BLUETOOTH-PAN
Personal area network (PAN) is a computer network designed for communication between computer devices (including telephones and personal digital assistants close to one person). The devices may or may not belong to the person in question. The reach of a PAN is typically a few meters. PANs can be used for communication among the personal devices themselves or for connecting to a higher level network and the Internet. Personal area networks may be wired with computer buses such as USB and FireWire. A wireless personal area network (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth.
A Bluetooth PAN is also called a piconet, and is composed of up to 8 active devices in a master-slave relationship. The first Bluetooth device in the piconet is the master, and all other devices are slaves that communicate with the master. A piconet typically has a range of 10 meters, although ranges of up to 100 meters can be reached under ideal circumstances.
SECURITY THREAT AND REQUIREMENTS OF WIRELESS PAN
A Bluetooth PAN is also called a piconet, and is composed of up to 8 active devices in a master-slave relationship. The first Bluetooth device in the piconet is the master, and all other devices are slaves that communicate with the master. A piconet typically has a range of 10 meters, although ranges of up to 100 meters can be reached under ideal circumstances.
SECURITY THREAT AND REQUIREMENTS OF WIRELESS PAN
Bluetooth offers several benefits and advantages. However, orga
nizations must not only address the security threats associated with Bluetooth before they implement the technologies; they must also measure the vulnerabilities of the devices they allow to participate in the Bluetooth networks. Specifically, agencies need to address security concerns for confidentiality, data integrity, and network availability. Moreover, since Bluetooth devices are more likely to be managed by users that are less security conscious than administrators, they are more likely to contribute to uncontrolled security drifts. This subsection will briefly cover some of the risks to security, i.e., attacks on confidentiality, integrity, and network availability.
Loss Of Confidentiality
nizations must not only address the security threats associated with Bluetooth before they implement the technologies; they must also measure the vulnerabilities of the devices they allow to participate in the Bluetooth networks. Specifically, agencies need to address security concerns for confidentiality, data integrity, and network availability. Moreover, since Bluetooth devices are more likely to be managed by users that are less security conscious than administrators, they are more likely to contribute to uncontrolled security drifts. This subsection will briefly cover some of the risks to security, i.e., attacks on confidentiality, integrity, and network availability.Loss Of Confidentiality
Threats to confidentiality involve, first of all, compromised Bluetooth devices. When a Bluetooth device that is part of a piconet becomes compromised (e.g., is in the possession of an unauthorized user), it may still receive information that the malicious user should not access. Moreover, the compromised device may still have network or information privileges, resulting in a compromise of the wider network as well. In the latter case, the compromised device may not only receive normal proprietary traffic but may also request that information as part of a targeted network attack. A trait of Bluetooth that makes this compromise unique is that the Bluetooth network requires device and not the user authentication to access resources. Once the device is authenticated, it is automatically connected to resources without the need for subsequent authentication. (Geoff Huston, the wireless internet)
Loss Of Integrity
Loss Of Integrity
Infringements of integrity result from the corruption of an organization’s or user’s data. The direct effect is similar to that of a confidentiality, or disclosure, threat: a compromised network. However, integrity threats extend beyond this, involving the alteration, addition, or deletion of information, which is then passed through the network without the user’s or network administrator’s knowledge. Information that is subject to corruption includes files on the network and data on user devices. For example, a malicious user might use an untrusted device, such as a PDA, to access the address book of another PDA or laptop. However, instead of just monitoring the information, as would be the case with a disclosure threat, the malicious user alters the contact information without the owner’s knowledge or may even delete the information completely. If undetected, such attacks could result in the agency or user losing confidence in its data and system. Users should verify that their Bluetooth product does not allow automatic data synchronization to prevent the alteration of any information without the acknowledgement user of that device.
Loss Of Avaiability
Loss Of Avaiability
Denial of service attacks cause in the loss of network availability for authorized users and devices. Denial of service attacks block authorized user access to system resources and network applications. Besides the typical DoS attacks directed against LANs and Internet services, Bluetooth devices are also susceptible to signal jamming. Bluetooth devices share bandwidth with microwave ovens, cordless phones, and other wireless networks and thus are exposed to interference. Malicious users can interfere with the flow of information by using devices that transmit in the 2.4 GHz ISM band. Disrupting the routing protocol prevents ad hoc network devices from negotiating the network’s dynamic topologies. Remote users may encounter jamming more frequently than on-site users. Remote users must contend with the same interference that users experience in the office. Further, since the remote environment is uncontrolled, remote devices are more likely to be in close immediacy to devices that are intentionally or unintentionally jamming their signals. Another threat associated with ad hoc devices is a battery exhaustion attack. This attack attempts to disable a device by draining its battery. A malicious user continually sends requests to the device asking for data transfers (assuming the user is part of the network topology) or asking the device to create a network. Although this type of attack does not compromise network security, it ultimately prevents the user from gaining access to the network, because the device cannot function. (Juha T. Vainio, May 25, 2000)
SOLUTIONS & SECURITY MEASURES FOR WPAN
SOLUTIONS & SECURITY MEASURES FOR WPAN
Wireless Personal Area Network and other Bluetooth technologies are relatively new standard and have yet to become common in the marketplace. However, solutions and improvements are available to help secure WPAN networks. These measures include management solutions, operational solutions, and technical solutions
Management Solutions.
Management Solutions.
The first line of protection is to provide a sufficient level of knowledge and understanding for those who will deal with WPAN & Bluetooth enabled devices & networks. Organizations using wireless personal area network technology need to establish and document security policies that address the use of Bluetooth enabled devices and the user’s responsibilities. The policy document should include a list of approved uses for WPAN’s, the type of information that may be transferred in the network, and any disciplinary actions that may result from misuse. The security policy should also specify a proper password usage scheme.
Operational Solutions
Operational Solutions
Since Bluetooth devices do not register when they join a network, they are invisible to network administrators. Consequently, it is difficult for administrators to apply traditional physical security measures. However, there are some security approaches that can be applied, including establishing spatial distance and securing the gateway Bluetooth devices that connect remote Bluetooth networks or devices. Establishing spatial distance requires setting the power requirements low enough to prevent a device operating on the organizations premises from having sufficient power to be detected outside physical boundaries. This spatial distance in effect creates a more secure boundary. Currently, Bluetooth devices have a useful range of approximately 30 feet. Organizations that require both high levels of security and low levels of security should maintain a secure perimeter so that on site network users can maintain secure connections in their office premises. Agencies with requirements for high levels of security should also restrict unauthorized personnel from using PDAs, laptops, and other electronic devices within the secure perimeter. (Tom karygiannis, Les Owens, Nov 2002)
Technical Solutions
Technical Solutions
As with WLANs and Bluetooth technical solutions & improvements fall into one of two categories: software security solutions and hardware security solutions. Bluetooth software solutions focus on Personal Identification Number (PIN) and private authentications, while hardware solutions involve the use of the Bluetooth device address and link keys that reside at the link level. Again, it should be noted that hardware solutions, which generally have software components, are into simply as hardware solutions.
WI-FI PRODUCTS
WI-FI PRODUCTS
There are several products available now which enable to connect to Wi-Fi Networks around the area. Earlier when Wi-Fi was first started commercially, there were not many devices came built with Wi-Fi network card (Wireless card) which connects to Wi-Fi network. But now almost every handset device on mobile comes with Wi-Fi, Laptops comes with built in Wireless connectivity , desktop computers comes along with Wireless connectivity. Following are few products which provide connectivity to Hotspots.
Desktop Wireless Wi-Fi Cards
Desktop wireless Wi-Fi cards enable desktop computers to connect to Wi-Fi network available in the area. Wi-Fi network provides height speed internet if available and can share files with in the clients in the network. This kind of network is mostly used in Colleges and Universities, libraries etc. Wi-Fi desktop cards are mostly plugged in Mother board on PCI slot. Some mother board comes with built in Wi-Fi connectivity
Laptop / Notebook Wireless Wi-Fi Cards
Wi-Fi cards uses in laptops / notebooks to connect to wireless internet around through Wi-Fi network. Most laptops now comes with built in Wi-Fi enable feature. Old model laptops which do not come along with built in Wi-Fi wireless card can plug in Wi-Fi PCMCI slot card to connect to hotspot
Wireless Wi-Fi Routers
Wireless Wi-Fi routers is used to connect clients( having Wi-Fi cards ) with server. Wi-Fi router is attached to server and configure with IP address or in some cases just with internet connection. Now this IP helps connect clients to the server for High speed internet and file sharing with server and other clients. Routers are mostly used when server is expected to handle multiple clients at given time.
There are several products available now which enable to connect to Wi-Fi Networks around the area. Earlier when Wi-Fi was first started commercially, there were not many devices came built with Wi-Fi network card (Wireless card) which connects to Wi-Fi network. But now almost every handset device on mobile comes with Wi-Fi, Laptops comes with built in Wireless connectivity , desktop computers comes along with Wireless connectivity. Following are few products which provide connectivity to Hotspots.
Desktop Wireless Wi-Fi Cards
Desktop wireless Wi-Fi cards enable desktop computers to connect to Wi-Fi network available in the area. Wi-Fi network provides height speed internet if available and can share files with in the clients in the network. This kind of network is mostly used in Colleges and Universities, libraries etc. Wi-Fi desktop cards are mostly plugged in Mother board on PCI slot. Some mother board comes with built in Wi-Fi connectivityLaptop / Notebook Wireless Wi-Fi Cards
Wi-Fi cards uses in laptops / notebooks to connect to wireless internet around through Wi-Fi network. Most laptops now comes with built in Wi-Fi enable feature. Old model laptops which do not come along with built in Wi-Fi wireless card can plug in Wi-Fi PCMCI slot card to connect to hotspot
Wireless Wi-Fi Routers
Wireless Wi-Fi routers is used to connect clients( having Wi-Fi cards ) with server. Wi-Fi router is attached to server and configure with IP address or in some cases just with internet connection. Now this IP helps connect clients to the server for High speed internet and file sharing with server and other clients. Routers are mostly used when server is expected to handle multiple clients at given time.
Wireless Wi-Fi USB Adapters 
There is easy solution for Desktop / laptop owners who do not have Wi-Fi card already into their systems, they can use USB Wi-Fi drive which connects to USB port on systems and performs as Wi-Fi cards. However USB Wi-Fi drive comes with relevantly lesser data transfer capability and lesser range.
Handhelds and PDAs
Almost all handsets and PDAs manufactures install Wireless network card to their products. PDAs (Personal digital assistance) and other mobile devices scans Wi-Fi network around, if found can connect to network for Surfing and file sharing.
Almost all handsets and PDAs manufactures install Wireless network card to their products. PDAs (Personal digital assistance) and other mobile devices scans Wi-Fi network around, if found can connect to network for Surfing and file sharing.
WI-FI SECURITY
Wi-Fi SecurityWi-Fi Security feature protects your network and gets quick access associated with Win2K, XP. It supports WEP or WPA and gives you real-time interloper alerts you from free blockers and you feel glad when there is no spyware and no adware in your network to spoil your files. Any users get access to the Internet by means of laptop, handhold games, smart cell phones and PDA. The most important thing is it tenders a trouble-free and cheap method to safe and sound your network connection at any hotspot all over the world. Wi-Fi Security examines data and perceives entrance point in real time and identifies the user who wants to spoil your files.
When we talk about Wi-Fi Security then a detail list come in view to make our network more secure. Wi-Fi discover different security tools such as Airsnort pull through encryption keys when adequate packets have been collected. Airfart sense wireless devices and count their signal powers and make it easy for user to understand, AP Radar used to manage the configuration, Boingo Software helpful for you to include thousand of location all over the world. DStumbler offer a complete set for auditing, KisMAC one of
the best security weapons, iStumbler used to analyze your dashboard, MacStumbler display information about nearby network, MiniStumbler offering convenience, Wireless Mon allows users to check the position of wireless and so on.Wi-Fi Security Raw Packet confines tools consist of Air cap facilitate troubleshooting tools such as Wire shark to provide information about protocols and radio signals, eternal offers active and passive analysis of many protocols, libpcap allow link-layer in Windows environments and it contains driver used to extend the OS. The Wi-Fi interference recognition and preclusion Systems is the most powerful wireless instruction system and provide complete security against policy compliance and threats such as Airtight Networks Spectra Guard Enterprise and Sentry which not only detect the threat also remove and delete it from your system, Manage engine Wi-Fi manage the security tools and check that all’s are working or not. It is a big solution of WLAN and Wireless Solutions from Wild Packets, it has a unique gift to address wireless network.
The Analyzers of WiFi Security execute a real-time photograph of all WLAN communications and actions these tools always in action to recognize your data and analysis. There is a long list of analyzers such as Javvin Network Packet analyzer ensure the network performance and prevent the network security, Network Chemistry Packetyzer serve the net with Ethereal packet detain and analysis library, NetScout Sniffer Portable venture network relations. The network instruments observer, tamosoft commview for Wi-Fi and wireshark such a great tool to manage and monitor your network security.
Wi-Fi Security for end clients offer a complete control over the entire network from design to development and including AirMagnet StreetWISE offer automatically diagnose, AirPatrol AirSafe will turn off your network if sense any one interrupt in it, AirTight SpectraGuard S
AFEdetect classically and make a solution, AirDefense Personal defend the system from the risks that could depiction confidential data and secret dealings and same as AirDefense Personal, Aruba Networks Endpoint Compliance, HotSpotDK, Sana Primary Response Air Cover, and ZENworks USB/Wireless Security provide you a safeguard for your data and transaction. The WiFi networks, robotically sense the necessary WiFi security settings, and caution you about insecure or treacherous networks. keep in mind the following things to make you network secure, don’t put on air your SSID, always enable WPA encryption as an alternative of WEP, Utilize MAC filtering for entrance power and immobilize remote administration.
WI-FI TECHNOLOGY
WI-FIWireless Fidelity – popularly known as Wi-Fi, developed on IEEE 802.11 standards, is the recent technology advancement in wireless communication. As the name indicates, WI-FI provides wireless access to applications and data across a radio network. WI-FI sets up numerous ways to build up a connection between the transmitter and the receiver such as DSSS, FHSS, IR – Infrared and OFDM. The development on WI-FI technology began in 1997 when the Institute of Electrical and Electronic Engineers (IEEE) introduced the 802.11 technology that carried higher capacities of data across the network. This greatly interested some of major brands across the globe such as the world famous Cisco Systems or 3COM. Initially, the price of Wi-Fi was very high but around in 2002, the IT market witnessed the arrival of a break through product that worked under the new 802.11 g standards. In 2003, IEEE sanctioned the standard and the world saw the creation of affordable Wi-Fi for the masses.
Wi-Fi provides its users with the liberty of connecting to the Internet from any place such as their home, office or a public place without the hassles of plugging in the wires. Wi-Fi is quicker than the conventional modem for accessing information over a large network. With the help of different amplifiers, the users can easily change their location without disruption in their network access. Wi-Fi devices are compliant with each other to grant efficient access of information to the user. Wi-Fi location where the users can connect to the wireless network is called a Wi-Fi hotspot. Through the Wi-Fi hotspot, the users can even enhance their home business as accessing information through Wi-Fi is simple. Accessing a wireless network through a hotspot in some cases is cost-free while in some it may carry additional charges. Many standard Wi-Fi devices such as PCI, miniPCI, USB, Cardbus and PC card, ExpressCard make the Wi-Fi experience convenient and pleasurable for the users. Distance from a wireless network can lessen the signal strength to quite an extent; some devices such as Ermanno Pietrosemoli and EsLaRed of Venezuela Distance are used for amplifying the signal strength of the network. These devices create an embedded system that corresponds with any other node on the Internet.
The market is flooded with various Wi-Fi software tools. Each of these tools is specifically designed for different types of networks, operating systems and usage type. For accessing multiple network platforms, Aircrack-ng is by far the best amongst its counterparts. The preferred Wi-Fi software tools list for Windows users is: KNSGEM II, NetStumbler, OmniPeek, Stumbverter, WiFi Hopper, APTools. Unix users should pick any of the following: Aircrack, Aircrack-ptw, AirSnort, CoWPAtty,Karma . Whereas, Mac users are presented with these options: MacStumble, KisMAC, Kismet. It is imperative for users to pick out a Wi-Fi software tool that is compatible with their computer and its dynamics.
Wi-Fi uses radio networks to transmit data between its users. Such networks are made up of cells that provide coverage across the network. The more the number of cells, the greater and stronger is the coverage on the radio network. The radio technology is a complete package deal as it offers a safe and consistent connectivity. Radio bands such as 2.4GHz and 5GHz depend on wireless hardware such Ethernet protocol and CSMA. Initially, Phase Shift Keying (PSK), a modulation method for conveying data was used, however now it has been replaced with CCK. Wi-Fi uses many spectrums such as FHSS and DSSS. The most popular Wi-Fi technology such as 802.11b operates on the range of 2.40 GHz up to 2.4835 GHz band. This provides a comprehensive platform for operating Bluetooth strategy, cellular phones, and other scientific equipments. While 802.11a technology has the range of 5.725 GHz to 5.850 GHz and provides up to 54 Mbps in speed. 802.11g technology is even better as it covers three non-overlapping channels and allows PBCC. 802.11e technology takes a fair lead by providing excellent streaming quality of video, audio, voice channels etc.
To connect to a Wi-Fi network an adapter card is essential. Additional knowledge about the SSID, infrastructure, and data encryption is also required. The Wi-Fi users don’t have to be concerned with the security issues. The security methods such as MAC ID filtering, Static IP addressing and WEP encryption ensure the user privacy to the maximum.
3G
International Mobile Telecommunica
tions-2000 (IMT-2000)', better known as 3G or 3rd Generation, is a family of standards for mobile telecommunications defined by the International Telecommunication Union,[1] which includes GSM EDGE, UMTS, and CDMA2000 as well as DECT and WiMAX. Services include wide-area wireless voice telephone, video calls, and wireless data, all in a mobile environment. Compared to 2G and 2.5G services, 3G allows simultaneous use of speech and data services and higher data rates (up to 14.0 Mbit/s on the downlink and 5.8 Mbit/s uplink ).
==Overview==! bandwidth of data ! pre-4G ! width="3%" duplex ! width="3%" channel ! description ! geographical areas - - ! TDMA Single‑Carrier (IMT‑SC) colspan="2" EDGE (UWT-136) EDGE Evolution none rowspan="3" FDD TDMA evolutionary upgrade to GSM/GPRS[nb 1] worldwide, except Japan and South Korea - ! CDMA Multi‑Carrier (IMT‑MC) colspan="2" CDMA2000 EV-DO UMB[nb 2] rowspan="4" CDMA evolutionary upgrade to cdmaOne (IS-95) Americas, Asia, some others - ! CDMA Direct Spread (IMT‑DS) rowspan="3" UMTS[nb 3] W-CDMA[nb 4] rowspan="3" HSPA rowspan="3" LTE rowspan="3" family of revolutionary standards. worldwide - ! rowspan="2" CDMA TDD (IMT‑TC) TD‑CDMA[nb 5] rowspan="4" TDD Europe - TD‑SCDMA[nb 6] China - ! FDMA/TDMA (IMT‑FT) colspan="2" DECT colspan="2" none FDMA/TDMA short-range; standard for cordless phones Europe, USA - ! IP‑OFDMA colspan="2" colspan="2" WiMAX (IEEE 802.16) OFDMA late addition worldwide }
tions-2000 (IMT-2000)', better known as 3G or 3rd Generation, is a family of standards for mobile telecommunications defined by the International Telecommunication Union,[1] which includes GSM EDGE, UMTS, and CDMA2000 as well as DECT and WiMAX. Services include wide-area wireless voice telephone, video calls, and wireless data, all in a mobile environment. Compared to 2G and 2.5G services, 3G allows simultaneous use of speech and data services and higher data rates (up to 14.0 Mbit/s on the downlink and 5.8 Mbit/s uplink ).==Overview==! bandwidth of data ! pre-4G ! width="3%" duplex ! width="3%" channel ! description ! geographical areas - - ! TDMA Single‑Carrier (IMT‑SC) colspan="2" EDGE (UWT-136) EDGE Evolution none rowspan="3" FDD TDMA evolutionary upgrade to GSM/GPRS[nb 1] worldwide, except Japan and South Korea - ! CDMA Multi‑Carrier (IMT‑MC) colspan="2" CDMA2000 EV-DO UMB[nb 2] rowspan="4" CDMA evolutionary upgrade to cdmaOne (IS-95) Americas, Asia, some others - ! CDMA Direct Spread (IMT‑DS) rowspan="3" UMTS[nb 3] W-CDMA[nb 4] rowspan="3" HSPA rowspan="3" LTE rowspan="3" family of revolutionary standards. worldwide - ! rowspan="2" CDMA TDD (IMT‑TC) TD‑CDMA[nb 5] rowspan="4" TDD Europe - TD‑SCDMA[nb 6] China - ! FDMA/TDMA (IMT‑FT) colspan="2" DECT colspan="2" none FDMA/TDMA short-range; standard for cordless phones Europe, USA - ! IP‑OFDMA colspan="2" colspan="2" WiMAX (IEEE 802.16) OFDMA late addition worldwide }
ATM
ASYNCHRONOUS TRANSFER MODE :
Traditional LAN technologies do not guarantee that data arrives on time or in the proper order. While Ethernet and Token Ring can detect errors, they provide no service guarantees and are not responsible for the recovery of missing or corrupted data packets.
Because a traditional LAN is connectionless, it cannot provide mechanisms that can guarantee successful transmission. For example, it cannot determine the status of the destination adapter to ensure that it can receive a frame. It cannot ensure that bandwidth is available throughout the transmission. Unanticipated blockage, due to the media access control scheme of shared access technologies, can hinder a traditional LAN technology from supporting time-sensitive applications such as video or voice traffic. Traditional LANs can use upper-level protocol drivers to verify packet transmission (retransmitting, if necessary), partition big messages into smaller ones, and use time stamps for synchronization. However, these services add time to the transmission, and none of them provides end-to-end QoS guarantees.
Traditional Internetworking
ATM virtual channel and packet transmission.
ATM is a connection-oriented, unreliable (does not acknowledge the receipt of cells sent), virtual circuit packet switching technology.
Unlike most connectionless networking protocols, ATM is a deterministic networking system — it provides predictable, guaranteed quality of service. From end to end, every component in an ATM network provides a high level of control. ATM technology includes:
Scalable performance. ATM can send data across a network quickly and accurately, regardless of the size of the network. ATM works well on both very low and very high-speed media.Flexible, guaranteed Quality of Service (QoS). ATM allows the accuracy and speed of data transfer to be specified by the client. This feature distinguishes ATM from other high-speed LAN technologies such as gigabit Ethernet.
Unlike most connectionless networking protocols, ATM is a deterministic networking system — it provides predictable, guaranteed quality of service. From end to end, every component in an ATM network provides a high level of control. ATM technology includes:
Scalable performance. ATM can send data across a network quickly and accurately, regardless of the size of the network. ATM works well on both very low and very high-speed media.Flexible, guaranteed Quality of Service (QoS). ATM allows the accuracy and speed of data transfer to be specified by the client. This feature distinguishes ATM from other high-speed LAN technologies such as gigabit Ethernet.
The QoS feature of ATM also supports time dependent (or isochronous) traffic. Traffic management at the hardware level ensures that quality service exists end-to-end. Each virtual circuit in an ATM network is unaffected by traffic on other virtual circuits. Small packet size and a simple header structure ensure that switching is done quickly and that delays due to high traffic are minimized.
Unobstructed speed.
Unobstructed speed.
ATM imposes no architectural speed limitations. Its pre-negotiated virtual circuits, fixed-length cells, message segmentation and re-assembly in hardware, and hardware-level switching all help support extremely fast forwarding of data.
Integration of different traffic types. ATM supports integration of voice, video, and data services on a single network. ATM over Asymmetric Digital Sub
scriber Line (ADSL) enables residential access to these services.
Integration of different traffic types. ATM supports integration of voice, video, and data services on a single network. ATM over Asymmetric Digital Sub
scriber Line (ADSL) enables residential access to these services.Connection Types: LAN vs. ATM
Traditional LANs, such as Ethernet and Token Ring, use a connectionless, unreliable approach, that cannot guarantee successful transmission when sending information across the network. Likewise, TCP/IP data transfers between networks are connectionless and unreliable. ATM, which is a connection-oriented, circuit-based technology, differs from the traditional approaches to networking.
Traditional LAN
In a traditional LAN, each client uses a network adapter card, which has a software driver. Above that driver is a protocol driver, such as TCP/IP. The protocol driver bundles information into frames of varying size and gives each bundle an appropriate header. As a result, when the adapter gains access to the media, the data packets are sent on the media to a destination hardware address.
Traditional LAN technologies do not guarantee that data arrives on time or in the proper order. While Ethernet and Token Ring can detect errors, they provide no service guarantees and are not responsible for the recovery of missing or corrupted data packets.
Because the end stations are joined by a common medium, each end station on the traditional LAN recognizes the frames, or packets, of data put on the wire by each of the others, regardless of whether the frame is passed sequentially from one station to the next (as in a ring topology) or broadcast to all stations simultaneously (as with Ethernet).
Each station has an adapter card, which processes the frame and examines the destination address. If the address applies to that computer, the frame is checked for errors. If there are no errors, the adapter initiates a hardware interrupt and passes the frame to the network adapter driver. The following figure, Traditional LAN: Connectionless Data Transmittal of a Packet, shows an example of a traditional LAN.
Traditional LAN: Connectionless Data Transmittal of a Packet
Because a traditional LAN is connectionless, it cannot provide mechanisms that can guarantee successful transmission. For example, it cannot determine the status of the destination adapter to ensure that it can receive a frame. It cannot ensure that bandwidth is available throughout the transmission. Unanticipated blockage, due to the media access control scheme of shared access technologies, can hinder a traditional LAN technology from supporting time-sensitive applications such as video or voice traffic. Traditional LANs can use upper-level protocol drivers to verify packet transmission (retransmitting, if necessary), partition big messages into smaller ones, and use time stamps for synchronization. However, these services add time to the transmission, and none of them provides end-to-end QoS guarantees.
Traditional Internetworking
If the destination address is remote rather than local, the chances of transmission failure increase. If a router on an Ethernet network detects a broadcast meant for another network, the router accepts the packet and passes it on using TCP/IP. A TCP/IP datagram is packet-switched to its destination individually. The header of each contains a globally significant switching address. This address allows a routing decision to be made each time the packet is forwarded, and packets to the same destination might follow completely different paths to get there, jumping over networks that use different underlying technology. No connection is required, but no delivery is guaranteed. The following figure, Two Packets Taking Different Routes Through a Traditional LAN, shows an example of two packets taking different routes through a traditional LAN.
Two Packets Taking Different Routes Through a Traditional LAN
Like an Ethernet data transfer, a routed data transfer cannot offer guarantees because bandwidth is never reserved ahead of time. The packets being sent over TCP/IP are simply transmitted on the wire and routed. While this allows flexibility in routing around obstructions, network performance can vary a great deal depending on conditions at the routers and on the amount of network traffic.
ATM Networks
Like an Ethernet data transfer, a routed data transfer cannot offer guarantees because bandwidth is never reserved ahead of time. The packets being sent over TCP/IP are simply transmitted on the wire and routed. While this allows flexibility in routing around obstructions, network performance can vary a great deal depending on conditions at the routers and on the amount of network traffic.
ATM Networks
In contrast to connectionless transmission protocols, ATM is connection-oriented. An ATM endpoint establishes a defined path known as a virtual channel (VC), also called virtual circuit, to the destination endpoint prior to sending any data on the network. It then sends a series of same-size frames, called cells, along the virtual channel towards the destination.
While establishing the connection, the ATM endpoint also negotiates a QoS contract for the virtual channel. The QoS contract spells out the bandwidth, maximum transit delay, acceptable variance in the transit delay, and so forth, that the VC provides, and this contract extends from one endpoint to the other through all of the intermediate ATM switches.
While establishing the connection, the ATM endpoint also negotiates a QoS contract for the virtual channel. The QoS contract spells out the bandwidth, maximum transit delay, acceptable variance in the transit delay, and so forth, that the VC provides, and this contract extends from one endpoint to the other through all of the intermediate ATM switches.
The path of ATM traffic is established at the outset, and the switching hardware merely needs to examine a simple header to identify the proper path. Beyond specifying a path, ATM allows a location to establish a full duplex connection (traffic travels in both directions) with multiple locations at the same time. Note, however, that ATM is an unreliable transmission protocol because it does not acknowledge the receipt of cells sent. As with LANs, missing or corrupted information must be detected and corrected by upper-layer protocols.
The following figure, “ATM Virtual Channel and Packet Transmission,” illustrates
The following figure, “ATM Virtual Channel and Packet Transmission,” illustrates
ATM virtual channel and packet transmission.
ATM Virtual Channel and Packet Transmission
Network Speed
Unlike Ethernet networks, ATM has no inherent speed limit, and its efficiency is not affected by the distance that the data has to travel. In addition, ATM establishes the pathway for a particular series of packets at the outset and ATM switches make minimal switching decisions thereafter. To travel across the ATM network, data is segmented into same-size cells, and encapsulated with a header that contains information about switching, congestion, and error-checking.
Cells are transmitted in order, and the ATM network uses Virtual Path Identifier and Virtual Channel Identifier (VPI/VCI) numbers in the ATM header to forward them efficiently. A switch reads the header, compares the VPI/VCI to its switching table to determine the correct output port and new VPI/VCI, and then forwards the cell. All the addressing information that the ATM switch needs is contained in the header and is always found in the same place. This makes the forwarding task simple to implement in hardware by, reducing latency. Moreover, with ATM from end to end, there is no data translation required if a packet must travel from a LAN through a WAN to reach a destination LAN. The following figure, “ATM Fixed-Length Cells,” shows two ATM end stations sending fixed-length cells from A to B (although ATM traffic is bi-directional).
Unlike Ethernet networks, ATM has no inherent speed limit, and its efficiency is not affected by the distance that the data has to travel. In addition, ATM establishes the pathway for a particular series of packets at the outset and ATM switches make minimal switching decisions thereafter. To travel across the ATM network, data is segmented into same-size cells, and encapsulated with a header that contains information about switching, congestion, and error-checking.
Cells are transmitted in order, and the ATM network uses Virtual Path Identifier and Virtual Channel Identifier (VPI/VCI) numbers in the ATM header to forward them efficiently. A switch reads the header, compares the VPI/VCI to its switching table to determine the correct output port and new VPI/VCI, and then forwards the cell. All the addressing information that the ATM switch needs is contained in the header and is always found in the same place. This makes the forwarding task simple to implement in hardware by, reducing latency. Moreover, with ATM from end to end, there is no data translation required if a packet must travel from a LAN through a WAN to reach a destination LAN. The following figure, “ATM Fixed-Length Cells,” shows two ATM end stations sending fixed-length cells from A to B (although ATM traffic is bi-directional).
ATM Fixed-Length Cells
Because ATM uses small (53-byte), fixed-length cells that require less logic to process, the network spends no time determining where a particular cell begins and ends. The small cell size ensures that delays in forwarding cells are minimized. Because the cell size is so predictable, buffer usage and analysis algorithms can be simplified and optimized.
Traditional LAN technologies, such as Ethernet, have inherent speed limitations Either the underlying infrastructure (the cable) or the segment length must be changed to support fast traffic. However, unlike Ethernet and Token Ring, ATM has no such imposed limitations. If you can invent a faster physical layer — if you can design a quicker method of transmitting data from one place to another over one wire or many wires — ATM can work over that physical layer and at those new speeds. In addition, ATM allows information with different requirements and from different nodes to be transmitted nearly simultaneously without conflict.
ATM places fixed-length cells on the media when the data is produced according to the parameters of a negotiated connection. ATM can simultaneously handle the needs of isochronous (time-dependent) traffic, such as voice and video, and non-isochronous traffic, such as LAN data.
ATM places fixed-length cells on the media when the data is produced according to the parameters of a negotiated connection. ATM can simultaneously handle the needs of isochronous (time-dependent) traffic, such as voice and video, and non-isochronous traffic, such as LAN data.
STORAGE
Computer data storage, often called storage or memory, refers to computer components, devices, and recording media that retain digital data used for computing for some interval of time. Computer data storage provides one of the core functions of the modern computer, that of information retention. It is one of the fundamental components of all modern computers, and coupled with a central processing unit (CPU, a processor), implements the basic computer model used since the 1940s.
In contemporary usage, memory usually refers to a form of semiconductor storage known as random-access memory (RAM) and sometimes other forms of fast but temporary storage. Similarly, storage today more commonly refers to mass storage — optical discs, forms of magnetic storage like hard disk drives, and other types slower than RAM, but of a more permanent nature. Historically, memory and storage were respectively called main memory and secondary storage. The terms internal memory and external memory are also used.
The contemporary distinctions are helpful, because they are also fundamental to the architecture of computers in general. The distinctions also reflect an important and significant technical difference between memory and mass storage devices, which has been blurred by the historical usage of the term storage. Nevertheless, this article uses the traditional nomenclature.
In contemporary usage, memory usually refers to a form of semiconductor storage known as random-access memory (RAM) and sometimes other forms of fast but temporary storage. Similarly, storage today more commonly refers to mass storage — optical discs, forms of magnetic storage like hard disk drives, and other types slower than RAM, but of a more permanent nature. Historically, memory and storage were respectively called main memory and secondary storage. The terms internal memory and external memory are also used.
The contemporary distinctions are helpful, because they are also fundamental to the architecture of computers in general. The distinctions also reflect an important and significant technical difference between memory and mass storage devices, which has been blurred by the historical usage of the term storage. Nevertheless, this article uses the traditional nomenclature.
FIREWALLS
Firewall (computing), a technological barrier designed to prevent
unauthorized or unwanted communications between sections of a computer network
VOIP
Voice over Internet Protocol (VoIP) is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks. Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband phone.
Internet telephony refers to communications services — voice, facsimile, and/or voice-messaging applications — that are transported via the Internet, rather than the public switched telephone network (PSTN). The basic steps involved in originating an Internet telephone call are conversion of the analog voice signal to digital format and compression/translation of the signal into Internet protocol (IP) packets for transmission over the Internet; the process is reversed at the receiving end.[1]
VoIP systems employ session control protocols to control the set-up and tear-down of calls as well as audio codecs which encode speech allowing transmission over an IP network as digital audio via an audio stream. Codec use is varied between different implementations of VoIP (and often a range of codecs are used); some implementations rely on narrowband and compressed speech, while others support high fidelity stereo codecs.
Internet telephony refers to communications services — voice, facsimile, and/or voice-messaging applications — that are transported via the Internet, rather than the public switched telephone network (PSTN). The basic steps involved in originating an Internet telephone call are conversion of the analog voice signal to digital format and compression/translation of the signal into Internet protocol (IP) packets for transmission over the Internet; the process is reversed at the receiving end.[1]
VoIP systems employ session control protocols to control the set-up and tear-down of calls as well as audio codecs which encode speech allowing transmission over an IP network as digital audio via an audio stream. Codec use is varied between different implementations of VoIP (and often a range of codecs are used); some implementations rely on narrowband and compressed speech, while others support high fidelity stereo codecs.
TRANSCEVIERS
A transceiver is a device that has both a transmitter and a receiver which are combined and share common circuitry or a single housing. If no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s. Technically, transceivers must combine a significant amount of the transmitter and receiver handling circuitry. Similar devices include transponders, transverters, and repeaters.Content
1 Radio technology
2 Telephony
3 Ethernet
4 See also
5 References
6 External articles
Radio technology
Two-way radio
A modern HF transceiver with spectrum analyzer and DSP capabilities
In radio terminology, a transceiver means a unit which contains both a receiver and a transmitter. It was quite common to have these units separated. Ham radio operators can build their own equipment and it is always easier to design and build a simple unit having one of the functions, transmitting or receiving. Almost every modern amateur radio equipment is now a transceiver but there is an active market for pure radio receivers, mainly for Shortwave listening operators. An example of a transceiver would be a walkie-talkie, or a CB radio.
Telephony
On a wired telephone, the handset contains the transmitter and receiver for the audio and in the 20th century was usually wired to the base unit by Tinsel wire. The whole unit is colloquially referred to as a "receiver." On a mobile telephone or other radiotelephone, the entire unit is a transceiver, for both audio and radio.
A cordless telephone uses an audio and radio transceiver for the handset, and a radio transceiver for the base station. If a speakerphone is included in a wired telephone base or in a cordless base station, the base also becomes an audio transceiver in addition to the handset.
A modem is similar to a transceiver, in that it sends and receives a signal, but a modem uses modulation and demodulation. It modulates a signal being transmitted and demodulates a signal being received.
Ethernet
100BASE-TX to 100BASE-FX transceiver.
Transceivers are called Medium Attachment Units (MAUs) in IEEE 802.3 documents, which were widely used in 10base2 and 10base5 Ethernet networks. Fibre-optic gigabit and 10 gigabit Ethernet utilize transceivers known as GBIC, SFP, XFP, and XAUI.
TELECOMMUNICATION NETWORKING
A telecommunications network is a collection of nodes and links that is capable of carrying audio, visual, and data communications. While the term was once used to refer only to the collection of switches and wiring used by telephone service providers to provide audio connectivity to residential and business customers, it is now understood to include Internet, microwave, and wireless equipment as well as the more traditional forms of telephony. There are several different classes of telecommunication networks, with each of them having a slightly different focus.
The main function of any telecommunications network is to provide efficient transmission of information from a point of origin to a point of termination. A telephone call is the easiest way to understand the function. A call is initiated at a given point, with the signal routed through a series of nodes that may involve a combination of wired switches, Internet relays, and wireless nodes. The signal eventually terminates at a local switch, where is it then routed to the equipment used by the intended recipient. This process takes place within seconds, and establishes a connection that allows the parties to interact in a real-time fashion.
Today, there are several basic types of telecommunications networks in use. Along with the PSTA, or public switched telephone network, that most people are familiar with, there is also the Internet, a medium that is increasingly used for both voice and visual communications. Private computer networks are a common tool in many businesses today, as well as many institutions of higher learning. These basic types are all classified into several categories, which include such options as wide area networks, local area networks, and virtual private networks.
The main function of any telecommunications network is to provide efficient transmission of information from a point of origin to a point of termination. A telephone call is the easiest way to understand the function. A call is initiated at a given point, with the signal routed through a series of nodes that may involve a combination of wired switches, Internet relays, and wireless nodes. The signal eventually terminates at a local switch, where is it then routed to the equipment used by the intended recipient. This process takes place within seconds, and establishes a connection that allows the parties to interact in a real-time fashion.
Today, there are several basic types of telecommunications networks in use. Along with the PSTA, or public switched telephone network, that most people are familiar with, there is also the Internet, a medium that is increasingly used for both voice and visual communications. Private computer networks are a common tool in many businesses today, as well as many institutions of higher learning. These basic types are all classified into several categories, which include such options as wide area networks, local area networks, and virtual private networks.
COMPUTER NETWORKING
COMPUTER NETWORKING:
A computer network, often simply referred to as a network, is a collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of types and categories and also presents the basic components of a network.
WIRELESS NETWORKING
WIRELESS NETWORKINGWireless computer networking means that the communication between computers without the clustered wires. It is ideal for the situations where the cabling is not possible. There are different types of wireless network such as WLAN (which is based on the IEEE 802.11b standard), Wi-Fi, Wi-Max, GSM, Bluetooth and Infrared etc. The signals are usually transmitted through radio and electromagnetic waves. The hardware devices that are used in a wireless network are routers, switches, access point, wireless LAN cards, adapters, antennas, bridges, PCMCIA cards, WLAN access, station adapters and wireless modems.
Wireless network offers the flexibility, mobility, scalability to work everywhere within the range of your network. WLANs can be configured in a variety of ways to meet the needs of specific applications.
NETWORK PROTOCOLS
NETWORK PROTOCOLS
In networking, the communication language used by computer devices is called the protocol. Yet another way to classify computer networks is by the set of protocols they support. Networks often implement multiple protocols to support specific applications. Popular protocols include TCP/IP, the most common protocol found on the Internet and in home networks.
In networking, the communication language used by computer devices is called the protocol. Yet another way to classify computer networks is by the set of protocols they support. Networks often implement multiple protocols to support specific applications. Popular protocols include TCP/IP, the most common protocol found on the Internet and in home networks.
NETWORK DESIGN
NETWORK DESIGN:
Computer networks also differ in their design. The two types of high-level network design are called client-server and peer-to-peer. Client-server networks feature centralized server computers that store email, Web pages, files and or applications. On a peer-to-peer network, conversely, all computers tend to support the same functions. Client-server networks are much more common in business and peer-to-peer networks much more common in homes.
A network topology represents its layout or structure from the point of view of data flow. In so-called bus networks, for example, all of the computers share and communicate across one common conduit, whereas in a star network, all data flows through one centralized device. Common types of network topologies include bus, star, ring and mesh.
Computer networks also differ in their design. The two types of high-level network design are called client-server and peer-to-peer. Client-server networks feature centralized server computers that store email, Web pages, files and or applications. On a peer-to-peer network, conversely, all computers tend to support the same functions. Client-server networks are much more common in business and peer-to-peer networks much more common in homes.
A network topology represents its layout or structure from the point of view of data flow. In so-called bus networks, for example, all of the computers share and communicate across one common conduit, whereas in a star network, all data flows through one centralized device. Common types of network topologies include bus, star, ring and mesh.
DSL
The least expensive type of WAN uses the Internet over a dial-up modem. This type of WAN is not as popular, since the price of DSL has decreased enough to become competitive with dial-up accounts. A dial-up modem only operates at 56 kilobits per second (kbps), while a standard DSL connection is about 20 times faster. A dial-up connection also cannot share telephone service. Finally, dial-up is not an "always on" connection. When offices are in different time zones, this can effectively reduce WAN uptime.
A WAN is an excellent way for companies to utilize geographically remote resources and centralize productivity. A leased line or affordable DSL-based WAN allows employees, field personal, and management full or restricted access to pertinent data twenty-four hours a day, seven days a week. Considering the negligible cost of DSL today, a WAN makes good business sense.
Wide area networks (WANS)
Wide area networks (WANS)A Wide Area Network (WAN) is a network that spans a large geographical area, the most common example being the Internet. A WAN is contrasted to smaller local area networks (LANs) and metropolitan area networks (MANs). LANs are home or office networks, while a MAN might encompass a campus or service residents of a city, such as in a citywide wireless or WiFi network.
The Internet is a public WAN, but there are many ways to create a business model or private WAN. A private WAN is essentially two or more LANs connected to each other. For example, a company with offices in Los Angeles, Texas and New York might have a LAN setup at each office. Through leased telephone lines, all three LANs can communicate with each other, forming a WAN.
Routers are used to direct communications between LANs communicating on a WAN. The router, installed on the leased line, reads the "envelopes" or headers on each packet of data that passes through the WAN, sending it to the proper LAN. When the packet arrives at the LAN, a device called a switch sends the data packet on to the correct machine. Hence, the WAN acts like an interface between LANs for long-distance communication. A WAN that runs on a leased line is a private WAN, as there is no public traffic on the line.
Because leased lines are expensive, many businesses that require a WAN use an Internet Service Provider (ISP) to provide WAN access instead. In this case, each LAN in the WAN communicates through a standard digital subscriber line (DSL) account. The DSL Internet account uses an existing telephone line while sharing that line with the telephone.
Ethernet
Ethernet is by far the most commonly used LAN technology. A number of corporations use the Token Ring technology. FDDI is sometimes used as a backbone LAN interconnecting Ethernet or Token Ring LANs. Another LAN technology, ARCNET, once the most commonly installed LAN technology, is still used in the industrial automation industry.
Typically, a suite of application programs can be kept on the LAN server. Users who need an application frequently can download it once and then run it from their local hard disk. Users can order printing and other services as needed through applications run on the LAN server. A user can share files with others at the LAN server; read and write access is maintained by a LAN administrator. A LAN server may also be used as a Web server if safeguards are taken to secure internal applications and data from outside access.
In some situations, a wireless LAN may be preferable to a wired LAN because it is cheaper to install and maintain.
Typically, a suite of application programs can be kept on the LAN server. Users who need an application frequently can download it once and then run it from their local hard disk. Users can order printing and other services as needed through applications run on the LAN server. A user can share files with others at the LAN server; read and write access is maintained by a LAN administrator. A LAN server may also be used as a Web server if safeguards are taken to secure internal applications and data from outside access.
In some situations, a wireless LAN may be preferable to a wired LAN because it is cheaper to install and maintain.
TYPES OF NETWORKING
TYPES OF NETWORKINGLocal area networks (LANS)A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link. Typically, connected devices share the resources of a single processor or server within a small geographic area (for example, within an office building). Usually, the server has applications and data storage that are shared in common by multiple computer users. A local area network may serve as few as two or three users (for example, in a home network) or as many as thousands of users (for example, in an FDDI network). Major local area network technologies are: Ethernet Token Ring FDDI
Subscribe to:
Posts (Atom)
