The router supports the following tunnel protocols:

• Link Layer Discovery Protocol (LLDP)

• Link Aggregation Control Protocol (LACP)

• Operation, Administration, Management (OAM)

• Ethernet Local Management Interface (ELMI)

• Cisco Discovery Protocol (CDP)

Some of the L2 transport interfaces are:

• VPWS L2 transport main

• VPWS L2 subinterface

• L2 transport main bridge port

• L2 subinterface bridge port

• VPWS L2 bundle main port

• VPWS L2 bundle subinterface

• L2 bundle main bridge port

On a subinterface, when control packets such as LLDP and LACP are tunneled, the system tunnels the same control packets to the main interface.

The LACP packet for VPLS (also known as ELAN service) either gets peered or dropped.

The router tunnels Layer 2 packets between PEs.

The following figure depicts Layer 2 protocol tunneling.

L2CP packets are tunneled from NNI to NNI (depicted in red pipe). The Layer 2 traffic is sent through the Cisco NCS 5500 Series Routers, and these routers switch the traffic from end to end.

You do not need to configure L2CP tunneling explicitly. L2CP packets are tunneled over Layer 2 tunnel by default.

The following table lists the options that are supported on the router and displays the supported defaults and configuration options for the router.

Note	L2CP protocols over BVI is not supported. L2CP protocol on Cisco NCS 5700 Series Line Cards is supported from Release 7.6.1.