GE RX3i - Page 261

Chapter 13. Network Administration
248 PACSystems* RX7i & RX3i TCP/IP Ethernet Communications User Manual GFK-2224Q
Example: Two Networks Combined into a Supernet
Supernetting is a technique used to combine two smaller networks into a larger network by extending the host
portion of the subnet mask and reducing the network portion. Supernetting works only with adjacent networks
that share the same network id value , such as networks 1 and 2 in this example.
As with subnets, the subnet mask is used to divide the IP address into a custom netid portion and hostid
portion.
For example, the two networks 10.0.117.0 and 10.0.116.0 can be combined into a larger 10.0.116.0 network if
the subnet mask 255.255.254.0 is applied to both addresses.
11111111 11111111 11111110 00000000 = 255.255.254.0
netid bits
hostid bits
subnet mask
(dotted decimal)
(binary)
Figure 105: Subnet Mask Used to Effect a Supernet
10.0.116.1
Network 1
10.0.117.1
10.0.117.2
10.0.117.3
Network 2
10.0.116.2
Gateway
G
A
B
C
Figure 106: Resulting Supernet