TCP/IP
Chapter 11 Assignment

Exercises - even numbers

2. The hop count limit helps RIP instability by limiting the number of times a message can be sent through the same router, thereby limiting the back and forth updating that may occur if part of a network goes down.

4. OSPF messages are propagated immediately because a router using OSPF will immediately flood the network with news of any changes to its neighborhood. RIP messages are distributed slowly because a network using RIP relies on the periodic updates that occur every 30 seconds to carry any news from one router to the next and to the next. The process may take a lot of time.

6. Well to handle the table, one periodic timer is needed. 20 expiration timers are needed, one for each entry. And last for all, 5 garbage collection timers are needed, one for each invalid route.

8. The updated routing table
Network
Hops

Net1
3
C
Net2
2
C
Net3
1
F
Net4
5
G

10.
Router A EB

2 IP address for router of N2 Router Address
2
1 5
TOS

Metric for TOS IP address of router D Interface Number 1 1 8
TOS

Metric for TOS Router D EB

2 IP address for router of N3 Router Address
2
1 2
TOS

Metric for TOS IP address of router A Interface Number 1 1 8
TOS

Metric for TOS

Router E

EB

2 IP address for router of N4 Network mask for N4
3
1 2
TOS

Metric for TOS IP address of router N3 or F Router Number 2 1 5
TOS

Metric for TOS

Network N2
Network mask for N2
IP address of router C

Network N4
Network mask for N4
IP address of router E Network N5
Network mask for N5
IP address of router F

12. For figure 11.26
A. hello message sent by rputer C
2
1 44
163.43.27.4

Area ID
Checksum
Type
Data
255.255.0.0 Hello interval 0 1 Priority
Designated router for 163.43.0.0
Backup router for 163.43.0.0

B. Database description message sent by router C:
It