CTC 228 – Computer Networks Fall 2015 Instructor: Robert Spengler

Syllabus ● Get it at:

OSI Model Picture Credit: blog.butchevans.com

Picture Credit: ieee.org

Chapter 1: The Fundamentals ● Network components – Computer with Network Interface Card (NIC) – Network Medium – Interconnecting Device (maybe)

Chapter 1: IP and MAC address ● IP address is a logical address ● MAC address is a physical address ● Commonly used tools: – ipconfig – ping – arp -a

Chap 1: LAN, WAN, PAN... ● Local Area Network ● Wide Area Network ● Personal Area Network ● Internetwork ● Metropolitan Area Network ● Wireless Local Area Network

Chap 1: Encapsulation

Chap 1: Clients and Servers ● Client is accessing resources ● Server is providing resources ● This is not always a clear distinction

Group Work Case Project 1-2 ● Page 59 ● Bonus questions: – 1. Why would you use the 'ping' command? – 2.Why would you use the 'ipconfig' command? – 3. Is it possible that your network settings could be correct but the ping command could report an error? If yes, how? If no, why not?

Chapter 2 ● Repeaters ● Hubs ● Switches ● Wireless Access Point ● Routers (will be discussed later)

Chap 2: 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.

Chap 2: Routers ● Used to interconnect LANs to each other ● May directly connect or connect through intermediate routers

Chap 2: A Hub

Chap 2: A Switch

Chap 2: Old Wireless Access Point

Chap 2: So what is this thing?

Chap 2: But what about the back?

Chap 2: Tables and Gateways ● Hosts use a Default Gateway to get out ● Switches do their magic with MAC tables ● Routers do their magic with Routing tables ● These entries can be STATIC or DYNAMIC – Special route: Default Route

Chap 2 Group Project ● Project 2-8 ● Page 99 ● Bonus Questions: A computer has a standard NIC and a USB wireless adapter that are both connected to the same network. – 1. How many MAC addresses will it have? Why? – 2. How many IP address will it have? Why? ● Turn in before you leave.

Chapter 3 Topologies and Cables Ethernet Wifi Internet Access

Chapter 3 ● Topologies – Bus, Physical Star, Ring, Point-to-Point, Mesh ● Cables – UTP, Fiber Optic, Coaxial

Chap 3: Unshielded Twisted Pair

Chap 3: Coax

Chap 3: Fiber Optic Multimode vs Single-Mode

Chapter 3 Topologies and Cables Ethernet Wifi Internet Access

Chap 3: 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

Chap 3: Ethernet Frame

Chap 3: About Collisions and Errors ● If two devices in the same collision domain send frames at the same time, a collision might occur. – Unlikely with switches but common with hubs. ● Frames could get mangled on the wire, but since Ethernet is best effort, there is no acknowledgment or verification from receiver. – Errors are detected with a Cyclic Redundancy Check (CRC) added to the end of a frame.

Chapter 3 Topologies and Cables Ethernet Wifi Internet Access

Chap 3: 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

Chap 3: Wifi Standards

Chap 3: Wifi Channels

Chap 3: WiFi Security ● Traffic can be intercepted relatively easily ● Encryption protocols – Wired Equivalent Privacy (WEP) – Wi-Fi Protected Access (WPA) – WPA2

Chapter 3 Topologies and Cables Ethernet Wifi Internet Access

Chap 3: Internet Access Technology ● Cable Modem ● Dial-up ● DSL ● Satellite ● Ethernet

Chap 3 Group Project ● TO ● Case Project 3-1 ● Page 159 ● Bonus Question: If five users are simultaneously participating in a Wi-Fi network operating in ad-hoc mode, what is the network topology? Why?

Chapter 4 ● PVC is used as the jacket of UTP cables and is toxic when it burns ● UTP Cable types – CM, CMR (Riser), CMP (Plenum) – Also called Cat-5, Cat-5e, Cat-6

Chap 4: RJ45

Chap 4: Terms ● Crossover vs Straight-Through (patch) ● Horizontal wiring vs Vertical wiring ● Entrance facility and “point of demarcation”

Chap 4: Fiber Optic ● Tons of connector types ● Termination is a little difficult ● Can go great distances with great speed ● Multi mode and Single Mode

Chap 5: Protocol Stacks ● TCP/IP Stack actually has a lot more stuff than just TCP and IP.

Chap 5: In depth with the layers

Chap 5: IP address Two forms: IPv4 and IPv6 Going into detail on IPv4 Subnet Masks Classful and Classless

Chap 5: IPv4 Packet

Chap 5: 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

Chap 5: TCP and UDP