Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

Guide That Contains This Content
[+] Expand All
[-] Collapse All

    Layer 2 Protocol Tunneling on ACX Series Overview

    Layer 2 protocol tunneling (L2PT) allows Layer 2 protocol data units (PDUs) to be tunneled through a network.

    L2PT on ACX Series routers supports tunneling the following Layer 2 PDUs:

    • Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), and Multiple Spanning Tree Protocol (MSTP)
    • Cisco Discovery Protocol (CDP)
    • VLAN Trunk Protocol (VTP)
    • IEEE 802.1X authentication
    • IEEE 802.3ah Operation, Administration, and Maintenance (OAM) link fault management (LFM)
    • Ethernet local management interface (E-LMI)
    • Link Aggregation Control Protocol (LACP)
    • Link Layer Discovery Protocol (LLDP)
    • Multiple MAC Registration Protocol (MMRP)
    • Multiple VLAN Registration Protocol (MVRP)

    When a Layer 2 control PDU is received on a service provider edge port configured for L2PT, the multicast destination MAC address is rewritten with the predefined multicast tunnel MAC address of 01:00:0c:cd:cd:d0. The packet is transported across the provider network transparently to the other end of the tunnel and the original multicast destination MAC address is restored when the packet is transmitted.

    If a packet is received on a tunnel interface that already has a destination multicast MAC address of 01:00:0c:cd:cd:d0, the port enters an error state and is shut down. To clear the error condition, the administrator must enter the clear error mac-rewrite interface interface-name command.

    L2PT can be configured on the customer edge aggregated Ethernet interface using mac-rewrite CLI command at the [edit protocols layer2-control] hierarchy level.

    The destination MAC address used by different protocols is listed in Table 1:

    Table 1: Protocol Destination MAC Addresses


    Ethernet Encapsulation

    MAC Address


    Ether (0x888E)



    Ether (0x8809)


    Cisco Discovery Protocol (CDP)

    LLC (0xAAAA03)


    Ethernet local management interface (E-LMI)

    Ether (0x88EE)


    MVRP VLAN Registration Protocol (MVRP)

    Ether (0x88F6)


    Link Aggregation Control Protocol (LACP)

    Ether (0x8809)


    Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), and Multiple Spanning Tree Protocol (MSTP)

    LLC (0x424203)


    Link Layer Discovery Protocol (LLDP)

    Ether (0x88CC)


    Multiple MAC Registration Protocol (MMRP)

    Ether (0x88F5)


    VLAN Trunking Protocol (VTP)

    LLC (0xAAAA03)


    Modified: 2015-12-10