Networking An overview of the major components

Issues How will each computer be identified? How will you control who talks and when? What kind of wire? How many wires in cable? What type of connectors? When two PCs access one file, what happens? How can access to data and peripherals be controlled?

The parts We need a client; a PC that is requesting information or services We need a Network Interface Card (NIC)to identify client; a way to break files into packets for transmission and reassemble packets We need wire/cables or some method to get data from point A to point B PC Operating System has to understand and communicate over the network We need a server

Topologies

Packets and NICs Data is moved in packets or frames, much as you would move your belongings in boxes between apartments Every NIC has a Media Access Control address (MAC) that is unique; 48-bits long as 12 hex characters Frame MAC to MAC from Data CRC

Hardware Protocol Network Technology Defines the packet type Defines cabling and connectors used Defines everything necessary to get data from one computer to another We have two: Ethernet and Token Ring

Ethernet Mid-70’s by Digital Equipment, Intel and Xerox Dominant standard, thanks to Internet Three versions: coaxial, unshielded twisted pair and fiber optic Because frame type is constant, versions can be mixed on the network

Token Ring Developed by IBM Centered on communication with mainframe systems Completely incompatible with Ethernet Used to connect to IBM’s “Big Iron” systems and thus is far from dead More on this later

UTP Ethernet 10BaseT, or 100BaseT, or 1000BaseT 10-, 100-, 1000Mbps (1 Gbps) Uses a star bus topology, typically Use Unshielded Twisted Pair (UTP) cable (4 pairs = 8 wires) Connect to Hub (or Switch) which contains the bus One PC per segment; 100 meters per segment

CAT levels What Mike does not tell you is that the number of twists per inch/foot Of cable increase as the CAT level increases

Wiring Standards EZ-RJ-45 has holes here so wires stick out during assembly 18

More on cabling The space up in the false ceiling, in walls and under a raised floor is called a plenum space You should run plenum (non-toxic) cable in a plenum space It is 3x to 5x more expensive than PVC cable

Hubs and Switches In a star network, all devices connect to a central hub or switch (now that prices have come down). Max 1024 devices to a hub. When a wire breaks, only that device looses the network connection – the rest of the network remains functional Hubs act as repeaters, amplifying the signals – can use them to extend cable runs past 100 meters (~360 feet) They need electrical power…or PoE Hubs rebroadcast signal to all ports; switch tries to be selective

Crossover Cable Connect two PCs without hub 1-3, 2-6, 3-1 and 6-2 or “A” on one end and “B” on the other Be sure to mark these cables! Note that only 4 wires are required

Duplex Full-duplex: can both send and receive at the same time Half-duplex: either send or receive – like “push to talk” phones

Link Lights Should be solid on indicating good connection at both ends. Activity LED should flicker as data packets happen on the network. Both are first steps when troubleshooting network problems.

Token Ring Set of standards developed by IBM Completely incompatible with Ethernet Uses a ring topology A token gets passed from NIC to NIC around the ring Can only send a packet when you have token – thus no collisions 4- or 16 Mbps rings Originally built with two-pair shielded (STP) cable; can be UTP today

Connectors Unique, hermaphroditic connector called IBM-type Data Connector (IDC) or Universal Data Connector (UDC) They can plug to each other “Standard” cable has IDC on one end and 9-pin connector on the other (at network card end)

Hermaphroditic Connector

Connections, cont. Can use a Token Ring Hub (Mulitstation Access Unit (MAU)) – not interchangeable with hub for Ethernet Can use RJ-45 connectors and Cat5e cable with MAU Wire PCs/MAU Seg Ln MAU dist w/repeater STP m720 m UTP7245 m360 m

Serial/Parallel When all else fails Only for two PCs Need crossover versions of 1284 (Parallel) or RS-232 (Serial) Really, really slow by comparison to Ethernet or Token Ring FireWire can be used; so can USB

Network Operating System We have NICs to assemble and disassemble packets (1) We have wire to transmit packets (2) We need an OS that can communicate with the hardware and other PCs (3) We need a server, or resource, on our network (4) Every Windows version is a NOS – thanks to Apple for starting the idea – but we need to configure it

The Three Parts Need to install a network protocol to communicate with hardware Enable server software to share resources Install client software to enable the PC to access shared resources Windows is capable of all three

NOS Organization Client/Server –Take one machine and dedicate it to server function(s) –Dedicated OS, not used as workstation –Everybody else is a client –Novell Netware Server Client

Peer-to-Peer Everybody is equal – all share resources and use resources All are workstations Great for small networks with 10 or less systems Each system maintains its own security; Win 9x: –Read-Only –Full access –Depends on password * NT family allows NTFS permissions on NTFS volumes Need a local account on every system for each user that will access resources

Workgroup(s) A nice way to organize the network into functional groups No security value – can’t limit access Designed for small networks – up to 15 computers

Multiple Servers With C/S and P2P, you have to log in to each server independently

Domain-Based Use a directory service to store user and computer account information (security database) This is stored (and accessed) at only one place on network; can have mirrors too Novell (ver. 5+) uses NetWare Directory Service (NDS) Windows 2000 and 2003 use Active Directory Lightweight Directory Access Protocol, or LDAP 43

Administrator Account Windows 2000, XP and Vista Absolute power – can do anything: add, modify, remove anything Single account Loose password for this account and have to reinstall the OS

Protocols The “language” of the network – “above” the MAC address of the NIC Keeps track of machine names and addresses and organizes frames We need client software on each PC that can “speak” the protocol All networks use at least one protocol

NetBEUI NetBIOS Extended User Interface Great for small networks Very “chatty” protocol, but also very fast Won’t route, so constrained to small networks – 200 nodes Not directly supported in XP – but you can add it if necessary

IPX/SPX Novell’s idea; Internetwork Packet Exchange/Sequential Packet Exchange Can use it without a Netware server Client is called NWLink for Windows nodes Works well with routers, quick

TCP/IP From our UNIX brethren XP, OS X, Novell (version 5) all use it now Best for larger networks Not very speedy, takes up large amount of memory

AppleTalk Gets honorable mention Used on pre-OS X Mac systems Been around since 1984 Quick, but “chatty” Does not have a PC version

Client Software Need client software for every kind of server you want to access Windows installs Client for Microsoft Networks You can add File and Printer sharing to make your system a server on the network

Installing and Configuring a Wired Network Network Interface Card, with driver(s) or USB and virtual NIC Protocol decision Network client for that protocol –Client (Service) for Microsoft Networks –Client Service for NetWare –Client Service for the protocol (Have to enable File (and Printer) Sharing to share resources from your machine) 53

Installing a NIC Put it in available slot – usually PCI – if it is a separate device Plan on providing the driver files. You may be pleasantly surprised if Windows figures out the NIC without any help If you have to force the Add Hardware Wizard, you have done something very wrong

Configuring the Protocol NetBEUI – nothing to configure; just computer name (< 15 characters) NWLink – might have to set frame type (Auto Detect; 802.2, 802.3, 802.5); Netware File and Print Services requires additional software from Microsoft TCP/IP – Need to set IP address, subnet mask and default gateway. A+ exam will assume someone gives you this information

More TCP/IP Dotted Decimal Notation Classes of addresses: –Class A1-126 (first bit is zero) –Class B (first bit is one) –Class C (first two bits are one) Subnet mask – what is network and what is host Network Number Host number

IP addresses is Class B; subnet mask would be is network address is host, or computer, number is Class C; subnet mask is is Network address.108 is host, or computer, number

Default Gateway Where to send packets if destination is not on the local network Often, this is the router on your network

Gateway

Domain Name Service (DNS) Database of Internet names and IP addresses Internet names are controlled and restricted and cost money each year Top Level Domains:.COM,.EDU,.GOV,.ORG,.NET,.MIL and now we have a few more:.INFO,.BIZ,.NAME,.TV

..NET.MIL.COM Dot Aiconline.netHbo.com

DNS Servers

DHCP Dynamic Host Configuration Protocol Automatically assigns IP addresses on request Rather like rooms in a hotel Address can change from time to time – reboots and shutdowns Static IP, in contrast, does not change Cuts way down on the hassle of IP addressing and remembering what address goes where

WINS Windows Internet Name Server Enables Windows network names like Server1 to be correlated to IP addresses Going away; used by Win ME and earlier Being replaced with expanded DNS ability to resolve both Internet and Windows network names 64

TCP/IP tools Run from a command prompt window PING – can you reach an IP address? IPCONFIG – what’s going on here? (NSLOOKUP – for DNS server names and addresses) TRACERT – Shows the route a packet takes from you to another IP address

Automatic Private IP Addressing If a computer can not access a valid DHCP server, will give itself an address X.X – Last two numbers are random If IPCONFIG shows this type of number, you know something is wrong with network

Sharing Drive(s) or Folders First, turn on File/Printer Sharing Right-click resource and select Sharing, or Properties and then Sharing tab Provide a name for the resource – name will be used by others to access the resource Set access restrictions – if any Sharing a printer follows same path (will need a printer driver on accessing system)

Sharing Backup Drive Buy the drive Attach to one computer Share the drive (right click; sharing) Go to another PC on network; Map Network Drive (to get local name/letter) “Point” backup software to that drive letter and a folder unique to the PC

Mapping a Drive Source can be a networked hard disk drive or a folder on a drive You can assign a drive letter to that resource Within applications, you can refer to the network resource by that drive letter Will show up in My Computer

Sharing Printer(s) Make sure File and Printer sharing is turned on! Right click the printer – choose sharing, set the share name (For Win98, have to load printer driver files on system attaching to shared printer) Win XP/Vista: if sharing PC is XP, will automatically share driver also

Wander the Network My Network Places to “see” available resources on the network Can “map” a network resource to a drive letter UNC – Universal (to Microsoft only!) Naming convention: \\server\resource 74

Set up a Network Internet DSL or Cable Modem Router PC 1 PC 2 PC 3 DHCP function Firewall Function SPI – Stateful Packet Inspection Wireless access

Verify the Symptom Walk through the process with the user to get to the error/problem/issue as best you can Did it ever work? And then what changed? Can you isolate the symptom by using known good parts?

More Questions When did it (start to) happen? What has changed? Who did the changing? Can you reproduce the problem? What can you do to isolate the problem? Once fixed, have you tested the fix?

Mike’s Layers Check the NIC first, to see if it lights up Then check switches, hubs, routers for lights – or lack of them. My trip to SB. Check protocol used. Is it the right one? Are you trying to access something that is actually shared? Properly shared? Is laptop’s wireless turned on?