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
The
network layer is responsible for the source-to-destination delivery of packet
across multiple network links.
Transport layer delivery
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 sizes
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. Explain the main idea of UDP.
UDP is
called a connectionless, unreliable transport protocol. It does not add
anything to the services of IP except to provide process-to-process
communication instead of host-to-host communication. Also, it performs very
limited error checking.
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. Name the parameters of quality of services in a
network.
Reliability,
Delay, Jitter & Bandwidth.
12. What is meant by congestion? Why the congestion
occur in network?
Congestion
in a network occurs if user sends data into the network at a rate greater than
that allowed by network resources. Congestion occurs because the switches in a
network have a limited buffer size to store arrived packets.
13. What is Three-way Handshaking?
The
connection establishment in TCP is called three-way handshaking. The process
starts with the server. The server program tells its TCP that it ready to
accept a connection. This is called a request for a passive open. Although the
server TCP is ready to accept any connection from any machine in the world, it
cannot make the connection itself.
The
client program issues a request for an active open. A client that wishes to
connect to an open server tells its TCP that it needs to be connected to that
particular server. TCP can now start the three-way handshaking process.
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? What are
the two categories of QoS attributes?
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.
The two
main categories are
·
User Oriented
·
Network Oriented
18. What is TCP?
TCP
guarantees the reliable, in order delivery of a stream of bytes. It is a
full-duplex protocol, meaning that each TCP connection supports a pair of byte
streams, one flowing in each direction.
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? What is framing bits?
A frame
consists of one complete cycle of time slots, including one or more slot
dedicated to each sending device. One or more synchronization bits are usually
added to the beginning of each frame. These bitts are called framing bits.
22. What is interleaving?
The
switch moves from device to device at a constant rate and fixed order. This
process is called interleaving.
23. Give the difference between service point
address, logical address & physical address? Service point addressing
The
transport layer header includes a type of address called a service point
address or port address, which makes a data delivery from a specific process on
one computer to a specific process on another computer.
Logical addressing
If a
packet passes the network boundary we need another addressing to differentiate
the source and destination systems. The network layer adds headers, which
indicate the logical address of the sender and receiver.
Physical addressing
If the
frames are to be distributed to different systems on the network, the data link
layer adds the header, which defines the source machine’s address and the
destination machine’s address.
Glossary:
Congestion: Excessive network or internetwork traffic causing a general
degradation of service
First-In, First-Out (FIFO) Queue: A queue in which the first item in is the first item out.
Forward Explicit Congestion Notification
(FECN): A bit in the Frame Relay packet thatnotifies the destination
of congestion.
Internet Assigned Numbers Authority
(lANA): A group supported by the U.S. governmentthat was responsible
for the management of Internet domain names and addresses until October 1998.
Leaky Bucket Algorithm: An algorithm to shape bursty traffic.
Priority Queueing: A queuing technique in which packets are assigned to a priority
class, eachwith its own queue.
Pseudoheader: Information from the IP header used only for checksum calculation
in the UDPand TCP packet.
Quality of Service (QoS): A set of attributes related to the performance of the connection.
Socket Address: A structure holding an IP address and a port number.
Token: A small packet used
in token-passing access method.
Token Bucket: An algorithm that allows idle hosts to accumulate credit for the
future in theform of tokens.
Token Passing: An access method in which a token is circulated in the network.
The station thatcaptures the token can send data.
Transmission Control Protocol (TCP): A transport protocol in the TCP/IP protocol suite.
User Datagram Protocol (UDP): A connectionless TCP/IP transport layer protocol.
Weighted Fair Queuing: A packet scheduling technique to improve QoS in which the
packetsare assigned to queues based on a given priority number.
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