Description
Questions:
You are required to answer the following questions from the attached document:
Question Question
P.4 (only
parts a & b)
P.17
P.10 P.19
P.12 P.21
P.13 P.26
P4. Consider the network below.
a. Suppose that this network is a datagram network. Show the forwarding
table in router A, such that all traffic destined to host H3 is forwarded
through interface 3.
b. Suppose that this network is a datagram network. Can you write down a
forwarding table in router A, such that all traffic from H1 destined to host
H3 is forwarded through interface 3, while all traffic from H2 destined to
host H3 is forwarded through interface 4? (Hint: this is a trick question.)
P10. 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 0
11100000 00111111 11111111 11111111
11100000 01000000 00000000 00000000
through 1
11100000 01000000 11111111 11111111
11100000 01000001 00000000 00000000
through 2
11100001 01111111 11111111 11111111
otherwise 3
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
P12. Consider a datagram network using 8-bit host addresses. Suppose a
router uses longest prefix matching and has the following forwarding
table:Prefix Match Interface
1 0
10 1
111 2
otherwise 3
For each of the four interfaces, give the associated range of destination host
addresses and the number of addresses in the range.
P13. Consider a router that interconnects three subnets: Subnet 1, Subnet 2, and
Subnet 3. Suppose all of the interfaces in each of these three subnets are
required to have the prefix 223.1.17/24. Also suppose that Subnet 1 is
required to support at least 60 interfaces, Subnet 2 is to support at least 90
interfaces, and Subnet 3 is to support at least 12 interfaces. Provide three network addresses (of the form a.b.c.d/x) that satisfy these constraints.
P17. Consider the topology shown in Figure 4.17. Denote the three subnets with
hosts (starting clockwise at 12:00) as Networks A, B, and C. Denote the subnets without hosts as Networks D, E, and F.
a. Assign network addresses to each of these six subnets, with the following constraints: All addresses must be allocated from 214.97.254/23;
Subnet A should have enough addresses to support 250 interfaces; Subnet B should have enough addresses to support 120 interfaces; and
Subnet C should have enough addresses to support 120 interfaces. Of
course, subnets D, E and F should each be able to support two interfaces.
For each subnet, the assignment should take the form a.b.c.d/x or
a.b.c.d/x – e.f.g.h/y.
b. Using your answer to part (a), provide the forwarding tables (using longest
prefix matching) for each of the three routers.
P19. Consider sending a 2400-byte datagram into a link that has an MTU of
700 bytes. Suppose the original datagram is stamped with the identification number 422. How many fragments are generated? What are the
values in the various fields in the IP datagram(s) generated related to
fragmentation?
P21. Consider the network setup in Figure 4.22. Suppose that the ISP instead
assigns the router the address 24.34.112.235 and that the network address of
the home network is 192.168.1/24.
a. Assign addresses to all interfaces in the home network.
b. Suppose each host has two ongoing TCP connections, all to port 80 at
host 128.119.40.86. Provide the six corresponding entries in the NAT
translation table.
P26. Consider the following network. With the indicated link costs, use Dijkstra’s
shortest-path algorithm to compute the shortest path from x to all network
nodes. Show how the algorithm works by computing a table similar to
Table 4.3.