Chapter 2 Flashcards
Give any two Transport layer service.
TCP and UDP are two transport layer protocols that provide a different set of services to the network layer.
What is a Port?
a port or port number is a number assigned to uniquely identify a connection endpoint and to direct data to a specific service.
Give the datagram format of UDP?
The header consists of a 16-bit source port, a 16-bit destination port, a 16-bit length, and a 16-bit checksum.
What is the main difference between TCP & UDP?
The main difference between TCP (transmission control protocol) and UDP (user datagram protocol) is that TCP is a connection-based protocol and UDP is connectionless.
Name the techniques and policies that can prevent (avoid) congestion.
The techniques and policies that can help prevent (avoid) congestion in networks are:
Traffic Shaping – Controls the rate of data transmission by regulating the data flow, typically using methods like leaky bucket or token bucket algorithms.
Admission Control – Limits the number of users or data flows admitted into the network to ensure it does not exceed capacity, preventing potential congestion.
List out various congestion control techniques.
- Traffic Shaping
- Congestion Avoidance
- Window-Based Flow Control
- Admission Control
- Load Shedding
What is the use of UDP’s Pseudo header?
The pseudo header conceptually prefixed to the UDP header contains the source address, the destination address, the protocol, and the UDP length. This information gives protection against misrouted datagrams. This checksum procedure is the same as is used in TCP.
Outline Stop and Wait ARQ mechanism.
A stop-and-wait ARQ sender sends one frame at a time; it is a special case of the general sliding window protocol with transmit and receive window sizes equal to one in both cases. After sending each frame, the sender doesn’t send any further frames until it receives an acknowledgement (ACK) signal.
What do you mean by slow start in TCP congestion?
Slow start, defined by RFC 5681. is part of the congestion control strategy used by TCP in conjunction with other algorithms to avoid sending more data than the network is capable of forwarding, that is, to avoid causing network congestion
Differentiate congestion control and flow control.
Flow control is an end-to-end mechanism that controls the traffic between a sender and a receiver. Flow control occurs in the data link layer and the transport layer. Congestion control is used by a network to control congestion in the network.
List the different phases used in TCP Connection.
The three phases of TCP operations
Connection establishment.
Data transfer.
Connection termination.
List the advantages of Connection oriented services over connectionless services.
Advantages of Connection-Oriented Services
This is mostly a reliable connection.
Congestions are less frequent.
Sequencing of data packets is guaranteed.
Problems related to duplicate data packets are alleviated.
Suitable for long connection.
Define SCTP.
Stream Control Transmission Protocol (SCTP) is a connection-oriented network protocol for transmitting multiple streams of data simultaneously between two endpoints that have established a connection in a computer network.
Define Multihoming concept of SCTP.
The ability of an endpoint to support multiple IP addresses is known as multihoming, which means SCTP can transmit to an alternative IP address belonging to the endpoint in case of a network failure or adverse conditions.
What happens in a three-way handshaking between any 2devices?
A ‘Three-Way Handshake’ is a special sequence of three TCP segments exchanged between a client and a server to establish an end-to-end connection over an unreliable IP network, ensuring both hosts are aware of the connection status before data transfer begins.
If data length is 16 bytes, calculate the efficiency of transmission in TCP.
Given:
- Data length = 16 bytes
- TCP header = 20 bytes
Total segment size = 16 + 20 = 36 bytes
Efficiency = (Data length / Total segment size) × 100
= (16 / 36) × 100
= 44.44%
In TCP whether FIN segment closes connection in one direction or two directions?
TCP allows you to close each direction of the connection independently. A TCP connection is considered to be half-closed when it’s closed in one direction and still open in the other direction.
What does the Transport layer Provide?
Layer 4 of the OSI Model: Transport Layer provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers.
Compare TCP Header and UDP Header.
The size of a Header in TCP is 20 bytes. The size of a Header in UDP is 8 bytes. It offers an extensive acknowledgment of data and error checking. It follows basic mechanisms of data checking like checksums.
Define Demultiplexing.
Demultiplexing (a.k.a. demuxing) is the process of extracting each individual signal from within a single stream, where these signals have previously been combined via multiplexing.
