3Com CoreBuilder 2500 User Manual - page 56
4-4
C
HAPTER
4: R
OUTING
WITH
IP T
ECHNOLOGY
An example of an IP address that includes network, subnetwork, 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 subnetwork part
■
52
is the host part
As shown in this example, the 32 bits of an IP address and subnet mask
are usually written using an integer shorthand. This notation translates
four consecutive 8-bit groups into four integers ranging from 0 through
255. The subnet mask in the example is written as 255.255.255.0.
Router Interfaces
A router interface connects the router to a subnetwork. In traditional
routing models, the interface is the same as the port because only one
interface can exist per port. In the IP routing model for the
CoreBuilder
™
2500 system, more than one port can connect to the same
subnetwork.
Each router interface has an IP address and a subnet mask. This router
interface address defines both the number of the network to which the
router interface is attached and its host number on that network. A
router interface IP address serves two functions:
■
For sending IP packets to or from the router.
■
For defining the network and subnetwork numbers of the segment
connected to that interface. See Figure 4-4.
Figure 4-4
Router Interfaces in the CoreBuilder 2500 System
158.101.1.1
158.101.1.2
158.101.2.2
158.101.2.1
Router
158.101.3.1
158.101.3.2
Network 1
Network 2
Network 3
1
2
3
Interface 1
Interface 2
Interface 3