Quality of Service

Question 1

Allows the network administrator to prioritize certain types of traffic over others

Answer 1

Quality of Service

Question 2

What type of traffic and voice traffic require greater resources, such as bandwidth, from the network than other types of traffic?

Answer 2

Video and Voice traffic

Question 3

What transactions is time sensitive and have greater needs than as FTP transfer or web traffic(HTTP)

Answer 3

Financial traffics

Question 4

What are the 3 types of priority queues ?

Answer 4

High priority queue
Medium priority queue
Low priority queue

Question 5

When should a device implement QoS?

Answer 5

During congestion

Question 6

Examples of congestion points

Answer 6

aggregation, speed mismatch, LANs to WAN

Question 7

Without QoS mechanisms, What happens when a router receives a digital audio stream for VoIP ?

Answer 7

Compensation for the jitter that is encountered

Question 8

Features of traffic

• Less resources used
• Fairly steady and not very large
• Requires at least 20 kbps of bandwidth with no more than 1% packet loss

Answer 8

Voice packets

Question 9

Features of Traffic

• More demanding
• Bursty and greedy
• Consume lots of resources
• Requires at least 384 kbps in bandwidth , 0.1 < 1 % packet loss

Answer 9

Video Traffic

Question 10

One way requirement for voice traffic - latency, jitter, loss

Answer 10

150 ms, 30 ms, 1%

Question 11

Disadvantages of voice traffic

Answer 11

very sensitive to delay and dropped packets

Question 12

One way requirements for video traffic - latency, jitter, loss, bandwidth

Answer 12

L - <=200 - 400 ms
J - <= 30 – 50ms
L - <= 0.1 – 1%
BW - (384 Kb/s – 20+ Mb/s)

Question 13

What traffic that uses TCP to performs error recovery

Answer 13

Data traffic

Question 14

Factors to consider for data delay

Answer 14

Does the data come from an interactive application?

Is the data mission critical?

Question 15

4 types of algorithm types for queueing

Answer 15

FIFO
Weighted Fair Queuing (WFQ)
Class-based WFQ (CBWFQ)
Low latency Queuing ( LLQ)

Question 16

An algorithm that involves buffering and forwarding of packets in the order of arrival

Answer 16

FIFO

Question 17

An algorithm that uses automated scheduling method that provides fair bandwidth allocation to all network traffic

Answer 17

Weighted Fair Queuing (WFQ)

Question 18

An algorithm that extends the standard WFQ functionality to provide support for user-defined traffic classses

Answer 18

Class-based WFQ

Question 19

An algorithm that uses strict priority queuing to CBWFQ which reduces jitter in vice conversations

Answer 19

LLQ

Question 20

Advantages of LLQ

Answer 20

Delay-sensitive data (voice) is sent first

Question 21

What are the 3 model types of implementing QoS ?

Answer 21

Best-effort
Integrated Services (IntServ)
Differentiated Services (DiffServ)

Question 22

QoS model that is less resource intensive and more scalable

Answer 22

DiffServ

Question 23

QoS model that provides the highest guarantee of QoS, but is resource-intensive

Answer 23

IntServ

Question 24

QoS model that treats all network packets the same way

Answer 24

Best-effort

Question 25

Benefits of Best-effort

Answer 25

Easiest and quickest model to deploy | Most scalable

Question 26

QoS model that uses resource reservation and an admission-control mechanism as building blocks to establish and maintain QoS

Answer 26

IntServ

Question 27

``` QoS model that enforces and applies QoS mechanisms on a hop-by-hop basis uniformly applying global meaning to each traffic class to provide both flexibility and scalability ```

Answer 27

DIffServ

Question 28

QoS model that divides network traffic into classes based on business requirements.

Answer 28

DiffServ

Question 29

3 Main categories from QoS implementation tools

Answer 29

Classification and marking tools Congestion avoidance tools Congestion management tools

Question 30

Ways to avoid packet loss

Answer 30

increase link capacity Guarantee enough bandwidth Drop lower-priority packets before congestion occurs

Question 31

A tool that monitors network traffic loads in an effort to anticipate and avoid congestion at common network bottlenecks before congestion becomes a problem

Answer 31

Congestion Avoidance

Question 32

What happens when an edge router using IntServ QoS determines that the data pathway cannot support the level of QoS requested?

Answer 32

Data is not forwarded along the pathway

Question 33

How many levels of priority are possible when using class of service (CoS) marking on frames?

Answer 33

8 (0-7)

Question 34

What is the default queuing method used on the LAN interfaces of Cisco devices?

Answer 34

FIFO

Question 35

Which QoS technology provides congestion avoidance by allowing TCP traffic to be throttled before buffers become full and tail drops occur?

Answer 35

weighted random early detection

Question 36

Which QoS technique retains excess packets in a separate queue for later transmission?

Answer 36

shaping