Operation Manual

Switch
SIP Software Release 6-0-0
J613-M0524-00
81
VLAN tagging provides the advantages of more efficient and flexible use of
switch ports and network resources, while maintaining the level of security
given by port-based VLANs. With VLAN tagging, a port can belong to
several VLANs.
A VLAN Identifier (VID) is defined for each VLAN, and this VID is used to
switch traffic through a VLAN aware network so that frames are only
transmitted on ports belonging to the VLAN.
Vlan Tagging - 802.1Q
The 802.1Q standard recommends the use of the 802.1Q VLAN tags for
Ethernet frames traffic prioritization. VLAN tags are 4-byte headers in which
three bits are reserved for priority indication.
VLANs are created with standard Layer 2 Ethernet. A VLAN Identifier
(VID) is associated with each VLAN. VLANs aim to offer the following
benefits:
 VLANs are supported over all IEEE 802 LAN MAC protocols, and over shared
media LANs as well as point-to-point LANs.
 VLANs facilitate easy administration of logical groups of stations that can
communicate as if they were on the same LAN. They also facilitate easier
administration of moves, adds, and changes in members of these groups.
 Traffic between VLANs is restricted. Bridges forward unicast, multicast, and
broadcast traffic only on LAN segments that serve the VLAN to which the traffic
belongs.
 As far as possible, VLANs maintain compatibility with existing bridges and
end stations.
The VLAN field in the Ethernet file is located after both destination and
source as detailed in Figure 23.
For both signaling and media packets, the VLAN priority section is
configurable independently.