Applying IEEE 802.1ad Rewrite Rules to Dual VLAN Tags
By default, when you apply an IEEE 802.1ad rewrite rule to an output logical interface, the software rewrites the IEEE bits in the outer VLAN tag only.
For MX Series routers and IQ2 PICs, you can rewrite the IEEE 802.1ad bits in both the outer and inner VLAN tags of the tagged Ethernet frames. When you enable the CoS rewrite for both tags, the same IEEE 802.1ad rewrite table is used for the inner and outer VLAN tag.
When you apply IEEE 802.1ad rewrite rules for inner and outer VLAN tags, you cannot rewrite the Canonical Format Identifier (CFI) bit for the inner VLAN tag.
To rewrite both the outer and inner VLAN tags, include the vlan-tag outer-and-inner statement at the [edit class-of-service
interfaces interface-name unit logical-unit-number rewrite-rules ieee-802.1ad (rewrite-name |
default)] hierarchy level:
[edit class-of-service interfaces interface-name unit logical-unit-number rewrite-rules ieee-802.1ad (rewrite-name | default)] vlan-tag outer-and-inner;
To explicitly specify the default behavior, include the vlan-tag outer statement at the [edit class-of-service
interfaces interface-name unit logical-unit-number rewrite-rules ieee-802.1ad (rewrite-name |
default)] hierarchy level:
[edit class-of-service interfaces interface-name unit logical-unit-number rewrite-rules ieee-802.1ad (rewrite-name | default)] vlan-tag outer;
For more information about VLAN tags, see the Junos OS Network Interfaces Library for Routing Devices.
Example: Applying an IEEE 802.1ad Rewrite Rule to Dual VLAN Tags
Apply the dot1p_dei_rw rewrite rule to both inner
and outer VLAN tags of Ethernet-tagged frames exiting the ge-2/0/0.0 interface:
class-of-service {
interfaces {
ge-2/0/0 {
unit 0 {
rewrite-rules {
ieee-802.1ad dot1p_dei_rw vlan-tag outer-and-inner;
}
}
}
}
}