ITEC 90 (SIR TABERNA) Flashcards
e-commerce, banking, inventorying, telecommunications, archiving, health
- Commercial
– critical infrastructure, homeland security, policing
- Social
email, chat, videoconferencing, social networking, entertainment
- Human interaction/communication
– Network every (electronic) device (computers, phones, sensors, planes, cars, TVs, appliances, heart monitors, …)
Modern trend
A system that carries a commodity between 2 or more entities
Network
A system that carries information between 2 or more entities, in the form of electric signals
Computer network
The task of connecting nodes via links, so that nodes can exchange information, reliably, timely, efficiently, safely, privately, “greenly”, and with low cost
Network Design
Applications
- WWW, email, chat, videoconferencing, e-commerce, audio/video streaming, VOIP, file sharing
Who deploys the network
- Enterprise, government, end-user
Where is the network deployed
- Home, building, campus, state, country, continent, globe
think again a transportation network
Metrics ()
How many cars can it service
-(throughput)?-
How fast can it service them
delay-
collisions, losses, outage probabilities, etc
- How reliable can it service them
Can it provide any guarantees
(QoS)quality of service-
Each node is directly connected to all others via a link
Point-to-point links:
All nodes share the same physical medium
Multiple access
A dedicated circuit is established across a set of links
Circuit-Switched
Circuit-Switched
Packet-Switched
End-to-end permanent connection
Circuit-Switched Networks
Once communication is complete, connection is ended and links are released.
Circuit-Switched Networks
- Dedicated path for communication
- No need for a destination address since a path is already established
Circuit-Switched Networks
- Predictable bitrate and delay
- Good for delay-sensitive applications
- Guaranteed bandwidth (Quality of Service)
- Rare packet loss
- Packets are delivered in order
- Reliable communication
- Forwarding based on time slot or frequency (multiplexing)
- No need to inspect a packet header for address
- Simple data routing
- Forwarding based on time slot or frequency
- No IP (and TCP/UDP) header on each packet
- Low per-packet overhead
Disadvantages of Circuit Switching
- Bursty traffic leads to idle connection during silent period
- Wasted bandwidth
Disadvantages of Circuit Switching
- Connection refused when resources are not sufficient
- Unable to offer “okay” service to everybody
- Blocked connections
Disadvantages of Circuit Switching
- No communication until the connection is set up
- Unable to avoid extra latency for small data transfers
- Connection set-up delay
Disadvantages of Circuit Switching
- Network nodes must store per-connection information
- Unable to avoid per-connection storage and state
- Network state
- Each packet contains identification info (source/destination address seq. number, etc)
Packet Switched Networks
Advantages of Packet Switching
- Links are not reserved during idle period
- No wasted bandwidth
Advantages of Packet Switching
- Frequency, time, statistical multiplexing
- Multiplexing (see next slides)
Advantages of Packet Switching
- More connections of lesser quality
- No blocking of users
- Service
Advantages of Packet Switching
- Can adapt to network congestion and failures
- Adaptation
Disadvantages of Packet Switching
- Harder to build applications requiring QoS
- No guaranteed bandwidth
Disadvantages of Packet Switching
- Need a header with source/dest. address, etc
- Per packet overhead
Disadvantages of Packet Switching
- Packets can be lost, corrupted or delivered out-of-order
- Complex end-to-end control
Disadvantages of Packet Switching
- No congestion control, can lead to arbitrary delays and packet drops
- Delay and Congestion
Three pairs of senders/receivers share the same physical link to communicate
Multiplexing
Multiplexing Methods
-Time Division Multiplexing
-Frequency Division Multiplexing
-Statistical multiplexing
- Division of the communication medium into a number of channels of variable bandwidth
Statistical multiplexing
- A computer network is a set of computers connected together for the purpose of sharing resources.
- The most common resource shared today is connection to the Internet.
- The connection between computers can be done via cabling, most commonly the Ethernet cable, or wirelessly through radio waves
Computer Networks
- Also known as network equipment or computer networking devices, are physical devices which are required for communication and interaction between devices on a computer network.
Network Hardware
- It is designed to help set up, manage, and/or monitor computer networks.
Network Software
- Also called as Communicating Devices
- Network Devices are components used to connect computers or other electronic devices together so they can share files or resources like printers or fax machines.
- Devices used to setup a Local Area Network (LAN) are the most common
Network Devices
- NIC (Network Interface Card)
- Repeater
- Hub
- Modem
- Server
- Switch
type of network devices used by the public
- The ___ provides a device with the physical connection to the network. NICs can provide connections for any type of networking media, including wireless media. Not only do servers and workstations have NICs, so do network printers and all other network devices.
- It has specific MAC Address (48 bit)
- Ethernet is a physical and data link layer technology for local area network.
Network Interface Card
- Network repeaters regenerate incoming electrical, wireless or optical signals.
- With physical media like Ethernet or Wi-Fi, data transmissions can only span a limited distance before the quality of the signal degrades.
Repeater
- A repeater can connect different types of media (such as coax to twisted pair).
- Repeaters extend the distance a network can reach.
- Repeaters do not increase network traffic.
Advantages OF REPEATER
- A repeater extends the collision domain.
- Repeaters cannot filter information, so the same information goes to all nodes.
- Repeaters cannot connect different logical network architectures.
- A network can include only a limited number of repeaters
DISADVANTAGES OF REPEATER
are devices used to link several computers together.
- They repeat any signal that comes on one port and copy it to other ports (a process that is also called broadcasting)
- A _____is the central point of connection for cable segments in a physical star topology. Technically, a hub is a multiport repeater for use with twisted pair cable.
- Hubs and switches serve as a central connection for all of your network equipment and handles a data type known as frames. Frames carry your data. When a frame is received, it is amplified and then transmitted on to the port of the destination PC.
Hub
- They are cheap and readily available.
- They are easy to deploy and maintain.
- They can connect media operating at different speeds.
Advantages OF HUB
- Hubs can’t filter the information passing through them so all packets transmit to all segments (all connected devices).
- Collision of Data.
- It will broadcast to all the ports
DISADV OF HUB
– simply connect all ports together electrically and are usually not powered.
- Passive Hub
use electronics to amplify and clean up the signal before it broadcast to the other ports.
- Active Hub
- Short for MODulator/DEModulator
- A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines.
Modem
is a Modem that is built onto the computer motherboard. These Modems cannot be removed.
-a modem that comes as an expansion board you can insert into a computer
Onboard Modem
connects to a PCI slot inside a newer desktop computer or ISA slot on an older computer.
Internal Modem
is located within a box and is hooked up externally to the computer, usually the Serial Ports or USB port. The picture is an example of an external USRobotics Modem.
External Modem
is modem that is installed outside of the CPU and is used with older laptops PCMCIA slot.
-External modem connected to the CPU via the COM port or USB
Removable Modem
- A computer or device on a network that manages network resources.
Server
a computer and storage device dedicated to storing files. Any user on the network can store files on the server.
- File server
a computer that manages one or more printers, and a network server is a computer that manages network traffic.
- Print server
a computer system that processes database queries
- Database server
- Switches are actually multiport bridges that function at the Data Link layer of theOSI model.
- It uses a database of MAC addresses to determine where computers are located and very efficiently send packets only where they need to go.
- Each switch port has a separate collision domain
Switch
- They limit the collision domain.
- They can segment the network into multiple segments with separate collision domains.
- They support intelligent management capabilities.
- They can limit broadcast traffic propagated between segments.
Advantages OF SWITCH
- They are typically more expensive than a hub of the same size.
- Some switches are complex and difficult to configure.
- Additional optional functionality can add to the potential complexity.
Disadvantages OF SWITCH
- A bridge is a product that connects a local area network (LAN) to another local area network that uses the same protocol (for example, Ethernet)
Bridge
is a device that forwards data packets along networks
- However, they are smaller than bridges because they are more intelligent devices; as such, they analyze every packet, causing packet- forwarding delays. Because of this intelligence, they are more expensive.
- Routers connect different network segments that may be located in the same building or thousands of miles apart. They can connect different types of networks, such as Token Ring and Ethernet networks, or using different routed protocols.
- The router changes the packet’s size, format, and addressing to fi t the type of destination network on which the packet is being sent. They use the network address and the IP address in the TCP/IP environment, for example, to determine the best path for the packet to take to reach the destination quickly.
Router
connect networks
Routers
create a network
Switches
links computers to the Internet, so users can share the connection
router
acts as a dispatcher, choosing the best path for information to travel so it’s received quickly.
router
- A device that adds wireless connectivity to a laptop or desktop computer.
Wi-Fi Card
the layer closest to transport medium
physical
The most common resource shared today is
connection to the Internet.
is a set of computers connected together for the purpose of sharing resources.
computer network
The connection between computers can be done via
cabling
most commonly the Ethernet cable
cabling
WWW, email, chat, videoconferencing, e-commerce, audio/video streaming, VOIP, file sharing, are example of?
APPLICATION
is the central point of connection for cable segments in a physical star topology. Technically, a hub is a multiport repeater for use with twisted pair cable
HUB
They repeat any signal that comes on one port and copy it to other ports (a process that is also called broadcasting)
HUB
serve as a central connection for all of your network equipment and handles a data type known as frames. Frames carry your data. When a frame is received, it is amplified and then transmitted on to the port of the destination PC.
Hubs and switches
carry your data
FRAMES
When a frame is received, it is ______ and then transmitted on to the port of the destination PC.
amplified
provides a device with the physical connection to the network. NICs can provide connections for any type of networking media, including wireless media
NIC
is a physical and data link layer technology for local area network.
ETHERNET
type of network devices used by the public
NIC (Network Interface Card)
Repeater
Hub
Modem
Server
Switch
Advantages OF HUB
They are cheap and readily available.
They are easy to deploy and maintain.
They can connect media operating at different speeds.
ADVANTAGES OF REPEATER
A repeater can connect different types of media (such as coax to twisted pair).
Repeaters extend the distance a network can reach.
Repeaters do not increase network traffic.
Advantages OF SWITCH
Q
They limit the collision domain.
They can segment the network into multiple segments with separate collision domains.
They support intelligent management capabilities.
They can limit broadcast traffic propagated between segments.
is flow priority for computer network
HOV lane of transport netwrok
street address for computer network
ip address
payload for computer network
people of transport network
broadband for computer network
highway/ path
routing algorhitim for cpmputer network
following a route network
is a device or program that enables a computer to transmit data over, for example, telephone or cable lines
MODEM
known as node address
network tree
a base 2 numbersing system
binary
the subnet mask determines the network version and host portion
newer technology
value of the first octet determines thenetwork portion and the host portion determines
older technology
a special addres
broadcast address
the address assigned
host address
other called is subnet mask
prefix length
used to identufy the network and host portion
subnet mask
used efficiently in various situations
address classes
all are real numbers
number system
all digit start with 0
0
a base-n number system has 10 og digits
decimal
base 2 has 2 digits
binary
base-16 has 16 digits
hexadecimal
the first column is always the number of 1’s
1’s
internet and most internal workd
classless ip addressing
have all 0’s in the host portion
network address
have all 1’s in the host portion
broadcast address
cannot have 0’s and 1’s in the host
host adresses
subnet mask has
32
other called for prefix length
IP subnet mask length
subnet mask has two portion
network and host
unique combination 0’s and 1’s in the host portion of the address
subnet
in 16-bit available how many possible addresses
2 raise to 16
in 8-bit available how many possible addresses
2 raise to 8
connected to a computer used as communication
ip address
was in various testing until mid-2000’s
IPV6
has 18 million addreses
private network
has 270 million addresses
multicast
organization reviewed the internet protocol
IETF
ip address two parts:
network number,
host number
to represent the value of each byte
DOTTED NOTATION
THE ADDRESSES ASSIGNED
HOST ADDRESS
USED EFFICIENTLY IN VARIOUS SITUATIONS
ADDRESS CLASSES
