Module 12: Wireless Protocols

Question 1

Mobile Ad Hoc Networks (MANET)

Answer 1

formed by wireless hosts which may be mobile without necessarily using a pre-existing infrastructure
may need to traverse multiple links to reach a destination

Question 2

why care about MANET?

Answer 2

Question 3

challenges in MANET

Answer 3

limited wireless transmission range

broadcast nature of the wireless medium (hidden terminal problem)

packet losses due to transmission changes

mobility-induced route changes

mobility-induced packet losses

battery constraints

potentially frequent network partitions

Question 4

why is routing in MANET different?

Answer 4

Question 5

Taxonomy of MANET Routing Protocols

Answer 5

Question 6

trade-offs (proactive vs. reactive)

Answer 6

Question 7

Which one of the following would you select for low latency?
(proactive or reactive)

Answer 7

proactive (routes are pre-calculated so you don’t have to add this additional latency)

Question 8

dynamic source routing (DSR)

Answer 8

Question 9

What is true about DSR?

Answer 9

DSR stands for Dynamic Source Routing

DSR has route caching

DSR is a reactive protocol

(NOT a protocol for wired networks)

Question 10

Route Error

Answer 10

Question 11

DSR - hidden terminal problem

Answer 11

could cause messages to be lost
but we could introduced randomness to avoid collision
hurts route latency but better choice than collisions

Question 12

DSR optimization: route caching

Answer 12

Question 13

use of route caching

Answer 13

Question 14

Use of route caching: can reduce propagation of route requests

Answer 14

this also reduces the collision problem

Question 15

route caching: BEWARE

Answer 15

Question 16

DSR advantages

Answer 16

Question 17

DSR disadvantages

Answer 17

Question 18

Which of the following is not a disadvantage of the DSR?

Answer 18

This protocol needs to periodically flood the network in order to build a local view of the network in each node

real problems:

This protocol has stale routes problem

The connection setup delay is higher

There could be hidden terminal type of problems

Question 19

recap: link state

Answer 19

Question 20

OLSR = optimized link state routing

Answer 20

Question 21

Which of the following is the difference between Link State Routing and OLSR when a node X sends a broadcast message?

Answer 21

In OLSR the broadcast message is only forwarded by its multipoint relays, whereas in Link State Routing the broadcast message is forwarded by all its neighbors

Question 22

DTN

Answer 22

delay tolerant network

Question 23

epidemic routing protocol: dealing with network partitions

Answer 23

Question 24

epidemic routing protocol

Answer 24

Question 25

In epidemic routing protocol, when two nodes are adjacent to each other, the two nodes send all of their own messages to each other.

Answer 25

False

Question 26

If a source, S, wishes to transmit a message to a destination but no connected path is available, then S will send the data to any nodes that are close by and leverage carriers to transitively deliver the message to its destination at some later point in time.

Answer 26

False

Question 27

ZRP - zone routing protocol

Answer 27

hybrid!

Question 28

ZRP

Answer 28

Question 29

intr-zone routing

Answer 29

Question 30

inter-zone routing

Answer 30

Question 31

If given a node X, and another node Y which is more than d hops away from X, then

Answer 31

Routes from X to Y are maintained reactively