A-10 APPENDIX A: BRIDGING AND ROUTINGOnce the packet is received by the Router A, attached to LAN 1, it stripsoff the network header (refer to Figure A-5) and examines the Layer 3datalink header information. It then reviews its routing tables in orderto establish where to forward the data packet. It is possible that theLAN 1 router has multiple outgoing ports that would allow differenttransmission routes to the destination network. In our example usingFigure A-3, a packet could go via Router D to get to Router B, or itcould go more directly across a single direct link between Router A andRouter B.Figure A-5 Data Packet Containing Hardware And Software AddressesIP RoutingThe local router contains, within its routing table, information whichwill allow it to determine the best data transmission route. The type ofinformation the router uses to make these assessments is protocoldependent, and some communications protocols may employ a rangeof routing algorithms, and accompanying routing protocols. In the caseof the TCP/IP protocol suite, the AccessBuilder 500 utilizes the RoutingInformation Protocol (RIP). RIP is also known as a distance vectorprotocol.
