The Basics of Networking

Rick Graziani What is networking? Communication! An interconnection of computers and other devices: –Printers –Servers (computers) –Scanners –Network Devices Hubs Switches Routers Firewall Modem

Rick Graziani Most successful networking applications?

Rick Graziani What is in a network? Computers…

Rick Graziani What is in a network? Hubs and Switches… Hub: Only one device at a time can talk. Switch: Multiple devices can talk at the same time.

Rick Graziani What is in a network? Telephone Modems…

Rick Graziani What is in a network? DSL and Cable Modems…

Rick Graziani Extending your network and protecting yourself!

Rick Graziani Connecting your DSL or Cable Modem When using NAT (Network Address Translation, the Router helps hide your network

Rick Graziani They also allow more devices on your home network!

Rick Graziani What is the Internet? The Internet was originally designed by DARPA (Defense Advanced Research Projects Agency) in response to the U.S.S.R. launching Sputnik, the first satellite. Out of this came the Internet, a way for computers to communicate from different parts of the world. These computers can be any type of computer using any type of operating system, as long as they are using the protocol TCP/IP.

Rick Graziani What is TCP/IP? What is a protocol? A protocol is nothing more than an agreement, a standard way of organizing network information. The sender and receiver, and everyone in between, must agree on how this information is organized. The actual letter (data) is inside (encapsulated) the envelope.

Rick Graziani TCP/IP Transmission Control Protocol / Internet Protocol TCP/IP is a suite of protocols. IP (Internet Protocol) is used for sender and receiver addressing. Every computer on the Internet or a network must have an IP address to communicate. Part of the IP address is the network address. Example: The destination address is which includes all computers from to Source IP Address: Destination IP Address This is known as an IP Packet

Rick Graziani What is the IP Address on my computer?

Rick Graziani Pinging another computer

Rick Graziani Routers Routers are network devices that connect two or more networks together. Computers usually belong to a single network. Router connect multiple networks.

Rick Graziani DSL Router When using NAT (Network Address Translation, the Router helps hide your network

Rick Graziani Rick’s IP Packet Analogy…

Rick Graziani Do I need to know IP Addresses? No! Domain is a related group of networked computers: –Cabrillo.edu –Yahoo.com –Google.com All you need to know is the domain name.

Rick Graziani Domain Name Servers (DNS) I know the Domain Name but IP uses IP addresses. How does a Domain Name (yahoo.com) get translated to an IP address ( )? Using a Domain Name Server Source IP address Destination IP address

Rick Graziani Domain Name Servers (DNS)

Rick Graziani Domain Name Servers (DNS)

Rick Graziani Domain Name Servers (DNS)

Rick Graziani Domain Name Servers (DNS)

Rick Graziani Does my computer use a DNS server? Yes!

Rick Graziani Ethernet Networks Most Local Area Networks (LANs) use the Ethernet protocol. Each Ethernet Network Interface Card (NIC) has an “Ethernet Address”. Yes, computers have two addresses: Ethernet Address and an IP Address

Rick Graziani Ethernet Networks So, how is an Ethernet Address used?

Rick Graziani Ethernet Networks How is the Ethernet address used? The packet is put inside an Ethernet frame. The Ethernet source address (MAC address) is your computer. If the two computers are on the same LAN (Local Area Network) then the destination MAC address is the other computer. If the two computers are on different LANs then the destination MAC address is that of the router. Much more in CIS 81. Inside the packet Inside the Ethernet Frame Source Ethernet address Destination Ethernet address

Rick Graziani Ethernet Networks Hubs and Switches connect Ethernet devices on the same LAN. Routers connect LANs together over WANs (Wide Area Networks).

Rick Graziani WANs (Wide Area Networks) Telecommunications companies –SBC –Quest –MCI –AT&T

What does an IT (Information Technology) or Networking person do? Networks are no longer a luxury, but a requirement to keep the organization running.

Rick Graziani Computer Support Specialist Installing computer hardware and software. Troubleshooting Maintenance and upgrades

Rick Graziani Networking: System Administrator Installing, configuring, and maintaining network servers UNIX, LINUX, Microsoft Web, DNS, DHCP, Mail Servers Backup and recovery, user administration Security

Rick Graziani Networking: Network Technician/Analyst Install, manage, troubleshoot network infrastructure: –Routers, Switches, Cables, Wireless Access Points Issues: Security, Quality of Service, Video On Demand, Voice over IP

Rick Graziani Keeping up on technology Wireless Security

Rick Graziani Knowing what you are doing…

Rick Graziani Understanding what others do not