Information Technology Reference
In-Depth Information
When you find a column of bits that do not match, stop. You are at the summary boundary.
11000000.10101000.00000001.00000000
11000000.10101000.00000001.00100000
11000000.10101000.00000001.01000000
11000000.10101000.00000001.01100000
4.
Count the number of leftmost matching bits, which in this example is 25. This number becomes
your subnet mask for the summarized route, /25 or 255.255.255.128.
5.
To find the network address for summarization, copy the matching 25 bits and add all 0 bits to
the end to make 32 bits. In this example, the network address is 192.168.1.0.
6.
Summary Route Exercise 1
Referring to Figure 2-3, what summary route would R1 send to BBR for the four networks? Write
your answer in the space provided.
Figure 2-3
Summary Route Exercise 1 (Answer)
192.168.1.0/25
192.168.1.128/26
R1
BBR
192.168.1.192/27
Summary Route
192.168.1.0/24
192.168.1.224/27
11000000.10101000.00000001.00000000
11000000.10101000.00000001.10000000
11000000.10101000.00000001.11000000
11000000.10101000.00000001.11100000
Summary Route: 192.168.1.0/24
