CSC 116 – Computer Networks

Fall 2015Instructor: 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” ( 192.168.2.3)

IPv6: 128-bit addresses • Use hexadecimal

( 3ffe:1900:4545:1243:2001:f8ff:fe21:67cf)

Special IP Addresses

10.0.0.0 – 10.255.255.255,

172.16.0.0 – 172.31.255.255, and

192.168.0.0 – 192.168.255.255 are PRIVATE IP Addresses used for internal networks

169.254.0.0 – 169.254.255.255 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:

802.11a 54Mbps but poor reception 802.11b/g/n 11/54/600Mbps and better reception 802.11ac 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