Allied Telesis C613-02013-00 manual

Layer 2 Switching 41

VLANs to be used with VLAN tags are created and destroyed in the same way as VLANs with only untagged ports, by using the commands:

CREATE VLAN=vlanname VID=2..4094

DESTROY VLAN={vlanname2..4094ALL}

A VLAN may have VLAN-aware devices connected to some ports that require VLAN tagging, and legacy devices connected to other ports that cannot accept VLAN tags. Whether VLAN tagged or untagged frames are transmitted on a port for a particular VLAN is determined when the port is added to that VLAN. Ports are added to and deleted from VLANs using the commands:

ADD VLAN={vlanname1..4094} PORT={port-listALL}

[FRAME=TAGGEDUNTAGGED]

DELETE VLAN={vlanname1..4094} PORT={port-listALL}

The FRAME parameter specifies whether VLAN tag headers are included in frames transmitted on the specified ports. If TAGGED is specified, a VLAN tag is added to frames prior to transmission. The port is then called a tagged port for this VLAN. If UNTAGGED is specified, the frame is transmitted without a VLAN tag. The port is then called an untagged port for this VLAN. A port can be untagged for one and only one of the VLANs to which it belongs, or for none of the VLANs to which it belongs. A port can have the FRAME parameter set to TAGGED for zero or more VLANs to which it belongs. It is not possible to add an untagged port to a VLAN if the port is already present in any other port-based VLAN except the default VLAN. If the port is an untagged member of the default VLAN, adding it untagged to another VLAN deletes it from the default VLAN. The default setting is UNTAGGED.

A port can be tagged (receive and send VLAN tagged frames) for some VLANs, and untagged for zero or one VLAN. A VLAN can have both tagged and untagged ports. But a particular port cannot transmit both tagged and untagged frames for the same VLAN (that is, it cannot be added to the same VLAN as both a tagged and an untagged port).

Figure 11 shows a network that must be configured with VLAN tagging, since the server on port 2 on Switch A belongs to both the admin and marketing VLANs. Using VLAN tags, port 26 on Switch A and port 25 on Switch B belong to both the marketing VLAN and the training VLAN, so devices on both VLANs can use this uplink.

Note that ports tagged for some VLANs and left in the default VLAN as untagged ports will transmit broadcast traffic for the default VLAN. If this is not required, the unnecessary traffic in the switch can be reduced by deleting those ports from the default VLAN.

Rapier Switch Software Release 2.2.1 C613-02013-00 Rev A