4-4 CHAPTER 4: ROUTING WITH IP
Figure 4-3 How a Subnet Mask is Applied to the IP Address
An example of an IP address that includes the network, subnet, and
host parts is 158.101.230.52 with a subnet mask of 255.255.255.0. This
address is divided as follows:
■158.101 is the network part
■230 is the subnet part
■52 is the host part
Router Interfaces A router interface is the connection between the router and a subnet.
In traditional routing models, the interface would be the same as the
port, since only one interface could exist per port. In the LANplex
system’s IP routing, more than one port can be connected to the same
subnet. Therefore, the router interface is the relationship between the
ports and the subnets in your IP network.
Each router interface has an IP address and a subnet mask. This address
defines both the number of the network the router interface is attached
to and its host number on that network. A router interface’s IP address
serves two functions:
■The IP address is used when sending IP packets to or from the router
itself.
■The IP address defines the network and subnet numbers of the
segment connected to that interface. See Figure 4-4.
IP Address Network Subnet & Host
Subnet Mask
networ Host
subn
Subnet
Network
Apply the subnet mask
Result = subnet and host boundary
Take the IP address
101111111111 00000001111111111111