Manual

Layer 2 Tunnel Protocol Version 3

Prerequisites for Layer 2 Tunnel Protocol Version 3

Cisco IOS Releases 12.0(29)S and 12.2(25)S

Prerequisites for Layer 2 Tunnel Protocol Version 3

• Before you configure an Xconnect attachment circuit for a customer edge (CE) device (see the

section “Configuring the Xconnect Attachment Circuit”), the CEF feature must be enabled. To

enable CEF on an interface, use the ip cef or ip cef distributed command.

• You must configure a loopback interface on the router for originating and terminating the L2TPv3

traffic. The loopback interface must have an IP address that is reachable from the remote provider

edge (PE) device at the other end of an L2TPv3 control channel.

• To enable Simple Network Management Protocol (SNMP) notifications of L2TP session up and

down events, enter the snmp-server enable traps l2tun session command before configuring

L2TPv3.

Restrictions for Layer 2 Tunnel Protocol Version 3

The following subsections contain information on restrictions:

• Supported Port Adapters for the Cisco 7200 and 7500 Series Routers

• General L2TPv3 Restrictions

• Cisco 7200-Specific Restrictions

• Cisco 7500-Specific Restrictions

• Cisco 10720-Specific Restrictions

• Cisco 12000 Series-Specific Restrictions

• Frame Relay-Specific Restrictions

• VLAN-Specific Restrictions

• ATM VP Mode Single Cell Relay over L2TPv3 Restrictions

• ATM AAL5 SDU over L2TPv3 and Single Cell Relay VC Mode over L2TPv3 Restrictions

• ATM Port Mode Cell Relay over L2TPv3 Restrictions

• ATM Cell Packing over L2TPv3 Restrictions

• Protocol Demultiplexing for L2TPv3 Restrictions

• L2TPv3 Control Message Hashing Restrictions

Supported Port Adapters for the Cisco 7200 and 7500 Series Routers

L2TPv3 is supported on the following port adapters in the Cisco 7200 and 7500 series routers:

• Single-port Fast Ethernet 100BASE-TX

• Single-port Fast Ethernet 100BASE-FX

• Dual-port Fast Ethernet 100BASE-TX

• Dual-port Fast Ethernet 100BASE-FX

• Gigabit Ethernet port adapter

• 12-port Ethernet/2-port FE adapter

• 4-port synchronous serial port adapter