Avaya Cajun P580, User Manual, Page: 162 / 770

6-4 User Guide for the Avaya P580 and P882 Multiservice Switches, v6.0
Chapter 6
The Ethernet version of the Tag Header consists of 4 bytes, two bytes for
Tag Protocol ID and two bytes for Tag Control. The Tag Protocol ID bytes
contain an Ethernet Type value of 81-00 which identifies the frame as a
tagged frame. The Tag Control specifies tag formats that are used to embed
explicit VLAN membership information within each frame in a 12-bit VID
that provides 4094 possible VLAN ID’s. IEEE 802.1Q defines the bridging
rules for VLANs (ingress and egress rules which are described in detail in
“
VLAN Operation ” later in this chapter).
VLAN Operation
VLAN operation is based on three sets of rules:
■
Ingress Rules
■
Forwarding Rules
■
Egress Rules
Ingress Rules
Every frame received by the switch is classified to one VLAN. There are
two ways in which frames are classified to VLANs:
■
Untagged frames are classified to the VLAN associated with the
port on which the frame is received (Port-based VLANs).
■
Tagged frames are classified to the VLAN identified by the VLAN
tag in the tag header of the frame.
* Note: The switch supports a feature called Automatic
VLAN Creation for tagged frames. For more
information, see “
VLAN Considerations ” for more
information.
Forwarding Rules
These rules determine the set of ports on the switch through which members
of the VLAN can be reached. This is called binding a port to a VLAN. A
port may be bound to a VLAN using the web agent in the following three
ways:
1. Setting the Port VLAN attribute in the Switch Port Configuration web
page.This identifies the VLAN to which all untagged frames received
on the port are forwarded. Static Binding, the port is bound to the
VLAN selected in the Port VLAN parameter.
* Note: A port has one Port VLAN. Changing this to a new
VLAN removes the port from the old VLAN.