User guide

Packet Over SONET Module Installation and User Guide 3-41
Configuring VLAN-Related Attributes
Configuring VLAN Tag Nesting Attributes
The config dot1q tagnesting command provides support for 802.1Q tags by
allowing a tag push or pop attribute to be associated with a VLAN ID. The push
attribute indicates that a new tag is to be added to the frame, while the pop attribute
indicates that the top-level tag is to be removed from the frame. The command also
gives you the option to preserve the 802.1p priority of the frame or set it to a configured
value when a new tag is added (pushed) to the frame. VLAN ID (VID) mapping occurs
before a new tag is pushed, and after a nested tag is popped.
To configure the VLAN tag nesting attributes for a PoS port, use the following
command:
config dot1q tagnesting {<vlanid> | <vlanid_range>} [off | pop |
push <new_vlanid> {priority <priority>}] ports <portlist> {egress | ingress}
The vlanid parameter is an integer in the range from 1 to 4095. The vlanid_range
parameter is specified in the form
start_vlanid-end_vlanid, where the start and end
values are both integers in the range from 1 to 4095 and must be separated by a
hyphen.
The
push keyword indicates that a new tag is to be added to frames containing the VID
specified in
vlanid or to one of the VIDs in the range specified in vlanid_range. The
new tag added to frames contains the value specified in
new_vlanid.
The
pop keyword indicates that the top-level tag is to be removed from frames when
that tag contains either the VID specified in
vlanid or any one of the VIDs in the range
specified in
vlanid_range.
If you do not specify a VID or a range of VIDs, the command settings are applied to all
VIDs.
Tag operations can be performed in either the egress direction (to the SONET link) or
the ingress direction (from the SONET link). If you do not specify a direction, the
default behavior is that tag operations are performed in the egress direction. If you do
not use either the
egress or ingress keyword and tag pushing is configured, a
corresponding tag pop operation is automatically configured for the ingress direction. If
you do not use either the egress or ingress keyword and tag nesting is disabled using
the
off keyword, tag nesting is disabled in both directions.
The optional
priority keyword provides a way to overwrite the 802.1p priority with a
user-configured value when a new tag is pushed. Using the
priority keyword in the
command indicates that the 802.1p priority field is to be set to the value specified in