Question

Consider a datagram network using 32-bit host addresses. Suppose a router has four links, numbered 0 through 3, and packets are to be forwarded to the link interfaces as follows: Destination Address Range Link Interface 11100000 00000000 00000000 00000000 through 11100000 00111111 11111111 11111111 11100000 01000000 00000000 00000000 through 11100000 01000000 11111111 11111111 11100000 01000001 00000000 00000000 through 11100001 01111111 11111111 11111111 otherwise a. Provide a forwarding table that has five entries, uses longest prefix matching, and forwards packets to the correct link interfaces. b. Describe how your forwarding table determines the appropriate link interface for datagrams with destination addresses: "11001000 10010001 01010001 01010101" "11100001 01000000 11000011 00111100" "11100001 10000000 00010001 01110111"

Answer 1

1)

Prefix Match Deciaml representation Link Interface

11100000 00000000 (224.0) 0

11100000 01000000 (224.64) 1

11100000 01000001 (224.65) 2

11100001 01111111 (225.127) 3

otherwise   3

2)for 11001000 10010001 01010001 01010101

first two binarys from left represents 200.145...

so refering to table it belongs to otherwise entry so interface is 3

for 11100001 01000000 11000011 00111100

first two binarys represents 225.64......

so refering to table it belongs to 3rd entry so interface is 2

for 11100001 10000000 00010001 01110111

first two binarys represents 225.128......

so refering to table it belongs to 4th entry so interface is 3