User`s guide

248 XSR User’s Guide

VPN Applications Chapter 11

Configuring the Virtual Private Network

Figure 45 Site-to-Site Client Mode Topology

In this scenario, you may use OSPF to advertise the corporate network’s

reachability via an established tunnel. OSPF can also monitor the health of a

VPN link.

Advertising these networks becomes extremely valuable when the client

connects to more than one server. In that case, the client will maintain two

VPN interfaces, expressed on the XSR as VPN 1 and VPN 2. Routes learned

by OSPF will instruct the IP routing engine which IP addresses are reachable

via the VPN 1 interface and which are reachable via the VPN 2 interface.

Based on the example shown in Figure 45, the following OSPF settings should

be applied to the interfaces.

Corporate network

INTERNET

VPN 1

Server

VPN tunnel

Client

To another client

Private segment invisible from server

Point-to-multipoint interface.

Terminates, not initiates

Point-to-point interface.

This endpoint’s IP address

is assigned by the server.

The other tunnel endpoint’s

IP address is configured on

the server’s VPN interface.

VPN 1

NAT

tunnels