Assignment 1
Question one:
a) Explain the difference between Connectionless and connection-oriented protocols with
examples for each in no more than one page.
b) Explain the difference between Reliable and Unreliable protocols with examples for each in
no more than one page.
A:
S. Comparison Connection-oriented Service Connection Less Service
No Parameter
1. Related It is designed and developed based on It is service based on the postal system.
System the telephone system.
2. Definition It is used to create an end to end It is used to transfer the data packets
connection between the senders to the between senders to the receiver
receiver before transmitting the data without creating any connection.
over the same or different network.
3. Virtual path It creates a virtual path between the It does not create any virtual
sender and the receiver. connection or path between the sender
and the receiver.
4. Authentication It requires authentication before It does not require authentication
transmitting the data packets to the before transferring data packets.
receiver.
5. Data Packets All data packets are received in the Not all data packets are received in the
Path same order as those sent by the same order as those sent by the
sender. sender.
6. Bandwidth It requires a higher bandwidth to It requires low bandwidth to transfer the
Requirement transfer the data packets. data packets.
7. Data It is a more reliable connection service It is not a reliable connection service
Reliability because it guarantees data packets because it does not guarantee the
transfer from one end to the other end transfer of data packets from one end
with a connection. to another for establishing a
connection.
8. Congestion There is no congestion as it provides There may be congestion due to not
an end-to-end connection between providing an end-to-end connection
sender and receiver during between the source and receiver to
transmission of data. transmit of data packets.
9. Examples Transmission Control Protocol (TCP) is User Datagram Protocol (UDP), Internet
an example of a connection-oriented Protocol (IP), and Internet Control
service. Message Protocol (ICMP) are examples
of connectionless service.
B:
B:
Reliable protocol implies the Protocol provides assurance of the delivery of data to the intended recipient(s), as
opposed to an unreliable protocol, which does not provide notifications to the sender as to the delivery of
transmitted data or messages.
Reliability is a synonym for assurance, which is the term used by the ITU and ATM Forum in the context of
the ATM Service-Specific Coordination Function, for example for transparent assured delivery with AAL5.
Reliable protocols typically incur more overhead than unreliable protocols, and as a result, function more slowly and
with less scalability. This often is not an issue for unicast protocols, but it may become a problem for
reliable multicast protocols.
TCP, the main protocol used on the Internet, is a unicast Reliable protocol. UDP, often used in computer games or in
other situations where speed is an issue and the loss of a little data is not as important because of the transitory nature
of the data, is an unreliable protocol.
Often, a unicast Reliable protocol is also connection-oriented. For example, TCP is connection-oriented, with the virtual-
circuit ID consisting of source and destination IP Address and port numbers.
Some unreliable protocols are connection-oriented as well. These include ATM and frame relay. There are also reliable
connectionless protocols, such as AX.25 when it passes data in I-frames. But this combination occurs rarely: reliable-
connectionless is uncommon in commercial and academic networks.
