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Enabling VLAN Tagging

 

You can configure the router to receive and forward single-tag frames, dual-tag frames, or a mixture of single-tag and dual-tag frames.

Note

If you configure VLAN tagging on Gigabit Ethernet IQ, IQ2, and IQ2-E interfaces on M320, M120, and T Series routers, Junos OS creates an internal logical interface that reserves 50 Kbps of bandwidth from Gigabit Ethernet IQ interfaces and 2 Mbps of bandwidth from Gigabit Ethernet IQ2 and IQ2-E interfaces. As a result, the effective available bandwidth for these interface types is now 999.5 Mbps and 998 Mbps, respectively.

  1. To configure the router to receive and forward single-tag frames with 802.1Q VLAN tags, include the vlan-tagging statement at the [edit interfaces interface-name] hierarchy level:
  2. To configure the router to receive and forward dual-tag frames with 802.1Q VLAN tags, include the stacked-vlan-tagging statement at the [edit interfaces interface-name] hierarchy level:
  3. Mixed tagging is supported for Gigabit Ethernet interfaces on Gigabit Ethernet IQ2 and IQ2-E, and IQ or IQE PICs on M Series and T Series routers, for all router Gigabit and 10-Gigabit Ethernet interfaces on MX Series routers, and for aggregated Ethernet interfaces with member links in IQ2 and IQ2-E PICs or in MX Series DPCs. Mixed tagging enables to configure two logical interfaces on the same Ethernet port, one with single-tag framing and one with dual-tag framing.Note

    Mixed tagging is not supported on Fast Ethernet interfaces.

    To configure mixed tagging:

    1. Configure the flexible-vlan-tagging statement at the [edit interfaces ge-fpc/pic/port] hierarchy level.
    2. Configure the vlan-tags statement with inner and outer options or the vlan-id statement at the [edit interfaces ge-fpc/pic/port unit logical-unit-number] hierarchy level:
    Note

    If you configure the physical interface MTU for mixed tagging, then you must increase the MTU to 4 bytes more than the MTU value you would configure for a standard VLAN-tagged interface.

    For example, if the MTU value is configured to be 1018 on a VLAN-tagged interface, then the MTU value on a flexible VLAN tagged interface must be 1022—4 bytes more. The additional 4 bytes accommodates the future addition of a stacked VLAN tag configuration on the same physical interface.

    If the same physical interface MTU value is configured on both the VLAN and flexible VLAN-tag routers, the L2 circuit configuration does not come up and a MTU mismatch is logged. However, normal traffic flow is unaffected.

    For encapsulation type flexible-ethernet-services, all VLAN IDs are valid.

  4. For 1-, 4-, and 8-port Gigabit Ethernet IQ2 and IQ2-E PICs, for 1-port 10-Gigabit Ethernet IQ2 and IQ2-E PICs, for all MX Series router Gigabit Ethernet, Tri-Rate Ethernet copper, and 10-Gigabit Ethernet interfaces configured for 802.1Q flexible VLAN tagging, and for aggregated Ethernet interfaces on IQ2 and IQ2-E PICs or MX Series DPCs, you can configure mixed tagging support for untagged packets on a port. Untagged packets are accepted on the same mixed VLAN-tagged port. To accept untagged packets, include the native-vlan-id statement and the flexible-vlan-tagging statement at the [edit interfaces interface-name] hierarchy level:

    The logical interface on which untagged packets are to be received must be configured with the same native VLAN ID as that configured on the physical interface. To configure the logical interface, include the vlan-id statement (matching the native-vlan-id statement on the physical interface) at the [edit interfaces interface-name unit logical-unit-number] hierarchy level.