Microwave Transmission Network
Code Division Multiple Access
Universal Mobile Telecommunications Service
Transmitting video in IP packets
Attenuation, distortion, and noise
DHCP server
Radio waves
Transmitting video in IP packets
Attenuation, distortion, and noise
DHCP server
Radio waves
Asynchronous transfer mode
Multimode step index
Wavelength of frequency
coaxial cable
Fiber optic
Multimode step index
Wavelength of frequency
coaxial cable
Fiber optic
Twisted Wire
Topologies
Satellite
Topologies
Satellite
Metropolitan Area Network Local Area Network
Tcp\ip
Network
Data communication is the transfer of data from one device to another via some form of transmission medium.A data communications system must transmit data to the correct destination in an accurate and timely manner.
Tcp\ip
Network
Data communication is the transfer of data from one device to another via some form of transmission medium.A data communications system must transmit data to the correct destination in an accurate and timely manner.
The five components that make up a data communications system are the message, sender, receiver, medium, and protocol.
Text, numbers, images, audio, and video are different forms of information.
Data flow between two devices can occur in one of three ways: simplex, half-duplex, or full-duplex.
A network is a set of communication devices connected by media links.
In a point-to-point connection, two and only two devices are connected by a dedicated link. In a multipoint connection, three or more devices share a link.
Topology refers to the physical or logical arrangement of a network. Devices may be arranged in a mesh, star, bus, or ring topology.
A network can be categorized as a local area network (LAN), a metropolitan-area network (MAN), or a wide area network (WAN).
A LAN is a data communication system within a building, plant, or campus, or between nearby buildings.
A MAN is a data communication system covering an area the size of a town or city.
A WAN is a data communication system spanning states, countries, or the whole world.
An internet is a network of networks.
The Internet is a collection of many separate networks.
TCP/IP is the protocol suite for the Internet.
There are local, regional, national, and international Internet service providers (ISPs).
A protocol is a set of rules that governs data communication; the key elements of a protocol are syntax, semantics, and timing.
Standards are necessary to ensure that products from different manufacturers can work together as expected.
The ISO, ITU-T, ANSI, IEEE, and EIA are some of the organizations involved in standards creation.
Forums are special-interest groups that quickly evaluate and standardize new technologies.
A Request for Comment (RFC) is an idea or concept that is a precursor to an Internet standard.
A signal is periodic if it consists of a continuously repeating pattern.
Each sine wave can be characterized by its amplitude, frequency, and phase.
Frequency and period are inverses of each other.
A time-domain graph plots amplitude as a function of time.
A frequency-domain graph plots each sine wave’s peak amplitude against its frequency.
By using Fourier analysis, any composite signal can be represented as a combination of simple sine waves.
The spectrum of a signal consists of the sine waves that make up the signal.
The bandwidth of a signal is the range of frequencies the signal occupies. Bandwidth is determined by finding the difference between the highest and lowest frequency components.
Bit rate (number of bits per second) and bit interval (duration of 1 bit) are terms used to describe digital signals.
A digital signal is a composite signal with an infinite bandwidth.
Bit rate and bandwidth are proportional to each other.
The Nyquist formula determines the theoretical data rate for a noiseless channel.
The Shannon capacity determines the theoretical maximum data rate for a noisy channel.
Attenuation, distortion, and noise can impair a signal.
Attenuation is the loss of a signal’s energy due to the resistance of the medium.
The decibel measures the relative strength of two signals or a signal at two different points.
Distortion is the alteration of a signal due to the differing propagation speeds of each of the frequencies that make up a signal.
Noise is the external energy that corrupts a signal.
We can evaluate transmission media by throughput, propagation speed, and propagation time.
The wavelength of a frequency is defined as the propagation speed divided by the frequency.
Twisted-pair cable, coaxial cable, and optical fiber are the most popular types of guided media. Twisted-pair cable consists of two insulated copper wires twisted together. Twisting allows each wire to have approximately the same noise environment. *
Twisted-pair cable is used in telephone lines for voice and data communications.
Coaxial cable has the following layers (starting from the center): a metallic rod-shaped inner conductor, an insulator covering the rod, a metallic outer conductor (shield), an insulator covering the shield, and a plastic cover.
Coaxial cable can carry signals of higher frequency ranges than twisted-pair cable.
Coaxial cable is used in cable TV networks and traditional Ethernet LANs.
Fiber-optic cables are composed of a glass or plastic inner core surrounded by cladding, all encased in an outside jacket.
Fiber-optic cables carry data signals in the form of light. The signal is propagated along the inner core by reflection.
* Fiber-optic transmission is becoming increasingly popular due to its noise resistance, low attenuation, and high-bandwith capabilities.
* Signal propagation in optical fibers can be multimode (multiple beams from a light source) or single-mode (essentially one beam from a light source).
* In multimode step-index propagation, the core density is constant and the light beam changes direction suddenly at the interface between the core and the cladding.
* In multimode graded-index propagation, the core density decreases with distance from the center. This causes a curving of the light beams.
* Fiber-optic cable is used in backbone networks, cable TV networks, and Fast Ethernet networks.
* Unguided media (usually air) transport electromagnetic waves without the use of a physical conductor.
* Wireless data is transmitted through ground propagation, sky propagation, and line-of-sight propagation.
* Wireless data can be classifed as radio waves, microwaves, or infrared waves.
* Radio waves are omnidirectional. The radio wave band is under government regulation.
* Microwaves are unidirectional; propagation is line of sight. Microwaves are used for cellular phone, satellite, and wireless LAN communications.
* The parabolic dish antenna and the horn antenna are used for transmission and reception of microwaves.
* Infrared waves are used for short-range communications such as those between a PC and a peripheral device.
There are two popular approaches to packet switching: the datagram approach and the virtual circuit approach.
In the datagram approach, each packet is treated independently of all other packets.
At the network layer, a global addressing system that uniquely identifies every host and router is necessary for delivery of a packet from network to network.
The Internet address (or IP address) is 32 bits (for IPv4) that uniquely and universally defines a host or router on the internet.
The portion of the IP address that identifies the network is called the netid.
The portion of the IP address that identifies the host or router on the network is called the hostid.
There are five classes of IP addresses. Classes A, B, and C differ in the number of hosts allowed per network. Class D is for multicasting, and class E is reserved.
The class of a network is easily determined by examination of the first byte.
Unicast communication is one source sending a packet to one destination.
Multicast communication is one source sending a packet to multiple destinations.
Subnetting divides one large network into several smaller ones.
Subnetting adds an intermediate level of hierarchy in IP addressing.
Default masking is a process that extracts the network address from an IP address.
Subnet masking is a process that extracts the subnetwork address from an IP address
Supernetting combines several networks into one large one.
In classless addressing, there are variable-length blocks that belong to no class. The entire address space is divided into blocks based on organization needs.
The first address and the mask in classless addressing can define the whole block. A mask can be expressed in slash notation which is a slash followed by the number of 1s in the mask. Every computer attached to the Internet must know its IP address, the IP address of a router, the IP address of a name server, and its subnet mask (if it is part of a subnet).
DHCP is a dynamic configuration protocol with two databases.
The DHCP server issues a lease for an IP address to a client for a specific period of time.
Network address translation (NAT) allows a private network to use a set of private addresses for internal communication and a set of global Internet addresses for external communication.
NAT uses translation tables to route messages.
The IP protocol is a connectionless protocol. Every packet is independent and has no relationship to any other packet.
Every host or router has a routing table to route IP packets.
Asynchronous Transfer Mode (ATM)
Text, numbers, images, audio, and video are different forms of information.
Data flow between two devices can occur in one of three ways: simplex, half-duplex, or full-duplex.
A network is a set of communication devices connected by media links.
In a point-to-point connection, two and only two devices are connected by a dedicated link. In a multipoint connection, three or more devices share a link.
Topology refers to the physical or logical arrangement of a network. Devices may be arranged in a mesh, star, bus, or ring topology.
A network can be categorized as a local area network (LAN), a metropolitan-area network (MAN), or a wide area network (WAN).
A LAN is a data communication system within a building, plant, or campus, or between nearby buildings.
A MAN is a data communication system covering an area the size of a town or city.
A WAN is a data communication system spanning states, countries, or the whole world.
An internet is a network of networks.
The Internet is a collection of many separate networks.
TCP/IP is the protocol suite for the Internet.
There are local, regional, national, and international Internet service providers (ISPs).
A protocol is a set of rules that governs data communication; the key elements of a protocol are syntax, semantics, and timing.
Standards are necessary to ensure that products from different manufacturers can work together as expected.
The ISO, ITU-T, ANSI, IEEE, and EIA are some of the organizations involved in standards creation.
Forums are special-interest groups that quickly evaluate and standardize new technologies.
A Request for Comment (RFC) is an idea or concept that is a precursor to an Internet standard.
Signals
* Data must be transformed into electromagnetic signals prior to transmission across a network.
* Data and signals can be either analog or digital.A signal is periodic if it consists of a continuously repeating pattern.
Each sine wave can be characterized by its amplitude, frequency, and phase.
Frequency and period are inverses of each other.
A time-domain graph plots amplitude as a function of time.
A frequency-domain graph plots each sine wave’s peak amplitude against its frequency.
By using Fourier analysis, any composite signal can be represented as a combination of simple sine waves.
The spectrum of a signal consists of the sine waves that make up the signal.
The bandwidth of a signal is the range of frequencies the signal occupies. Bandwidth is determined by finding the difference between the highest and lowest frequency components.
Bit rate (number of bits per second) and bit interval (duration of 1 bit) are terms used to describe digital signals.
A digital signal is a composite signal with an infinite bandwidth.
Bit rate and bandwidth are proportional to each other.
The Nyquist formula determines the theoretical data rate for a noiseless channel.
The Shannon capacity determines the theoretical maximum data rate for a noisy channel.
Attenuation, distortion, and noise can impair a signal.
Attenuation is the loss of a signal’s energy due to the resistance of the medium.
The decibel measures the relative strength of two signals or a signal at two different points.
Distortion is the alteration of a signal due to the differing propagation speeds of each of the frequencies that make up a signal.
Noise is the external energy that corrupts a signal.
We can evaluate transmission media by throughput, propagation speed, and propagation time.
The wavelength of a frequency is defined as the propagation speed divided by the frequency.
Transmission Media
* Transmission media lie below the physical layer.
Twisted-pair cable, coaxial cable, and optical fiber are the most popular types of guided media. Twisted-pair cable consists of two insulated copper wires twisted together. Twisting allows each wire to have approximately the same noise environment. *
Twisted-pair cable is used in telephone lines for voice and data communications.
Coaxial cable has the following layers (starting from the center): a metallic rod-shaped inner conductor, an insulator covering the rod, a metallic outer conductor (shield), an insulator covering the shield, and a plastic cover.
Coaxial cable can carry signals of higher frequency ranges than twisted-pair cable.
Coaxial cable is used in cable TV networks and traditional Ethernet LANs.
Fiber-optic cables are composed of a glass or plastic inner core surrounded by cladding, all encased in an outside jacket.
Fiber-optic cables carry data signals in the form of light. The signal is propagated along the inner core by reflection.
* Fiber-optic transmission is becoming increasingly popular due to its noise resistance, low attenuation, and high-bandwith capabilities.
* Signal propagation in optical fibers can be multimode (multiple beams from a light source) or single-mode (essentially one beam from a light source).
* In multimode step-index propagation, the core density is constant and the light beam changes direction suddenly at the interface between the core and the cladding.
* In multimode graded-index propagation, the core density decreases with distance from the center. This causes a curving of the light beams.
* Fiber-optic cable is used in backbone networks, cable TV networks, and Fast Ethernet networks.
* Unguided media (usually air) transport electromagnetic waves without the use of a physical conductor.
* Wireless data is transmitted through ground propagation, sky propagation, and line-of-sight propagation.
* Wireless data can be classifed as radio waves, microwaves, or infrared waves.
* Radio waves are omnidirectional. The radio wave band is under government regulation.
* Microwaves are unidirectional; propagation is line of sight. Microwaves are used for cellular phone, satellite, and wireless LAN communications.
* The parabolic dish antenna and the horn antenna are used for transmission and reception of microwaves.
* Infrared waves are used for short-range communications such as those between a PC and a peripheral device.
There are two popular approaches to packet switching: the datagram approach and the virtual circuit approach.
In the datagram approach, each packet is treated independently of all other packets.
At the network layer, a global addressing system that uniquely identifies every host and router is necessary for delivery of a packet from network to network.
The Internet address (or IP address) is 32 bits (for IPv4) that uniquely and universally defines a host or router on the internet.
The portion of the IP address that identifies the network is called the netid.
The portion of the IP address that identifies the host or router on the network is called the hostid.
There are five classes of IP addresses. Classes A, B, and C differ in the number of hosts allowed per network. Class D is for multicasting, and class E is reserved.
The class of a network is easily determined by examination of the first byte.
Unicast communication is one source sending a packet to one destination.
Multicast communication is one source sending a packet to multiple destinations.
Subnetting divides one large network into several smaller ones.
Subnetting adds an intermediate level of hierarchy in IP addressing.
Default masking is a process that extracts the network address from an IP address.
Subnet masking is a process that extracts the subnetwork address from an IP address
Supernetting combines several networks into one large one.
In classless addressing, there are variable-length blocks that belong to no class. The entire address space is divided into blocks based on organization needs.
The first address and the mask in classless addressing can define the whole block. A mask can be expressed in slash notation which is a slash followed by the number of 1s in the mask. Every computer attached to the Internet must know its IP address, the IP address of a router, the IP address of a name server, and its subnet mask (if it is part of a subnet).
DHCP is a dynamic configuration protocol with two databases.
The DHCP server issues a lease for an IP address to a client for a specific period of time.
Network address translation (NAT) allows a private network to use a set of private addresses for internal communication and a set of global Internet addresses for external communication.
NAT uses translation tables to route messages.
The IP protocol is a connectionless protocol. Every packet is independent and has no relationship to any other packet.
Every host or router has a routing table to route IP packets.
Asynchronous Transfer Mode (ATM)
A cell-based network technology protocol that supports simultaneous transmission of data, voice and video typically at T1/E1 or higher speeds.
Code Division Multiple Access (CDMA)
A digital wireless technology that uses a modulation technique in which many channels are independently
coded for transmission over a single wideband channel.
Time Division Synchronous Code
Division Multiple Access (TD-SCDMA)
A 3G mobile telecommunications standard, being pursued in the People's Republic of China by the
Chinese Academy of Telecommunications Technology (CATT).
Global System for Mobile
Communications (GSM)
A digital wireless technology that is widely deployed in Europe and, increasingly, in other parts of the
world.
General Packet Radio Service (GPRS)
A packet-based digital intermediate speed wireless technology based on GSM. (2.5 generation)
Universal Mobile Telecommunications
Service (UMTS)
A third-generation digital high-speed wireless technology for packet-based transmission of text, digitized
voice, video, and multimedia that is the successor to GSM.
Voice Over IP (VoIP)
A telephone service that uses the Internet as a global telephone network.
Transmitting video in IP packets (IMS)
An internationally recognized standard defining a generic architecture for offering Voice over IP and
multimedia services to multiple-access technologies.
Triple Play
A marketing term for the provisioning of the three services: high-speed Internet, television (Video on
Demand or regular broadcasts) and telephone service over a single broadband connection.
Internet Protocol TV (IPTV)
Transmitting video in IP packets. Also called “TV over IP,” IPTV uses streaming video techniques to
deliver scheduled TV programs or video on demand (VOD).
Protocol
A specific set of rules, procedures or conventions governing the format, means and timing of
transmissions between two devices.
Session
