25.1. Special routing

If you are linking two LANs, you will need to set up specific routes to the 'foreign' LANs. This is easily done using the /etc/ppp/ip-up script. The only difficulty arises if your machine handles multiple PPP links.

This is because the /etc/ppp/ip-up is executed for EVERY ppp connection that comes up, so you need to carefully execute the correct routing commands for the particular link that comes up - and not when any other link comes up!