Networking Chapter 5

What does the transport layer do?

Uses the source and destination port addresses to link the application layer software to the network. TCP is also responsible for segmenting --- breaking large messages into smaller segments for transmission and reassembling them at the receiver's end.

What does the network layer do?

The TCP segments ad IP packets are created by the sending computer and never change until the message reaches its final destination. The IP packet contains the original source and ultimate destination address for the packet. The sending computer also creates a data link layer frame for each message, which contains the data link layer address of the current computer sending packet and the data link layer address of the next computer in the route.

Compare and contrast the three types of addresses used in a network

Application layer address - when a user types an Internet address into a Web browser, the request is passed to the network as part of an application layer packet formatted using the HTTP protocol.
Network Layer Address - it is IP for example (www.indiana.edu) is translated into an IP address that is 4 bytes long when using IPv4.
Data link Layer Address - with Ethernet the IP addresses are 6 bytes in length. They are only needed on multipoint circuits which have more than one computer on them.

How is TCP different from UDP

The UDP packet is much smaller than the TCP packet only 8 bytes. HTTP always uses TCP. UDP is most commonly used for control messages such as addressing, routing control messages and network management.

What is a subnet?

Group of computers on the same LAN with IP numbers using the same prefix
Assigned addresses that are 8 bits in length

Subnet Mask

Used to make it easier to separate the subnet part of the address from the host part.

How does dynamic Addressing work?

an approach in which a server is designated to supply a network layer address to a computer each time the computer connects to the network

Benefits of Dynamic Addressing

Greatly simplifies network management in non dial up networks too.
Changes need to be made only to the DHCP server not to each individual computer.

Address Resolution

to send a message, the sender must be able to translate the application layer address of the destination into a network layer address and in turn translate that into a data link address.

DHCP

Dynamic Host Configuration Protocol - most common standard for dynamic addressing, instead of a network address layer, there is a special software package installed on the client that instructs it to contact a DHCP server to obtain an address.

Autonomous System

- a network operated by one organization that runs part of the internet.

How are packets sent from one Autonomous system to another?

Computers within each system know bout other computers in the system and exchange information. Packets can be sent within the 5 protocols. Each system has a border router that connects it to the adjacent autonomous systems and exchanges route information.

How a computer determines where to send a packet to another computer that is on its own subnet?

Computer determines where to send a packet to another computer on its own subnet by using address resolution. Computer must know correct data link layer address and sends broadcast message. Request using Address Resolution Protocol.

Host

any device that sends or receives information

Peripheral

any device connected to a host

LAN

group of computers under one administrative control

WLAN

group of wireless devices that connect to access points

PAN

bluetooth technology

MAN

network that spans across of large campus or city

WAN

the Internet

peer-to-peer

devices connected together with no central administration

client-server

central administration provided for a network

share resources

primary benefit of a computer network

bandwidth

amount of data that can be transmitted

binary

0 or 1

latency

delay

half-duplex

data flows in one direction at a time

full-duplex

data flows in both directions at the same time

TCP/IP

defines how computers talk to each other

IP address

logical address

subnet mask

indicates the network portion of an IP address

IPv6

128 bits long

IPv4

32 bits long

8 bits

one BYTE

Class A range

1-126

Class B range

128-191

Class C range

192-223:

:

separates the block in an IPv6 address

global prefix

first 3 block of an IPv6 address

static

manual configuration of an IP address

MAC address

physical address

DHCP

automatic configuration of an IP address

169.254.x.x

means there is no DHCP server available for use

Private addresses

not seen by the public

4

number of pings to test connectivity

octet

groups of addresses in an IPv4 address

ping

tests connectivity between devices

ICMP

protocol used to send control and error message to computers

32

number of bits in an IPv4 address

3

number of parts in an IPv6 address

port number

keeps track of conversations on a network

modem

converts digital to analog signals and vice versa

media

cabling

hub

send out traffic to all ports

multiport bridge

switch

switch

builds a MAC table ; sends out traffic to specified ports

PoE

Power over Ethernet-provides current to certain devices on the network

access point

uses radio waves to provide access to wireless devices

ISR

multipurpose device; combines functionality of router, AP, and switch

UDP

lower overhead responsibilities

physical topology

physical layout of network components

logical topology

how hots access the medium to talk on the network

VoIP

telephone calls made over data networks

Firewall

determines what is permitted or denied on a network

UTP

most common cable used in networks

STP

wire pairs wrapped in metallic foil to shield wires from electrical noise

Fiber optic

use of light to transmit data

Straight through

cable type used to connect unlike devices

Crossover

cable type used to connect like devices

Bus topology

each computer connects to a common cable

Ring topology

hosts are connected in a physical ring or circle; no collisions

Star topology

hosts connect to a central connection point

Extended star topology

a star network with additional network devices connected to the main central device

Mesh topology

all devices connected to each other

Hybrid topology

combination of two or more basic network topologies

Broadcast logical topology

first come, first serve on the network

Token passing logical topology

network access controlled by passing an electronic token

802.3 standard

ethernet standard

802.11 standard

wireless devices standard

CSMA/CD

used by Ethernet networks to control media access

Computer network benefit

ability to share resources

IP address 169.254.x.x

unable to find DHCP server; IP address automatically assigned by Windows OS

NIC configuration components

Protocol
IP address
MAC address

SSID

Name of the wireless network

Wireless encryption methods

WEP
WPA
WPA2

ipconfig

command to display basic network adapter configurations

VPN

private network that connects remote sites over the public network (Internet)

Dialup

connection over a phone line

DSL

uses existing phone lines to provide high speed communication

Broadband

transmit and receive multiple frequencies over one cable

Access VPN

Enables employees to access an organization's networks from a remote location. Employees have access to the network and all the resources on it in the same way as employees physically located on the network.

Asynchronous Transfer Mode (ATM)

A communication switch that handles interface speeds ranging from 25 million to 622 million bps. It multiplexes data streams onto the same BN by using cell relay techniques. ATM switches can handle multimedia traffic, such as data, graphics, voice, and video.

Basic Rate Interface (BRI)

In ISDN, two 64,000-bps B circuits for data transmission and one 16,000-bps D circuit for signaling (2 B+D). Also called basic rate access.

Canadian Radio-Television and Telecommunications Commission (CRTC)

Federal government agency in Canada that regulates data and voice communications.

Channel Service Unit/Data Service Unit (CSU/DSU)

Transforms digital data between telephone company lines and local equipment. Converts the signals into a format compatible with the data terminal equipment.

Circuit-Switched Services

A method of communications whereby an electrical connection between calling and called stations is established on demand for exclusive use of the circuit until the connection is terminated.

Cloud

Computers connected through a communication network, such as the Internet.

Cloud Architecture

Users lease connection points into the common carrier's network (the cloud)

Committed Information Rate (CIR)

Data rate the PVC must guarantee to transmit. If the network accepts the connection, it guarantees to provide that level of service.

Common Carrier

An organization in the business of providing regulating telephone, telegraph, telex, and data communications services, such as AT&T, MCI, Bell-South, and NYNEX. This term is applied most often to U.S. and Canadian commercial organizations, but sometimes it is used to refer to telecommunications entities, such as government-operated suppliers of communication services in other countries (see also PTT)