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Scenarios 251
Using the binary to decimal table below, perform the following steps to accomplish route
summarization.
1
List the octets, 70, 72, and 74 in the right hand column.
2
Convert the octets, 70, 72, and 74 into binary.
3
Identify all the columns where the octets share common values.
4
Identify the first column where the octets do not share common values.
5
Summarize the block on the contiguous block of common values.
NOTE
172.168.64.0 MASK 255.255.240.0 summarizes the three addresses above. Note that all three
addresses above. Note that all three addresses share the same binary values for their first four bits.
Routes can be summarized at 172.168.64.0/20 at the ABR or the ASBR.
Figure 7-13 shows a proposed OSPF network after optimization.
Figure 7-13
Shouting N' Routing Optimized Network Topology
Binary Values
Decimal Values
128
64
32
16
8
4
2
1
0
1
0
0
0
1
1
0
70
0
1
0
0
1
0
0
0
72
0
1
0
0
1
0
1
0
74
CIE
R1
CIE
R2
OSPF
Area 0
CIE
R1
CIE
R2
OSPF
Area 0
CIS
CIE
87200333.book Page 251 Wednesday, August 22, 2001 2:37 PM