3Com 510, 520, 530 manual IP Routing

A routing environment allows stations to communicate indirectly. Following the example in Figure A-3, let us assume that a station on LAN 1 wants to communicate with a network server on LAN 2. The station on LAN 1, constructs a Layer 2 datalink header (see Figure A-5), with the source station’s hardware address, and also the destination hardware address of the local router. To direct the packet to its final network destination, the source station must complete the Layer 3 network header with the destination network address of LAN 2.

Once the packet is received by the Router A, attached to LAN 1, it strips off the network header (refer to Figure A-5) and examines the Layer 3 datalink header information. It then reviews its routing tables in order to establish where to forward the data packet. It is possible that the LAN 1 router has multiple outgoing ports that would allow different transmission routes to the destination network. In our example using Figure A-3, a packet could go via Router D to get to Router B, or it could go more directly across a single direct link between Router A and Router B.

Routing IP and IPX A-9

Figure A-5 Data Packet Containing Hardware And Software Addresses

IP Routing

The local router contains, within its routing table, information which will allow it to determine the best data transmission route. The type of information the router uses to make these assessments is protocol dependent, and some communications protocols may employ a range of routing algorithms, and accompanying routing protocols. In the case of the TCP/IP protocol suite, the OfficeConnect Remote utilizes the Routing Information Protocol (RIP). RIP is also known as a distance vector protocol.