Assigning A Vlan Tag - Nokia ESB26 User Manual

17. Virtual LANs (VLANs)
Figure 17-1 VLAN Spanning Two Switches
The switch-to-switch connections are typically called trunks. Using tags, multiple VLANs can
span multiple switches using one or more trunks. In a port-based VLAN, each VLAN requires
its own pair of trunk ports. Using tags, multiple VLANs can span two switches with a single
trunk. Another benefit of tagged VLANs is the ability to use multiple VLANs through one
port. This is particularly useful if you have a device (such as a server), that must belong to
multiple VLANs. The device must have a NIC that supports 802.1Q tagging.

Assigning a VLAN Tag

Each VLAN may be assigned an 802.1Q VLAN tag. As ports are added to a VLAN with an
802.1Q tag defined, you need to decide whether each port will have tagging assigned for that
VLAN.
The default mode of the switch is to have all ports assigned to the default VLAN that has the
name default and an 802.1Q VLAN tag (VLAN ID) of 1.
Not all ports in the VLAN must be tagged. As traffic from a port is forwarded out of the
switch, the switch determines (in real time) if each destination port should use tagged or
untagged packet formats for that VLAN. The switch adds and strips tags, as required, by the
port configuration for that VLAN. Packets arriving tagged with a VLAN ID that is not
configured on a port will be discarded.
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