1. What is function of transport layer?
The protocol in the transport layer takes care in the delivery of data from
one application program on one device to an application program on another
device. They act as a link between the upper layer protocols and the services
provided by the lower layer.
2. What are the duties of the transport layer?
The services provided by the transport layer
End-to- end delivery
Addressing
Reliable delivery
Flow control
Multiplexing
3. What is the difference between network layer delivery and the transport
layer delivery?
Network layer delivery Transport layer delivery
The network layer is responsible for
the the source-to-destination
delivery of packet
across multiple network links.
The transport layer is responsible for
source-to-destination delivery of the
entire message.
4. What are the four aspects related to the reliable delivery of data?
The four aspects are,
Error control
Sequence control
Loss control
Duplication control
5. What is meant by segment?
At the sending and receiving end of the transmission, TCP divides long
transmissions into smaller data units and packages each into a frame called a
segment.
6. What is meant by segmentation?
When the size of the data unit received from the upper layer is too long for
the network layer datagram or data link layer frame to handle, the transport
protocol divides it into smaller usable blocks. The dividing process is called
segmentation.
7. What is meant by Concatenation?
The size of the data unit belonging to a single session are so small that
several can fit together into a single datagram or frame, the transport protocol
combines them into a single data unit. The combining process is called
concatenation.
8. What are the types of multiplexing?
The types of multiplexing are,
Upward multiplexing
Downward multiplexing
9. What are the two possible transport services?
Two basic types of transport services are,
Connection service
Connectionless services
10. The transport layer creates the connection between source and destination.
What are the three events involved in the connection?
For security , the transport layer may create a connection between the two
end ports. A connection is a single logical path between the source and
destination that is associated with all packets in a message. Creating a connection
involves three steps:
• Connection establishment
• Data transfer & Connection release.
11. What are the techniques used in multiplexing?
The three basic techniques of multiplexing are,
Frequency-division multiplexing
Time-division multiplexing
Wave-division multiplexing
12. What is meant by congestion?
Congestion in a network occur if user send data into the network at a rate
greater than that allowed by network resources.
13. Why the congestion occur in network?
Congestion occur because the switches in a network have a limited buffer
size to store arrived packets.
14. How will the congestion be avoided?
The congestion may be avoided by two bits
BECN - Backward Explicit Congestion Notification
FECN - Forward Explicit Congestion Notification
15. What is the function of BECN BIT?
The BECN bit warns the sender of congestion in network. The sender can
respond to this warning by simply reducing the data rate.
16. What is the function of FECN?
The FECN bit is used to warn the receiver of congestion in the network.
The sender and receiver are communicating with each other and are using some
types of flow control at a higher level.
17. What is meant by quality of service?
The quality of service defines a set of attributes related to the performance
of the connection. For each connection, the user can request a particular attribute
each service class is associated with a set of attributes.
18. What are the two categories of QoS attributes?
The two main categories are
User Oriented
Network Oriented
19. List out the user related attributes?
User related attributes are
SCR – Sustainable Cell Rate
PCR – Peak Cell Rate
MCR- Minimum Cell Rate
CVDT – Cell Variation Delay Tolerance
20. What are the networks related attributes?
The network related attributes are,
Cell loss ratio (CLR)
Cell transfer delay (CTD)
Cell delay variation (CDV)
Cell error ratio (CER)
21. What is frame?
A frame consists of one complete cycle of time slots, including one or
more slot dedicated to each sending device.
22. What is interleaving?
The switch moves from device to device at a constant rate and fixed order.
This process is called interleaving.
23. What is framing bits?
One or more synchronization bits are usually added to the beginning of
each frame. These bitts are called framing bits.
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