LAN FundamentalsLAN Fundamentals

ETT 592

LAN Administration

Network ModelsNetwork Models

• Shared Processing

• Distributed Processing– Peer to Peer– Client Server

Shared ProcessingShared Processing

• Mainframe/Unix/Windows Terminal Server environment

• All users share the same processor

• Users connect via “terminal emulation”

Peer to PeerPeer to Peer

• EASY!!!!• CHEAP!!!!!• Allows File and

Peripheral Sharing

• No centralized control

• Generally insecure• Unreliable

Client ServerClient Server

• Centralized Management

• High Security• Reduced client

management• Easy backup• Scalability

• Higher hardware cost (dedicated server)

• Server is failure point

• More difficult to manage

LAN ComponentsLAN Components

• File Server

• Application Software

• Workstations / Client OS

• NICs

• Shared Peripherals

• Data Files

• NOS

File ServerFile Server

• Central system• Controls authentication• Provides management of resources and

peripherals• Often multi-processor• Significant HD capacity• BIG Box• Becomes the weakest link

Application SoftwareApplication Software

• Programs that perform tasks– Office Suites– Database applications

WorkstationWorkstation

• Provide connection to network

• May or may not have HD

• May or may not be “dumb terminals”

• Can be running a variety of OS’s depending on network capabilities

Workstation OSWorkstation OS

• Singletasking vs. Multitasking– Cooperative (like kids sharing)– Preemptive (like kids sharing with

supervision)

• Single User vs. Multi User

• Network protocol support

NICsNICs

• Network Interface Cards

• Allow physical connection between network and the computer

• Manufactured by MANY companies.– Buy from a major vendor– Try to standardize

Data FilesData Files

• The most significant reason we network today

• Provides shared, controlled access to resources

• Provides centralized backup of resources

Server StorageServer Storage

• HD capacity

• MTBF

• RAID 0, 1, 5

So What is RAID ???So What is RAID ???

• Redundant Array of Inexpensive Disks

• Can be done through OS or using special SCSI controller cards

RAID 0RAID 0

• Disk Striping w/o parity

• Data written to multiple disks

• No increase in security

• Great Increase in I/O

RAID 1RAID 1

• Disk Mirroring / Duplexing• Mirroring

– Two drives, single controller– Redundancy, no I/O benefit

• Duplexing– Two drives, two controllers– Redundancy, I/O read benefit

• Storage capacity ½ of drive space

RAID 5RAID 5

• Disk Striping with Parity

• Data and parity blocks spread across all drives

• Writes may be a bit slower

• Reads are faster

• Get redundancy

• Storage capacity is #drives-1

Shared PeripheralsShared Peripherals

• Printers

• Fax Servers

NOSNOS

• Network Operating Systems

• Windows NT

• Windows 2000

• Windows XP

• Unix / Linux

• Mac OS X

Hot SwapHot Swap

• Ability to replace parts while system is running– Power supplies– HD

The weakest linkThe weakest link

• Server failure or downtime leads to productivity loss– Clustering prevents this

• Server failure leads to inability to authenticate– PDC and BDC

• File retrieval is often slower– Data files compared to application software

• Security Problems

The weakest link (cont)The weakest link (cont)

• Power Problems– Redundant power supplies– UPS– Generators

How are networks builtHow are networks built

• Several components that must first be considered.

Network TopologiesNetwork Topologies

• Bus

• Star

• Ring

• Mesh

Access TypesAccess Types

• Contention Based– CSMA/CD

• Deterministic– Token Passing

Cable TypesCable Types

• Coax– RG58

• UTP– CAT3– CAT5– CAT6e

• Fiber Optic

Network TypesNetwork Types

• Ethernet– 10Base-2– 10Base-T– 100Base-T

• Token Ring– Standard Token Ring– FDDI

10Base-210Base-2

• Bus Configuration

• RG58 wire with 50ohm terminator

10Base-210Base-2

• Maximum Segment Distance 185m (607 ft)

• Maximum network length 925m(3,035 ft)

10Base-T/ 10Base-10010Base-T/ 10Base-100

• Ethernet / Star configuration

• Category 3 UTP=10mbs

• Category 5 UTP=100mbs

10Base-T/ 10Base-10010Base-T/ 10Base-100

• Number of stations set by concentrator

• 1,024 stations per network

• 100 m to concentrator (328 ft)

Token RingToken Ring

• Token Passing Scheme

• Systems are connected to MAU

• Operate at 4 or 16mb

• Now use “Early Token Release”

• Tend to handle network load better

FDDI (Fiber Distributed FDDI (Fiber Distributed Data Interface)Data Interface)

• Token passing scheme

• Dual counter rotating rings

• Fiber optic cable

• Class A connections are fault tolerant

• Class B connections are not fault tolerant

How do the parts work How do the parts work togethertogether

• OSI Model is the theoretical basis

• No one adheres exactly to the model, but everyone understands what it means.

OSI ModelOSI Modelhttp://webopedia.internet.com/quick_ref/OSI_Layers.html

Physical LayerPhysical Layer

• Cabling, Topology

• Electrical Communications Stuff

• Cable and how it connects to the card

Data LinkData Link

• Organizes frames into structured data packets

• 802.3 (CSMA/CD Ethernet)

• 802.5 (Token Ring)

• 802.11 (Wireless)

Network LayerNetwork Layer

• Responsible for routing data in subnetted network– If a transport protocol doesn’t support this

layer it is unroutable

• IP address converted to/from MAC Address

Transport LayerTransport Layer

• Makes sure data gets from one point to another

• Error Detection and recovery

Session LayerSession Layer

• Logical connection between network devices

Presentation LayerPresentation Layer

• Translates data from application layer to transmission format

• Encoding/Decoding

• ASCII, .DOC, .MPG, .JPG

Application LayerApplication Layer

• End User Software

• Email, File Transfer, Word,

How to rememberHow to remember

• Application• Presentation• Session• Transport• Network• Data Link• Physical

Please Do Not Throw Sausage Pizza Away

Network GearNetwork Gear

• Hubs ( a splitter )– OSI layer 1 (Physical)

• Switches ( an intelligent splitter )– OSI layer 2 (Data Link)

• MAUs ( a hub for a token ring network )– OSI layer 1 (Physical)

• Routers (moves data between networks and subnets )– OSI layer 3 (Network)

IP AddressingIP Addressing

• Address Classifications

• Subnetting

IP Address ClassesIP Address Classes

Class Range # Networks Hosts/ Network

A 1-126 126 16,777,214

B 128-191.255 16,384 65,534

C 192.0.0-225.255.255

2,097,152 254

So you want an addressSo you want an address

• Class A addresses are all gone

• Class B addresses are basically gone

• Class C addresses are available

Reserved AddressesReserved Addresses

• Class A 10.0.0.0-10.255.255.255

• Class B 172.16.0.0 – 172.31.255.255

• Class C 192.168.0.0 – 192.168.255.255

• Loop Back 127.0.0.1

• Reserved addresses are NEVER routed

What’s a subnet?What’s a subnet?

• Logical organization of computers

• A way to reduce network traffic

• A way to efficiently use assigned addresses

Getting an IP addressGetting an IP address

• Hard Coding– Manual Entry of

• DNS Servers (Domain Name Services)• Gateways (Routers)• IP Address

• DHCP– Dynamic Host Control Protocol

IP Configuration IP Configuration ExampleExample