Transcript Networking - WWW4 Server

Networking
Chapter 4
Reading Quiz
Learning Outcomes
• Appreciate Networking Mediums, Topologies, and necessary
Hardware
• Protocols
• Distinguish between different Client/Server Relationships
• Understand SSH & X Protocol uses
• Expose to VCL
Client/ Server Relationship
• Server
• A powerful machine dedicated to governing access to
information, common type web server, however there are more,
databases, files, email & printers
• Client
• A normal PC where applications run and access information off of
a server
• AFS Connection
• You are the Client, AFS is the Server
Network Media
Wired Connections
• Twisted Pair Cable
• Most common media to physically connect two devices together,
incorrectly referred to as “Ethernet cable”, contains several pair of cables
twisted around one another, maximum range 100m
Only two pairs are used,
unless you are running
Gigabit ethernet
Network Media
Wired Connections
• Coaxial Cable
• Single copper conductor at its center, a plastic layer provides
insulation & a braided metal shield, which block interference.
Maximum range 500 m
Network Media
Wired Connections
• Fiber Optic Cable
• Uses pulses of light that travel up to the speed of light to transfer
data great distances.
• Uses translucent fibers, normally glass or plastic, then coated by a
plastic coating and kevlar fibers to provide strength, finally PVC
surrounds outside, max range 145 km (90 mi)
• Primary choice for telecommunication industry
Network Media
Wireless Connections
• Wireless communications use RF (radio frequency) to
broadcast a signal between a wireless client and a base station
or two wireless clients
• Due to the 802.11 standard networking computers is simple
now
Networking Media
802.11 breakdown
• 802.11
• Wireless LAN access providing 1 or 2 Mbps in the 2.4 GHz band
• 802.11a
• Provides speeds up to 54 Mbps in the 5 GHz band, standard used in
NC State classrooms, was not consumer cost effective
• 802.11b
• Provides speeds of 11 Mbps, with a fallback to 5.5, 2 &1, in the 2.4
GHz band
• 802.11g
• Provides speeds of 20+ Mbps in the 2.4 GHz band, current NC State
wireless access as a whole
• 802.11n
• New extension to 802.11 approved in Oct 2009, using two antennae
to provide speeds up to 150 Mbps, rivaling Ethernet speeds
Networking Media
Wireless Fun Facts
• MIMO (Multiple-Input and Multiple-Output)
• A new “smart antenna” using multiple antenna to the receiving and
transmitting end to boost effectiveness.
• Bluetooth
• Allows short ranged connection between two devices, normally
devices that want to connect to a computer, operates in 2.45 GHz
band at 10-100m.
• Bluetooth 2.0 allows speeds up to 2.1 Mbps
• Bluetooth 3.0 allows speeds up to 24 Mbps
• Cell Phone/WiMax
• The G standard is used to provide Telecommunications access to
cellphones
• 3G minimum speeds of 200 kb/s
• 4G minimum speeds of 100 Mb/s up to 1 Gb/s
• WiMax
• Using existing cellphone towers and signals, the 802.16 standard is trying
to become the first national broadband system with speeds being
updated to 1 Gb/s
Network Topology
• LAN (Local Area Network)
• Small network consisting of nodes, computer & other network
devices, used to segregate larger networks into manageable
pieces
• WAN (Wide Area Network)
• Industries own/maintain these geographically larger networks
than LANs, how Time Warner Cable provides internet access
• Fiber to Node: Fiber optic cable is run to a centralized node which
splits it into multiple connections to be send out separately
• MAN (Metropolitan Area Network
• A mix between LAN & WAN normally used by an ISP to connect
several offices together.
• Uses a mix of routers & specialized switches
Types of Networks
• Star Network
• Based off of a concentrator, which is a single device that manages
the network, also acts as a repeater, strengthening the signal over
the network.
• Useful network type because if one
node fails it doesn’t stop the flow of
traffic, however if the concentrator
fails the entire network goes down
• Examples of concentrators are
routers or switches
Types of Networks
• Tree Network
• Groups a lot of Star Networks together and is managed in a
hierarchal manner, with the node above the current one having
to handle more traffic than the previous one
Types of Networks
• Bus Network
• Set of clients connected via a single shared connection line
known as a bus
• Advantages
• Easiest and cheapest to implement and extend
• To add a device you just simply need an interface card and a free
node
• Disadvantages
• A line break will cause the entire network to go down
• Limited number of connections can be made before the network will
slow to a crawl
Types of Networks
• Ring Network
• Each node has two neighbors, easy to add devices since all
devices have equal access, however to send information, the
packet has to be sent through each node until it reaches its
desired recipient
Establishing a Network
Connection
• Protocols
Layer
Example
Link Layer
Ethernet
Internet Layer
Internet Protocol (IP)
Transport Layer
Transmission Control Protocol (TCP)
Application Layer
HyperText Transfer Protocol (HTTP)
Each protocol adds an
extra level of
abstraction on top of
the last, this prevent
duplication
Application
Transport
Internet
Link
Establishing a Network
Connection
• Obtain an IP address
• It’s like your home address but for your computer,
some network use a Dynamic Host Configuration
Protocol (DHCP) to automatically assign an available IP
address
• IPv4 uses 32 bit address to assign access with a
maximum of 4,294,967,296 unique addresses
• IPv6 is the only solution to the inevitable
exhaustion, which uses 128 bit address and can
assign up to 3.4 x 1038 addresses, however IPv4 &
IPv6 are not directly compatible which is why
people are slow to transition
Establishing a Connection
Tricks
• NAT (Network Address Translation)
• Allows all computer connected to a router to use a
single public IP address, while the router assigns its
own private IP address to it’s clients
• DNS (Domain Name System)
• Allows you to use a domain name instead of an IP
address, so instead of typing in the actual IP address to
Google’s search engine server you just type
www.google.com
• DNS servers keep track of the Domain Names and
their corresponding IP addresses
Home Network
SSH
• Encryption is what makes SSH impervious to attacks from
outside the network
• Tunneling is the means to transfer the encrypted packets
X Protocol
• A special type of client/server relationship on the same
computer
• The X Protocol program acts as the server, while individual
applications at as the client
• Applications & input devices tell the X Server what to display
and the X Server sends the monitor what should be shown.
RDP
• Remote Desktop Protocol
• Allows resources to be accessed from any machine
running Microsoft Terminal Services
• Achieves this by using separate tunnels to send
different pieces of information & instructions so that
the client can receive, decode, and create a smooth
connection to the remote computer
P2P
• Peer to Peer
• Used by most torrent sites, a peer to peer connection is when a
group of computers on a network simultaneously send and
receive information from one another.