Lesson 3 - Intradomain routing

Question 1

What is the difference between the forwarding and routing?

Answer 1

By forwarding we refer to transferring a packet from an incoming link to an outgoing link within a single router. By routing we refer to how routers work together using protocols to determine the good paths

Question 2

What is the main idea behind link state routing algorithm?

Answer 2

It is a dynamic routing algorithm in which each router shares knowledge of its neighbors with every other router in the network. A router sends its information about its neighbors only to all the routers through flooding. Information sharing takes place only whenever there is a change.

Question 3

Name an example of link state routing algorithm

Answer 3

1. Open shortest path first 2. IS-IS

Question 4

What is the computational complexity of the link state routing algorithm?

Answer 4

Complexity is on the order of the total nodes squared (n^2) By the end of the algorithm, will search through n*(n+1)/2 nodes.

Question 5

What is the main idea behind distance vector routing algorithm?

Answer 5

protocol used in packet-switched networks that utilizes distance to decide the best packet forwarding path.

Question 6

Explain the steps of distance vector routing

Answer 6

1. determine local distances to neighbors 2. receive new routes from neighbors 3. update routing if shorter paths exist.

Question 7

When does count to infinity problem occur in DV?

Answer 7

When there is a large increase in cost between nodes, such as a severed connection.

Question 8

What is poison reverse in DV?

Answer 8

one node (y) intentionally misinforms it’s neighbor (z) along it’s optimal path that the cost to destination (x) is infinity. It does this so the neighbor (z) does not try to travel the reverse path (through y to x).

Question 9

What is RIP?

Answer 9

Routing Information Protocol (RIP) is a dynamic routing protocol which uses hop count as a routing metric to find the best path between the source and the destination network. It is a distance vector routing protocol which has AD value 120 and works on the application layer of OSI model.

Question 10

What is OSPF?

Answer 10

Open Shortest Path First (OSPF) is a routing protocol which uses a link state routing algorithm to find the best path between the source and the destination router.

Question 11

What is hot potatoe routing

Answer 11

Sending messages from entry to exit of the AS through the shortest path within the AS.