HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual page 907

N o t e
Using the Web Browser Interface for Advanced Configuration Tasks
9. You can configure a key, which guards against unauthorized packets
accessing the tunnel. (However, this key is not as secure as those, for
example, established using IPSec.) Check the box to the left of the Tunnel
Key Value field and enter the same key that is configured for the remote
tunnel endpoint.
10. Keepalives prevent the router from keeping an inactive tunnel open. If you
click the Tunnel Keepalive box, the tunnel interface will send periodic
messages to the remote endpoint. If the interface receives a response from
the peer, it keeps the tunnel open.
Specify how often the interface should send such messages in minutes
and seconds in the Period fields.
Because keepalives may be lost, occasionally the peer may not respond
even when it is still active. You should allow the tunnel to try to reach the
peer several times. The value that you enter in the Retries field determines
how many times the interface will send a keepalive without reply before
closing the tunnel.
11. The route to the tunnel destination must not use the tunnel interface as
the forwarding interface. (Such a route would start a recursive loop
because the router would send encapsulated traffic back through the
tunnel to be encapsulated again.) You should instead route traffic to the
destination through a WAN interface.
If the route table does not include a route to the tunnel destination, you
should check the Configure a static route for this tunnel box.
12. Click Apply.
13. If you checked the Configure a static route for this tunnel box, the Route
Table window now displays. See "Configuring RIP" on page 14-113 to learn
how to configure the route. The tunnel destination should be the destina-
tion address, and the interface through which the router eventually con-
nects to the remote end of the tunnel should be the forwarding interface.
If the destination for the tunnel is also the remote tunnel interface's IP address,
you should be careful to configure an exact match for this address in the static
route. If you simply configure a static route to the tunnel network through the
WAN interface, the router will favor the directly connected route to the tunnel
network through the tunnel interface. The tunnel will go down due to recursive
routing.
Setting Up Generic Routing Encapsulation (GRE) Tunnels
14-107