Networking FundamentalsNotes: highly technical, constantly changing

Goal: give you a sense of the basic choices

What is a network?

A collection of nodes linked together to allow transmissions between them

Basic Parts of a Network Architecture Topology: arrangement of nodes

Which node is connected to which node Transmission Media: Mechanism of flow

Wire or wireless Network Source

Make (build it yourself) or Buy Choices here determine hardware/software

Purpose of all networks facilitate communication…

internal and external to organization allow sharing of resources

hardware, data, applications

Network Architecture Components

What’s in a node that we link up: Single User Input/Output Devices

Dumb terminals, PCs, Thin Clients, Point of Sales, ATMs, etc. Host Systems (multi-user computers, see next slide) Network devices

Create net of devices, connect computers to them

Transmission media Wires (if wire based) Transceivers (if wireless)

Connection hardware Modems, codecs, network interface cards (NIC) Inter-networking: switches, routers, gateways

Plus software that runs them, personnel that install maintain hardware + software

Host Systems in Networks

Multi-user platforms Operating system must

Be secure, allocate resources to multiple users May connect I/O devices to them May connect hosts to each other using network

Categories Large Scale Processing Power

Mainframe or Enterprise Servers 1000s of users, lots of applications

Supercomputers Traffic cop on huge networks

Mid-Range Processing Power Mid-range servers (minicomputers) - 100s of users PC-based servers - up to 100 users

Network server or Specific service– Print server, file server, application server

Super-mini - traffic cop on large networks

I/O Devices on Nets

Dumb Terminals Only processing power is ability to ‘talk’ to host Screen + keyboard + comm chip Text interface, control keys, no mouse

PC Able to compute + connect Sophisticated graphical user interface

Thin Client, Network Machine (other names) Less than PC, more than Dumb Terminal

Older technology, no storage only memory, nice screen Designed to display web pgs

Computer + Mechanical systems Point of Sales Terminal

Automated cash register ATM (automatic teller machines Gas pumps

User Interface of an Application(text based interface)

What it looks like if you connect to host using a PC(text based interface inside a window)

I/O Devices on Nets - Dumb Terminals

Networking Architecture Types

Centralized ‘legacy’ systems Host does all processing, storage

1st mainframes, later mid-range

Users - dumb terminals, then PCs Connecting Devices

direct line or dial-up using modem

Topology - Star Telecomm Processors

multiplexers (Mux’s), front-end processor

Networking Architectures

Decentralized Architectures Independent machines (no network)

PCs = ‘Sneakernet’ Peer-to-peer (all machines equal, linked to each other)

a bunch of PCs in a LAN or a bunch of minis/mainframes in a WAN

topology = mesh

Distributed Architectures (Cent + Decent) Network server (manages network) Additional servers (file, apps, print)

Topology = star, bus, or ring

Topologies - Node layout + (protocol )Pictures show PC nets (LANs) but can use for internetworking too

Star (circuit switch or traffic host)

Bus (contention)

Tree (a set of bus nets)

Ring (packet switch)

Peer to Peer (store & forward)

A

A B

B

C

C

D

A B

C

D

network ready printer

(Switch, router, gateway) or host

AB

C ED

print servernet server

Networking Choices

Step 1: Which Architecture(s)? Decentralize (no net) - Stand-alone machines

Centralize - Single Host (s) Which type of I/O device?

Decentralized Net - Peer to Peer Who to connect to who?

Distributed LAN(s) w/ Network Server(s) Additional servers?

Primitive servers: file server, printer server – dedicated or not dedicated to the network

Advanced servers: web, mail and/or db server(s) Combination of the above Internetworking - connect nets to each other

Backbone, hubs, WAN

Connection Choices

Step 2: Transmission Media Choices Wires

metallic (transmit sound) twisted pair - cheap, easy to use, short distance

– Unshielded (interference prone, slow)– Shielded (faster, less interference)

coaxial - longer distance, up to 5500 channels fiber-optic (transmit light)

Dense (500,000 channels), very fast, secure Wireless

Short range options within/between buildings

Long range options across town + mobile IS

Wireless - Short Range Options

Wi-Fi (radio waves) - send soundcheap, slow, interference prone, diffusedistance: 75-800 depending on wallsBluetooth = radio protocol (handhelds)

Infrared - send lightcheap, faster than radio, distance: 50 ftno interference, stopped by walls

Laser - high frequency lightvery fast, costly, distance:1000 ft

Wireless - Long Range Options

Microwave - high frequency radio Antenna Based Network

line of sight - <= 30 miles apart cellular, pagers, mobile radio

honeycomb of antennas Satellites - extends microwave line of sight

geosynchronous orbit (22,000 miles) propagation delay global positioning system

low-orbit (500 miles) VSAT - very small aperture terminals

Must connect to vendor satellites

Mobile Options

Wireless mouse/keyboard (infrared/radio)

Personal Area Network (peer to peer) Bluetooth (radio wave)

Link up to 8 devices in 10meter area Wi-Fi in ad-hoc mode (radio)

Cellular Radio Honeycomb of antennas (peer to peer stars) Options in Cellular

Original Cellular - analog based (800-900 mhz) PCS - digital (1900 mhz)

RFID - tag w/ data about item It can transmit via radio over short distance

Passive (read only, can chg), Active

Other Transmission Concepts

Bandwidth - width of highway number of signals can send

Send diff signal on diff wire Narrow band - unshielded twisted pair (1 channel) Medium band - multiple shielded (10s of channels) Broadband - large coaxial (100s of channels)

Send diff signal on diff frequencies as bandwidth increases

speed may increase volume you can send (text vs graphics)

Speed Bits per Second (bps), kbs, mbs, gbs Can increase rate thru compression

Networking Part II

Internetworking IssuesSource Issues

Telecomm ArchitecturesTelecomm Software

Inter-networking

Networks that connect networks together Backbone or Campus Network

a network that connects… LANs, hosts, enterprise storage, etc.

Helper device - concentrator Wide Area Network

a long distance network of hubs hub = connects multiple backbones

Topology – any of the topologies can be used Internet is peer to peer (mesh) Hub is star (unless has ring,bus inside) FDDI (ring), Ethernet = bus

Inter-Networking Devices

Switch or Bridge Box with 2 connectors Connects networks of same type

Router Box with several connectors Can translate between similar nets

Gateway Intelligent device w/ many links Use to connect very different nets Examples:

internet gateway for orgs connect US net to European net

Step 3: Source of Connection

Where do you get your connections? Choices

You do it yourself Public Switched Telephone Network

Dial-up with phone call + modem Direct connection with ISDN

gives you higher bandwidth connection one data channel + one voice channel

– your home PC will look like a PC on the co network Dedicated line (ex: T1 line w/ 24 channels)

High bandwidth, expensive DSL = 1 voice + 2 data channels (2 way)

ADSL – Asynchronous (send data channel sm)

Sources (cont’d)

Other vendors DSL Vendors, Cable co, Satellite Vendor

Value Added Network providers PSTN + Satellite VPN - build network off internet or public net

Simulates point-to-point (packet in a packet)– Public – they dedicate a channel to you– Internet – they agree to store and forward for you

Industry based networks Swift = banking

Build + Buy Lay cable VSAT + Satellite VPN – you work with vendors to create it MAN, National or Regional Networks

Traditional Architectures

Data Communication architectureonline transaction processingbulk data transfer network

Voice architecture - PBXphone calls, audioconf, voicemail, etc.

Imaging architecture - video, fax, videoconferencingimage-based transactions, files, databases

Email architecturecluster of email servers (post offices)

Newer Architectures

Centralized and Distributed Databases Database Servers Storage Area Networks

Web-Based Architectures Web Servers (and other devices)

Mobile systems Inter-organizational Systems

Direct connect/open network, web-based Grid computing

Reclaim unused PC resources for all to use Sensor Networks for security

Connect cameras, eyes (asset sensors)

Client/Server Architecture

Client/Server is advanced form of Distributed It is a way of looking at infrastructure “let the best processor do the job”

PCs excel at ... Host systems excel at … So take an activity and let them share it

Database Server PC makes query, server retrieves data

Mail Server PC creates mail, mail server routs it

Web Server Server has web page, PC displays it

2-Tier vs. 3 Tier Architecture

Client-Server is 2 tier Applications are split up

part of software on client part of software on server

Database is on server Problems:

when client s/w is updated as volume grows

3 Tier Architecture Separate platforms for three different

functions input, process and storage

Three-Tier (or n-tier) architecture

Front-End (Input - what users see) PCs or Thin Clients w/ GUI

Windows or Web-based Interface Give access to middle tier, display what middle

tier says Middle Tier (Processing)

Application/transaction server(s) Does authentication & processing

Back-End (Storage) Database server(s) & SANs

Other possible layers Legacy System(s) - old centralized apps Load balancers

Telecomm Software

Connection Software dialer that talks to modem for dial-up software that controls

NIC (wire) Access point (wireless)

Network operating systems Host operating system Server vs. Client in a small network

Network management software Monitor traffic, security Assists with troubleshooting, planning

Typical Tradeoffs

Wire Options Twisted Pair

10Base-T = 10Mbs (ethernet) 100Base-T = 100 (fast ethernet) 1000Base-T = 1000 (giga-ether) Token Ring = 4 – 16mbs ISDN (max 1.5m), SDSL (3mps), ADSL (9mps)

Coaxial 10Base 2 = 10 mbs (thinwire or thickwire) Broadband - up to giga-bps

Frame relay = 56kbs - 45mbs ATM = 1.5m - 9 gbs

T1 = 1.5mbs, T3 = 45mps Fiber-Optic

10Base-F (ethernet) = 10mbs 100 Base (fast ether) = 100 mbs FDDI (Fiber Dist Dat Interface) = 100 mbs SONET (synch optical net) = 45m-40gbs

Wireless Options

Radio = up to 54 mbs Bluetooth radio wave = up to 1 mbs 802.11b = 11/5 mbs, 2.4Ghtz freq (wi-fi) 802.11a = 54/22 mbs, 5Ghtz

Less interference (ex: baby monitors) 802.g = /16 to 20mbs, 2.4

Can be slower if add 11b devices to it Can get interference from other 2.4 devices

802.11 dualband = a and b or all three 802.11e - future

Cellular = .01 mbs to .38 mbs Traditional (analog), PCS (digital) and 3G (faster digital)

Microwave = up to 600 mbs Satellite = up to 1 gbs Infrared = 1 mbs to 4 mbs