UTStarcom iSpirit 3026 Manual page 52

untagged of a VLAN, if it's already an untagged member of another VLAN, it will be removed
from it, i.e., the last configuration takes effect.
A port can be an tagged member port of multiple VLANs. In this case, it's also called VLAN
Relay Port. A port can belong to a VLAN as untagged and belong to other multiple VLANs as
tagged simultaneously.
4.VLAN relay
If a port is a tagged member port of two or more VLANs, it's also called as a relay port of VLAN.
Two switches can connect through a relay port, thus they can have two or more common VLANs
between them.
A relay example is shown in Figure3-2: Two switches connect through a replay port, which
belongs to VLAN 2 and VLAN 3. Each switch has two VLANs, VLAN 2 and VLAN 3, and each
VLAN has a user. Thus user 1 can communicate with user 3, user 2 with user 4, but user 1 can't
with user 2, neither for user 3 with user 4.
5.Data transmission in a VLAN
When a switch receives a data packet from a port, it will follow these steps for layer2
transmission:
Determine which VLAN this packet belongs to;
Check whether it's broadcast, multicast or unicast;
Determines output ports based on its type, there can be 0 ports, one or more ports. If
0,discard the packet;
Tag or untag the packet based on the member port type;
Send the packet.
(1) To determine which VLAN this packet belongs to:
Figure3-2. Relay Port Vlan