The document summarizes key topics related to data link control and computer networks, including:
- Announcements about an upcoming midterm exam covering data link control topics.
- An overview of different types of flow control mechanisms used in the data link layer, including stop-and-wait and sliding window protocols.
- Details on error detection techniques like parity checking and cyclic redundancy checks (CRCs).
- Automatic repeat request (ARQ) error control mechanisms like stop-and-wait ARQ, go-back-N ARQ, and selective reject ARQ.
- An introduction to the High Level Data Link Control (HDLC) standard and its use of primary, secondary, and combined station types in different link configurations.
This document summarizes key topics related to data link control and protocols. It discusses framing methods like fixed-size and variable-size framing. It also covers flow control, error control, and protocols for both noiseless and noisy channels. Specific protocols described include the Simplest Protocol, Stop-and-Wait Protocol, Stop-and-Wait ARQ, Go-Back-N ARQ, and Selective Repeat ARQ. The document provides details on their design, algorithms, and flow diagrams to illustrate how each protocol handles framing, flow control, and error control.
S.VIJAYALAKSHMI M.SC(CS) discusses Media Access Control and multiple access protocols. The main task of MAC protocols is to minimize collisions and utilize bandwidth by determining when nodes can access the shared channel, what to do when the channel is busy, and how to handle collisions. Early protocols like Aloha and slotted Aloha were inefficient at high loads due to many collisions. CSMA protocols reduce collisions by having nodes listen first before transmitting, but collisions are still possible due to propagation delays.
Distance Vector & Link state Routing AlgorithmMOHIT AGARWAL
1) Each router maintains a routing table containing the outgoing link and distance to reach each destination node. 2) Routers periodically share their routing tables with neighbors so each can update its own table. 3) This allows routers to continuously determine the shortest paths to all destinations as network conditions change.
This document presents an overview of computer network congestion and congestion control techniques. It defines congestion as occurring when too many packets are present in a network link, causing queues to overflow and packets to drop. It then discusses factors that can cause congestion as well as the costs. It outlines open-loop and closed-loop congestion control approaches. Specific algorithms covered include leaky bucket, token bucket, choke packets, hop-by-hop choke packets, and load shedding. The document concludes by noting the importance of efficient congestion control techniques with room for improvement.
The document discusses various protocols and approaches for improving the performance of TCP over wireless networks. It notes that wireless networks have higher bit error rates, lower bandwidth, and mobility issues compared to wired networks. Several protocols are described that aim to distinguish wireless losses from congestion losses to avoid unnecessary TCP reactions:
- Indirect TCP splits the connection and handles losses locally at the base station. Snoop caches packets at the base station for retransmission.
- Mobile TCP further splits the connection and has the base station defer acknowledgments. It can also inform the sender about handoffs versus interface switches.
- Multiple acknowledgments uses two types of ACKs to isolate the wireless and wired portions of the network.
-
This document discusses various data link control protocols. It covers framing, flow and error control, and specific protocols like HDLC and PPP. Framing involves adding structure like headers and trailers to organize data into packets. Flow and error control techniques like stop-and-wait ARQ and sliding window protocols are used to ensure reliable transmission over noisy channels. HDLC is a widely used bit-oriented protocol that defines frame structures and error control. PPP is a point-to-point protocol commonly used for dial-up internet access.
Connection Establishment & Flow and Congestion ControlAdeel Rasheed
On these slides i describe all the detail about Connection Establishment & Flow and Congestion Control. For more detail visit: https://chauhantricks.blogspot.com/
This document summarizes key topics related to data link control and protocols. It discusses framing methods like fixed-size and variable-size framing. It also covers flow control, error control, and protocols for both noiseless and noisy channels. Specific protocols described include the Simplest Protocol, Stop-and-Wait Protocol, Stop-and-Wait ARQ, Go-Back-N ARQ, and Selective Repeat ARQ. The document provides details on their design, algorithms, and flow diagrams to illustrate how each protocol handles framing, flow control, and error control.
S.VIJAYALAKSHMI M.SC(CS) discusses Media Access Control and multiple access protocols. The main task of MAC protocols is to minimize collisions and utilize bandwidth by determining when nodes can access the shared channel, what to do when the channel is busy, and how to handle collisions. Early protocols like Aloha and slotted Aloha were inefficient at high loads due to many collisions. CSMA protocols reduce collisions by having nodes listen first before transmitting, but collisions are still possible due to propagation delays.
Distance Vector & Link state Routing AlgorithmMOHIT AGARWAL
1) Each router maintains a routing table containing the outgoing link and distance to reach each destination node. 2) Routers periodically share their routing tables with neighbors so each can update its own table. 3) This allows routers to continuously determine the shortest paths to all destinations as network conditions change.
This document presents an overview of computer network congestion and congestion control techniques. It defines congestion as occurring when too many packets are present in a network link, causing queues to overflow and packets to drop. It then discusses factors that can cause congestion as well as the costs. It outlines open-loop and closed-loop congestion control approaches. Specific algorithms covered include leaky bucket, token bucket, choke packets, hop-by-hop choke packets, and load shedding. The document concludes by noting the importance of efficient congestion control techniques with room for improvement.
The document discusses various protocols and approaches for improving the performance of TCP over wireless networks. It notes that wireless networks have higher bit error rates, lower bandwidth, and mobility issues compared to wired networks. Several protocols are described that aim to distinguish wireless losses from congestion losses to avoid unnecessary TCP reactions:
- Indirect TCP splits the connection and handles losses locally at the base station. Snoop caches packets at the base station for retransmission.
- Mobile TCP further splits the connection and has the base station defer acknowledgments. It can also inform the sender about handoffs versus interface switches.
- Multiple acknowledgments uses two types of ACKs to isolate the wireless and wired portions of the network.
-
This document discusses various data link control protocols. It covers framing, flow and error control, and specific protocols like HDLC and PPP. Framing involves adding structure like headers and trailers to organize data into packets. Flow and error control techniques like stop-and-wait ARQ and sliding window protocols are used to ensure reliable transmission over noisy channels. HDLC is a widely used bit-oriented protocol that defines frame structures and error control. PPP is a point-to-point protocol commonly used for dial-up internet access.
Connection Establishment & Flow and Congestion ControlAdeel Rasheed
On these slides i describe all the detail about Connection Establishment & Flow and Congestion Control. For more detail visit: https://chauhantricks.blogspot.com/
There are two types of network links: point-to-point links between two nodes and broadcast links where nodes share a common transmission medium. Broadcast links use multiple access protocols to determine how nodes access the shared medium as only one node can transmit at a time. Common multiple access protocols for broadcast links include Aloha, CSMA, and CSMA/CD which use random access or carrier sensing to regulate transmissions and avoid or detect collisions between nodes transmitting simultaneously. Controlled access protocols like token passing also exist where nodes must obtain a token to transmit on the shared medium.
The network layer is responsible for host-to-host delivery of data packets. It provides packetizing, routing, and forwarding services. Packetizing involves encapsulating the transport layer payload with a network header at the source host and decapsulating it at the destination host. Routing determines the best path between source and destination hosts using routing protocols. Forwarding involves routers inspecting packet headers and sending packets to the next network along the path.
Stop-and-wait ARQ is a method used in telecommunications to reliably transmit information between connected devices. It ensures packets are not lost and are received in the correct order. The sender transmits one frame at a time and waits for an acknowledgment before sending the next frame. If the acknowledgment is not received within a timeout period, the sender retransmits the frame. Sequence numbers are used to detect duplicate or out-of-order frames.
The document discusses network layer performance and congestion control. It covers key network layer performance metrics like delay, throughput and packet loss. It then discusses various sources of delay like transmission, propagation, processing and queuing delays. It also discusses throughput and packet loss. The second half of the document focuses on congestion control techniques including open-loop methods like retransmission policies and closed-loop methods like backpressure and explicit signaling.
Go-Back-N (GBN) is an ARQ protocol that allows a sender to transmit multiple frames before receiving an acknowledgement. The sender maintains a window of size N, meaning it can transmit N frames before waiting for a response. The receiver window is always size 1, acknowledging frames individually. If a frame times out without an ACK, the sender retransmits that frame and all subsequent frames in the window. GBN improves efficiency over stop-and-wait by allowing transmission of multiple frames while reducing waiting time at the sender.
This document describes the sliding window protocol. It discusses key concepts like both the sender and receiver maintaining buffers to hold packets, acknowledgements being sent for every received packet, and the sender being able to send a window of packets before receiving an acknowledgement. It then explains the sender side process of numbering packets and maintaining a sending window. The receiver side maintains a window size of 1 and acknowledges by sending the next expected sequence number. A one bit sliding window protocol acts like stop and wait. Merits include multiple packets being sent without waiting for acknowledgements while demerits include potential bandwidth waste in some situations.
HDLC is a bit-oriented protocol defined by ISO for point-to-point and multipoint communication over data links. It supports full-duplex communication and provides reliability, efficiency and flexibility. HDLC defines three types of stations - primary, secondary and combined. It uses three frame types - unnumbered, information and supervisory frames. HDLC also specifies three data transfer modes - normal response mode, asynchronous response mode and asynchronous balanced mode. [/SUMMARY]
This document discusses the types of delays that can occur in packet switched networks:
- Processing delay is the time for a router to examine a packet's header and determine where to send it. Queuing delay is the time a packet waits in a queue before transmission. Transmission delay is the time to push a packet onto the link. Propagation delay is the time for a bit to propagate between nodes.
- Queuing delay depends on traffic intensity, which is the ratio of arrival rate to transmission rate - if greater than 1, queues can grow without bound. Packet loss occurs when queues are full.
- The total nodal delay is the sum of processing, queuing, transmission, and propagation delays
The document summarizes key concepts related to network layer addressing, error reporting, and multicasting from Chapter 21. It includes:
1) Address mapping allows mapping between logical and physical addresses either statically or dynamically using protocols like ARP.
2) ICMP compensates for IP's lack of error reporting and host/management queries through error messages and query messages.
3) IGMP manages multicast group membership and communication on local networks through group management and messages.
4) ICMPv6 is modified from ICMPv4 for IPv6 with updated error reporting and query messages.
The document discusses network topologies and their characteristics. It describes physical and logical topologies. Common topologies include mesh, star, bus, ring, tree and hybrid configurations. Mesh provides redundancy but is expensive to implement while star is popular for its ease of installation and fault isolation. Bus uses the least cabling but a single break disables the network. Ring passes signals in one direction making it susceptible to breaks. Hybrid combines different topologies to balance advantages and disadvantages. The optimal topology depends on factors like cost, growth and cable requirements.
The document outlines an educational activity plan consisting of several steps:
1. A 5 minute warm up video will motivate students.
2. Students will brainstorm essential questions about network cable types and features for 15 minutes.
3. The teacher will then demonstrate different cable types for 10 minutes before assigning independent research activities.
This document provides an overview of congestion control presented by a group. It defines congestion as occurring when there is too much traffic on a subnet causing it to go out of buffer. The main causes of congestion are identified as insufficient memory, slow processors, high packet arrival rates, and low bandwidth lines. Several principles for preventing congestion are discussed, including load shedding, choke packets, traffic shaping using leaky bucket and token bucket algorithms, and random early detection. The presentation concludes with the group welcoming questions.
This document discusses different types of multiplexing techniques. It describes that multiplexing allows simultaneous transmission of multiple signals across a single data link using a multiplexer device. At the receiving end, a demultiplexer separates the combined signals. The key types of multiplexing covered are frequency division multiplexing (FDM), time division multiplexing (TDM), and wave division multiplexing (WDM). FDM uses different frequencies, TDM divides time into slots, and WDM uses different light wavelengths. Synchronous and asynchronous TDM are also explained, with synchronous TDM assigning fixed time slots and asynchronous using flexible slots.
This document provides an overview of the transport layer and transport layer protocols. It begins with an introduction to the transport layer, describing its location and functions such as providing process-to-process communication between hosts using logical connections. It then discusses transport layer services including addressing with port numbers, encapsulation/decapsulation, multiplexing/demultiplexing, flow control, error control, congestion control. Finally it describes some common transport layer protocols like UDP, TCP and their mechanisms.
The network layer is responsible for delivering packets from source to destination. It must know the topology of the subnet and choose appropriate paths. When sources and destinations are in different networks, the network layer must deal with these differences. The network layer uses logical addressing that is independent of the underlying physical network. Routing ensures packets are delivered through routers and switches from source to destination across interconnected networks.
The document discusses data link layer protocols, including LLC, MAC, and Ethernet standards. It describes the functions of the physical layer, data link layer, and logical link control sublayer. It also covers IP addressing schemes like IPv4 addresses, network classes, public vs private addresses, and subnetting. CIDR is introduced as a method to improve address space utilization and routing scalability on the internet.
This document summarizes Carrier Sense Multiple Access (CSMA) techniques for digital data communication systems. It describes four CSMA access modes: 1-Persistent, Non-Persistent, P-Persistent, and O-Persistent. It also discusses CSMA protocol modifications like CSMA with Collision Detection (CSMA/CD), CSMA with Collision Avoidance (CSMA/CA), and Virtual Time CSMA (VTCSMA). Applications of different CSMA techniques are provided. At the end, it mentions including a MATLAB code sample for CSMA/CD.
The document discusses data link control protocols that manage the exchange of data over a communication link. It covers several important topics:
1) Framing involves packing data bits into distinguishable frames using techniques like byte stuffing and bit stuffing.
2) Flow and error control ensure reliable data transmission by preventing buffer overflows and allowing retransmission of corrupted frames. Common methods are stop-and-wait and sliding window protocols.
3) Specific protocols like go-back-N and selective reject are examined, combining framing, flow control, and error handling over noiseless and noisy channels. Utilization rates under different protocols are also calculated.
The document summarizes key concepts about data link control protocols from William Stallings' Data and Computer Communications textbook. It describes flow control, error detection, and error control mechanisms like stop-and-wait, sliding windows, and automatic repeat request (ARQ). It also provides details about the High-Level Data Link Control (HDLC) protocol, including HDLC frame structure, types of frames, station types, transfer modes, and general operation.
There are two types of network links: point-to-point links between two nodes and broadcast links where nodes share a common transmission medium. Broadcast links use multiple access protocols to determine how nodes access the shared medium as only one node can transmit at a time. Common multiple access protocols for broadcast links include Aloha, CSMA, and CSMA/CD which use random access or carrier sensing to regulate transmissions and avoid or detect collisions between nodes transmitting simultaneously. Controlled access protocols like token passing also exist where nodes must obtain a token to transmit on the shared medium.
The network layer is responsible for host-to-host delivery of data packets. It provides packetizing, routing, and forwarding services. Packetizing involves encapsulating the transport layer payload with a network header at the source host and decapsulating it at the destination host. Routing determines the best path between source and destination hosts using routing protocols. Forwarding involves routers inspecting packet headers and sending packets to the next network along the path.
Stop-and-wait ARQ is a method used in telecommunications to reliably transmit information between connected devices. It ensures packets are not lost and are received in the correct order. The sender transmits one frame at a time and waits for an acknowledgment before sending the next frame. If the acknowledgment is not received within a timeout period, the sender retransmits the frame. Sequence numbers are used to detect duplicate or out-of-order frames.
The document discusses network layer performance and congestion control. It covers key network layer performance metrics like delay, throughput and packet loss. It then discusses various sources of delay like transmission, propagation, processing and queuing delays. It also discusses throughput and packet loss. The second half of the document focuses on congestion control techniques including open-loop methods like retransmission policies and closed-loop methods like backpressure and explicit signaling.
Go-Back-N (GBN) is an ARQ protocol that allows a sender to transmit multiple frames before receiving an acknowledgement. The sender maintains a window of size N, meaning it can transmit N frames before waiting for a response. The receiver window is always size 1, acknowledging frames individually. If a frame times out without an ACK, the sender retransmits that frame and all subsequent frames in the window. GBN improves efficiency over stop-and-wait by allowing transmission of multiple frames while reducing waiting time at the sender.
This document describes the sliding window protocol. It discusses key concepts like both the sender and receiver maintaining buffers to hold packets, acknowledgements being sent for every received packet, and the sender being able to send a window of packets before receiving an acknowledgement. It then explains the sender side process of numbering packets and maintaining a sending window. The receiver side maintains a window size of 1 and acknowledges by sending the next expected sequence number. A one bit sliding window protocol acts like stop and wait. Merits include multiple packets being sent without waiting for acknowledgements while demerits include potential bandwidth waste in some situations.
HDLC is a bit-oriented protocol defined by ISO for point-to-point and multipoint communication over data links. It supports full-duplex communication and provides reliability, efficiency and flexibility. HDLC defines three types of stations - primary, secondary and combined. It uses three frame types - unnumbered, information and supervisory frames. HDLC also specifies three data transfer modes - normal response mode, asynchronous response mode and asynchronous balanced mode. [/SUMMARY]
This document discusses the types of delays that can occur in packet switched networks:
- Processing delay is the time for a router to examine a packet's header and determine where to send it. Queuing delay is the time a packet waits in a queue before transmission. Transmission delay is the time to push a packet onto the link. Propagation delay is the time for a bit to propagate between nodes.
- Queuing delay depends on traffic intensity, which is the ratio of arrival rate to transmission rate - if greater than 1, queues can grow without bound. Packet loss occurs when queues are full.
- The total nodal delay is the sum of processing, queuing, transmission, and propagation delays
The document summarizes key concepts related to network layer addressing, error reporting, and multicasting from Chapter 21. It includes:
1) Address mapping allows mapping between logical and physical addresses either statically or dynamically using protocols like ARP.
2) ICMP compensates for IP's lack of error reporting and host/management queries through error messages and query messages.
3) IGMP manages multicast group membership and communication on local networks through group management and messages.
4) ICMPv6 is modified from ICMPv4 for IPv6 with updated error reporting and query messages.
The document discusses network topologies and their characteristics. It describes physical and logical topologies. Common topologies include mesh, star, bus, ring, tree and hybrid configurations. Mesh provides redundancy but is expensive to implement while star is popular for its ease of installation and fault isolation. Bus uses the least cabling but a single break disables the network. Ring passes signals in one direction making it susceptible to breaks. Hybrid combines different topologies to balance advantages and disadvantages. The optimal topology depends on factors like cost, growth and cable requirements.
The document outlines an educational activity plan consisting of several steps:
1. A 5 minute warm up video will motivate students.
2. Students will brainstorm essential questions about network cable types and features for 15 minutes.
3. The teacher will then demonstrate different cable types for 10 minutes before assigning independent research activities.
This document provides an overview of congestion control presented by a group. It defines congestion as occurring when there is too much traffic on a subnet causing it to go out of buffer. The main causes of congestion are identified as insufficient memory, slow processors, high packet arrival rates, and low bandwidth lines. Several principles for preventing congestion are discussed, including load shedding, choke packets, traffic shaping using leaky bucket and token bucket algorithms, and random early detection. The presentation concludes with the group welcoming questions.
This document discusses different types of multiplexing techniques. It describes that multiplexing allows simultaneous transmission of multiple signals across a single data link using a multiplexer device. At the receiving end, a demultiplexer separates the combined signals. The key types of multiplexing covered are frequency division multiplexing (FDM), time division multiplexing (TDM), and wave division multiplexing (WDM). FDM uses different frequencies, TDM divides time into slots, and WDM uses different light wavelengths. Synchronous and asynchronous TDM are also explained, with synchronous TDM assigning fixed time slots and asynchronous using flexible slots.
This document provides an overview of the transport layer and transport layer protocols. It begins with an introduction to the transport layer, describing its location and functions such as providing process-to-process communication between hosts using logical connections. It then discusses transport layer services including addressing with port numbers, encapsulation/decapsulation, multiplexing/demultiplexing, flow control, error control, congestion control. Finally it describes some common transport layer protocols like UDP, TCP and their mechanisms.
The network layer is responsible for delivering packets from source to destination. It must know the topology of the subnet and choose appropriate paths. When sources and destinations are in different networks, the network layer must deal with these differences. The network layer uses logical addressing that is independent of the underlying physical network. Routing ensures packets are delivered through routers and switches from source to destination across interconnected networks.
The document discusses data link layer protocols, including LLC, MAC, and Ethernet standards. It describes the functions of the physical layer, data link layer, and logical link control sublayer. It also covers IP addressing schemes like IPv4 addresses, network classes, public vs private addresses, and subnetting. CIDR is introduced as a method to improve address space utilization and routing scalability on the internet.
This document summarizes Carrier Sense Multiple Access (CSMA) techniques for digital data communication systems. It describes four CSMA access modes: 1-Persistent, Non-Persistent, P-Persistent, and O-Persistent. It also discusses CSMA protocol modifications like CSMA with Collision Detection (CSMA/CD), CSMA with Collision Avoidance (CSMA/CA), and Virtual Time CSMA (VTCSMA). Applications of different CSMA techniques are provided. At the end, it mentions including a MATLAB code sample for CSMA/CD.
The document discusses data link control protocols that manage the exchange of data over a communication link. It covers several important topics:
1) Framing involves packing data bits into distinguishable frames using techniques like byte stuffing and bit stuffing.
2) Flow and error control ensure reliable data transmission by preventing buffer overflows and allowing retransmission of corrupted frames. Common methods are stop-and-wait and sliding window protocols.
3) Specific protocols like go-back-N and selective reject are examined, combining framing, flow control, and error handling over noiseless and noisy channels. Utilization rates under different protocols are also calculated.
The document summarizes key concepts about data link control protocols from William Stallings' Data and Computer Communications textbook. It describes flow control, error detection, and error control mechanisms like stop-and-wait, sliding windows, and automatic repeat request (ARQ). It also provides details about the High-Level Data Link Control (HDLC) protocol, including HDLC frame structure, types of frames, station types, transfer modes, and general operation.
This document discusses digital communication and data link control. It covers flow control methods like stop and wait and sliding windows to prevent buffer overflow. It also discusses fragmentation, error detection using cyclic redundancy checks, and error control protocols like automatic repeat request (ARQ) using stop and wait, go back N, and selective reject. Finally, it summarizes the High-Level Data Link Control (HDLC) protocol including frame structure, address fields, control fields, information fields, frame check sequences, and the initialization, data transfer, and disconnection phases of HDLC operation.
This document discusses various data link layer protocols for flow control. It describes an unrestricted simplex protocol with infinite buffer capacity and no need for flow control. For a simplex stop-and-wait protocol, a sequence number is needed to distinguish frames when the channel is noisy. A simplex protocol for a noisy channel uses positive acknowledgement and retransmission. This becomes a duplex channel, requiring a type field and ability to piggyback acknowledgements. A sliding window protocol maintains a sender and receiver window of allowed sequence numbers. It provides flexibility while ensuring ordered delivery to the network layer. Different sliding window protocols are examined, including ones using go-back-N and selective repeat.
TCP uses congestion control to prevent network congestion collapse. It uses additive increase multiplicative decrease (AIMD) where the sending rate is increased slowly but cut in half after a loss. TCP paces packets using a congestion window that limits unacknowledged data. It uses slow start to quickly reach bandwidth and congestion avoidance to increase the window by 1 packet per RTT. This models TCP behavior and shows throughput is related to window size, loss rate, and RTT.
- TCP uses congestion control and avoidance to prevent network congestion collapse. It operates in a distributed manner without centralized control.
- TCP's congestion control is based on additive increase, multiplicative decrease (AIMD) and uses a congestion window and packet pacing to smoothly increase and decrease transmission rates in response to packet loss as a signal of congestion.
- The key mechanisms are slow start for initial rapid ramp up, congestion avoidance for gradual increase, fast retransmit for quick recovery from single losses, and timeout for recovery from multiple losses or ack losses. These mechanisms work together to keep TCP stable and efficient under different network conditions.
Flow control is used to prevent a sender from overwhelming a receiver. It uses feedback from the receiver to control sending. Stop-and-wait protocols only allow one frame to be sent before waiting for acknowledgement. Go-back-n protocols allow multiple unacknowledged frames but require resending all frames if any are lost. Selective repeat protocols only resend lost frames to improve efficiency.
This document provides a summary of the transport layer of computer networks. It discusses key topics like UDP, TCP, connection management, flow control, congestion control, and quality of service. UDP provides a connectionless, unreliable service while TCP provides connection-oriented, reliable byte streaming. TCP uses three-way handshaking for connection establishment and termination. It implements flow control using sliding windows and employs congestion control algorithms like additive increase/multiplicative decrease. The document also covers transport layer concepts like ports, checksums, and retransmission methods in TCP.
TCP provides reliable, ordered, and error-checked delivery of data between applications running on hosts communicating over an IP network. It uses three-way handshake for connection establishment, acknowledgments and retransmissions for reliability, flow control using sliding windows, and congestion control using slow start and congestion avoidance. TCP has timers for retransmissions, persistence, keepalives, and ensuring connections have terminated.
Different protocols for data communication networks Nt Arvind
Different protocols for data communication networks.
Variable-size framing protocols add header and trailer flags or bytes to distinguish frames. Character protocols use byte stuffing to avoid flag patterns in data. Bit protocols use bit stuffing to avoid flag bit patterns. Stop-and-wait protocols send one frame then wait for ACK before sending again. Go-back-N protocols send multiple frames before needing ACKs and resend missing frames. Selective repeat protocols resend only missing frames. HDLC is a common bit-oriented protocol that uses frame types and sequence/control fields. PPP is a byte-oriented protocol that carries user data or protocol information.
The document discusses flow control in TCP. It explains that TCP uses a sliding window mechanism for flow control to balance the sender's transmission rate with the receiver's reception rate. The size of the sliding window is determined by the receiver's advertised window size and the congestion window size. TCP provides reliable, in-order delivery of data segments through error control methods like checksums, acknowledgements, and retransmissions. It also addresses problems like delayed ACKs, silly window syndrome, and solutions to improve TCP transmission efficiency.
The document discusses flow control in TCP. It explains that TCP uses a sliding window mechanism for flow control to balance the sender's transmission rate with the receiver's reception rate. The sliding window allows packets within the window to be transmitted, and slides to the right when acknowledgments are received, making room for more packets. Problems like delayed acknowledgments, silly window syndrome, and solutions like Nagle's algorithm are also covered. TCP provides reliable data transfer using error control mechanisms like checksums, acknowledgments, and retransmissions of lost packets.
The document discusses the data link layer. It covers the following key points in 3 sentences:
The data link layer provides services such as error detection, multiple access control for shared mediums, and link layer addressing. It discusses various techniques for error detection and correction as well as multiple access protocols including CSMA/CD, TDMA, and ALOHA. The data link layer is implemented in network interface cards in each host and is responsible for framing data, performing error checking, and transferring frames between adjacent nodes over a link.
This document summarizes key concepts about congestion control in TCP including:
- TCP uses additive increase multiplicative decrease (AIMD) to dynamically adjust the congestion window size and maintain efficiency and fairness.
- TCP has slow start and congestion avoidance states that govern how the congestion window is adjusted in response to acknowledgements.
- TCP responds to packet loss through fast retransmit, fast recovery, and halving the congestion window size to reduce congestion according to protocols like Tahoe, Reno, and New Reno.
Queuing theory and traffic analysis in depthIdcIdk1
This document provides a summary of concepts in queuing theory and network traffic analysis. It discusses queuing theory concepts like Little's Law, M/M/1 queues, and Kendall's notation. It then covers an empirical study of router delay that models delays using a fluid queue and reports on busy period metrics. Finally, it discusses the concept of network traffic self-similarity found in measurements of Ethernet LAN traffic.
TFWC is a proposed window-based congestion control algorithm that is designed to be TCP-friendly for real-time multimedia applications, while addressing some issues with the standard rate-based TFRC algorithm. TFWC uses a TCP-like acknowledgment clock and window sizing equation to achieve smooth throughput similar to TFRC, but provides better fairness when competing with TCP traffic and is simpler to implement without needing to measure round-trip times. Analysis shows that TFWC provides fairness comparable to TFRC, smoothness on par with TFRC, and faster responsiveness to changes in available bandwidth.
Module15: Sliding Windows Protocol and Error Control gondwe Ben
Here are the key steps in stop-and-wait ARQ when frame 1 is lost:
1. Station A transmits frame 0 and waits for ACK
2. Station B receives frame 0 and sends ACK
3. Station A receives ACK and transmits frame 1
4. Frame 1 is lost in transmission
5. Station A's timer expires before receiving ACK for frame 1
6. Station A retransmits frame 1
The key aspects are that the sender transmits one frame at a time and waits for ACK before sending the next frame. If ACK is not received within the timeout period, the frame is retransmitted.
Flow and error control are important functions of the data link layer. Flow control coordinates the amount of data sent before receiving acknowledgement to prevent buffers from overflowing. Error control detects and corrects damaged frames using automatic repeat request (ARQ) protocols. Three common ARQ protocols are described: stop-and-wait, go-back-N, and selective repeat. Stop-and-wait sends one frame at a time while the others use sliding windows to allow multiple outstanding frames. Go-back-N resends frames from the last acknowledged in order, while selective repeat resends only damaged frames.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
2. Announcements
• Midterm: November 25, Tuesday, 10:40 – 12:30
— in FASS G062 (FASS auditorium)
• Exam will be closed book, closed notes
— calculators are allowed
— you are responsible all topics I covered in the class even if some of
them are not in the book (I sometimes used other books) and not in
the ppt files (I sometimes used board and showed applications on
the computer)
• I prepared some handouts for the topics that I covered from other
books (available at SUCourse under "resources") but I do not
promise any completeness
• There really are some parts that I only covered on the board
3. Flow Control
• In Data Link Layer, we deal with issues related
to point to point links
—Flow control is one of these issues
• Flow control is needed since the sending entity
should not overwhelm the receiving entity
—Recipient needs some time to process incoming
packets
—If sender sends faster than recipient processes, then
buffer overflow occurs
• flow control prevents buffer overflow
4. Performance Metrics and
Delays (Section 5.3)
• Transmission time (delay)
—Time taken to emit all bits into medium
• Propagation time (delay)
—Time for a bit to traverse the link
• Processing time (delay)
—time spent at the recipient or intermediate node for
processing
• Queuing time (delay)
—waiting time at the queue to be sent out
5. Model of Frame Transmission
transmission
time
propagation time
6. Stop and Wait Flow Control
• Source transmits frame
• Destination receives frame and replies with
acknowledgement (ACK)
• Source waits for ACK before sending next frame
• Destination can stop flow by not sending ACK
• Works well for large frames
• Inefficient for smaller frames
7. Stop and Wait Flow Control
• However, generally large block of data split into
small frames
—Called “Fragmentation”
• Limited buffer size at receiver
• Errors detected sooner (when whole frame received)
– On error, retransmission of smaller frames is needed
• Prevents one station occupying medium for long periods
• Channel Utilization is higher when
—the transmission time is longer than the propagation time
—frame length is larger than the bit length of the link
—actually last two expressions mean the same
—see the derivations on board
8. Figure 5.6
Stop and Wait Link Utilization
propagation time = D, transmission time = T
t0 + T
t0 + Tt0 + D
t0 + D
t0 +T+D t0 +T+D
t0 +T+2D t0 +T+2D
D> T D< T
9. Sliding Window Flow Control
• The problem of “Stop and Wait” is not able to send
multiple packets
• Sliding Window Protocol allows multiple frames to be in
transit
• Receiver has buffer of W (called window size) frames
• Transmitter can send up to W frames without ACK
• Each frame is numbered
—Sequence number bounded by size of the sequence number
field (k bits)
—thus frames are numbered modulo 2k
(0 … 2k
-1)
• ACK includes number of next frame expected
12. Sliding Window Enhancements
in Implementation
• Receiver can acknowledge frames without
permitting further transmission (Receive Not
Ready)
—Must send a normal acknowledgement to resume
• If the link is duplex, use piggybacking
—Send data and ack together in one frame
• frame has both data and ack fields
—If no data to send, use acknowledgement frame
—If data but no acknowledgement to send, send last
acknowledgement number again
13. Sliding Windows Performance - 1
• two cases: W >= 2a+1 and W < 2a+1, where a=D/T
• details are on board
≥
T
2T
D
D+T
2D+T
( W.T ≥ 2D+T )
15. END OF MIDTERM EXAM
• The rest of this ppt file is not in the midterm
exam coverage
16. Error Detection and Control
• So far we have seen flow control mechanisms
where frames are transmitted without errors
—in real life any transmission facility may introduce
errors
• So we have to
—detect errors
—if possible, correct errors (not in the scope of CS 408)
—adopt flow control algorithms such that erroneous
frames are retransmitted
17. Types of Errors
• Single bit errors
—isolated errors
—affects (flips) one bit, nearby bits are not altered
—not so common in real life
• Burst errors
—a sequence of bits are affected
—most common case
—a burst error of length B is a contiguous sequence of
B bits in which the first and the last and some
intermediate bits are erroneously flipped.
• not necessarily all bits between the first and the last one
18. Error Detection
• Additional bits added by transmitter as error
detection code
—receiver checks this code
• Parity
—single bit added to the end of the data
—Value of parity bit is such that data and parity have
even (even parity) or odd (odd parity) number of ones
—Even number of bit errors goes undetected
• thus not so useful
20. Cyclic Redundancy Check (CRC)
• For a data block of k bits, transmitter generates n-
k bit frame check sequence (FCS) and appends it
to the end of the data bits
• Transmits n bits, which is exactly divisible by
some number (generator)
—the length of the generator is n-k+1 and first and last
bits are 1
• Receiver divides the received frame by generator
—If no remainder, assume no error
• Division is binary division (not the same as
integer or real division)
• See board for the math details and example
21. Cyclic Redundancy Check (CRC)
• Standard CRCs (generators are standard)
—checks all single, double and odd number of errors
—checks all burst errors with length less than or equal
to the length of FCS (n-k)
—checks most of the burst errors of longer length
• for bursts of length n-k+1 (length of generator), probability of
an undetected error is 1/2n-k-1
• for longer bursts, probability of an undetected error is 1/2n-k
22. Error Control
• Actions to be taken against
—Lost frames
—Damaged frames
• Automatic repeat request (ARQ) mechanism
components
—Error detection
—Positive acknowledgment
—Retransmission after timeout
—Negative acknowledgement and retransmission
24. Stop and Wait ARQ
• Source transmits single frame
• Wait for ACK
• If received frame is damaged, discard it
—If transmitter receives no ACK within timeout,
retransmits
• If ACK damaged,transmitter will not recognize it
—Transmitter will retransmit after timeout
—Receiver gets two copies of frame, but disregards
one of them
—Use ACK0 and ACK1
• ACKi means “I am ready to receive frame i”
26. Stop and Wait - Pros and Cons
• Simple
• Inefficient
27. Go-Back-N ARQ
• Based on sliding window
• If no error, ACK as usual with next frame
expected
—ACKi means “I am ready to receive frame i” and “I
received all frames between i and my previous ack”
• Sender uses window to control the number of
unacknowledged frames
• If error, reply with rejection (negative ack)
—Discard that frame and all future frames until the
frame in error received correctly
—Transmitter must go back and retransmit that frame
and all subsequent frames
28. Go-Back-N ARQ -
Damaged Frame
• Receiver detects error in frame i
• Receiver sends “reject i”
• Transmitter gets “reject i”
• Transmitter retransmits frame i and all
subsequent frames
29. Go-Back-N ARQ - Lost Frame (1)
• Frame i lost
• Transmitter sends frame i+1
• Receiver gets frame i+1 out of sequence
• Receiver sends “reject i”
• Transmitter goes back to frame i and
retransmits it and all subsequent frames
30. Go-Back-N ARQ- Lost Frame (2)
• Frame i lost and no additional frame sent
• Receiver gets nothing and returns neither
acknowledgment nor rejection
• Transmitter times out and sends
acknowledgment frame with P bit set to 1 (this is
actually a command for ack request)
—Receiver interprets this as an ack request command
which it acknowledges with the number of the next
frame it expects (i )
• Transmitter then retransmits frame i
31. Go-Back-N ARQ- Damaged/Lost
Acknowledgment
• Receiver gets frame i and sends
acknowledgment (i+1) which is lost
• Acknowledgments are cumulative, so next
acknowledgement (i+n) may arrive before
transmitter times out on frame i
==> NO PROBLEM
• If transmitter times out, it sends
acknowledgment request with P bit set, as
before
32. Go-Back-N ARQ- Damaged
Rejection
• As in lost frame (2)
—sender asks the receiver the last frame received and
continue by retransmitting next frame
34. Selective Reject
• Also called selective retransmission
• Only rejected frames are retransmitted
• Subsequent frames are accepted by the
receiver and buffered
• Minimizes retransmissions
• Receiver must maintain large enough buffer
• Complex system
36. Issues
• RR with P=1 is from HDLC standard
—pure protocol just have retransmissions after timeout
• as explained in Tanenbaum
37. Issues – Window Size
• Given n-bit sequence numbers, what is Max
window size?
—go-back-n ARQ 2n
-1
• Why?
• what about receiver’s window size?
– It is 1, why?
—selective-reject(repeat) 2n-1
• Why?
• See the reasons on the board
38. Issues – Buffer Size
• Go-back-n ARQ
—sender needs to keep a buffer equal to window size
• for possible retransmissions
—receiver does not need any buffer (for flow/error
control)
• why?
• Selective reject
—sender needs to keep a buffer of window size for
retransmissions
—receiver keeps a buffer equal to window size
39. Issues - Performance
• Notes on board
• Appendix at the end of Chapter 14
—selective reject ARQ is not in the book
40. High Level Data Link Control
• HDLC
• ISO Standard
• Basis for some other DLL protocols
41. HDLC Station Types
• Primary station
—Controls operation of link
—Frames issued are called commands
• Secondary station
—Under control of primary station
—Frames issued called responses
• Combined station
—May issue commands and responses
42. HDLC Link Configurations
• Unbalanced
—One primary and one or more secondary stations
—Supports full duplex and half duplex
• Balanced
—Two combined stations
—Supports full duplex and half duplex
43. HDLC Transfer Modes (1)
• Normal Response Mode (NRM)
—Unbalanced configuration
—Primary initiates transfer to secondary
—Secondary may only transmit data in response to
command from primary
—Terminal-host communication
• Host computer as primary
• Terminals as secondary
—not so common nowadays
44. HDLC Transfer Modes (2)
• Asynchronous Balanced Mode (ABM)
—Balanced configuration
—Either station may initiate transmission without
receiving permission
—Most widely used
45. Frame Structure
• All transmissions in frames
• Single frame format for all data and control
exchanges
47. Flag Fields
• Delimit frame at both ends
• 01111110
• Receiver hunts for flag sequence to synchronize
• Bit stuffing used to avoid confusion with data
containing 01111110
—0 inserted after every sequence of five 1s
—If receiver detects five 1s it checks next bit
• If 0, it is deleted
• If 1 and seventh bit is 0, accept as flag
—If sixth and seventh bits 1, sender is indicating abort
49. Address Field
• Identifies secondary station that sent or will
receive frame
• Usually 8 bits long (but 7 bits are effective)
• May be extended to multiples of 7 bits with prior
agreement
—leftmost bit of each octet indicates that it is the last
octet (1) or not (0)
50. Frame Types
• Information - data to be transmitted to user
—Acknowledgment is piggybacked on information
frames (only positive acknowledgment)
• Supervisory – ARQ messages
(RR/RNR/REJ/SREJ) when piggyback not used
(actually only RR can be piggybacked; for the
other, we need Supervisory frames)
• Unnumbered – supplementary link control
functions. For examples,
—setting the modes
—disconnect
• Control field is different for each frame type
52. Poll/Final Bit
• Use depends on context. A typical use is below.
• Command frame
—P bit set to 1 to solicit (poll) supervisory frame from
peer
• Response frame
—F bit set to 1 to indicate response to soliciting
command
53. Information Field
• Only in information and some unnumbered
frames
• Must contain integral number of octets
• Variable length
54. Frame Check Sequence Field
• FCS
• Error detection
• 16 bit CRC
• Optional 32 bit CRC
55. HDLC Operation
• Exchange of information, supervisory and
unnumbered frames
• Three phases
—Initialization
—Data transfer
—Disconnect
56. Initialization
• Issue one of six set-mode commands
—Signals other side that initialization is requested
—Specifies mode (NRM, ABM, ARM)
—Specifies 3- or 7-bit sequence numbers
• If request accepted HDLC module on other side
transmits "unnumbered acknowledged" (UA)
frame
• If request rejected, "disconnected mode" (DM)
sent
• All sent as unnumbered frames
57. Data Transfer
• Both sides may begin to send user data in I-frames
— N(S): sequence number of outgoing I-frames
• modulo 8 or 128, (3- or 7-bit)
— N(R) acknowledgment for I-frames received
• seq. number of I-frame expected next
• S-frames are also used for flow and error control
— Receive ready (RR) frame acknowledges last I-frame received
• Indicating next I-frame expected
• Used when there is no reverse data
— Receive not ready (RNR) acknowledges, but also asks peer to suspend
transmission of I-frames
• When ready, send RR to restart
— REJ initiates go-back-N ARQ
• Indicates last I-frame received has been rejected
• Retransmission is requested beginning with N(R)
— Selective reject (SREJ) requests retransmission of single frame
58. Disconnect
• Send disconnect (DISC) frame
• Remote entity must accept by replying with UA
—Informs layer 3 user about the termination of
connection
61. Other DLC Protocols
(LAPB,LAPD)
• Link Access Procedure, Balanced (LAPB)
—Part of X.25 (ITU-T)
—Subset of HDLC - ABM (Async. Balanced Mode)
—Point to point link between user and packet switching
network node
—HDLC frame format
• Link Access Procedure, D-Channel (LAPD)
—Part of ISDN (ITU-T)
—ABM
—Always 7-bit sequence numbers (no 3-bit)
—always 16-bit CRC
—16-bit address field
62. Other DLC Protocols (LLC)
• Logical Link Control (LLC)
—IEEE 802
—For LANs (Local Area Networks)
—Link control split between medium access control layer (MAC)
and LLC (on top of MAC)
—Different frame format
• Two addresses needed (sender and receiver) – actually at MAC layer
• Sender and receiver SAP addresses
• Control field is same as HDLC (16-bit version for I and S frames; 8-bit
for U frames)
—No primary and secondary - all stations are peers
—Error detection at MAC layer
• 32 bit CRC
63. Other DLC Protocols (LLC)
• LLC Services
—3 alternatives
—Connection Mode Services
• Similar to HDLC ABM
—Unacknowledged connectionless services
• no connection setup
• No flow-control, no error control, no acks (thus not reliable)
• good to be used with TCP/IP. Why?
—Acknowledged Connectionless Service
• No connection setup
• reliable communication