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Semester 1Semester 1

CHAPTER 3CHAPTER 3

Le Chi TrungLe Chi Trung

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ContentContent

• Basic LAN devices

• Basics of data flow through LANs

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ScheduleSchedule

No Name Est time No Name30-Jul Chapter 2 Online Exam

3.1 Basics LAN devices 1:00:003.2 The evolution of network devices

01-Aug 3.3 The basics of data flow through LANs 0:30:00 Discussion3.4 The building of LANs 3.4.2 Basic LAN setup

Summary Chapter 3 0:30:0003-Aug Chapter 3 Online Exam

DateLesson Lab

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BASIC LAN DEVICESBASIC LAN DEVICES

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Are you able to describe this diagram?Are you able to describe this diagram?

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Physical & Logical TopologiesPhysical & Logical Topologies

• Physical topologies

– Define the actual layout of the wire (media)

• Logical topologies

– Define how the media is accessed by the hosts

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Physical TopologiesPhysical Topologies

Bus

Ring

Star

ExtendedStar

Hierarchical

Mesh

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Physical Topology:Physical Topology: Bus Bus

• Single backbone

• All hosts directly connected to backbone

• Each end of the bus must be properly terminated

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Physical Topology:Physical Topology: Ring Ring

• No backbone

• A host is directly connected to each of its neighbors

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Physical Topology:Physical Topology: Star Star

• All devices connected to a central point

• Center of star is usually a hub or a switch

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Physical Topology:Physical Topology: Extended Star Extended Star

• Connects individual star topologies together.

• At the center of the star is a hub or a switch.

• Extends the length and size of the network.

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Physical Topology:Physical Topology: Hierarchical Hierarchical

• Like the extended star except a computer controls traffic (not a hub or a switch).

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Physical Topology:Physical Topology: Mesh Mesh

• Each host has its own connection to every other host.

• Used in situations where communication must not be interrupted.

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Logical TopologiesLogical Topologies

Broadcast

Token Passing

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Logical Topology:Logical Topology: BroadcastBroadcast

• Each host on the LAN sends its data (or broadcasts its data) to every other host.

• First-come, first-serve.

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Logical Topology:Logical Topology: Token PassingToken Passing

• Access to media is controlled by an electronic token.

• Possession of the token gives the host the right to pass data to its destination.

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TechnologiesTechnologies

Ethernet

FDDI

Token Ring

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Technology:Technology: Token Ring Token Ring

Token Ring

Token Passing

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Technology:Technology: FDDI FDDI

FDDI

Token Passing

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Technology:Technology: Ethernet Ethernet

Ethernet

Broadcast

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HostsHosts

Computer Server

Printer

NICNIC

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LAN Media SymbolsLAN Media Symbols

TokenRing

FDDIRing

EthernetLine

SerialLine

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OSI Review:OSI Review: Layer 1 Layer 1

• Responsibility:– Transmission of an unstructured bit stream

over a physical link between end systems.

• Concerned:– Bits.

– Electrical specifications.

– Physical data rate.

– Distances.

– Physical connector.

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LAN Device:LAN Device: Transceiver Transceiver

• Connect different media technologies.

• Layer 1 device.

UTP

BNC

AUI

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LAN Device:LAN Device: Repeater Repeater

• Regenerates and repeats the signal.

• Layer 1 device.

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LAN Device:LAN Device: Hub Hub

• A multi-port repeater.

• Layer 1 device.

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OSI Review:OSI Review: Layer 2 Layer 2

• Responsibility:– Provides for the reliable transfer of data

cross a physical link.

• Concerned:– Frames.

– Physical address (HW or MAC): Flat.

– Line discipline.

– Error and flow control.

– “Segment”.

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LAN Device:LAN Device: NIC NIC

• Network interface of hosts.

• Build-in physical address.

• Layer 2 device.

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LAN Device:LAN Device: Bridge Bridge

• Keeps traffic local by filtering traffic based on physical addresses.

• Layer 2 device.

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LAN Device:LAN Device: Switch Switch

• A multi-port bridge.

• Layer 2 device.

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OSI Review:OSI Review: Layer 3 Layer 3

• Responsibility:– Connection and path selection between two

end system across networks.

• Concerned:– Packets.

– Logical address: Hierarchical.• Networks and Hosts addressing.

– Route , Routing table, Routing protocol.

– “Network”.

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LAN Device:LAN Device: Router Router

• Makes decisions based on network addresses (logical addresses).

• Layer 3 device.

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LAN Device:LAN Device: Router Functions Router Functions

• Path determination:

– The process of evaluating a packet’s destination IP address so that the router can decide which port to send out the packet.

• Packet switching:

– The router re-encapsulates the packet in the protocol needed for the specified port and then switches the packet out that port.

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LAN Device:LAN Device: Cloud Cloud

• Another network

• Include layer 1 – 7 devices

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Devices function at LayersDevices function at Layers

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Teaching TopologyTeaching Topology

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History of NetworkingHistory of Networking

Homework

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ReviewReview

• Physical and logical topologies.

• LAN devices.

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DATA FLOW THROUGH LANsDATA FLOW THROUGH LANs

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Air Mail ExampleAir Mail Example

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EncapsulationEncapsulation

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Encapsulation:Encapsulation: Example Example

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Host to host communicationHost to host communication

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Packet Flow: Packet Flow: Layer 1 DeviceLayer 1 Device

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Packet Flow: Packet Flow: Layer 2 DeviceLayer 2 Device

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Packet Flow:Packet Flow: Layer 3 Device Layer 3 Device

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Packet Flow:Packet Flow: Layer 1-7 Device Layer 1-7 Device

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Packet Traveling Over NetworkPacket Traveling Over Network

Homework

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Preparation for LABPreparation for LAB

• 3.4.1: Readiness.

• 3.4.2: Building a simple network.

• Lab companion:

– 3.4.2

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ReviewReview

• Encapsulation.

• Data flow.