The present invention has both a master router and a slave router on a route. The slave router comprises an address setting section 9 for setting a physical address and a network address of the master router as well as its own physical address, and a control section 12 for conducting routing operation...http://www.google.se/patents/US5815668?utm_source=gb-gplus-sharePatent US5815668 - Slave inter-lan connection device, an inter-lan connection system and a hot standby method of said inter-lan connection system 
