configuration using Local Management are
presented in
Chapter 3 , VLAN Configuration .This brief section describes the actions
that must be taken in very general terms, and is intended only to aid in the
Administrator’s understanding of VLAN switch operation.