Possible questions for the
examination.
PSTN/ISDN
- What is routing, and what are its possible
goals?
- What are the main functions of routing and
their main characteristics?
- What are the advantages and disadvantages
of centralizing and distributing routing?
- Spell out and explain briefly FHR, AAR,
DAR, DNHR, LLR, RCAR, and DCR.
- Explain the principle of number analysis
in a telephone exchange.
- Explain the relationship between routing
and (subscriber) number portability. Describe the architecture realizing
number portability in Finland.
- What is meant by routing in
circuit-switched networks? What is meant by dimensioning the network?
- Show the taxonomy of the routing systems
in circuit switching.
- Compare the use of local and global
information in routing.
- Describe the operating principle of
alternative routing. Use an example.
- What is meant by an optimal route? Explain
the interest conflict between one user and all users concerning
optimality.
- Describe the principle of fixed
hierarchical routing and the algorithm for routing.
- Explain the principles of originating
office control and sequential office control using a routing tree.
- 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.
- For what is an influence graph needed?
Give an example of the use of the influence graph.
- Provide an example on cross overflow and
analyze the case using an influence graph.
- Explain the principle of adaptive routing
- Explain the principle of DAR routing.
Explain also the use of trunk-line reservation parameters in DAR.
- Explain the principle of DAR. What
variations of the algorithm exist?
- Describe BT’s routing algorithm based on
DAR.
- Explain the routing algorithm of the
general sticky principle (yleinen tartuntaperiaate).
- Describe the routing principle of the
long-distance network of Canada.
Internet
- What information of the IPv4 protocol
headers does the Internet routing utilize?
- Explain the basic method for the Internet
to recover from routing loops. How does the network recover from black
holes?
- What are the current principles of
Internet addressing?
- Considering routing (addressing), explain
how the IP protocol is adapted to the underlying network.
- Explain how IP routing is adapted to a
situation where there are several routers in one LAN segment.
- Compare the headers of IPv4 and IPv6.
Which are the main differences? How are options handled in IPv6?
- Stateless autoconfiguration in IPv6.
- How did CIDR change Internet routing?
- Define the autonomic system. Describe the
structure of Internet on the level of autonomic systems.
- Describe the main alternatives of routing
architectures. [Skipped
2002]
- Describe the packet-forwarding algorithm
in an Internet router. [Skipped
2002]
Distance-vector routing
protocols
- Describe the reception algorithm of
distance vector protocol.
- Describe the functioning principles behind
RIP using a little example network. (There are no faults in the network
and all links weights are 1).
- Using an example, describe how RIP
recovers from losing a link. (The link weights are all equal).
- Routing loops – how do they appear, what
problems do they cause, how can they be prevented?
- Show the birth of a transient routing loop
in a RIP-network using an example.
- Show using an example that the RIP-network
recovers from a transient routing loop.
- When does the use of RIP lead counting
infinity?
- What countermeasures for routing loops can
be built into distance vector protocol?
- Show, that a routing loop is possible even
if the distance vector protocol uses poisoneous vectors.
- When does it pay off for the DV-protocol
to send?
- Evaluate the applicability of the distance
vector protocol to Internet routing.
- Illustrate the Bellman-Ford algorithm.
- Enumerate the basic characteristics of
RIP.
Link-state routing
protocols
- Compare distance-vector and link-state
routing protocols. What are the advantages of link-state routing compared
to distance-vector routing?
- Illustrate the principle of Internet
routing based on the link state approach.
- Illustrate the algorithm for distributing
the link states in link-state routing.
- How is the fractioned network re-united in
link-state routing?
- What actions can be taken to ensure the
integrity of the link-state databases in link-state routing?
- Illustrate the Dijkstra algorithm of
shortest-path-first without alternative paths.
- Illustrate Dijkstra’s shortest-path-first
algorithm that can also detect alternative paths.
- The pros and cons of distributing packet
traffic to alternative paths.
- What are the protocols used with OSPF?
Explain the concept of neighborhood in OSPF.
- Explain the OSPF flooding protocol in
broadcast networks and in point-to-point networks.
- Explain the concept of area in OSPF.
- Illustrate the principle of recovery from
internal (to an area) failure in OSPF. How can virtual links be used in
the recovery?
- Explain the concepts of stub-area and
not-so-stubby-area in OSPF.
- Illustrate the algorithm with which the
OSPF chooses the designated router and the Back-up designated router.
- Present the types of state records and
their usage in OSPF.
- Explain the actions relating to the age of
the state record in OSPF.
- Illustrate the use of OSPF’s network-LSA
in reducing the size of the link-state database.
- Present the suitable network topology
models of OSPF for ATM and Frame Relay networks.
- Describe the contents of the link state
database and the routing table of an OSPF router. How are these
constructed?
PNNI
- Why is PNNI based on source routing?
- Illustrate the reference model of the PNNI
node.
- What are the most important routing
functions of PNNI?
- Define the concept of peer group in PNNI.
- How does the hierarchy of peer groups work
in PNNI?
- Explain the concepts of logical node and
logical link in PNNI.
- Explain the duties and election of peer
group leader in PNNI.
- Explain the principle of topological
aggregation using the PNNI logical node.
- Explain the phases of startup of the PNNI
routing in an ATM-network
- Describe PNNI flooding protocol.
- The concept of uplink in PNNI.
- Illustrate the PNNI routing algorithm.
- Illustrate the functionality of crankback
in PNNI.
Multicast
- 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?
- Define the graph-related concepts: graph,
neighbor, simple graph, multigraph, path and loop.
- Define the graph-related concepts:
connected graph, directed graph, tree, spanning tree and forest.
- Present the data structures that are used
to describe graphs.
- Give the algorithm that creates the
minimal spanning tree from a given graph.
- 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?
- RPF algorithm and its characteristics.
- What are the two different ways that the
multicast can be limited to a changing group of receivers?
- Compare the advantages and disadvantages
of the center-based tree algorithm and the “flood and prune” algorithm.
- Present IGMPv2 and v3.
- Present the principles of DVMRP.
- What is a dependent downstream router in
DVMRP? What is a designated forwarder?
- How are the neighborhood relations handled
in DVMRP?
- The construction and updating of source
trees in DVMRP.
- The multicast algorithm of DVMRP in a
router.
- Explain the use of cached information in
DVMRP to minimize the multicast trees.
- The handling of Prune and Graft messages
in DVMRP.
- The principle of MOSPF multicast routing.
- How does the MOSPF use Dijkstra’s
algorithm?
- How can MOSPF be introduced gradually in
an OSPF domain?
- The effects of hierarchy to multicast
routing in MOSPF. [Skipped
2002]
- How do dense and sparse multicast groups
differ? Which protocols are best suited for these groups and why?
- 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?
- What is the rendezvous point (RP) in
PIM-SM? How is a RP selected for a group is there are several?
- Describe how packets are sent to a
multicast group in PIM-SM.
- 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
- Describe the elements involved in mobile
IP (IPv4 assumed). How is a packet routed to and from a mobile host?
- Explain discovery and registration
procedure in mobile IP (IPv4 assumed).
- How can a mobile host determine that it is
visiting a different network than before?
- 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?
- Why is source address filtering used? How
does it decrease the performance of mobile IP? How is the problem solved
in IPv6?
- 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?
- The function of the Foreign Agent in
Mobile IPv4 and Mobile IPv6.
- Compare encapsulation in Mobile IPv4 and
Mobile IPv6.
Routing in Ad hoc networks
- What characteristics are typical to mobile
ad hoc networks? How do these properties affect routing?
- 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.
- Describe the operation of the DSR (Dynamic
Source Routing) protocol.
- Describe the operation of the AODV (Ad-hoc
On-demand Distance Vector) routing protocol.
- How does the Zone Routing Protocol (ZRP)
combine proactive and reactive routing? What function do the peripheral
nodes have?
- Present a classification of routing
protocols for ad hoc networks. What are the main features of each class?
- How can geographical information be
utilized for routing in Ad hoc networks?