FCM9002 USER MANUAL
76-02-095 Rev.B
Page 30 of 145
When a tag is constructed the ID is taken from the default setting for the port.
The Tag Priority may either be set to the port default setting, or for IP packets
with DSCP priorities the tag priority may be based on the packet DSCP value.
3.2 S-Tag Mode
In the FCM9002 Service Tags are used when an extra tag is to be pushed onto
an already tagged frame. The Service Tag has a configurable Ethertype which
by default is set to 9100. QinQ mode is supported by simply configuring the
service tag ethertype to 8100.
The operation of the FCM9002 in the S-Tag mode is shown below:
In this mode, both tagged and untagged frames are supported on the user ports.
In the example above, port 1 is set to push the S-Tag 101 onto untagged frames
at ingress.
On port 2, frames ingress untagged and have the Stag 102 pushed to give a
packet with an Stag.
