5.1. In This Chapter

This chapter provides information about L2TPv3 tunnels.

Topics in this chapter include:

5.2. L2TPv3 Overview

Layer 2 Tunneling Protocol version 3 (L2TPv3) is a mechanism for the tunneling of Ethernet traffic over an IP network. For this application, the MS-ISA/MS-ISA2 functions as a resource module for the system, performing the L2TPv3 encapsulation and decapsulation functions.

Figure 41 shows L2TPv3 support for the IP transport model. Table 28 describes the tunnel processing steps in the figure.

Figure 41:  L2TPv3 Support for IP Transport 

5.3. Control Plane

The configuration of the L2TPv3 control plane is similar to that of L2TPv2. A number of the same commands are used for both, but there are new commands specific to L2TPv3. The L2TPv3-specific commands are located in a separate L2TPv3 context in both the general configuration area as well as within the group configuration context.

L2TPv3 control plane parameters can be configured at either the global level within the config>router>l2tp context, which may include some L2TPv3-specific parameters. This should be used for parameters that are the same for the majority of L2TPv3 tunnels. The same parameters can be configured on a per-tunnel group basis. The tunnel group can be configured within either the base router context or a VPRN service context.

Below is a simple example for an L2TPv3 tunnel group configured within the base routing context.

5.4. Public SAP

The public SAP is the access interface to the L2TPv3 tunnel over which encapsulated traffic is sent to or received from the far end. The IP address bound to this SAP is on the same subnet as the local L2TPv3 tunnel endpoint.

The public SAP must be configured in the same routing context as the L2TPv3 tunnel group configuration. As shown in Figure 41, the public SAP can be associated with an IES or VPRN service to connect to the outside or public access network.

Below is a simple example for an L2TPv3 public SAP configured within the base routing context.

5.5. Private SAP

The private SAP is the access interface to the L2TPv3 over which unencapsulated traffic is sent to or received from the far end. The public SAP must be configured within an Ethernet service, such as an Epipe, VPLS, or I-VPLS service.

The private SAP configuration includes the configuration of the following L2TPv3 session parameters:

Below is a simple example for an L2TPv3 private SAP configured within the base routing context.