OSI model

Question 1

What are protocols in the context of computer networks ?

Answer 1

Protocols are standardized rules which allow devices to communicate inside the computer network

Question 2

What kind of requirements should protocols consider ?

Answer 2

1. ) IDENTIFICATION OF THE RECIVEVER AND THE SENDER
2. ) COMMON LANGUAGE ( data format , encryption )
3. ) SPEED AND DELIVERY METHOD ( LATENCY, FRAME RATE AND JITTER )
4. ) REQUESTS FOR CONFIRMATION AND CONFIRMATION ( ERROR HANDLING , TYPE OF COMMUNICATION )

Question 3

What is jitter, latency , and frame rate ?

Answer 3

Latency - the amount of time that it takes for data to be transferred from a source device to the destination device
Jitter - the variation in the latency
Frame rate - in the context of computer networks, the amount of “data packets” sent per second ( 2nd layer )

Question 4

Name 3 types of communication inside the computer network. Give examples.

Answer 4

Broadcast - type of communication usually found in local area networks where a given devices sends a message to all of the devices inside the network
- ARP message / DHCP discovery
Unicast - type of communication where a given device is sending data to only one specific device be it inside its own network or in some other network
= PING, ARP reply, telnet…
Multicast - type of a communication that is both found inside WANs and LANs although it is more common in local networks, it is characterized by a device sending data to multiple specific devices
- IP TV, RIR, EIGRP

Question 5

Explain the following ranges :
255.0.0.0 - 224.0.0.255

224.0.1.0 - 238.255.255.255

239.000.000.000 – 239.255.255.255

Answer 5

255.0.0.0 - 224.0.0.255
- address reserved for devices specifically designed for multicast messages
224.0.1.0 - 238.255.255.255
- this range is reserved for devices which require multicast capabilities such as applications with video stream and audio streaming services
239.000.000.000 – 239.255.255.255
- commonly used to allow devices to send multicast messages inside a private network

Question 6

What are the benefits of multicast messages ?

Answer 6

1. ) more economic use of bandwidth - since a given device does not have to send multiple data streams in order to send a message to multiple devices
2. ) less server load > less data stream&raquo_space; less resources required ( GPU, CPU, BANDWIDTH )
3. ) less network components load&raquo_space; less processing and less forwarding due to less data streams
4. ) allows the services of applications to be available to a large amount of users

Question 7

Describe the OSI model .

Answer 7

Refer to the OSI model word document if needed