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.
- Describe briefly the
following concepts related to circuit-switched networks: fixed
hierarchical routing (FHR), adaptive routing, crankback.
- Describe the principle and
the algorithm of fixed hierarchical routing (FHR).
- 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?
- Compare the use of global
and local information in routing. Give an example of a PSTN routing
algorithm that uses only local information. Give also an example of a
routing system in the circuit switched network that uses global
information.
- 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 the DAR routing
algorithm used by BT. Give also the algorithm of general sticky principle.
- 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 extensions implemented
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.
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 poisonous vectors.
- When does it pay off for
the DV-protocol to send?
- Evaluate the applicability
of the distance vector protocol to Internet routing.
- Give 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.
- 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?