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Understanding Networking

Understanding Networking. Joe Cicero Northeast Wisconsin Technical College. Presentation Purpose. The purpose of this presentation is to give the learner a VERY BASIC understanding of TCP /IP networking. What we will cover…. The NIC or Network Interface Card

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Understanding Networking

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  1. Understanding Networking Joe Cicero Northeast Wisconsin Technical College

  2. Presentation Purpose • The purpose of this presentation is to give the learner a VERY BASIC understanding of TCP /IP networking.

  3. What we will cover… • The NIC or Network Interface Card • TCP/IP or Transmission Control Protocol Internet Protocol • IP or Internet Protocol Addressing • What a Gateway is • Internet Addresses vs. Private IP Addresses • NAT or Network Address Translation • DNS or Domain Name Service • DHCP or Dynamic Host Configuration Protocol vs. Static Addressing • Special IP Addresses – 169, 127 • Cross-over cables • Hubs • Switches • Wireless • Ad hoc vs. Infrastructure

  4. The Network Interface Card • Since most of us have a phone, we will use it to describe what is needed and how things work on a network. • The network interface card or NIC is like your phone. Your phone allows you to connect to the telephone network. • The NIC is the physical device that enables the computer to connect to a computer network.

  5. Language / Protocol • We all speak some language to communicate with someone on the other end of our phone. If we call someone who doesn’t speak our language and we don’t speak their language it is impossible to communicate with them. • One “language”, we call it a protocol, our computer uses to “speak” to other computers is Transmission Control Protocol Internet Protocol or TCP IP.

  6. The IP address • You have a phone number. You are the only one with this number. If two individuals had the same phone number the system wouldn’t work correctly. Would a caller get a busy signal if only one of the numbers was in use? Would both phones ring if neither was in use or would neither? • Each computer connected to a network has an Internet Protocol (IP) address. There can be only one address per computer on the network. If more than one computer has the same address the computer turned on first will “answer calls” for that IP and the other will not.

  7. To view your active IP Addressing information on a Windows computer you should always type “ipconfig /all” at the command prompt! NOTE: Viewing it in the Internet Protocol (TCP/IP) Properties box DOES NOT GUARANTEE an active IP!

  8. Gateways • You don’t have to dial an area code when you call someone in your area, your phone can directly communicate with other phones in your area. If you want to dial outside of your area you have to dial in an area code or country code etc. • Computers on the same network can communicate directly with other computers on their network. If computers need to communicate with a computer outside of the network they use a gateway. The gateway is “aware” of other networks and “routes” the traffic to them.

  9. How many IP addresses are there? • Just like there is a limited number of phone numbers, there is a limited number of IP addresses. • Most computers currently are using IP version 4 (IPv4) which only has 4,294,967,296 possible unique addresses. However, many are reserved for special purposes, such as private networks (~18 million addresses). This reduces the number of addresses that can be allocated as public Internet addresses. • THERE EVENTUALLY WILL BE A SHORTAGE OF IPv4 ADDRESSES

  10. Internetvs. Private Network Addresses • As the previous slide said there are private addresses that you can use on private networks (NOT THE INTERNET). These addresses will work on your network but won’t work on the Internet. • They are: • 10.0.0.0 – 10.255.255.255 16,777,216 single class A • 172.16.0.0 – 172.31.255.255 1,048,57 class B • 169.254.0.0 – 169.254.255.255 65,536 class B • 192.168.0.0 – 192.168.255.255 65,536 class C

  11. What do/did we do about the shortage? • NAT or Network Address Translation was the “patch” for the shortage. Every device on the Internet has to have an individual address. • Every device on your network has to have an individual address. • If you have a device BETWEEN your network and the Internet that understands how to communicate with your network and has a valid Internet address, every computer doesn’t need a valid Internet address. If you think about it, just at NWTC, that saves thousands of IP addresses.

  12. One device, multiple purposes • Sometimes your NAT device is also your gateway, router, firewall, etc.

  13. IP Address / Domain Name Relationship • So we know that every computer on the Internet has to have an address that is unique. Why can I type a name in Internet Explorer to get to a website? • Humans would have a hard time remembering tons of numbers so there is this great thing called a domain name server that associates numbers like 72.14.203.99 with names like www.google.com. Type either one into your browser and you will go to the same place.

  14. DNS – Domain Name Server • If you type the Preferred DNS server number incorrectly you will NOT be able to use a Domain name but you will still be able to use an IP address!

  15. DHCP vs. Static Addresses • OK, OK, The phone company gives me my phone number, and I’ve never had to type any numbers into my computer and it works – what’s the deal? • There is this thing called DHCP or Dynamic Host Configuration Protocol. If your computer is setup to use it AND there is another computer setup to give out addresses, you don’t have to do anything.

  16. Statically Assigned Address

  17. No DHCP, No Static, and I still have an address! • Joe, you must be wrong. I have a computer that isn’t connected to a network and therefore can’t be getting an address from a DHCP server, I didn’t set an address and yet…by magic, it has an address! • When your Windows-based computer (configured for DHCP) is initializing, it broadcasts three or more "discover" messages. If a DHCP server does not respond after several discover messages are broadcast, the Windows computer assigns itself a Class B 169.254.0.0 address.

  18. Who is 127.0.0.1? • At home I’m on a 192.168.1.0 network. I disconnected my router and pinged 127.0.0.1 and got a response! Is there an invisible computer on my network? • 127.0.0.1 is the standard IP address used for a loopback network connection. This means that if you try to connect to 127.0.0.1, you are immediately looped back to your own machine. • In other words, 127.0.0.1 is you!

  19. Other Special IP Addresses • An IP Address that ends in a zero denotes the “network”. You cannot assign a computer to the address xxx.yyy.zzz.0 • Typically an IP Address that ends in 255 denotes the “broadcast” address. You should not assign a computer xxx.yyy.zzz.255

  20. Cross-over cables • Your phone at home may have a “phone cord” just like a computer using a wired network has a data cable. Sometimes these are referred to as a drop cord or patch cord. • The computer sends data on some of the wires and receives data on some of the wires. • In order to connect two computers directly together (no other equipment in-between them), you need a “cross-over” cable. This cable switches the wires on the end of the cables allowing to computers to communicate.

  21. Hubs • Another way for you to connect two or more computers together is through a “hub”. • When a “packet” of information is sent to a hub it retransmits the “packet” to ALL computers connected to it. Only the computer that is at the correct address answers. Hubs are not used much anymore because of the increased “traffic” on the network due to the way they work!

  22. Switches • Another way for you to connect two or more computers together is through a “switch”. • A switch keeps track of every computer connected to it and where it is plugged into on the switch. When a “packet” of information is sent to a switch, it retransmits the “packet” to the computer the “packet” is for. Switches were more expensive than hubs but are cheap now and are used more often due to the way they work!

  23. Wireless Networking • You may have a cordless phone or a cell phone that uses radio waves to communicate with other phones. • We can use radio waves with computers too. This is called wireless networking.

  24. Ad hoc vs. Infrastructure • Just like we need to have a special cable made to make two computers communicate without a hub or switch, we may need to make special setting changes to make two or more computers communicate without an access point.

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