3Com 2500 manual The routing table consists of the following elements

Elements of IP Routing 4-5

Network 1

Network 2

158.101.1.2

Interface 1

IP Address

158.101.1.1

Interfaces

158.101.2.2

1 2

Router

3

158.101.3.2

Interface

158.101.2.1

158.101.3.1

Network 3

Figure 4-4 Router Interfaces in the LANplex System

Routing Table A routing table allows a router or host to determine how to send a packet toward the packet’s ultimate destination. The routing table contains an entry for every destination network, subnet, or host to which the router or host is capable of forwarding packets. A router or host uses the routing table when the destination IP address of the packet it is sending is not on a network or subnet to which it is directly connected. The routing table provides the IP address of a router that can forward the packet toward its destination.

The routing table consists of the following elements:

■Destination IP Address — the destination network, subnet, or host

■Subnet Mask — the subnet mask corresponding to the destination IP address

■Metric — a measure of the “distance” to the destination. In the Routing Information Protocol (RIP), the metric is the number of hops.

■Gateway — the IP address of the next hop router (the IP address of the interface through which the packet travels)

■Interface — the interface number through which a packet must travel to reach that router

Figure 4-5 shows the routing table of the router in Figure 4-4.