Peer-to-Peer Networks

1. In the peer to peer computer network model we simply use the same Workgroup for all the computers and a unique name for each computer in a computer network.
2. There is no master or controller or central server in this computer network and computers join hands to share files, printers and Internet access.
3. It is practical for workgroups of a dozen or less computers making it common environments, where each PC acts as an independent workstation and maintaining its own security that stores data on its own disk but which can share it with all other PCs on the network.
4. Software for peer-to-peer network is included with most modern desktop operating systems such as Windows and Mac OS.

Modem: What is a Modem? Types of Modems

Modem is abbreviation for Modulator – Demodulator. Modems are used for data transfer from one computer network to another computer network through telephone lines. The computer network works in digital mode, while analog technology is used for carrying massages across phone lines.

Network Security

Data on the network is analogous to possessions of a person. It has to be kept secure from others with malicious intent. This intent ranges from bringing down servers on the network to using people's private information like credit card numbers to sabotage of major organizations with a presence on a network. To secure data, one has to ensure that it makes sense only to those for whom it is meant. This is the case for data transactions where we want to prevent eavesdroppers from listening to and stealing data. Other aspects of security involve protecting user data on a computer by providing password restricted access to the data and maybe some resources so that only authorized people get to use these,  and identifying miscreants and thwarting their attempts to cause damage to the network among other things.

The various issues in Network security are as follows :

1. Authentication: We have to check that the person who has requested for something or has sent an e-mail is indeed allowed to do so. In this process we will also look at how the person authenticates his identity to a remote machine.
2. Integrity: We have to check that the message which we have received is indeed the message which was sent. Here CRC will not be enough because somebody may deliberately change the data. Nobody along the route should be able to change the data.
3. Confidentiality: Nobody should be able to read the data on the way so we need Encryption
4. Non-repudiation: Once we sent a message, there should be no way that we can deny sending it and we have to accept that we had sent it.
5. Authorization: This refers to the kind of service which is allowed for a particular client. Even though a user is authenticated we may decide not to authorize him to use a particular service.

For authentication, if two persons know a secret then we just need to prove that no third person could have generated the message. But for Non-repudiation we need to prove that even the sender could not have generated the message. So authentication is easier than Non-repudiation. To ensure all this, we take the help of cryptography. We can have two kinds of encryption :

1. Symmetric Key Encryption: There is a single key which is shared between the two users and the same key is used for encrypting and decrypting the message.
2. Public Key Encryption: There are two keys with each user : a public key and a private key. The public key of a user is known to all but the private key is not known to anyone except the owner of the key. If a user encrypts a message in his private key then it can be decrypted by anyone by using the sender's public key. To send a message securely, we encrypt the message in the public key of the receiver which can only be decrypted by the user with his private key.

Symmetric key encryption is much faster and efficient in terms of performance. But it does not give us Non-repudiation. And there is a problem of how do the two sides agree on the key to be used assuming that the channel is insecure ( others may snoop on our packet ). In symmetric key exchange, we need some amount of public key encryption for authentication. However, in public key encryption, we can send the public key in plain text and so key exchange is trivial. But this does not authenticate anybody. So along with the public key, there needs to be a certificate. Hence we would need a public key infrastructure to distribute such certificates in the world.

What Is a Gaming Router?

You my have noticed some home broadband routers being marketed as gaming routers. People can play online games through routers that aren't considered gaming routers, but certain kinds of routers offer a few specific network performance features that make them more attractive to gamers:

• high-speed Ethernet ports: Gamers often prefer wired connections to wireless and expect Gigabit Ethernet speeds at a minimum
• high-speed Wi-Fi: When Ethernet cables aren't a practical option, gamers need the fastest Wi-Fi connectivity available; nowadays, this means802.11ac and sometimes even dual band routersupport
• traffic prioritization features: Gaming routers support special Quality of Service (QoS)configuration options that allow the network data for games to be processed faster at the expense of processing other kinds of traffic slower - examples of these technologies include Qualcomm StreamBoost

What Is Project Loon?

What Is Project Loon?

This week, Google's Project Loon was accepting applications from residents in central California (USA) to test the experimental system. Project Loon is a unique method of providing wireless Internet service in rural areas using a network of high-altitude air balloons. Those participating in the upcoming California trial will have a special antenna installed at their residence that connects with the balloons floating more than 10 miles above the earth, which in turn route traffic back to Internet providers on the ground.

The first public trial of Project Loon was held in June in New Zealand, but for only 50 lucky users; it remains to be seen how widely useful such a system can become.

What Is a Socket?

Normally, a server runs on a specific computer and has a socket that is bound to a specific port number. The server just waits, listening to the socket for a client to make a connection request.
On the client-side: The client knows the hostname of the machine on which the server is running and the port number on which the server is listening. To make a connection request, the client tries to rendezvous with the server on the server's machine and port. The client also needs to identify itself to the server so it binds to a local port number that it will use during this connection. This is usually assigned by the system.

If everything goes well, the server accepts the connection. Upon acceptance, the server gets a new socket bound to the same local port and also has its remote endpoint set to the address and port of the client. It needs a new socket so that it can continue to listen to the original socket for connection requests while tending to the needs of the connected client.

On the client side, if the connection is accepted, a socket is successfully created and the client can use the socket to communicate with the server.
The client and server can now communicate by writing to or reading from their sockets.

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Definition: A socket is one endpoint of a two-way communication link between two programs running on the network. A socket is bound to a port number so that the TCP layer can identify the application that data is destined to be sent.

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An endpoint is a combination of an IP address and a port number. Every TCP connection can be uniquely identified by its two endpoints. That way you can have multiple connections between your host and the server.
The java.net package in the Java platform provides a class, Socket, that implements one side of a two-way connection between your Java program and another program on the network. The Socket class sits on top of a platform-dependent implementation, hiding the details of any particular system from your Java program. By using the java.net.Socket class instead of relying on native code, your Java programs can communicate over the network in a platform-independent fashion.
Additionally, java.net includes the ServerSocket class, which implements a socket that servers can use to listen for and accept connections to clients. This lesson shows you how to use the Socket and ServerSocket classes.
If you are trying to connect to the Web, the URL class and related classes (URLConnection, URLEncoder) are probably more appropriate than the socket classes. In fact, URLs are a relatively high-level connection to the Web and use sockets as part of the underlying implementation. See Working with URLs for information about connecting to the Web via URLs.

Types of Servers

Device Servers

A device server is defined as a specialized, network-based hardware device designed to perform a single or specialized set of server functions. It is characterized by a minimal operating architecture that requires no per seat network operating system license, and client access that is independent of any operating system or proprietary protocol. In addition the device server is a "closed box," delivering extreme ease of installation, minimal maintenance, and can be managed by the client remotely via a Web browser.

Print servers, terminal servers, remote access servers and network time servers are examples of device servers which are specialized for particular functions. Each of these types of servers has unique configuration attributes in hardware or software that help them to perform best in their particular arena.

Print Servers

Print servers allow printers to be shared by other users on the network. Supporting either parallel and/or serial interfaces, a print server accepts print jobs from any person on the network using supported protocols and manages those jobs on each appropriate printer.

Print servers generally do not contain a large amount of memory; printers simply store information in a queue. When the desired printer becomes available, they allow the host to transmit the data to the appropriate printer port on the server. The print server can then simply queue and print each job in the order in which print requests are received, regardless of protocol used or the size of the job.

Multiport Device Servers

Devices that are attached to a network through a multiport device server can be shared between terminals and hosts at both the local site and throughout the network. A single terminal may be connected to several hosts at the same time (in multiple concurrent sessions), and can switch between them. Multiport device servers are also used to network devices that have only serial outputs. A connection between serial ports on different servers is opened, allowing data to move between the two devices.

Given its natural translation ability, a multi-protocol multiport device server can perform conversions between the protocols it knows, like LAT and TCP/IP. While server bandwidth is not adequate for large file transfers, it can easily handle host-to-host inquiry/response applications, electronic mailbox checking, etc. And it is far more economical than the alternatives of acquiring expensive host software and special-purpose converters. Multiport device and print servers give their users greater flexibility in configuring and managing their networks.

Whether it is moving printers and other peripherals from one network to another, expanding the dimensions of interoperability or preparing for growth, multiport device servers can fulfill your needs, all without major rewiring.

Access Servers

While Ethernet is limited to a geographic area, remote users such as traveling sales people need access to network-based resources. Remote LAN access, or remote access, is a popular way to provide this connectivity. Access servers use telephone services to link a user or office with an office network. Dial-up remote access solutions such as ISDN or asynchronous dial introduce more flexibility. Dial-up remote access offers both the remote office and the remote user the economy and flexibility of "pay as you go" telephone services. ISDN is a special telephone service that offers three channels, two 64 Kbps "B" channels for user data and a "D" channel for setting up the connection. With ISDN, the B channels can be combined for double bandwidth or separated for different applications or users. With asynchronous remote access, regular telephone lines are combined with modems and remote access servers to allow users and networks to dial anywhere in the world and have data access. Remote access servers provide connection points for both dial-in and dial-out applications on the network to which they are attached. These hybrid devices route and filter protocols and offer other services such as modem pooling and terminal/printer services. For the remote PC user, one can connect from any available telephone jack (RJ45), including those in a hotel rooms or on most airplanes.

Network Time Servers

A network time server is a server specialized in the handling of timing information from sources such as satellites or radio broadcasts and is capable of providing this timing data to its attached network. Specialized protocols such as NTP or udp/time allow a time server to communicate to other network nodes ensuring that activities that must be coordinated according to their time of execution are synchronized correctly. GPS satellites are one source of information that can allow global installations to achieve constant timing.

Types of LAN Technology

Ethernet

Ethernet is the most popular physical layer LAN technology in use today. It defines the number of conductors that are required for a connection, the performance thresholds that can be expected, and provides the framework for data transmission. A standard Ethernet network can transmit data at a rate up to 10 Megabits per second (10 Mbps). Other LAN types include Token Ring, Fast Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet, Fiber Distributed Data Interface (FDDI), Asynchronous Transfer Mode (ATM) and LocalTalk.

Ethernet is popular because it strikes a good balance between speed, cost and ease of installation. These benefits, combined with wide acceptance in the computer marketplace and the ability to support virtually all popular network protocols, make Ethernet an ideal networking technology for most computer users today.

The Institute for Electrical and Electronic Engineers developed an Ethernet standard known as IEEE Standard 802.3. This standard defines rules for configuring an Ethernet network and also specifies how the elements in an Ethernet network interact with one another. By adhering to the IEEE standard, network equipment and network protocols can communicate efficiently.

Fast Ethernet

The Fast Ethernet standard (IEEE 802.3u) has been established for Ethernet networks that need higher transmission speeds. This standard raises the Ethernet speed limit from 10 Mbps to 100 Mbps with only minimal changes to the existing cable structure. Fast Ethernet provides faster throughput for video, multimedia, graphics, Internet surfing and stronger error detection and correction.

There are three types of Fast Ethernet: 100BASE-TX for use with level 5 UTP cable; 100BASE-FX for use with fiber-optic cable; and 100BASE-T4 which utilizes an extra two wires for use with level 3 UTP cable. The 100BASE-TX standard has become the most popular due to its close compatibility with the 10BASE-T Ethernet standard.

Network managers who want to incorporate Fast Ethernet into an existing configuration are required to make many decisions. The number of users in each site on the network that need the higher throughput must be determined; which segments of the backbone need to be reconfigured specifically for 100BASE-T; plus what hardware is necessary in order to connect the 100BASE-T segments with existing 10BASE-T segments. Gigabit Ethernet is a future technology that promises a migration path beyond Fast Ethernet so the next generation of networks will support even higher data transfer speeds.

Gigabit Ethernet

Gigabit Ethernet was developed to meet the need for faster communication networks with applications such as multimedia and Voice over IP (VoIP). Also known as "gigabit-Ethernet-over-copper" or 1000Base-T, GigE is a version of Ethernet that runs at speeds 10 times faster than 100Base-T. It is defined in the IEEE 802.3 standard and is currently used as an enterprise backbone. Existing Ethernet LANs with 10 and 100 Mbps cards can feed into a Gigabit Ethernet backbone to interconnect high performance switches, routers and servers.

From the data link layer of the OSI model upward, the look and implementation of Gigabit Ethernet is identical to that of Ethernet. The most important differences between Gigabit Ethernet and Fast Ethernet include the additional support of full duplex operation in the MAC layer and the data rates.

10 Gigabit Ethernet

10 Gigabit Ethernet is the fastest and most recent of the Ethernet standards. IEEE 802.3ae defines a version of Ethernet with a nominal rate of 10Gbits/s that makes it 10 times faster than Gigabit Ethernet.

Unlike other Ethernet systems, 10 Gigabit Ethernet is based entirely on the use of optical fiber connections. This developing standard is moving away from a LAN design that broadcasts to all nodes, toward a system which includes some elements of wide area routing. As it is still very new, which of the standards will gain commercial acceptance has yet to be determined.

Asynchronous Transfer Mode (ATM)

ATM is a cell-based fast-packet communication technique that can support data-transfer rates from sub-T1 speeds to 10 Gbps. ATM achieves its high speeds in part by transmitting data in fixed-size cells and dispensing with error-correction protocols. It relies on the inherent integrity of digital lines to ensure data integrity.

ATM can be integrated into an existing network as needed without having to update the entire network. Its fixed-length cell-relay operation is the signaling technology of the future and offers more predictable performance than variable length frames. Networks are extremely versatile and an ATM network can connect points in a building, or across the country, and still be treated as a single network.

Power over Ethernet (PoE)

PoE is a solution in which an electrical current is run to networking hardware over the Ethernet Category 5 cable or higher. This solution does not require an extra AC power cord at the product location. This minimizes the amount of cable needed as well as eliminates the difficulties and cost of installing extra outlets.

Types of Networks Explained

In describing the basics of networking technology, it will be helpful to explain the different types of networks in use.

Local Area Networks (LANs)

A network is any collection of independent computers that exchange information with each other over a shared communication medium. Local Area Networks or LANs are usually confined to a limited geographic area, such as a single building or a college campus. LANs can be small, linking as few as three computers, but can often link hundreds of computers used by thousands of people. The development of standard networking protocols and media has resulted in worldwide proliferation of LANs throughout business and educational organizations.

Wide Area Networks (WANs)

Often elements of a network are widely separated physically. Wide area networking combines multiple LANs that are geographically separate. This is accomplished by connecting the several LANs with dedicated leased lines such as a T1 or a T3, by dial-up phone lines (both synchronous and asynchronous), by satellite links and by data packet carrier services. WANs can be as simple as a modem and a remote access server for employees to dial into, or it can be as complex as hundreds of branch offices globally linked. Special routing protocols and filters minimize the expense of sending data over vast distances.

Wireless Local Area Networks (WLANs)

Wireless LANs, or WLANs, use radio frequency (RF) technology to transmit and receive data over the air. This minimizes the need for wired connections. WLANs give users mobility as they allow connection to a local area network without having to be physically connected by a cable. This freedom means users can access shared resources without looking for a place to plug in cables, provided that their terminals are mobile and within the designated network coverage area. With mobility, WLANs give flexibility and increased productivity, appealing to both entrepreneurs and to home users. WLANs may also enable network administrators to connect devices that may be physically difficult to reach with a cable.

The Institute for Electrical and Electronic Engineers (IEEE) developed the 802.11 specification for wireless LAN technology. 802.11 specifies over-the-air interface between a wireless client and a base station, or between two wireless clients. WLAN 802.11 standards also have security protocols that were developed to provide the same level of security as that of a wired LAN.
The first of these protocols is Wired Equivalent Privacy (WEP). WEP provides security by encrypting data sent over radio waves from end point to end point.

The second WLAN security protocol is Wi-Fi Protected Access (WPA). WPA was developed as an upgrade to the security features of WEP. It works with existing products that are WEP-enabled but provides two key improvements: improved data encryption through the temporal key integrity protocol (TKIP) which scrambles the keys using a hashing algorithm. It has means for integrity-checking to ensure that keys have not been tampered with. WPA also provides user authentication with the extensible authentication protocol (EAP).

Network Operating System Examples

         Examples of Network Operating System=>

 

• Windows NT server and workstation - Can use multiple processors and run on Intel or RISC computers. Performs preemptive multitasking.

• Windows 95 - Cannot use multiple processors or run on RISC computers. It cannot use NT drivers, but it can use older drivers.
• OS/2 - supports preemptive multitasking and multithreading and protects applications from each other. It runs on Intel or RISC computers. Supports 1 processor. Requires a minimum of a 386 and 8M of RAM. Some DOS drivers will work for OS/2. Won't run on DEC Alpha systems.
• MacIntosh - supports cooperative and preemptive multitasking and uses a windows, icons, mouse environment for system control.

Network Operating Systems (NOS)

Network operating systems typically are used to run computers that act as servers. They provide the capabilities required for network operation. Network operating systems are also designed for client computers and provide functions so the distinction between network operating systems and stand alone operating systems is not always obvious. Network operating systems provide the following functions:

• File and print sharing.
• Account administration for users.
• Security.

Installed Components

• Client functionality
• Server functionality

Functions provided:

• Account Administration for users
• Security
• File and print sharing

Network services

• File Sharing
• Print sharing
• User administration
• Backing up data

Types of Network

Main Networks are

• Ethernet
• FDDI
• Token Ring
• ARCnet
• AppleTalk

Other Network Types

• Fiber channel - Operates at 256 Mbps or 1 Gbps. It was developed for peripheral devices like disk arrays, but is now used for point to point networking for full duples server to server communications. It is the lowest cost 1 Gbps network.
• Gigabit Ethernet - This type of ethernet places ethernet packets in fiber channel packets. The fiber channel network works like an ethernet bridge.

DNS

Domain Name System (DNS) is used on the internet to correlate between IP address and readable names. There are servers providing DNS information to clients. The part of the system sending the queries is called the resolver and is the client side of the configuration. The name server answers the queries. Read RFCs 1034 and 1035. These contain the bulk of the DNS information and are superceded by RFCs 1535-1537. Naming is in RFC 1591. The main function of DNS is the mapping of IP addresses to human readable names.

What is Network

Definition of Network=>
When you have two or more computers connected to each other, you have a network. The purpose of a network is to enable the sharing of files and information between multiple systems. The Internet could be described as a global network of networks. Computer networks can be connected through cables, such as Ethernet cables or phone lines, or wireless, using wireless networking cards that send and receive data through the air.

Networking Terms

ADSP - AppleTalk data stream protocol manages the flow of data between two established socket connections. AEP - AppleTalk echo protocol uses echoes to tell if a computer, or node, is available. AFP - AppleTalk Filing protocol - Makes network files appear local by managing file sharing at the presentation layer. AGP - Accelerated Graphics Port. This bus is developed for fast video cards. It is currently up to 4X mode speed. API - Application Programming Interface. APPC - Advanced Peer-to-Peer Communications provides peer to peer services at the transport and session layer. APPN - Advanced Peer-to-Peer Networking supports the computer connections at the network and transport layers. Architecture - The method that is used to transmit packets on a network. Sometimes the term architecture includes topology. An example is ethernet. ARCnet - Attached Resource Computer Network is an architecture using star and bus topology. ARP - Address resolution Protocol is used to resolve the hardware address of a card to package the ethernet data. It works at the data link layer. RFC 826. ARUP - AppleTalk update routing is a newer version of RTMP. ASP - AppleTalk session protocol controls the starting and ending of sessions between computers called nodes. It works at the session level. ATM - Asynchronous Transfer Mode may be used over a variety of media with both baseband and broadband systems. It uses fixed length data packets of 53 bytes called cell switching. ATP - AppleTalk Transaction Protocol provides a Transport Layer connection between computers. attenuation - signal loss due to impedance. AU - Access Unit provides access to resources like fax, telex, and teletex. AUI - Attachment uint interface used to attach a station to a thicknet cable. Backbone - Main cable used to connect computers on a network. Bandwidth - Indicates the amount of data that can be sent in a time period. Measured in Mbps which is one million bits per second. Baseband - Data bits are defined by discrete signal changes. BDC - Backup Domain Controller is a backup for a PDC BGP - Border Gateway Protocol, a dynamic routing protocol. RFC 1267. BNC - British Naval Connector. BOOTP - Boot Protocol. RFC 951, 1542. Bridge - Read the outermost section of data on the data packet, to tell where the message is going. It reduces the traffic on other network segments, since it does not send all packets but only sends packets intended for that segment they are attached to. Broadband - Uses analog signals to divide the cable into several channels with each channel at its own frequency. Each channel can only transmit one direction. Broadcast - A transmission to all interface cards on the network. Brouter - Will function similar to a bridge for network transport protocols that are not routable, and will function as a router for routable protocols. BSC - Binary Synchronous Communication sends bits in frames which are timed sequences of data. A possible SNA communications architecture, CCITT - International Telegraph and Telephone Consultative Committee. CDDI - A copper version of FDDI which uses category 5 cable. Obviously the distance is more limited than FDDI. CHAP - Challenge Handshake Authentication Protocol is a three way handshake protocol which is considered more secure than PAP. CIDR - Classless Inter Domain Routing. Client - This computer requests resources for its use from a computer that provides the resource (a server). CDPD - Cellular Digital Packet Data will allow network connections for mobile users using satellites. CSMA/CD - Carrier-sense multiple-access with collision detection for controlling access to the network media. CSU - Channel service unit used to connect to digital leased lines on the line side. DAS - Dual attachment stations are used by FDDI networks for servers and concentrators are attached to both rings. DAT - Digital Audio Tape

• DBMS - Database Management Systems are used to share data on a network.
• DCE - Data communications equipment.
• DDP - Datagram Delivery Protocol is a routable protocol that provides for data packet transportation. It operates at the network layer at the same level of the IP protocol.
• DDS - Digital data service is a leased dedicated digital line.
• DECnet - From Digital Equipment Corporation is a suite of protocols which may be used on large networks that integrate mainframe and minicomputer systems
• DHCP - Dynamic Host Configuration Protocol is used to assign IP addresses dynamically to network cards works at the application layer. RFC 1541.
• Direct sequence modulation - The data is broken into parts and transmitted simultaneously on multiple frequencies.
• DLC - Data Link Control operates at the data link layer and is designed for communications between Hewlett-Packard network printers and IBM mainframe computers on a DECnet network.
• DNA - Digital Network Architecture is a term from DECNet
• DNS - Domain Name System is used on the internet to correlate between IP address and readable names. RFC 1034, 1035, 1535-1537, 1591.
• DRDA - Distributed Relational Database Architecture is from IBM.
• DSU - Digital service unit used to connect to digital leased lines on the LAN side.
• DTD - Document Type Definition.
• DTE - Data terminal equipment.
• DUN - Dial up networking.
• DVM - Digital volt meter.
• EGP - Exterior Gateway Protocol. Used between routers of different systems.
• EIA - Electronic Industries Association .
• EISA - Extended ISA used when the 80286 through 80486 series microprocessors were being produced. It is backward compatible with ISA.
• EMI - Electromagnetic Interference.
• Ethernet - A network architecture that uses carrier-sense multiple-access with collision detection (CSMA/CD) for controlling access to the network media and baseband broadcasts. It uses star topology.
• FDDI - Fiber Distributed Data Interface is a network architecture normally used to send longer distances. Topology is ring with two counter rotating rings for reliability with no hubs. Cable type is fiber-optic.
• Frame Relay - Error checking is handled by devices at both sides of the connection. Frame relay uses frames of varying length and it operates at the data link layer of the OSI model. A permanent virtual circuit (PVC) is established between two points on the network. Frame relay speed is between 56Kbps and 1.544Mbps.
• Frequency hopping - The transmitter and receiver change predetermined frequencies at the same time (in a synchronized manner).
• FTP - File Transport Protocol is a TCP/IP protocol running at the application layer.
• Gateway - A gateway can translate information between different network data formats or network architectures. It can translate TCP/IP to AppleTalk so computers supporting TCP/IP can communicate with Apple brand computers. Not the same as a default gateway used by a client to send packets to.
• HTML - Hypertext Markup Language is the format many files for web viewing are in. It is a language with "mark-up" text included for formatting.
• HTTP - Hypertext Transfer Protocol is the protocol used to communicate between web servers and web browser software clients.
• Hub - A type of repeater used on several network architectures which usually connects several stations.
• IAB - Internet Architecture Board
• IANA - Internet Assigned Numbers Authority.
• ICMP - Internet Control Message Protocol is used to perform network error reporting and status. It works at the transport layer. RFC 792.
• IETF - Internet Engineering Task Force. Sets Internet technical standards.
• IGMP - Internet Group Management Protocol, used for managing multicast groups. RFC 1112.
• IMAP4 - Internet Mail Access Protocol version 4 is the replacement for POP3
• Impedance - The amount of resistance to the transmission device.
• Infared - Infared is just below the visible range of light between 100Ghz and 1000Thz.
• Interference - Electromagnetic Interference (EMI). Crosstalk - When wires pick up electromagnetic signals from nearby wires also carrying signals.
• InterNIC - Internet Network Information Center, the authority for allocating internet addresses.
• Intranet - Refers to using internet technologies such as a web server on an internal network.
• IP - Internet Protocol os used for software addressing of computers and works at the data link layer. RFC 791.
• IPIP tunneling - Tunneling IP packets in IP packets. Used for VPN tunneling.
• IPSec - Internet protocol security, developed by IETF, implemented at layer 3. it is a collection of security measures that address data privacy, integrity, authentication, and key management, in addition to tunneling. Used for VPN.
• IPX - Internetwork Packet Exchange supports the transport and network layers of the OSI network model. Provides for network addressing and routing. It provides fast, unreliable, communication with network nodes using a connection less datagram service.
• IRQ- Interrupt Request
• IRTF - Internet Research Task force.
• ISA - Industry Standard Architecture internal computer bus. Used when the original 8088 8bit microprocessor based personal computers were produced. (16 bit).
• ISAKMP/Oakley - Internet Security Association and Key Management Protocol Authentication.
• ISDN - Integrated Services Digital Network is a method of sending voice and data information on a digital phone line. Two 64Kbps B-channels with one 16Kbps D channel is provided with basic ISDN service
• ISP - Internet Service Provider
• ISOC - Internet Society, promotes internet policies.
• ITU - International Telecommunication Union.
• FTP - File Transfer Protocol.
• L2F - Layer2 Forwarding, works at the link layer of the OSI model. It has no encryption. Being replaced by L2TP. It is used for VPN.
• L2TP - Layer 2 tunneling protocol (RFC 2661). Used for VPN tunneling.
• LAN - Local Area Network
• LDA - Local delivery agent on the receiving machine receives the mail from its MTA. This program is usually procmail.
• LU - Logical Units are ports that users use to access network resources is an SNA term.
• MAC - Media Access Control address. Basically a network card unique hardware address.
• Mail notifier - This program notifies the recipient that they have mail. Normally this requires two programs, biff and comsat. Biff allows the administrator or user to turn on comsat service.
• MAN- Metropolitan area network refers to a network which connects several LANS over various media that is large enough to cover an area the size of a city.
• MAPI - Microsoft's Messaging API which is incorporated throughout Microsoft's office products supports mail at the application level.
• MAU - Multistation access unit used by Token Ring Networks.
• MBONE - Being on the MBONE means you are on a network that supports multicasting.
• MCI - Microchannel architecture by IBM and used mainly on IBM brand computers for the internal bus. Established in 1988. (16 or 32 bits).
• Media - The hardware method used to connect computers over a network. The three main types are copper cable, fiber optic cable, and wireless.
• Media converter - Used to adapt from one cable type to another.
• MHS - Message Handling Service by Novell is used for mail on Netware networks.
• MIB - Management Information BASE specifies variables the network elements maintain. Works with the TCP/IP protocol SNMP.
• MIME - Multipurpose Internet Mail Extension is the protocol that defines the way files are attached to SMTP messages.
• MOTIS - Message-oriented text interchange system.
• MS - Message Store is a storage area for messages that can't be delivered immediately when the recipient is off-line.
• MTA - Message transfer agent is used to pass mail from the sending machine to the receiving machine. There is a MTA program running on both the sending and receiving machine. Sendmail is a MTA.
• MTU - Maximum Transmission Unit is the maximum size of each data packet for the ethernet protocol.
• MUA - Mail users agent. This is the program a user will use to type e-mail. It usually incorporates an editor for support. The user types the mail and it is passed to the sending MTA. This may also be called the user agent (UA).
• Multicasting - Transmitting to a group of interface cards on the network.
• NADN - Nearest Active Downstream Neighbor is a Token ring Architecture term.
• NAU - Network Addressable Units is an SNA term.
• NAUN - Nearest Active Upstream Neighbor is a Token ring Architecture term.
• NAT - Network Address Translation.
• NBF - NetBIOS Frame Protocol.
• NBNS - NetBIOS Name Server. A server that maps NetBIOS names to IP addresses. This service is provided by the nmbd daemon on Linux.
• NBP - Name-binding protocol of the AppleTalk suite of protocols translates addresses into names.
• NBT - NetBIOS over TCP/IP defined by RFC 1002.
• NCP - NetWare Core Protocol provides for client/server interactions such as file and print sharing. It works at the application, presentation, and session levels.
• NCP - Network Control Program performs routing, session management tasks. It runs in the communications controller. It is an SNA networking term.
• NDIS - Network Driver Interface Specification from Microsoft, is used on Microsoft networks. It allows multiple protocols to be used on a network card and supports the data link layer of the network model.
• NetBEUI - NetBIOS Extended User Interface works at the transport layer and provides data transportation. It is not a routable transport protocol which is why NBT exists on large networks to use routable TCP protocol on large networks.
• NetBIOS - Network Basic Input Output System by Microsoft.
• Network Operating System - Typically used to run computers that act as servers, but may be used on various types of computers today.
• NFS - Network File System. A protocol that allows UNIX and Linux systems remotely mount each other's file systems. RFC 1094
• NIC - Network interface card. Also called LAN adapters.
• NNTP - Network News Transport Protocol is used to link newsgroups for discussions on the web
• OC - Optical Carrier level, see SONET.
• ODBC - Open Database Connectivity (ODBC) from Microsoft lets application developers integrate database connections in applications. It is an application programming interface (API). ODBC drivers convert an application's query int SQL and send it to the database engine program.
• ODI - Open Data-link Interface operates at the data link layer allowing IPX to work with any network interface card.
• OSI - Open Systems Interconnect is a suite of protocols developed by the International Standards Organization (ISO) which corresponds with the layers of the OSI model.
• OSPF - Open Shortest Path First, a dynamic routing protocol. RFC 1247.
• PAP - Password Authentification Protocol is a two way handshake protocol designed for use with PPP.
• PAP - Printer access protocol of the AppleTalk suite of protocols manages information between workstations and printers.
• PCI - Peripheral Component Interconnect internal computer bus. The popular expansion bus of choice. It is significantly faster than EISA. This is a 32bit bus with plug and play capability from Intel.
• PDC - Primary Domain Controller is an NT server providing central control of user access permissions and accounts on a network.
• PDL - Page description language is a printing language.
• PDN - Public data network.
• Peer - A computer that can act as both a client and a server.
• Plenum - Space above a false ceiling in an office area where heat ducts and cables may be run. Plenum cabling is special fire resistant cabling required for use in these areas due to fire hazards.
• POP - Point of presence is each point at the end of the transport media (internet) when talking about VPN.
• POP3 - Post Office Protocol version 3 is used by clients to access an internet mail server to get mail. It is not a transport layer protocol.
• Protocol - A set of standards sets of standards that define all operations within a network. There are various protocols that operate at various levels of the OSI network model such as transport protocols include TCP, SPX.
• PPP - Point to Point Protocol, used for serial connections to a network ot the internet. (RFC 1332, 1548)
• PPTP - Point to point tunneling protocol (RFC 2637) Used for VPN tunneling.
• PU - Physical Units are a network device used to communicate with hosts. It is an SNA term.
• PVC - Permanent virtual circuit is set up once in communication switches to establish a permanent circuit.
• RADIUS - Remote Authentication Dial-In User Service is used for dial in clients to connect to other computers or a network. It provides authentication and accounting when using PPTP or L2TP tunneling.
• RAID - Redundant Array of Inexpensive disks is a fault tolerant method of storing data, meaning that a failure can occur and the system will still function.
• RARP -Reverse Address Resolution Protocol used for disk less computers to determine their IP address using the network. It works at the data link layer. RFC 903.
• RAS - Remote Access Service (RAS) with Windows NT allows users connecting to the network using a modem to use network resources. The NT RAS server can handle 256 connections.
• Redirector - it runs on a windows operating system and directs requests for network resources to the appropriate server and makes network resources seem to be local resources.
• Repeater - Used on a network to regenerate signals to be sent over long distances or tie computers together on a network.
• Resolver - Used as part of DNS, it is the client side asking for DNS information.
• RIP - Routing Information Protocol, a dynamic routing protocol. A distance-vector algorithm is used to calculate the best route for a packet. RFC 1058, 1388 (RIP2).
• Rlogin - Remote login between UNIX hosts. This is outdated and is replaced by Telnet.
• Router - Routes data packets between two networks. It reads the information in each packet to tell where it is going.
• RPC - Remote Procedure Call. A protocol invented by Sun Microsystem to allow remote computers to invoke functions on other hosts. RFC 1057.
• RR - Resource Records are a part of the DNS database.
• RTMP - Routing table maintenance protocol is used to update routers with information about network status and address tables. The whole address table is sent across the network.
• S/Key - A one time password system, secure against replays. RFC 2289.
• SAP - Service Advertising Protocol packets are used by file and print servers to periodically advertise the address of the server and the services available. It works at the application, presentation, and session levels.
• SAS - Single Attachment stations attached to one ring and used by FDDI networks to attach workstations to concentrators.
• SDH - Synchronous Digital Hierarchy
• SDLS - Synchronous Data Link Control is a possible SNA communications architecture.
• Sector Sparing - A method of fault tolerance that automatically identifies and marks bad sectors as not available. It is also called hot-fixing.
• Server - For the most part it provides resources on the network for other computers to use.
• SGML - Standardized General Markup Language is the base language for document publishing and is used to define XML, HTML and more.
• Shielding - Used to minimize interference.
• SLED - Single Large Inexpensive disk - The concept that a large disk costs less per amount of storage than several smaller ones. Somehow this concept is used as a means of fault tolerance.
• SLIP - Serial Line interface Protocol used to connect serially to a network or internet. RFC 1055, 1144 (Compressed). Replaced by PPP.
• SMAU - Smart Multistation Access Unit.
• SMB - Server Message Block protocol works at the presentation level to provide peer to peer communication.
• SMDS - Switched Multi-megabit Data Service uses fixed length cell switching and runs at speeds of 1.533 to 45Mbps.
• SMS - SMS - Systems Management Server from Microsoft can collect information of software on each computer and can install and configure new software on the client computers. It will also monitor network traffic.
• SMTP - Simple Mail Transfer Protocol is a TCP protocol for mail transport running at the application layer. RFC 821, 822.
• SNA - System Network Architecture by IBM is a suite of protocols mainly used with IBM mainframe and AS/400 computers.
• SNMP - Simple Network Management Protocol. RFC 1155, 1157, 1213, 1441.
• SONET - Synchronous Optical Network is a physical layer standard that defines voice, data, and video delivery methods over fiber optic media. It defines data rates in terms of optical carrier (OC) levels.
• Spread spectrum - It uses several frequencies at the same time.
• SPX - Sequenced Packet Exchange operates at the transport layer providing connection oriented communication on top of IPX.
• SQL - Structured Query Language is a database access language. It is used by most client/server database applications.
• SSCP - Systems Services Control Point manages all resources in the host's domain. An SNA term.
• STP - Shielded Twisted Pair cable. 100 meter maximum length. 16-155 Mbps speed. Lower electrical interference than UTP
• STS
• SVC - Switched virtual circuit is temporarily set up by switching mechanisims to establish a connection between devices for a session.
• TACACS - Offers authentication, accounting, and authorization.
• T Carrier - Multiplexors are used to allow several channels on one line. The T1 line is basic T Carrier service.
• TCP - Transport Control protocol is a connection oriented reliable protocol working at the transport layer. RFC 793.
• TDI - Transport Driver Interface is a standard for passing messages between the drivers at the data link layer and the protocols working at the network layer such as IP or NetBEUI. It was produced by Microsoft.
• TDR - Time-domain reflectometer sends a sonar like electrical pulse down a cable and can determine the location of a break in the cable.
• TFTP - Trivial File Transfer Protocol. RFC 1350.
• Telnet - Remote session at the application layer. RFC 854.
• Thicknet - Half inch rigid cable. Maximum cable length is 500 meters. Transmission speed is 10Mbps. Expensive and is not commonly used. (RG-11 or RG-8).
• Thinnet - Thinnet uses a British Naval Connector (BNC) on each end. Thinnet is part of the RG-58 family of cable*. Maximum cable length is 185 meters. Transmission speed is 10Mbps.
• TIA - Telecommunications Industries Association .
• TLD - Top Level domain
• Token Ring - A network architecture developed by IBM which sends tokens around a ring of computers to allow media access. Standardized to IEEE 802.5
• Topology - The shape of the physical connection of a network with regard to repeaters and networked computers. The three main types are ring, bus, and star.
• UA - Users agent. This is the program a user will use to type e-mail. It usually incorporates an editor for support. The user types the mail and it is passed to the sending MTA. This may also be called the mail user agent (MUA).
• UDP - User Datagram Protocol is a connection less unreliable protocol working at the transport layer. RFC 768.
• UNC - Universal Naming Convention is used to allow the use of shared resources without mapping a drive to them.
• Unicast - A transmission to a single interface card.
• URL - Universal Resource Location is a term used to describe the name of a web based resource such as a web page or location of a file for down loading.
• UTP - Unshielded Twisted Pair cable. Normally UTP contains 8 wires or 4 pair. 100 meter maximum length. 4-100 Mbps speed.
• VIM - Vendor-Independent Messaging protocol from Lotus supports mail at the application level and is supported by many vendors exclusive of Microsoft.
• VPN - Virtual Private Networking. The function of VPN is to allow two computers or networks to talk to each other over a transport media that is not secure, but the network is made secure by VPN security protocols.
• W3C - World Wide Web Consortium, sets standards for the web working with the IETF.
• WAN - Wide Area Network is larger than a MAN and may be an enterprise network or a global network.
• WINS - Windows Internet Name Service is the Microsoft implementation of NetBIOS name service.
• wireless bridge - Microwave or Infared is used between two line of site points where it is difficult to run wire.
• X.25 - This is a set of protocols developed by the CCITT/ITU which specifies how to connect computer devices over a internetwork.
• X.400 - International Telecommunication Union standard defines transfer protocols for sending mail between mail servers.
• X.500 - This is a recommendation outlining how an organization can share objects and names on a large network. It is hierarchical similar to DNS, defining domains consisting of organizations, divisions, departments, and workgroups.
• XML - Extensible Markup Language is a subset of SGML and is used widely on the web.
• ZIP - Zone information protocol used with RTMP to map zones. Routers use zone information tables (ZITs) to define network addresses and zone names.

Components of Network

Components of Network

• Network Services

• Transmission Media

• Protocols

Network Services :

Network services ha function to provide multiple type of services used by network devices 5 most common are :

• File services
• print services
• Message services
• Application services
• Database services
• 
  

Transmission Media :

It is a medium either wired or wireless to connect two or more communication devices to each other.

Protocols :

protocols are set of rules and regulation in which communication between two devices takes place.

e.g. http,telnet,ftp,dns,ppp,tcp,ip,smtp

Networking Topologies

There are many networking topologies we will go through each of them

1. LAN
2. MAN
3. WAN
4. PAN
5. CAN
6. SAN
7. WLAN
8. VPN

Networking Models

Basically there are 3 type of networking models 

(NOT TOPOLOGY IT'S DIFFERENT THING)

1.Centralized
2.Collaborative
3.Distributive (2 sub types)

• Peer to peer
• Client - server

Centralized

This type of model consists of a central server having various terminals which can be accessed from other computer systems in the network.

In this case information is being stored centrally into the sever.

Collaborative

when your request is being processed by two or more computer systems then this type of network model is called collaborative network model.

Distributive (Peer-to-peer)

This type of networking contains two or more hosts which are connected to each other & working separately no one is controlling no one!

Distributive (client / server)

this type of model contains servers which are providing services to their clients.

what is network? what is networking?

Network :

It's a scenario (basically an environment) in which two or more communication devices are connected to each other, communicating with each other is call a network.

Communication device can vary as : 

Computer System , Laptops , PDA , Mobile Phones , Modems , Routers ,Switches etc

Networking :

It's a practical approach used to (or taken to) setup a network is called Network.

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