Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IoT > Routing > Flashcards

Routing Flashcards

1
Q

What are the two main types of data transfer?

A

Packet switching

Circuit switching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the advantages and disadvantages of circuit switching?

A

Pro: dedicated connection between machines, guaranteed performance
Con: Expensive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the pros and cons of packet switching?

A

Pros: good utilisation of available bandwidth
Cons: may have poor performance at busy times, packets may have to queue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the main considerations of routing?

A

Minimising packet delays
Minimising hop count
Maximising available bandwidth
minimising financial cost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two main approaches to routing?

A

Distance vector protocols

Link state protocols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe distance vector protocols

A

Neighbours exchange lists of distances to known destinations

Best next hop is determined at each node

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe link state protocols

A

Link state information is flooded to all routers in the network
Routers have complete topology information
Route is calculated based on desired criteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name 5 alternative routing approaches

A 
Flooding
Deflection routing ('hot potato')
Source routing
Gradient descent
RPL
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe flooding and state an advantage and disadvantage

A

Packets are flooded to all nodes
Pro: good for survivability of the packet
Con: exponential growth of traffic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe deflection routing and name an advantage and disadvantage

A

Switches maintain multiple paths to the destination, if the preferred path is congested an alternative can be used
Pro: switches have reduced buffer size
Con: time to delivery and packet reordering have greater variability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe source routing and state an advantage and disadvantage

A

Sender specifies a complete route to the destination. Nodes strip off their identifier on receipt and forward to the next node in the path
Pros: less load on intermediate nodes, can avoid particular hosts
Cons: source must know the route to all hosts, link failures cause disruption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe gradient descent and state an advantage

A

Gradient is built around a single sink node, nodes can only pass messages to lower tiers
Pros: adds path diversity, allows energy management using elevation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does MANET stand for?

A

Mobile Ad-Hoc Networks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the advantages of a MANET?

A

Ease of deployment
Speed of deployment
Decreased infrastructure dependence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the variants of MANET?

A

Fully symmetrical

Asymmetric

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe dynamic source routing (DSR)

A

The network is flooded with request messages
When the destination receives the request it sends a route reply (RREP)
The RREP is sent back on the reversed route the request was sent on
When the source node receives the RREP it caches the route and the data is transmitted

17
Q

What are the disadvantages of route caching? (DSR)

A

Stale caches can negatively affect performance
Host mobility may become stale
Several routes may be tried before a good route is found

18
Q

What are the advantages of DSR?

A

Routes maintained only between communicating nodes

Route caching may reduce discovery overheads

19
Q

What are the disadvantages of DSR?

A

Packets grow with route length

Flood requests may not reach all nodes

20
Q

What is the difference between ad-hoc on demand distance vector (AODV) routing and dynamic source routing (DSR)?

A

DSR stores the route in the packet header

AODV maintains routing tables at the nodes

21
Q

How does AODV work?

A

The route request is forwarded
On forwarding the node sets up a temporary reverse route to the source (AODV assumes bi-directional links)
When the destination node receives the request, it sends an RREP back along the temporary reverse path set up by the request

22
Q

Describe route replies (AODV)

A

Intermediate nodes may reply with routes

The likelihood of a node issuing a RREP is not as high as in DSR

23
Q

Describe timeouts (AODV)

A

Routing tables maintaining reverse paths are wiped after a timeout period
Forward paths are purged if not used for a set timeout interval

24
Q

How are link failures reported in AODV?

A

When a next-hop link is broken all active neighbours are informed
Link failures are propagated using route error (RERR) messages that also update destination sequence numbers

25
Q

How are route errors handled in AODV?

A

If a node is unable to forward a packet it generates an RERR message
When the source node receives the RERR it initiates a new route discovery

26
Q

How are link failures detected in AODV?

A

Neighbouring nodes periodically send each other short messages to indicate active neighbour presence
Absence of this message is an indicator of link failure

IoT (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions