1. Basic Egress VLAN Tagging
Whether a VLAN tag by default is added or not is a function of the VLAN configuration explained in the VLAN section on the Bridge Configuration page.
By using Basic Tagging it is possible to modify the value of the PCP and DEI in the VLAN tag.
By using ES0 Tagging it is possible to pop, modify or push a VLAN tag.
1.1. Basic Tagging
When a VLAN tag is added at egress the PCP and DEI values can be assigned in different ways:
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Use the PCP and DEI values classified at ingress (default setting)
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Use default port PCP and DEI values
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Map Priority and DPL to PCP and DEI values via a configurable table
To use the PCP and DEI values classified at ingress on eth0 (this is the default setting):
# qos e_mode eth0 --classified 1
To assign default port PCP value to 5 and default port DEI value to 1 on eth0:
# qos e_def eth0 --pcp 5 --dei 1
To use the default port PCP and DEI values assigned above on eth0:
# qos e_mode eth0 --default 1
To configure the [Priority, DPL] to [PCP, DEI] mapping table on eth0:
# qos e_tag_map eth0 --pcp 0123456701234567 --dei 0000000011111111
The command above sets the mapping table to its default values.
The pcp and dei parameters consist of 16 values where the leftmost value corresponds to index 0 and the rightmost value corresponds to index 15.
The index can be calculated as (priority + (DPL * 8)).
If priority is 6 and DPL is 1 then index is 14 and PCP will be assigned to 6 and DEI to 1.
To use the mapping table defined above on eth0:
# qos e_mode eth0 --mapped 1
Besides this tagging the rewriter can update tags based on rules in the ES0 VCAP. See Rewriter VLAN Tagging.