Cloud Service models

Question 1

Infrastructure Stack/Application Stack

Answer 1

The Infrastructure Stack or Application Stack contains multiple components that make up the total service. There are parts that you manage as well as portions the vendor manages. The portions the vendor manages and you are charged for is the unit of consumption
Application
Data
Run time
Conatiner
OS
Virtualization
Servers
Infrastructure
Facilities

Question 2

Type of Cloud service models

Answer 2

On- Premises
Data Center hosting
Infrastructure as a Service
Platform as a Service
Software as a Service

Question 3

On - Premises Cloud service model

Answer 3

On-Premises: The individual manages all components from data to facilities. Provides the most flexibility, but also most IT intensive.

Question 4

DC Hosting

Answer 4

Data Center Hosting: Place equipment in a building managed by a vendor. You pay for the facilities only.

Question 5

Iaas

Answer 5

Infrastructure as a Service (IaaS): Vendor manages facilities and everything else related to servers up to the OS. You pay per second or minute for the OS used to the vendor. Lose some flexibility, but big risk reductions.

Question 6

Paas

Answer 6

Platform as a Service (PaaS): Good for running an application only. The unit of consumption is the runtime environment. You manage the application and the data, but the vendor manges all else.

Question 7

Saas

Answer 7

Software as a Service (SaaS): You consume the software as a service. This can be Outlook or Netflix. There are almost no risks or additional costs, but very little control.

There are additional services such as Function as a Service, Container as a Service, and DataBase as a Service which be explained later.

Question 8

Physical layer

Answer 8

Transmission and reception of RAW bit streams between the device and the physical medium
Ex: Physical medium : copper(electrical), fibre (light), RF (wifi)
Physical Hub: more than 2 devices can be connected
anything the hub receives on any of the ports it will be retransmitted to the all other ports devices connected to it including error and collisions. Hub forms the full connector cable
1. No device addressing: one device transmits all other devices receives it (broadcast).
2. All data is processed by all ports .
3. anything received on one port will be transmitted to all other ports.
4. If multiple devices try to transmit over a medium then collision happen
5. No media access control and no collision detection on layer 1.
6. More devices connected in layer higher the chance of data collision and corruption
Summary:
1. Physical shared medium
2. Standards for transmitting onto the medium
3. Standards for receiving from the medium
4. No access control
5. No uniquely identified devices
6. No device to device communications

Question 9

Data link layer

Answer 9

Data link layer is the most critical layer of all 7 layers
Responsible for device to device communication
Layer 2 network run on layer 1
Frames - format layer 2 uses to send information over network
Unique hardware addresses: 48 bits hex
OUI - organizationally unique identifier
NIC - network interface controller
Layer 2 provides frames, layer 1 converts the frame as RAW data in to the physical medium
Frame -
1. preamble 56 bits/start frame delimiter (SF) 8 bits
2. Destination(device that receives the frame)/src MAC address(device that sends the frame)
3. ether type (16 bits) - which layer 3 protocol puts the frame
MAC header - MAC src/MAC dest/ET layer
Payload - 46 - 1500bits actual data sent by layer 3 which puts the frame
encapsulation- layer 3 sends the data (IP packet) via ethernet frame to layer 2 where the L2 source will send the frame to L2 dest
FCS - frame check sequence/ CRC check to see if there any corruption happened
Pbm of layer 1: No media access control so physical corruption can happen due to overlap this is addressed by layer 2 - MAC (media access control)