CSC 116 – Computer Networks Fall 2015 Instructor: Robert Spengler

Chap 9: LAN, WAN, PAN... Local Area Network Wide Area Network Personal Area Network Internetwork Metropolitan Area Network Wireless Local Area Network

OSI Model Picture Credit: blog.butchevans.com

Chap 9: The Fundamentals Network components  Computer with Network Interface Card (NIC)  Network Medium  Interconnecting Device (maybe)

Chapter 9: IP and MAC address IP address is a logical address – Work at the NETWORK layer – Someone decides what IP Address you get MAC address is a physical address – Work at the DATA LINK layer – Your MAC address is permanently embedded on your network card

Chap 9: More on IP Address Can be STATIC (always the same) or DYNAMIC (changed each time it connects to the network) Frequently assigned by Dynamic Host Configuration Protocol (DHCP)

More on IP Addresses Two Types IPv4: 32-bit addresses Use “Dotted-Decimal” ( ) IPv6: 128-bit addresses Use hexadecimal ( 3ffe:1900:4545:1243:2001:f8ff:fe21:67cf)

Special IP Addresses – , – , and – are PRIVATE IP Addresses used for internal networks – is the Automatic Private IP Addressing (APIPA) range. A computer gives itself one of these addresses if no network connection is detected.

Ipconfig shows IP information

Ping tests connectivity

Clients and Servers Client is accessing resources Server is providing resources This is not always a clear distinction

Connecting to the LAN Need a NIC if you're plugging in Need a Wireless NIC if you're going to WiFi in These are frequently built-in.

Network Hardware Repeaters Hubs Switches Wireless Access Point Routers (will be discussed later)

A Hub is a multi-port repeater

A Switch

Wireless Access Point

Routers Used to interconnect LANs to each other May directly connect or connect through intermediate routers

So what is this thing?

But what about the back?

Physical connections UTP Coaxial Fiber Optic

Unshielded Twisted Pair

Coax

Fiber Optic Multimode vs Single-Mode

Ethernet Invented in the 1970s but has been updated Uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Uses Media Access Control (MAC) addresses  12 Hexadecimal digits One Ethernet protocol data unit is called a frame  Contains source and destination MAC addresses

WiFi Two modes: infrastructure and ad-hoc Uses Carrier Sense Multiple Access Collision with Avoidance (CSMA/CA) Different standards and speeds:  a 54Mbps but poor reception  b/g/n 11/54/600Mbps and better reception  ac up to 6.7 Gbps

Wifi Standards

WiFi Security Traffic can be intercepted relatively easily Encryption protocols  Wired Equivalent Privacy (WEP)  Wi-Fi Protected Access (WPA)  WPA2

Transport Layer Transmission Control Protocol Reliable and connection-oriented User Datagram Protocol Unreliable and connectionless Both work with segments, use source and destination ports, and use checksums

TCP and UDP