chapter 9 computer networks
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Chapter 9 Computer Networks. Chapter Topics. OSI network layers Network Topology Media access control Addressing and routing Network hardware Network standards. OSI Network Layers. OSI Network Layers. - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 9
Computer Networks
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Chapter Topics
OSI network layers Network Topology Media access control Addressing and routing Network hardware Network standards
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OSI Network Layers
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OSI Network Layers
Presentation Layer – ensures that data transmitted by one network node is correctly interpreted by the other network node.
Session Layer – establishes and manages communication sessions.
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OSI Network Layers
Transport Layer – formats messages into packets suitable for transmission over the network.
Network Layer – routes packet to their proper destination.
Data Link Layer – interface between network software and hardware.
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OSI Network Layers
Physical Layer – the layer at which communication between devices actually takes place.
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Mathieson’s Three Layers
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Chapter Topics
OSI network layers Network Topology Media access control Addressing and routing Network hardware Network standards
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Network Topology
Definition of Network Topology Point-to-Point transmission Shared Connections Store and Forward Physical Topology (star, bus, ring) Logical Topology
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Network Topology
Network topology refers to: The spatial organization of network devices. The physical routing of network cabling. The flow of message from one network node to
another.
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Network Topology
Point-to-Point transmission – the line is laid over the shortest path and connected directly to both nodes. Used for small networks.
Shared connections – smaller shared links are connected to larger shared links. Used for larger networks.
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Network Topology
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Network Topology
Store and Forward - interconnected system of end nodes and transfer points used to route data among end nodes.
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Network Topology
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Network Topology
Physical topology – refers to the physical placement of cables and device connections to those cables.
Logical topology – refers to the path that messages traverse as they travel from node to node.
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Network Topology
Physical Topology Star Bus Ring
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Network Topology
Star Topology Uses a central node to which all other
nodes are connected. The central node can be a transfer
point. Advantage: simple wiring. Disadvantage: the failure of the hub
disables the entire network.
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Network Topology
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Network Topology
Bus Topology Connects each node to a common
transmission line. Transmitted messages travel from a
node across the common transmission line.
Advantage: simple wiring and low susceptibility to failure.
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Network Topology
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Network Topology
Ring Topology Connects each network node to two other
nodes and the entire network forms a closed loop.
Advantages: long maximum network length and low susceptibility to noise and distortion.
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Network Topology
Ring Topology
Disadvantages: Susceptibility to failure and difficulty adding , deleting and moving nodes.
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Network Topology
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Network Topology
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Network Topology
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Chapter Topics
OSI network layers Network Topology Media access control Addressing and routing Network hardware Network standards
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Media Access Control
Definition of a Collision Methods for dealing with Collisions Carrier Sense Multiple Access with Collision
Detection Token Passing
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Media Access Control
Collision – noise or interference in a message.
Methods for dealing with collisions: Carrier Sense Multiple Access/Collision Detection
(CSMA/CD) Token Passing
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Media Access Control
Carrier Sense Multiple Access/Collision Detection – (Commonly used on bus network topologies)
A node that wants to transmit listens (carrier sense) until no traffic is detected.
The node then transmits its message.
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Media Access Control
Carrier Sense Multiple Access/Collision Detection –
The node listens during and immediately after its transmission. If abnormally high signal levels are heard, which is a collision detection, then the node ceases transmission.
If a collision is detected, the node waits for a random time interval and then retransmits its message.
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Media Access Control
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Media Access Control
Token Passing
Used in ring network topologies. A token is passed from node to node. Only the node with the token can pass a
message. Advantage: simplicity. Disadvantage: inefficient use of data
transfer capacity.
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Chapter Topics
OSI network layers Network Topology Media access control Addressing and routing Network hardware Network standards
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Addressing and Routing
Definition of a Local Area Network Definition of a Wide Area Network Local Area Network Routing Wide Area Network Routing
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Addressing and Routing
Local Area Network – a network covering a floor or building.
Wide Area Network – a network a network that spans large physical distances, such as multiple buildings, cities, regions, or continents.
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Addressing and Routing
Local Area Network Routing
Each time a node is started, it sends a message announcing its presence and its address to the nearest hub.
Each hub maintains a table of addresses and transmission lines or connections ports and uses that table to make routing decisions.
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Addressing and Routing
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Addressing and Routing
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Addressing and Routing
Wide Area Network Routing
Each router knows: The addresses and physical locations of its own
nodes Other nearby routers Groups of addresses that they control Default destination for messages to the addresses
that it does not know
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Chapter Topics
OSI network layers Network Topology Media access control Addressing and routing Network hardware Network standards
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Network Hardware
Network Hardware Devices: Network interface units or network interface
cards Hub Bridges Routers Switches
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Network Hardware
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Technology Focus
Home Networks
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TCP/IP
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Chapter Topics
OSI network layers Network Topology Media access control Addressing and routing Network hardware Network standards
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Network Standards
The Institute of Electrical and Electronic Engineers (IEEE) has drafted a number of telecommunication and network standards – IEEE 803 standards.
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Network Standards
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Technology Focus - Ethernet
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Technology Focus - Ethernet
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Windows Commands
ipconfig ipconfig /all net statistics workstation net use net view
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Summary
Network topology refers to the spatial organization of network devices, the physical routing of network cabling and the flow of messages from one network node to another.
LANs are interconnected to form WANs.
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Summary
A media access control (MAC) protocol specifies rules for accessing a shared transmission medium.
Network hardware devices include NIUs, hubs, bridges, routers, and switches.
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Summary
The Open Systems Interconnection (OSI) model is an ISO conceptual model that divides network architecture into seven layers.
TCP/IP is the core Internet protocol suite.
The IEEE 802 standards cover many types of networks.