Cisco 10000-2P2-2DC Software Guide - Page 188

L2TP Network Server Chapter 5 Configuring the Layer 2 Tunnel Protocol Access Concentrator and Network Server Command Router# show vpdn session Router# show vpdn tunnel Purpose Verifies active L2TP sessions in a VPDN environment. Verifies active L2TP tunnel information in a VPDN environment. L2TP Network Server The Cisco 10000 series router can function as an L2TP network server (LNS). By using the managed LNS features introduced in Cisco IOS Release 12.2(4)BZ1, the Cisco 10000 series router terminates L2TP sessions from the LAC and places each session into the appropriate VRF instance based on the L2TP tunnel the session arrived in. The Cisco 10000 router then routes each session within the VRF to the destination network. The LNS is a peer to the LAC and sits on one side of an L2TP tunnel. The LNS routes packets to and from the LAC and a destination network. Acting as the LNS, you can configure the Cisco 10000 series router to terminate the PPP sessions and route the client IP packets onto the ISP or corporate network toward their final destination (see Figure 1-1 on page 1-3). You can also configure the LNS to place the sessions in VRFs before routing the packets, as shown in Figure 5-3. Figure 5-3 CPE Managed LNS Topology Access network (ATM or Ethernet) LAC IP transport network PPP in L2TP sessions Wholesale LNS provider Cisco 10000 ESR VRF 1 Retail LNS provider Provider 1 VRF 2 Provider 2 VRF n L2TP sessions are terminated and placed in a VRF Provider n 69867 All of a service provider's subscribers do not share the same L2TP trunk interface. Typically, the Cisco 10000 router uses virtual local area networks (VLANs) to separate a service provider's subscriber traffic. The Cisco 10000 series router can also use permanent virtual circuits (PVCs) or a separate physical interface for each provider to separate traffic. A virtual template interface configures the user sessions in a tunnel and applies to all users in the same VRF. The LNS feature is described in the following topics: • Virtual Template Interface, page 5-23 • Virtual Routing and Forwarding Instance, page 5-23 • Per VRF AAA, page 5-23 • Private Servers, page 5-24 • RADIUS Attribute Screening, page 5-24 • Packet Fragmentation, page 5-24 5-22 Cisco 10000 Series Router Software Configuration Guide OL-2226-23