Homework 6 - Chapter 5

Questions are worth 2 pts unless otherwise indicated.

1. (4 pts) A subnet has the same topology as given in Figure 5.13 on page 363. The routers receive the following new link state packets: (A, SEQ, Age, B 7, E 3), (B, SEQ, Age, A 7, C 4, F 4), (C, SEQ, Age, B 4, D 5, E 2), (D, SEQ, Age, C 5, F 6), (E, SEQ, Age, A 3, C 2, F 10), (F, SEQ, Age, B 4, D 6, E 10). Compute the new shortest paths from A to all other routers.
2. Describe how choke packets and load shedding differ for congestion control in datagram subnets.
3. Describe how tunneling can be used in a datagram subnet.
4. (4 pts) An ISP offers static IP services over DSL. In their advertisement, they say they will allocate an 8 address subnet for each subscriber.
   1. What is the netmask for this subnet?
   2. Will all 8 addresses be available for use by the user? Explain your answer.
5. A router has received 206.45.68.0/22, 206.45.72.0/22 and 206.45.76.0/22. All use the same outgoing line. Can the router aggregate them? If so, give the aggregated address. If not, explain why not.
6. A router has an aggregated block with the address 19.28.0.0/17. A set of 1024 addresses within that block, 19.28.60.0 to 19.28.63.255, is assigned to a different outgoing line than the rest of the block. Will the router have to deaggregate 19.28.0.0/17? Explain your answer.
7. (4 pts) A router has the following entries in its routing table:

        Address/mask        Interface
        138.168.0.0/16      eth0
        192.168.1.0/24      eth1
        71.138.209.16/29    eth2
        default             eth3
   

   Which interface will be used for packets with the following IP addresses?
   1. 136.168.201.110
   2. 71.138.209.157
   3. 192.168.1.50
   4. 71.138.209.18