Communication PIC-Microcontroller Lab Course by JAOM Center, Feb. 2013Introduction to Networking Instructor: Mohsen Sarakbi
Definition of Networking A network is nothing more than two or more computers connected to each other so that they can exchange information, such as e-mail messages or documents, or share resources, such as disk storage or printers. In most cases, this connection is made via electrical cables that carry the information in the form of electrical signals. Or by radio signals (wireless connection).
Why use a Network? Specifically, networks are about sharing three things: 1. Information (Files) 2. Resources (Printers) 3. Applications (Server – Clients)
Network Classifications Local Area Network (LAN) Metropolitan Area Network (MAN) Wide Area Network (WAN) Concept: Area covered. Number of devices attached.
Network Topology A topology refers to the manner in which the cable is run to individual workstations on the network.Types of topologies: Bus Star (Hub) Ring
Peer-to-Peer Networks A peer-to-peer network is a network where the computers act as both workstations and servers. great for small, simple, and inexpensive networks. In a strict peer-to-peer networking setup, every computer is an equal, a peer in the network. Each machine can have resources that are shared with any other machine.
Client and Server The terms "client" and "server" are used to describe individual computers that are part of a network where computing resources and workload are shared. A server is a computer that makes its resources available to the network and responds to the commands of a client. The server’s shared resources can be files (a file server); printers (a print server); processing power (an application server); etc… A client is a computer that uses the resources made available by a server.
Network Components Physical Media (Cables) Interconnecting Devices (NIC, HUB, Switches, Routers ..) Computers (Client - Server) Networking Software (TCP/IP) Applications (Email, web browsing, Chat, VoIP ..)
Computer Networking Models Models, also called protocol stacks, represented in layers, help to understand where things go right or wrong. OSI 7-layer model 7 Application 6 Presentation 5 Session 4 Transport 3 NetworkOSI 2 Data(Open Systems Interconnection) 1 Physical
Computer Networking Models All People Seem To Need Data Processing
Protocols Protocols are sets of rules. What do you want to do? (Application) Where are you going? (Addressing) How do you get there? (Media types) Did you get there? (Acknowledgments, Error checking)
Physical Layer (Layer 1) Electrical current Hub No addressing Nowadays: Pretty much just Cat 5 (or Cat 5e or Cat6) twisted pair copper wire and microwave (wireless). Twists in wire keep down interference Standard connecter: RJ45. Fiber (multi-mode or single-mode) coaxial copper (thick- and thin-net), Cable Modem, plain phone (DSL), microwaves (wireless Ethernet), etc.
Physical Layer (Layer 1) Coaxial Cable Thinnet Thicknet Coax transmits at 10 Mbps.. Twisted Pair. Shielded Twisted Pair (STP). STP Unshielded Twisted Pair (UTP). UTP is used in Ethernet networks (Cat5 (100Mbps) or Cat6 (1000Mbps)) Transmission rates vary between 10-100-1000-10000 Mbps. Fiber-Optic Cable. More distance More capacity More cost
Wireless (Layer 1) Terms: 802.11a/b/g/n Uses microwave radio waves in the 2.4Ghz (802.11b and g) and 5.4Ghz (802.11a and n) bands to transmit data. These are unregulated frequencies, so other things (cordless phones, Bluetooth, etc.) can use the same frequencies, but hopefully one or the other is smart enough to hop frequencies to stay clear of the other. 802.11b at 11Mbps, both 802.11a/g claim 54Mbps.
Data Link Layer (Layer 2) Ethernet! Addressing by MAC Address Framing Error detection Bridge or Switch
Ethernet IEEE 802.3 Ethernet is a popular, relatively inexpensive, easy-to-install LAN architecture with the following characteristics: Uses the CSMA/CD media access control. Data transmission normally occurs at 100Mbps or 1000 Mbps Typically implemented in a star topology Ethernet LANs use Twisted Pair cables An Ethernet LAN is often described in terms of three parameters: transmission rate, transmission type, and segment distance or cable type. "100baseT" means: 100 - transmission rate or through put of 100Mbps base - transmission type is baseband rather than broadband network (i.e., the signal is placed directly on the cable, one signal at a time) T – the cable type (e.g. Twisted pair) Few types of Ethernet: 10Base2, 10Base5, 10BaseT and 10BaseF, 100BaseT, 100BaseF, etc..
Ethernet Addressing Since there can be many users on an Ethernet network, everyone has to have their own unique address. This is called the Media Access Control (or MAC) address, or sometimes Ethernet address, physical address, adaptor address, hardware address, etc. It’s a 12-digit (48 bit) hexadecimal address that is unique to that Ethernet adaptor and no other in the world. It can be written as 00:30:65:83:fc:0a or 0030.6583.fc0a or 003065:83fc0a or 00-30-65-83-fc-0a The first 6 digits are the Vendor code, (003065 belongs to Apple), the last 6 are the individual interfaces own. How to get MAC address? CMD/IPconfig, Adapter properties Check your MAC address!
Hub vs. Switch Hubs are shared media devices. Everyone sees everyone’s packets, you’re only supposed to pay attention to those specifically directed to you, or to broadcasts. Not too secure, but cheap. Switches aren’t shared, most of the time. The switch pays attention to the packets and makes a list of the “sender” Ethernet addresses and makes a table (it removes old data after a while). When a packet comes along whose destination address is in the table, the packet only goes to that port. Unknown packets and broadcasts still go to all ports, but overall, there are nearly no collisions and is generally more secure.
Network Layer (Layer 3) IP Address & Subnet Mask Packets Routing Routers Network packets can be routed. This means they can be passed from one local network to another. Network Layer Protocols: Internet Protocol (IP)
IP Addressing (Layer 3) The Internet Protocol (IP) is the Network layer protocol used on the Internet. ARP: Address Resolution Protocol. Turns an IP number into an Ethernet number, very important You ask “Who’s 172.19.4.15” and if you get a reply, associate the Ethernet address with the IP address in your ARP table. IP addresses consists of 32 bits in decimal such as: 188.8.131.52 Each “octet, 8bits” consists of numbers between 0 and 255 Network address, Broadcast address, Subnet Mask and host IP address. IP Classes: A, B, C, D & E Privet IP vs. Public IP
Port number (Layer 3) Security and specify exact application Form: IP : Port In computer networking, a port number is part of the addressing information used to identify the senders and receivers of messages. HTTP: 80 HTTPS: 8080 or 443 FTP: 20/21 POP3: 110 Telnet: 23 VPN: 1723
Domain Name Resolution (DNS) Since most people find it easier to remember names instead of numbers, IP numbers can and almost always are associated with names. DNS exists to translate IPs to names Example: Any web site.
Routing. “How do you get there from here?” You can put an IP (Network layer) packet inside of an Ethernet (data layer) packet, but a Router got to pass it along Router makes routing table If you want to talk to someone outside your local network, you’ll send that Ethernet packet to your router’s Ethernet address Default Gateway
DHCP (Dynamic Host Configuration Protocol) s a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers (i.e., a scope) configured for a given network Relates IP – Names addressing automatically DHCP assignment can be reserved for a device by reserve the IP address to the MAC address of that device Reserved DHCP
Encapsulation This is called “encapsulation” and is why a layered model is so handy.
VPN A Virtual Private Network (VPN) extends a private network and the resources contained in the network across public networks like the Internet. It enables a host computer to send and receive data across shared or public networks as if it were a private network with all the functionality, security and management policies of the private network. This is done by establishing a virtual point-to-point connection through the use of dedicated connections, encryption, or a combination of the two. The VPN connection across the Internet is technically a wide area network (WAN) link between the sites but appears to the user as a private network link—hence the name “virtual private network”.
VPN No QoS Protocols: Layer 2Tunneling Protocol (L2TP) IP security (IPSec) Secure Sockets Layer (SSL) and Transport Layer Security (TLS) Point-To-Point Tunneling Protocol (PPTP)
Lab IPconfig Check IP Check Default network Build a LAN Share files Router GUI (DHCP, NAT, FILTER, ACL, ..) Check public IP and Rout thru internet Create a VPN connection VPN Server & Client Use different internet access Check IPs on both Set as home network/ Firewall options Share files!