Possible questions for the examination.

PSTN/ISDN

1. What is routing, and what are its possible goals?
2. What are the main functions of routing and their main characteristics?
3. What are the advantages and disadvantages of centralizing and distributing routing?
4. Spell out and explain briefly FHR, AAR, DAR, DNHR, LLR, RCAR, and DCR.
5. Explain the principle of number analysis in a telephone exchange.
6. Explain the relationship between routing and (subscriber) number portability. Describe the architecture realizing number portability in Finland.
7. What is meant by routing in circuit-switched networks? What is meant by dimensioning the network?
8. Show the taxonomy of the routing systems in circuit switching.
9. Compare the use of local and global information in routing.
10. Describe the operating principle of alternative routing. Use an example.
11. What is meant by an optimal route? Explain the interest conflict between one user and all users concerning optimality.
12. Describe the principle of fixed hierarchical routing and the algorithm for routing.
13. Explain the principles of originating office control and sequential office control using a routing tree.
14. The nodes A, B, C and D form a completely looped network. Node E connects to A and C. Describe, from the user’s point of view, optimal routing from B to D using the augmented routing tree.
15. For what is an influence graph needed? Give an example of the use of the influence graph.
16. Provide an example on cross overflow and analyze the case using an influence graph.
17. Explain the principle of adaptive routing
18. Explain the principle of DAR routing. Explain also the use of trunk-line reservation parameters in DAR.
19. Explain the principle of DAR. What variations of the algorithm exist?
20. Describe BT’s routing algorithm based on DAR.
21. Explain the routing algorithm of the general sticky principle (yleinen tartuntaperiaate).
22. Describe the routing principle of the long-distance network of Canada.

Internet

1. What information of the IPv4 protocol headers does the Internet routing utilize?
2. Explain the basic method for the Internet to recover from routing loops. How does the network recover from black holes?
3. What are the current principles of Internet addressing?
4. Considering routing (addressing), explain how the IP protocol is adapted to the underlying network.
5. Explain how IP routing is adapted to a situation where there are several routers in one LAN segment.
6. Compare the headers of IPv4 and IPv6. Which are the main differences? How are options handled in IPv6?
7. Stateless autoconfiguration in IPv6.
8. How did CIDR change Internet routing?
9. Define the autonomic system. Describe the structure of Internet on the level of autonomic systems.
10. Describe the main alternatives of routing architectures. [Skipped 2002]
11. Describe the packet-forwarding algorithm in an Internet router. [Skipped 2002]

Distance-vector routing protocols

1. Describe the reception algorithm of distance vector protocol.
2. Describe the functioning principles behind RIP using a little example network. (There are no faults in the network and all links weights are 1).
3. Using an example, describe how RIP recovers from losing a link. (The link weights are all equal).
4. Show the birth of a transient routing loop in a RIP-network using an example.
5. Show, using an example, that the RIP-network recovers from a transient routing loop.
6. When does the use of RIP lead counting infinity?
7. What countermeasures for routing loops can be built into distance vector protocol?
8. Show, that a routing loop is possible even if the distance vector protocol uses poisoneous vectors.
9. When does it pay off for the DV-protocol to send?
10. Evaluate the applicability of the distance vector protocol to Internet routing.
11. Illustrate the Bellman-Ford algorithm.
12. Enumerate the basic characteristics of RIP.

Link-state routing protocols

1. Compare distance-vector and link-state routing protocols. What are the advantages of link-state routing compared to distance-vector routing?
2. Illustrate the principle of Internet routing based on the link state approach.
3. Illustrate the algorithm for distributing the link states in link-state routing.
4. How is the fractioned network re-united in link-state routing?
5. What actions can be taken to ensure the integrity of the link-state databases in link-state routing?
6. Illustrate the Dijkstra algorithm of shortest-path-first without alternative paths.
7. Illustrate Dijkstra’s shortest-path-first algorithm that can also detect alternative paths.
8. The pros and cons of distributing packet traffic to alternative paths.
9. What are the protocols used with OSPF? Explain the concept of neighborhood in OSPF.
10. Explain the OSPF flooding protocol in broadcast networks and in point-to-point networks.
11. Explain the concept of area in OSPF.
12. Illustrate the principle of recovery from internal (to an area) failure in OSPF. How can virtual links be used in the recovery?
13. Explain the concepts of stub-area and not-so-stubby-area in OSPF.
14. Illustrate the algorithm with which the OSPF chooses the designated router and the Back-up designated router.
15. Present the types of state records and their usage in OSPF.
16. Explain the actions relating to the age of the state record in OSPF.
17. Illustrate the use of OSPF’s network-LSA in reducing the size of the link-state database.
18. Present the suitable network topology models of OSPF for ATM and Frame Relay networks.

PNNI

1. Why is PNNI based on source routing?
2. Illustrate the reference model of the PNNI node.
3. What are the most important routing functions of PNNI?
4. Define the concept of peer group in PNNI.
5. How does the hierarchy of peer groups work in PNNI?
6. Explain the concepts of logical node and logical link in PNNI.
7. Explain the duties and election of peer group leader in PNNI.
8. Explain the principle of topological aggregation using the PNNI logical node.
9. Explain the phases of startup of the PNNI routing in an ATM-network
10. Describe PNNI flooding protocol.
11. The concept of uplink in PNNI.
12. Illustrate the PNNI routing algorithm.
13. Illustrate the functionality of crankback in PNNI.

Multicast

1. Multicast applications and intended uses in the Internet. How does the communication based on multicast differ from the typical communication model of the point-to-point communication?
2. Define the graph-related concepts: graph, neighbor, simple graph, multigraph, path and loop.
3. Define the graph-related concepts: connected graph, directed graph, tree, spanning tree and forest.
4. Present the data structures that are used to describe graphs.
5. Give the algorithm that creates the minimal spanning tree from a given graph.
6. Why the minimal spanning tree (MST) is not used in the practical solutions of multicast in the Internet? How does the RPF multicast routing differ from the MST based solution?
7. RPF algorithm and its characteristics.
8. What are the two different ways that the multicast can be limited to a changing group of receivers?
9. Present IGMPv2 and v3.
10. Present the principles of DVMRP.
11. What is a dependent downstream router in DVMRP? What is a designated forwarder?
12. How are the neighborhood relations handled in DVMRP?
13. The construction and updating of source trees in DVMRP.
14. The multicast algorithm of DVMRP in a router.
15. Explain the use of cached information in DVMRP to minimize the multicast trees.
16. The handling of Prune and Graft messages in DVMRP.
17. The principle of MOSPF multicast routing.
18. How does the MOSPF use Dijkstra’s algorithm?
19. How can MOSPF be introduced gradually in an OSPF domain?
20. The effects of hierarchy to multicast routing in MOSPF. [Skipped 2002]
21. How do dense and sparse multicast groups differ? Which protocols are best suited for these groups and why?
22. Why does PIM-DM delay before executing a prune on a broadcast network? What happens if two routers forward the same multicast group to a broadcast network?
23. What is the rendezvous point (RP) in PIM-SM? How is a RP selected for a group is there are several?
24. Describe how packets are sent to a multicast group in PIM-SM.
25. Assume two neighboring networks connected by two routers. One network uses DVMRP and the other uses PIM-SM. How is a multicast transferred between them?

Mobile IP

1. Describe the elements involved in mobile IP (IPv4 assumed). How is a packet routed to and from a mobile host?
2. Explain discovery and registration procedure in mobile IP (IPv4 assumed).
3. How can a mobile host determine that it is visiting a different network than before?
4. A mobile host wants to participate in a multicast conference in its home network. How does it join the conference? How are the multicast packets transferred to the host?
5. Why is source address filtering used? How does it decrease the performance of mobile IP? How is the problem solved in IPv6?
6. What does triangle routing mean? Why must the packets be tunneled in both directions sometimes? How can the path to a mobile host be shortened in IPv6?
7. The function of the Foreign Agent in Mobile IPv4 and Mobile IPv6.
8. Compare encapsulation in Mobile IPv4 and Mobile IPv6.

Routing in Ad hoc networks

1. What characteristics are typical to mobile ad hoc networks? How do these properties affect routing?
2. What is the difference between proactive and reactive routing? Describe the main methods of obtaining routes for both types. Give examples of some protocols of both types.
3. Describe the operation of the DSR (Dynamic Source Routing) protocol.
4. Describe the operation of the AODV (Ad-hoc On-demand Distance Vector) routing protocol.
5. How does the Zone Routing Protocol (ZRP) combine proactive and reactive routing? What function do the peripheral nodes have?
6. Present a classification of routing protocols for ad hoc networks. What are the main features of each class?
7. How can geographical information be utilized for routing in Ad hoc networks?