Chapter4 1
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This document discusses medium access control protocols for local and metropolitan area networks. It covers static and dynamic channel allocation and describes several multiple access protocols including ALOHA, carrier sense multiple access, collision-free protocols, and limited-contention protocols. Specific protocols covered in more detail include pure ALOHA, persistent and nonpersistent CSMA, CSMA/CD, bit-map and binary countdown collision-free protocols, and wireless LAN protocols.
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The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between adjacent network nodes in a wide area network (WAN) or between nodes on the same local area network (LAN) segment.
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2) The TCP header contains fields for source/destination ports, sequence numbers, acknowledgement numbers, flags, window size, checksum, and options. The UDP header contains fields for source/destination ports, length, and checksum.
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Multiple Access Protocal
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2) The TCP header contains fields for source/destination ports, sequence numbers, acknowledgement numbers, flags, window size, checksum, and options. The UDP header contains fields for source/destination ports, length, and checksum.
3) The main differences between TCP and UDP are that TCP is connection-oriented, provides error control and flow control, and supports full duplex communication
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2) Features of PPP framing including negotiated field sizes and use of LCP control messages.
3) Functions of data link layer including framing, flow control, error control, and media access control. The relationship between the logical link control and media access control sublayers is also covered.
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ATM is a cell relay protocol designed to optimize fiber optic networks. It breaks data into fixed-size cells for uniform transmission. ATM aims to maximize bandwidth, interface existing systems, be inexpensive, support telecom hierarchies, ensure reliable delivery, and minimize software functions. Connections between endpoints are established through virtual paths and circuits identified by header fields. Cells contain a 5-byte header and 48-byte payload. Connections can be permanent or switched. ATM defines layers for applications, cell processing, and physical transmission. It supports various quality of service levels through parameters like cell error and loss rates.
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The document discusses various medium access control protocols for local area networks:
1. Static channel allocation protocols like Frequency-Division Multiplexing (FDM) can waste bandwidth if the number of users is not exactly equal to the number of allocated channels.
2. Dynamic channel allocation protocols do not pre-allocate channels. The ALOHA and CSMA protocols allow nodes to transmit whenever the channel is sensed to be idle, which can still result in collisions.
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2. It explains that distance vector algorithms can have issues with counting to infinity and routing loops. Techniques like poison reverse are used to address this.
3. It notes that link state algorithms have faster convergence but require more overhead, while distance vector algorithms are simpler but can be slower to converge.
4. Hierarchical routing is introduced as a way to scale routing by organizing routers into autonomous systems (AS) with inter and intra-
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This document summarizes Chapter 4 of Andrew S. Tanenbaum's book "Computer Networks". The chapter discusses multiple access protocols and how to allocate a single broadcast channel among competing users. It begins by explaining the channel allocation problem for broadcast networks and introduces static and dynamic allocation schemes. It then provides an overview of several multiple access protocols, including ALOHA (pure and slotted versions) and Carrier Sense Multiple Access protocols. The goal of these protocols is to determine which user gets to transmit on the shared channel to avoid collisions and improve channel utilization.
mac-adhoc.ppt
This document discusses MAC protocols for ad hoc wireless networks. It begins by outlining key issues in designing MAC protocols, such as bandwidth efficiency, quality of service support, and addressing hidden and exposed terminal problems. It then classifies MAC protocols into contention-based, contention-based with reservation mechanisms, and contention-based with scheduling mechanisms. Several example protocols are described for each category, including how they address the issues outlined earlier in the document.
14653128.ppt
The document discusses MAC protocols for wireless sensor networks. It begins by outlining issues in designing MAC protocols for ad-hoc wireless networks, such as bandwidth efficiency, quality of service support, synchronization, and the error-prone shared wireless medium. It then describes the design goals of MAC protocols. The document classifies MAC protocols into three categories: contention-based protocols, contention-based protocols with reservation mechanisms, and contention-based protocols with scheduling mechanisms. Several examples are provided for each category, including MACA, FAMA, and RTMAC protocols.
CS6003 ADHOC & SENSOR NETWORKS
MAC PROTOCOLS FOR AD HOC WIRELESS NETWORKS
Issues in designing a MAC Protocol- Classification of MAC Protocols- Contention based protocols- Contention based protocols with Reservation Mechanisms- Contention based protocols with Scheduling Mechanisms – Multi channel MAC-IEEE 802.11
Unit-2 Media Access Protocols.pdf
Fast Ethernet increased the bandwidth of standard Ethernet from 10 Mbps to 100 Mbps. It used the same CSMA/CD access method and frame format as standard Ethernet but with some improvements. Fast Ethernet could operate in half-duplex like standard Ethernet but full-duplex mode became popular as it doubled the effective bandwidth to 200 Mbps by allowing simultaneous transmission and reception. Fast Ethernet led to the use of switches which established many independent full-duplex point-to-point links, eliminating collisions and allowing full bandwidth utilization.
RANDOM ACCESS PROTOCOL IN COMMUNICATION
In random access ,each station has right to send the data. However , if more than one station tries to send ,collision will occur .To avoid this collision , protocols came into existence.
In random access method , no stations are superior & none is assigned the control over the other .
When a station has a data to send , it uses a procedure defined by a protocol whether to send or not .
Mac protocols for ad hoc wireless networks
The document discusses MAC protocols for ad hoc wireless networks. It addresses key issues in designing MAC protocols including limited bandwidth, quality of service support, synchronization, hidden and exposed terminal problems, error-prone shared channels, distributed coordination without centralized control, and node mobility. Common MAC protocol classifications and examples are also presented, such as contention-based protocols, sender-initiated versus receiver-initiated protocols, and protocols using techniques like reservation, scheduling, and directional antennas.
Packet radio protocol
Packet radio protocols allow multiple subscribers to access a shared channel for transmitting data packets. They use contention-based random access techniques like ALOHA. Pure ALOHA protocol has low efficiency due to partial packet collisions. Slotted ALOHA synchronizes transmissions to time slots to prevent partial collisions, improving efficiency. Performance is evaluated using metrics like throughput, which is highest at optimal channel load and drops off above and below this point.
M.A.C (Medium Access Control)
Medium access control protocols can be classified as random access, controlled access, or channelization protocols. Random access protocols have no central control and stations decide independently when to transmit. Common random access protocols include ALOHA, CSMA, CSMA/CD, and CSMA/CA. Controlled access protocols require stations to get permission before transmitting, using methods like reservation, polling, or token passing. Channelization protocols divide the channel bandwidth by frequency (FDMA), time (TDMA), or code (CDMA).
Medium access control unit 3-33
1) Medium Access Control (MAC) protocols regulate access to shared wireless channels and ensure performance requirements of applications are met. They assemble data into frames, append addressing and error detection, and disassemble received frames.
2) Common MAC protocols include Fixed Assignment (e.g. TDMA), Demand Assignment (e.g. polling), and Random Assignment (e.g. ALOHA, CSMA). Schedule-based MAC protocols avoid contention through resource scheduling while contention-based protocols (e.g. CSMA/CA) allocate resources on demand, risking collisions.
3) The document discusses various MAC protocols for wireless sensor networks and their objectives to minimize energy waste from idle listening, collisions,
Mac
The document discusses MAC (medium access control) protocols. It provides information on:
1) MAC protocols allow multiple terminals to transmit over a wireless channel by sharing its capacity and dealing with issues like addressing and obtaining access.
2) MAC protocols were originally designed for wired networks but are now used for wireless due to packet loss mainly from collisions.
3) IEEE 802.15.4 MAC protocols are used for wireless sensor networks and home automation. They operate at data rates of 20kbps, 40kbps, and 250kbps across multiple frequency bands.
Mac
The document discusses broadcast networks and medium access control (MAC) protocols. It introduces the concepts of broadcast networks, where a single shared medium allows all connected devices to receive messages. This leads to potential conflicts when multiple devices try to transmit simultaneously. MAC protocols are needed to coordinate transmissions and resolve conflicts. Common MAC protocols discussed include ALOHA, CSMA, CSMA/CD (Ethernet), and token passing (Token Ring). LAN standards like IEEE 802.3 that define MAC sublayer functions for CSMA/CD networks are also summarized briefly.
Thesis Presentation on Renewal theory based 802.15.6 latest.pptx
The document discusses the IEEE 802.15.4 MAC protocol. It describes the protocol's operational modes including non-beacon enabled mode using unslotted CSMA/CA and beacon-enabled mode using slotted CSMA/CA. It also discusses the superframe structure used in beacon-enabled mode including the contention access period, contention free period, and optional inactive period. Finally, it summarizes a research paper that proposes a 3-level renewal process model to analyze the contention access period performance metrics like throughput and service time.
Similar to Chapter4 1 (20)
Thesis Presentation on Renewal theory based 802.15.6 latest.pptx
Thesis Presentation on Renewal theory based 802.15.6 latest.pptx
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Chapter4 1
- 1. Chapter 4 The Medium Access Control Sublayer
- 2. The Channel Allocation Problem • Static Channel Allocation in LANs and MANs • Dynamic Channel Allocation in LANs and MANs
- 3. Dynamic Channel Allocation in LANs and MANs 1. Station Model. 2. Single Channel Assumption. 3. Collision Assumption. 4. (a) Continuous Time. (b) Slotted Time. 5. (a) Carrier Sense. (b) No Carrier Sense.
- 4. Multiple Access Protocols • ALOHA • Carrier Sense Multiple Access Protocols • Collision-Free Protocols • Limited-Contention Protocols • Wavelength Division Multiple Access Protocols • Wireless LAN Protocols
- 5. Pure ALOHA In pure ALOHA, frames are transmitted at completely arbitrary times.
- 6. Pure ALOHA (2) Vulnerable period for the shaded frame.
- 7. Pure ALOHA (3) Throughput versus offered traffic for ALOHA systems.
- 8. Persistent and Nonpersistent CSMA Comparison of the channel utilization versus load for various random access protocols.
- 9. CSMA with Collision Detection CSMA/CD can be in one of three states: contention, transmission, or idle.
- 10. Collision-Free Protocols The basic bit-map protocol.
- 11. Collision-Free Protocols (2) The binary countdown protocol. A dash indicates silence.
- 12. Limited-Contention Protocols Acquisition probability for a symmetric contention channel.
- 13. Adaptive Tree Walk Protocol The tree for eight stations.
- 14. Wavelength Division Multiple Access Protocols Wavelength division multiple access.
- 15. Wireless LAN Protocols A wireless LAN. (a) A transmitting. (b) B transmitting.
- 16. Wireless LAN Protocols (2) The MACA protocol. (a) A sending an RTS to B. (b) B responding with a CTS to A.