Hi,
Its meant to automatically add routes to your VPN devices routing table which tells the location of the remote VPN networks to the device. Additionally, if the device is also configured with dynamic routing protocol it can then redistribute that route for the VPN remote network to other routing devices on the network.
It is used both in Cisco Routers and Firewalls.
Here is one Cisco document about it
http://www.cisco.com/en/US/docs/ios-xml/ios/sec_conn_vpnav/configuration/15-2mt/sec-rev-rte-inject.html#GUID-A3101934-4491-450A-A6B2-23F0685F90E3
Here is a Cisco document describing a L2L VPN and RRI with ASAs and Cisco Routers
http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_configuration_example09186a00804acfea.shtml
- Jouni
