User`s guide

XSR User’s Guide 247
Chapter 11 VPN Applications
Configuring the Virtual Private Network
OSPF Commands
The same OSPF commands available for configuration in
FastEthernet/GigabitEthernet or Serial Interface mode are available in
Interface VPN mode. They are:

ip ospf authentication-key
 ip ospf cost
 ip ospf dead-interval
 ip ospf hello-interval
 ip ospf message-digest-key
 ip ospf priority
 ip ospf retransmit-interval
 ip ospf transmit-delay
Additionally, show ip ospf interface vpn is available in EXEC mode.
Configuring OSPF Over Site-to-Site in Client Mode
When the XSR is configured in a Client Mode, Site-to-Site application, it
creates an asymmetric connection with one side acting as the server and other
the client. The client initiates the tunnel upon node startup, requesting an IP
address from the server.
From the client’s point of view, the tunnel is a point-to-point connection; the
VPN (virtual) interface associated with the tunnel must be a point-to-point
connection. The server terminates connections from more than one client.
Each connected client is issued an IP address.
From the server’s point of view, connected tunnels form point-to-multipoint
links. Additionally, the server does not see a segment behind the client,
because in Client Mode NAT is employed inside the tunnel and all traffic
originated from trusted segment is NAT-ed to use an IP address assigned by
the server, as shown in Figure 45.