16 Questions
What is the primary advantage of the OSI model in terms of protocols?
It supports the replacement of old protocols with new ones.
What is the main drawback of the OSI model?
It was devised before the invention of protocols.
What is the purpose of encapsulation in the OSI model?
All of the above.
What happens during the encapsulation process in the OSI model?
Data is received from a higher layer and put into a data format that is understood by the lower layer.
Which layer of the OSI model is responsible for the exchange of information from the computer to the network?
Application layer (layer 7)
What is the primary function of the application layer in the OSI model?
To define the request of the user.
What is an analogy for the encapsulation process in the OSI model?
Sending a letter with an envelope and address.
What is the advantage of the OSI model in terms of services?
It supports both connection-oriented and connectionless services.
What is the primary function of the Session layer (layer 5)?
To verify the application requesting the information and the services requested on the server
What is the purpose of the Transport layer (layer 4)?
To ensure proper connection with the server and convert information into segments
What is formed at the Transport layer (layer 4)?
L4PDU
What is the primary function of the Network layer (layer 3)?
To add a network address to the segments
What is formed at the Network layer (layer 3)?
L3PDU
What is the primary function of the Data Link layer (layer 2)?
To arrange packets and wrap them into individual frames
Why are MAC addresses used in the Data Link layer (layer 2)?
To deliver packets between a router and other routers
What is the size constraint for the data fields in the Ethernet frame in the Data Link layer (layer 2)?
46-1500 bytes
Study Notes
OSI Layers and Protocols
- The OSI model has several protocols that operate within each layer, which will be discussed.
- Advantages of the OSI reference model include:
- Clear distinction between services, interfaces, and protocols
- Protocols are well-hidden and can be replaced as technology changes
- Supports both connection-oriented and connectionless services
- Drawbacks of the OSI reference model include:
- The model was devised before protocol invention
- Fitting protocols is a tedious task
- It is only used as a reference model
Encapsulation and Decapsulation
- Encapsulation is a process that hides or protects data from outside interference, making it simpler to use.
- It involves a lower-layer protocol receiving data from a higher-layer protocol and converting it into a recognizable format.
- Access to internal systems is arranged through a set of interfaces.
- Encapsulation can be compared to sending a letter with an envelope, address, and postage, which represents data encapsulation.
Encapsulation Process
Application Layer (Layer 7)
- Responsible for exchanging information between computer and network
- Defines user requests
- Interface layer between network applications used by users
Presentation Layer (Layer 6)
- Determines whether encryption or data translational is needed
- Adds header to data
Session Layer (Layer 5)
- Checks application requests and verifies services on the server
- Adds header to data (optional)
Transport Layer (Layer 4)
- Ensures proper connection with the server
- Converts information into segments
- Performs error checking and merging data
- Guarantees data wholeness
- Forms L4PDU
Network Layer (Layer 3)
- Adds network addresses for request and server
- Converts segments into packets
- Adds network header and forms L3PDU
Data Link Layer (Layer 2)
- Arranges packets into individual frames
- Adds MAC addresses (destination and source)
- Adds trailer to frame
- Ensures packet delivery via routers
- Transmits to media
- Data must fit within 46-1500 bytes of Ethernet frame
Learn about the protocols operating within the OSI model layers, including their advantages and disadvantages. Understand the OSI reference model and its features.
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