Transcript File - Computer networks@CSUDH

CTC 228 – Computer Networks
Fall 2015
Instructor: Robert Spengler
Syllabus
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Get it at:
http://ctc228.weebly.com/
OSI Model
Picture Credit: blog.butchevans.com
Picture Credit: ieee.org
Chapter 1: The Fundamentals
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Network components
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Computer with Network Interface Card (NIC)
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Network Medium
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Interconnecting Device (maybe)
Chapter 1: IP and MAC address
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IP address is a logical address
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MAC address is a physical address
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Commonly used tools:
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ipconfig
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ping
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arp -a
Chap 1: LAN, WAN, PAN...
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Local Area Network
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Wide Area Network
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Personal Area Network
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Internetwork
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Metropolitan Area Network
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Wireless Local Area Network
Chap 1: Encapsulation
Chap 1: Clients and Servers
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Client is accessing resources
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Server is providing resources
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This is not always a clear distinction
Group Work
Case Project 1-2
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Page 59
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Bonus questions:
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1. Why would you use the 'ping' command?
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2.Why would you use the 'ipconfig' command?
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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
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Repeaters
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Hubs
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Switches
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Wireless Access Point
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Routers (will be discussed later)
Chap 2: Connecting to the LAN
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Need a NIC if you're plugging in
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Need a Wireless NIC if you're going to WiFi in
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These are frequently built-in.
Chap 2: Routers
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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
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Hosts use a Default Gateway to get out
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Switches do their magic with MAC tables
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Routers do their magic with Routing tables
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These entries can be STATIC or DYNAMIC
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Special route: Default Route
Chap 2 Group Project
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Project 2-8
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Page 99
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Bonus Questions: A computer has a standard
NIC and a USB wireless adapter that are both
connected to the same network.
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1. How many MAC addresses will it have? Why?
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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
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Topologies
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Bus, Physical Star, Ring, Point-to-Point, Mesh
Cables
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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
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Invented in the 1970s but has been updated
Uses Carrier Sense Multiple Access with
Collision Detection (CSMA/CD)
Uses Media Access Control (MAC) addresses
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12 Hexadecimal digits
One Ethernet protocol data unit is called a
frame
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Contains source and destination MAC addresses
Chap 3: Ethernet Frame
Chap 3: About Collisions and Errors
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If two devices in the same collision domain
send frames at the same time, a collision
might occur.
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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.
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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
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Two modes: infrastructure and ad-hoc
Uses Carrier Sense Multiple Access Collision
with Avoidance (CSMA/CA)
Different standards and speeds:
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802.11a 54Mbps but poor reception
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802.11b/g/n 11/54/600Mbps and better reception
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802.11ac up to 6.7 Gbps
Chap 3: Wifi Standards
Chap 3: Wifi Channels
Chap 3: WiFi Security
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Traffic can be intercepted relatively easily
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Encryption protocols
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Wired Equivalent Privacy (WEP)
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Wi-Fi Protected Access (WPA)
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WPA2
Chapter 3
Topologies and Cables
Ethernet
Wifi
Internet Access
Chap 3: Internet Access Technology
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Cable Modem
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Dial-up
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DSL
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Satellite
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Ethernet
Chap 3 Group Project
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EMAIL TO [email protected]
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Case Project 3-1
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Page 159
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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
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PVC is used as the jacket of UTP cables and
is toxic when it burns
UTP Cable types
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CM, CMR (Riser), CMP (Plenum)
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Also called Cat-5, Cat-5e, Cat-6
Chap 4: RJ45
Chap 4: Terms
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Crossover vs Straight-Through (patch)
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Horizontal wiring vs Vertical wiring
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Entrance facility and “point of demarcation”
Chap 4: Fiber Optic
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Tons of connector types
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Termination is a little difficult
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Can go great distances with great speed
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Multi mode and Single Mode
Chap 5: Protocol Stacks
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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