Chapter 2Review of Computer Network Technology

Outline

1. Network Topology2. Local Area Networks3. Network Node Components4. Internet TCP/IP Protocols

Refer to net-inrtro.ppt

5. Transmission Technology

1. Network Topology- LAN Topology

Figure 2.1(b) Ring Topology

Figure 2.1(a) Bus Topology

Ethernet

DTE DTE DTE

DTE DTE

DTE

DTEDTE

DTE

DTE

DTE

DTE

DTE

Figure 2.1(d) Hub Configurations

DTE

DTE

DTE

DTE

Token Ring HubEthernet Hub

Figure 2.1(c) Star Topology

DTE

DTE

DTE

DTE

DTE DTE

BusBus

RingRing

StarStar

A Campus NetworkOf LANs

1. Network Topology- WAN Topology

MeshMesh TreeTree

2. Local Area Network Type of LANs

Ethernet Fast Ethernet Gigabit Ethernet Half-duplex Vs Full-duplex Switched Ethernet VLAN (Virtual LAN) Token Ring FDDI

Ethernet

• IEEE 802.3 standard• 10 Mbps data rate• CSMA/CDCSMA/CD

• Carrier Sense Multiple Access with Collision Carrier Sense Multiple Access with Collision DetectionDetection

• Analogy of a hollow pipe• Back Off Algorithm

• Packet Size: 64 ~ 1500 bytes• Segment length and drop cable length

EthernetTable 2.1 Ethernet LAN Topology Limits

TYPE DESCRIPTION SEGMENT LENGTH DROP CABLE

10Base2 Thin coax (0.25”) 200 meters Not allowed

10Base5 Thick Coax (0.5”) 500 meters Twisted pair: 50 meters

10Base-T Hub topology N/A Twisted pair: 100meters

10Base-F Hub topology N/A 2 km

10Base-T : 10 Mbps, Baseband, Twisted Pair

Fast Ethernet

PMD Sublayer

Convergence Layer

MAC Sublayer

LLCData Link

Physical

Network

Figure 2.4 100Base-T Fast Ethernet Protocol Architecture

LLC Logical Link controlMAC Medium Access ControlPMD Physical Medium Dependent

LAN - IEEE 802.x

Network

Data Link

Physical

LLC

MAC

802.1 (HLI)

802.2

802.

5

802.

3

802.

4

HLI: High Level InterfaceLLC: Logical Link ControlMAC: Medium Access Control

802.1: HLI802.2: LLC802.3: Ethernet802.4: Token Bus802.5: Token Ring

100 Mbps 100Base-T PMD (Physical Medium Dependent) subl

ayer – to be consistent with IEEE 802.3 UTP Category 5

Fast Ethernet

Gigabit Ethernet IEEE 802.3z 1 Gbps Packet size: 512 bytes

Table 2.2 Gigabit Ethernet Topology Limits

9micronSingle-Mode

50micronSingleMode

50 micronMultimode

62.5micron

Multimode

BalanceShielded

Cable

UTP

1000BASE-LX 10 km 3 km 550 m 440 m - -

1000BASE-SX - 550 m 260 m - -

1000BASE-CX - - - 25 m -

1000BASE-T - - - - 100 m

Full-Duplex Ethernet Half-Duplex Full-Duplex Coaxial Cables can not support full-dupl

ex. UTP + Hub with full-duplex support 10Base-T, 100Base-T, 100Base-F

↓ 10Base-Tx, 100Base-Tx, 100Base-Fx

Switched EthernetSwitched HubMulti-Port Bridge=

Virtual LAN

Advantages of VLAN

Performance Formation of Virtual Workgroups Simplified Administration Reduced Cost Security

Token Ring

DTE 4

DTE 3DTE 1

DTE 2

Figure 2.11 Token Ring LAN

TokenRing

3 to 1 ACK

1 to 3 MSG

DTE 1 hastoken control

IEEE 802.5

Dual Ring TR LAN

Figure 2.12(a) Token Ring Dual Ring Management

DTE 4

DTE 3DTE 1

DTE 2

RedundantRing

PrimaryRing

Failure Recovery in TR LAN

FDDI

• Fiber Distributed Date InterfaceFiber Distributed Date Interface• Uses fiber optics medium• Modified token ring protocol• Data rate 100 Mbps• Up to 500 DTEs in a single segments of 100 km wi

thout repeaters• Ideal for campus backbone network• Single and dual attached stations (SAS and DAS)• Dual attached stations load share the two rings

Dual Ring FDDI Network

Figure 2.13(a) Dual Ring FDDI Network Configuration

DAS

SASSAS

DAS

SAS Single Attached StationDAS Dual Attached Station

LAN Data Rate Race

E’Net10Mbps

FDDI100 Mbps

Fast E’Net100Mbps ATM

155.52 Mbps

Gbit E’Net1 Gbps

DuplexE’nets

ATMOC-n

3. Network Node Components

• Hubs• Bridges• Remote bridges• Routers• Gateways• Half bridge / half router• Switches

Basic Network Nodes

SwitchSwitch

BridgeBridge

RouterRouter

GatewayGateway

Networked Components

Hubs• Hub is a platform with multiple ports• Function dependent on what is housed

• LAN multi-port repeater• Switched LAN bridge (switched hub)

Stacked Hub

Bridges

Bridge

Local Bridge Remote Bridge

Simple

Multiport

MultiportMulti-protocol

Refer to Figure 2.17, page 77

Bridges Operates at Layer 2, the data link layer. Allows networks with different physical signaling, but

with compatible data link addressing schemes, to communicate.

Helps reduce traffic on a backbone LAN by filteringfiltering any information coming from one segment to another that does not need to be forwarded through the backbone.

A common use for a bridge is to allow users on an Ethernet LAN and a Token Ring LAN to communicate with each other.

Bridges Remote Bridges

Used to connect remote LANs Transparent Bridges

Used to connect LANs of the same types Use a Spanning Tree Algorithm for routing

Backward learning Routing Table of ports associated with destination addresses

Source Routing Bridges Used to network token-ring LANs Source is aware of the entire path to the destination.

Routers

• Routers operate at network layer• Routes packets between nodes of similar

network protocols• Routing table used to route packets• DLC and Physical layers could be different

under the same common network layer protocol

A Router Configuration

Gateway

• Gateway is router connecting two networks with dissimilar network protocols

• Gateway does the protocol conversion at the network layer

Protocol Converter• Protocol converterProtocol converter does the conversion at the

application layer

Gateway Configuration

Protocol interface

Physical medium

TP

NP

DP

Phy

TP

NP'

DP'

Phy'

Gateway

Network AProtocol P

Network BProtocol Q

Gateway

NP

DP

Phy

NP'

DP'

Phy'

Figure 2.22 Gateway Configuration

Tunneling Using Multiprotocol Routers

IP

MultiprotocolRouter

X.25

MultiprotocolRouter

IP

Ethe

rnet

Ethe

rnet

Tunnel

Figure 2.24 Tunneling Using Multiprotocol Routers

• Tunneling is transmission of packets (viamultiprotocol routers) by encapsulation

• In Figure 2.24, packets are encapsulated and transmitted through X.25 network in a serial mode

Half-Bridge/Half-Router•Half-bridge (half-router) is point-to-point communication

• Uses PPP protocol

• Helps low-end users to communicate with ISP on dial-up link saving the expense of dedicated link

• Router encapsulates packets in PPP frames and puts serial outputs to the bridge, and vice-versa

Switches

• Switches are embedded in bridges and routers• Switched network used in WAN• Two types of switched networks

• Circuit-switched• Packet-switched

• Datagram service• Virtual circuit

B

A D

C

DTE A DTE Z

Pkt3 Pkt2 Pkt1Pkt2 Pkt3 Pkt1

Pkt1Pkt3

Pkt2

Pkt2Pkt2

Figure 2.26(a) Datagram Configuration

B

A D

C

DTE A DTE Z

Pkt3 Pkt2 Pkt1Pkt3 Pkt2 Pkt1

Pkt3

Pkt2

Pkt1

Figure 2.26(b) Virtual Circuit Configuration

5. Transmission Technology

Transmission Technology

Medium Mode

Wired Wireless

LAN WAN

Digital Analog

LAN Mobile Satellite

Transmission MediaMedia

WirelineTransmission

WirelessTransmission

ElectricConductors

OpticalFiber

TwistedTwistedPairPair

CoaxialCoaxialCableCable

Mono-modeMono-mode Multi-modeMulti-mode

RadioRadio

MicrowaveMicrowaveSatelliteSatellite

TransmissionTransmission

InfraredInfrared

Laser LinksLaser Links

• Thin• Thick

• UTP• STP

Transmission ModesTransmission Modes

Figure 2.27(c) Cell Transmission (ATM)

Figure 2.27(b) Packet Transmission ( X.25)

User 1 User 2 User 3 User 4User 24

Time

Cha

nnel

Ban

dwid

th

Time

TimeDivision

Multiplexing(TDM)

User 2 User 3 User 4 User 5User 1

TimeB

andw

idth

Figure 2.27(a) T1 Time Division Multiplexing (TDM) Transmission

PacketMultiplexing

User 1

Ban

dwid

th

Time

User 3

User 4

User 2

User 3

User 1

5

User 1

User 4

User 1

User 1

5

CellMultiplexing

channel 2

channel 1

channel 24

TDM

PacketMultiplexing

CellMultiplexing