Topology refers to the shape of a network, or the network's layout. How different nodes in a network are connected to each other and how they communicate are determined by the network's topology. Topologies are either physical or logical. Below are diagrams of the five most common network topologies.
Mesh Topology
Devices are connected with many redundant interconnections between network nodes. In a true mesh topology every node has a connection to every other node in the network.
Star Topology
All devices are connected to a central hub. Nodes communicate across the network by passing data through the hub.
Bus Topology
All devices are connected to a central cable, called the bus or backbone.
Ring Topology
All devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it.
Tree Topology
A hybrid topology. Groups of star-configured networks are connected to a linear bus backbone.
Network topology is the study of the arrangement or mapping of the elements (links, nodes, etc.) of a network, especially the physical (real) and logical (virtual) interconnections between nodes.[1][2] A local area network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN will have one or more links to one or more other nodes in the network and the mapping of these links and nodes onto a graph results in a geometrical shape that determines the physical topology of the network. Likewise, the mapping of the flow of data between the nodes in the network determines the logical topology of the network. The physical and logical topologies might be identical in any particular network but they also may be different.
Any particular network topology is determined only by the graphical mapping of the configuration of physical and/or logical connections between nodes. LAN Network Topology is, therefore, technically a part of graph theory. Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ in two networks and yet their topologies may be identical.
Basic types of topologies
There are six basic types of topology in networks:
Bus topology
Star topology
Ring topology
Mesh topology
Tree topology
Hybrid topology
Classification of network topologies
There are also three basic categories of network topologies:
physical topologies
signal topologies
logical topologies
The terms signal topology and logical topology are often used interchangeably even though there is a subtle difference between the two and the distinction is not often made between the two.
Physical topologies
The mapping of the nodes of a network and the physical connections between them – i.e., the layout of wiring, cables, the locations of nodes, and the interconnections between the nodes and the cabling or wiring system[1].
Classification of physical topologies
Point-to-point
The simplest topology is a permanent link between two endpoints. Switched point-to-point topologies are the basic model of conventional telephony. The value of a permanent point-to-point network is the value of guaranteed, or nearly so, communications between the two endpoints. The value of an on-demand point-to-point connection is proportional to the number of potential pairs of subscribers, and has been expressed as Metcalfe's Law.
Permanent (dedicated)
Easiest to understand, of the variations of point-to-point topology, is a point-to-point communications channel that appears, to the user, to be permanently associated with the two endpoints. Children's "tin-can telephone" is one example, with a microphone to a single public address speaker is another. These are examples of physical dedicated channels.
Within many switched telecommunications systems, it is possible to establish a permanent circuit. One example might be a telephone in the lobby of a public building, which is programmed to ring only the number of a telephone dispatcher. "Nailing down" a switched connection saves the cost of running a physical circuit between the two points. The resources in such a connection can be released when no longer needed, as, for example, a television circuit from a parade route back to the studio.
Switched:
Using circuit-switching or packet-switching technologies, a point-to-point circuit can be set up dynamically, and dropped when no longer needed. This is the basic mode of conventional telephony.
Bus
Linear bus
The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has exactly two endpoints (this is the 'bus', which is also commonly referred to as the backbone, or trunk) – all data that is transmitted between nodes in the network is transmitted over this common transmission medium and is able to be received by all nodes in the network virtually simultaneously (disregarding propagation delays)[1].
Note: The two endpoints of the common transmission medium are normally terminated with a device called a terminator that exhibits the characteristic impedance of the transmission medium and which dissipates or absorbs the energy that remains in the signal to prevent the signal from being reflected or propagated back onto the transmission medium in the opposite direction, which would cause interference with and degradation of the signals on the transmission medium (See Electrical termination).
Distributed bus
The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has more than two endpoints that are created by adding branches to the main section of the transmission medium – the physical distributed bus topology functions in exactly the same fashion as the physical linear bus topology (i.e., all nodes share a common transmission medium).
Notes:
1.) All of the endpoints of the common transmission medium are normally terminated with a device called a 'terminator' (see the note under linear bus).
2.) The physical linear bus topology is sometimes considered to be a special case of the physical distributed bus topology – i.e., a distributed bus with no branching segments.
3.) The physical distributed bus topology is sometimes incorrectly referred to as a physical tree topology – however, although the physical distributed bus topology resembles the physical tree topology, it differs from the physical tree topology in that there is no central node to which any other nodes are connected, since this hierarchical functionality is replaced by the common bus.
Star
The type of network topology in which each of the nodes of the network is connected to a central node with a point-to-point link in a 'hub' and 'spoke' fashion, the central node being the 'hub' and the nodes that are attached to the central node being the 'spokes' (e.g., a collection of point-to-point links from the peripheral nodes that converge at a central node) – all data that is transmitted between nodes in the network is transmitted to this central node, which is usually some type of device that then retransmits the data to some or all of the other nodes in the network, although the central node may also be a simple common connection point (such as a 'punch-down' block) without any active device to repeat the signals.
Notes:
1.) A point-to-point link (described above) is sometimes categorized as a special instance of the physical star topology – therefore, the simplest type of network that is based upon the physical star topology would consist of one node with a single point-to-point link to a second node, the choice of which node is the 'hub' and which node is the 'spoke' being arbitrary[1].
2.) After the special case of the point-to-point link, as in note 1.) above, the next simplest type of network that is based upon the physical star topology would consist of one central node – the 'hub' – with two separate point-to-point links to two peripheral nodes – the 'spokes'.
3.) Although most networks that are based upon the physical star topology are commonly implemented using a special device such as a hub or switch as the central node (i.e., the 'hub' of the star), it is also possible to implement a network that is based upon the physical star topology using a computer or even a simple common connection point as the 'hub' or central node – however, since many illustrations of the physical star network topology depict the central node as one of these special devices, some confusion is possible, since this practice may lead to the misconception that a physical star network requires the central node to be one of these special devices, which is not true because a simple network consisting of three computers connected as in note 2.) above also has the topology of the physical star.
4.) Star networks may also be described as either broadcast multi-access or nonbroadcast multi-access (NBMA), depending on whether the technology of the network either automatically propagates a signal at the hub to all spokes, or only addresses individual spokes with each communication.
Extended star
A type of network topology in which a network that is based upon the physical star topology has one or more repeaters between the central node (the 'hub' of the star) and the peripheral or 'spoke' nodes, the repeaters being used to extend the maximum transmission distance of the point-to-point links between the central node and the peripheral nodes beyond that which is supported by the transmitter power of the central node or beyond that which is supported by the standard upon which the physical layer of the physical star network is based.
Note: If the repeaters in a network that is based upon the physical extended star topology are replaced with hubs or switches, then a hybrid network topology is created that is referred to as a physical hierarchical star topology, although some texts make no distinction between the two topologies.
Distributed Star
A type of network topology that is composed of individual networks that are based upon the physical star topology connected together in a linear fashion – i.e., 'daisy-chained' – with no central or top level connection point (e.g., two or more 'stacked' hubs, along with their associated star connected nodes or 'spokes').
Ring
The type of network topology in which each of the nodes of the network is connected to two other nodes in the network and with the first and last nodes being connected to each other, forming a ring – all data that is transmitted between nodes in the network travels from one node to the next node in a circular manner and the data generally flows in a single direction only.
Dual-ring
The type of network topology in which each of the nodes of the network is connected to two other nodes in the network, with two connections to each of these nodes, and with the first and last nodes being connected to each other with two connections, forming a double ring – the data flows in opposite directions around the two rings, although, generally, only one of the rings carries data during normal operation, and the two rings are independent unless there is a failure or break in one of the rings, at which time the two rings are joined (by the stations on either side of the fault) to enable the flow of data to continue using a segment of the second ring to bypass the fault in the primary ring.
Mesh
The value of fully meshed networks is proportional to the exponent of the number of subscribers, assuming that communicating groups of any two endpoints, up to and including all the endpoints, is approximated by Reed's Law.
Full
Fully connected
The type of network topology in which each of the nodes of the network is connected to each of the other nodes in the network with a point-to-point link – this makes it possible for data to be simultaneously transmitted from any single node to all of the other nodes.
Note: The physical fully connected mesh topology is generally too costly and complex for practical networks, although the topology is used when there are only a small number of nodes to be interconnected.
Partial
Partially connected
The type of network topology in which some of the nodes of the network are connected to more than one other node in the network with a point-to-point link – this makes it possible to take advantage of some of the redundancy that is provided by a physical fully connected mesh topology without the expense and complexity required for a connection between every node in the network.
Note: In most practical networks that are based upon the physical partially connected mesh topology, all of the data that is transmitted between nodes in the network takes the shortest path (or an approximation of the shortest path) between nodes, except in the case of a failure or break in one of the links, in which case the data takes an alternate path to the destination. This requires that the nodes of the network possess some type of logical 'routing' algorithm to determine the correct path to use at any particular time.
Tree
Also known as a hierarchical network.
The type of network topology in which a central 'root' node (the top level of the hierarchy) is connected to one or more other nodes that are one level lower in the hierarchy (i.e., the second level) with a point-to-point link between each of the second level nodes and the top level central 'root' node, while each of the second level nodes that are connected to the top level central 'root' node will also have one or more other nodes that are one level lower in the hierarchy (i.e., the third level) connected to it, also with a point-to-point link, the top level central 'root' node being the only node that has no other node above it in the hierarchy (The hierarchy of the tree is symmetrical.) Each node in the network having a specific fixed number, of nodes connected to it at the next lower level in the hierarchy, the number, being referred to as the 'branching factor' of the hierarchical tree.
Notes:
1.) A network that is based upon the physical hierarchical topology must have at least three levels in the hierarchy of the tree, since a network with a central 'root' node and only one hierarchical level below it would exhibit the physical topology of a star.
2.) A network that is based upon the physical hierarchical topology and with a branching factor of 1 would be classified as a physical linear topology.
3.) The branching factor, f, is independent of the total number of nodes in the network and, therefore, if the nodes in the network require ports for connection to other nodes the total number of ports per node may be kept low even though the total number of nodes is large – this makes the effect of the cost of adding ports to each node totally dependent upon the branching factor and may therefore be kept as low as required without any effect upon the total number of nodes that are possible.
4.) The total number of point-to-point links in a network that is based upon the physical hierarchical topology will be one less than the total number of nodes in the network.
5.) If the nodes in a network that is based upon the physical hierarchical topology are required to perform any processing upon the data that is transmitted between nodes in the network, the nodes that are at higher levels in the hierarchy will be required to perform more processing operations on behalf of other nodes than the nodes that are lower in the hierarchy.
Hybrid network topologies
The hybrid topology is a type of network topology that is composed of one or more interconnections of two or more networks that are based upon the same physical topology, but where the physical topology of the network resulting from such an interconnection does not meet the definition of the original physical topology of the interconnected networks (e.g., the physical topology of a network that would result from an interconnection of two or more networks that are based upon the physical star topology might create a hybrid topology which resembles a mixture of the physical star and physical bus topologies or a mixture of the physical star and the physical tree topologies, depending upon how the individual networks are interconnected, while the physical topology of a network that would result from an interconnection of two or more networks that are based upon the physical distributed bus network retains the topology of a physical distributed bus network).
Star-bus
A type of network topology in which the central nodes of one or more individual networks that are based upon the physical star topology are connected together using a common 'bus' network whose physical topology is based upon the physical linear bus topology, the endpoints of the common 'bus' being terminated with the characteristic impedance of the transmission medium where required – e.g., two or more hubs connected to a common backbone with drop cables through the port on the hub that is provided for that purpose (e.g., a properly configured 'uplink' port) would comprise the physical bus portion of the physical star-bus topology, while each of the individual hubs, combined with the individual nodes which are connected to them, would comprise the physical star portion of the physical star-bus topology.
Star-of-stars
Hierarchical star
A type of network topology that is composed of an interconnection of individual networks that are based upon the physical star topology connected together in a hierarchical fashion to form a more complex network – e.g., a top level central node which is the 'hub' of the top level physical star topology and to which other second level central nodes are attached as the 'spoke' nodes, each of which, in turn, may also become the central nodes of a third level physical star topology.
Notes:
1.) The physical hierarchical star topology is not a combination of the physical linear bus and the physical star topologies, as cited in some texts, as there is no common linear bus within the topology, although the top level 'hub' which is the beginning of the physical hierarchical star topology may be connected to the backbone of another network, such as a common carrier, which is, topologically, not considered to be a part of the local network – if the top level central node is connected to a backbone that is considered to be a part of the local network, then the resulting network topology would be considered to be a hybrid topology that is a mixture of the topology of the backbone network and the physical hierarchical star topology.
2.) The physical hierarchical star topology is also sometimes incorrectly referred to as a physical tree topology, since its physical topology is hierarchical, however, the physical hierarchical star topology does not have a structure that is determined by a branching factor, as is the case with the physical tree topology and, therefore, nodes may be added to, or removed from, any node that is the 'hub' of one of the individual physical star topology networks within a network that is based upon the physical hierarchical star topology.
3.) The physical hierarchical star topology is commonly used in 'outside plant' (OSP) cabling to connect various buildings to a central connection facility, which may also house the 'demarcation point' for the connection to the data transmission facilities of a common carrier, and in 'inside plant' (ISP) cabling to connect multiple wiring closets within a building to a common wiring closet within the same building, which is also generally where the main backbone or trunk that connects to a larger network, if any, enters the building.
Star-wired ring
A type of hybrid physical network topology that is a combination of the physical star topology and the physical ring topology, the physical star portion of the topology consisting of a network in which each of the nodes of which the network is composed are connected to a central node with a point-to-point link in a 'hub' and 'spoke' fashion, the central node being the 'hub' and the nodes that are attached to the central node being the 'spokes' (e.g., a collection of point-to-point links from the peripheral nodes that converge at a central node) in a fashion that is identical to the physical star topology, while the physical ring portion of the topology consists of circuitry within the central node which routes the signals on the network to each of the connected nodes sequentially, in a circular fashion.
Note: In an 802.5 Token Ring network the central node is called a Multistation Access Unit (MAU).
Hybrid mesh
A type of hybrid physical network topology that is a combination of the physical partially connected topology and one or more other physical topologies the mesh portion of the topology consisting of redundant or alternate connections between some of the nodes in the network – the physical hybrid mesh topology is commonly used in networks which require a high degree of availability..do you agree
Signal topology
The mapping of the actual connections between the nodes of a network, as evidenced by the path that the signals take when propagating between the nodes.
Note: The term 'signal topology' is often used synonymously with the term 'logical topology', however, some confusion may result from this practice in certain situations since, by definition, the term 'logical topology' refers to the apparent path that the data takes between nodes in a network while the term 'signal topology' generally refers to the actual path that the signals (e.g., optical, electrical, electromagnetic, etc.) take when propagating between nodes.
Example
In an 802.4 Token Bus network, the physical topology may be a physical bus, a physical star, or a hybrid physical topology, while the signal topology is a bus (i.e., the electrical signal propagates to all nodes simultaneously [ignoring propagation delays and network latency] ), and the logical topology is a ring (i.e., the data flows from one node to the next in a circular manner according to the protocol).[3]
Logical topology
The mapping of the apparent connections between the nodes of a network, as evidenced by the path that data appears to take when traveling between the nodes.
Classification of logical topologies
The logical classification of network topologies generally follows the same classifications as those in the physical classifications of network topologies, the path that the data takes between nodes being used to determine the topology as opposed to the actual physical connections being used to determine the topology.
Notes:
1.) Logical topologies are often closely associated with media access control (MAC) methods and protocols.
2.) The logical topologies are generally determined by network protocols as opposed to being determined by the physical layout of cables, wires, and network devices or by the flow of the electrical signals, although in many cases the paths that the electrical signals take between nodes may closely match the logical flow of data, hence the convention of using the terms 'logical topology' and 'signal topology' interchangeably.
3.) Logical topologies are able to be dynamically reconfigured by special types of equipment such as routers and switches.
Daisy chains
Except for star-based networks, the easiest way to add more computers into a network is by daisy-chaining, or connecting each computer in series to the next. If a message is intended for a computer partway down the line, each system bounces it along in sequence until it reaches the destination. A daisy-chained network can take two basic forms: linear and ring.
A linear topology puts a two-way link between one computer and the next. However, this was expensive in the early days of computing, since each computer (except for the ones at each end) required two receivers and two transmitters.
By connecting the computers at each end, a ring topology can be formed. An advantage of the ring is that the number of transmitters and receivers can be cut in half, since a message will eventually loop all of the way around. When a node sends a message, the message is processed by each computer in the ring. If a computer is not the destination node, it will pass the message to the next node, until the message arrives at its destination. If the message is not accepted by any node on the network, it will travel around the entire ring and return to the sender. This potentially results in a doubling of travel time for data.
Centralization
The star topology reduces the probability of a network failure by connecting all of the peripheral nodes (computers, etc.) to a central node. When the physical star topology is applied to a logical bus network such as Ethernet, this central node (traditionally a hub) rebroadcasts all transmissions received from any peripheral node to all peripheral nodes on the network, sometimes including the originating node. All peripheral nodes may thus communicate with all others by transmitting to, and receiving from, the central node only. The failure of a transmission line linking any peripheral node to the central node will result in the isolation of that peripheral node from all others, but the remaining peripheral nodes will be unaffected. However, the disadvantage is that the failure of the central node will cause the failure of all of the peripheral nodes also.
If the central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two-way round triptransmission time (i.e. to and from the central node) plus any delay generated in the central node. An active star network has an active central node that usually has the means to prevent echo-related problems.
A tree topology (a.k.a. hierarchical topology) can be viewed as a collection of star networks arranged in a hierarchy. This tree has individual peripheral nodes (e.g. leaves) which are required to transmit to and receive from one other node only and are not required to act as repeaters or regenerators. Unlike the star network, the functionality of the central node may be distributed.
As in the conventional star network, individual nodes may thus still be isolated from the network by a single-point failure of a transmission path to the node. If a link connecting a leaf fails, that leaf is isolated; if a connection to a non-leaf node fails, an entire section of the network becomes isolated from the rest.
In order to alleviate the amount of network traffic that comes from broadcasting all signals to all nodes, more advanced central nodes were developed that are able to keep track of the identities of the nodes that are connected to the network. These network switches will "learn" the layout of the network by "listening" on each port during normal data transmission, examining the data packets and recording the address/identifier of each connected node and which port it's connected to in a lookup table held in memory. This lookup table then allows future transmissions to be forwarded to the intended destination only.
Decentralization
In a mesh topology (i.e., a partially connected mesh topology), there are at least two nodes with two or more paths between them to provide redundant paths to be used in case the link providing one of the paths fails. This decentralization is often used to advantage to compensate for the single-point-failure disadvantage that is present when using a single device as a central node (e.g., in star and tree networks). A special kind of mesh, limiting the number of hops between two nodes, is a hypercube. The number of arbitrary forks in mesh networks makes them more difficult to design and implement, but their decentralized nature makes them very useful. This is similar in some ways to a grid network, where a linear or ring topology is used to connect systems in multiple directions. A multi-dimensional ring has a toroidal topology, for instance.
A fully connected network, complete topology or full mesh topology is a network topology in which there is a direct link between all pairs of nodes. In a fully connected network with n nodes, there are n(n-1)/2 direct links. Networks designed with this topology are usually very expensive to set up, but provide a high degree of reliability due to the multiple paths for data that are provided by the large number of redundant links between nodes. This topology is mostly seen in military applications. However, it can also be seen in the file sharing protocol BitTorrent in which users connect to other users in the "swarm" by allowing each user sharing the file to connect to other users also involved. Often in actual usage of BitTorrent any given individual node is rarely connected to every single other node as in a true fully connected network but the protocol does allow for the possibility for any one node to connect to any other node when sharing files.
Hybrids
Hybrid networks use a combination of any two or more topologies in such a way that the resulting network does not exhibit one of the standard topologies (e.g., bus, star, ring, etc.). For example, a tree network connected to a tree network is still a tree network, but two star networks connected together exhibit a hybrid network topology. A hybrid topology is always produced when two different basic network topologies are connected. Two common examples for Hybrid network are: star ring network and star bus network
A Star ring network consists of two or more star topologies connected using a multistation access unit (MAU) as a centralized hub.
A Star Bus network consists of two or more star topologies connected using a bus trunk (the bus trunk serves as the network's backbone).
While grid networks have found popularity in high-performance computing applications, some systems have used genetic algorithms to design custom networks that have the fewest possible hops in between different nodes. Some of the resulting layouts are nearly incomprehensible, although they function quite well.
We introduce superposition-based quantum networks composed of (i) the classical perceptron model of multilayered, feedforward neural networks and (ii) the algebraic model of evolving reticular quantum structures as described in quantum gravity. The main feature of this model is moving from particular neural topologies to a quantum metastructure which embodies many differing topological patterns. Using quantum parallelism, training is possible on superpositions of different network topologies. As a result, not only classical transition functions, but also topology becomes a subject of training. The main feature of our model is that particular neural networks, with different topologies, are quantum states. We consider high-dimensional dissipative quantum structures as candidates for implementation of the model.
Affiliations:1: Quantum Information Science and Technology Project, ATIP, Tokyo, Japan, and Universiteit van Amsterdam, The Netherlands;, Email: altmanc@admiral.umsl.edu 2: Instytut Matematyki, Uniwersytet Gdaski, Wita Stwosza 57, 80-952 Gdask, Poland, and Center Leo Apostel of the Vrije Universiteit Brussels (VUB), Krijgskundestraat 33, 1160 Brussel ski, Wita Stwosza 57, 80-952 Gdask, Poland, and Center Leo Apostel of the Vrije Universiteit Brussels (VUB), Krijgskundestraat 33, 1160 Brussel "> 3: Friedmann Lab. for Theoretical Physics, SPb UEF, Griboyedova 30–32, 191023, St. Petersburg, Russia
To check the IMEI (International Mobile Equipment Identity) Type-
*#06#
Information you get from the IMEI
XXXXXX XX XXXXXX X TAC FAC SNR SP
TAC = Type approval code FAC = Final assembly code SNR = Serial number SP = Spare
To check the phones Software revision type- *#0000#
Information you get from the Software revision- V 05.31 18-02-99 NSE-3 1ST Line = Software revision 2ND Line = The date of the software release 3RD Line = Phone type To enter the service menu type- *#92702689# (*#WAR0ANTY#) Serial number (IMEI) roduction date (MM/YY) Purchase date (MM/YY) You can only enter the date once. Date of last repair (0000=No repair) Transfer user data to another Nokia phone via Infra-Red Clock Stopping
To check weather your SIM Card supports clock stopping type- *#746025625# (*#SIM0CLOCK#) Revealing the Headphone and Car-Kit menus Please note that if you do these next tricks, the new menus can't be erased without retoring the factory default settings. To do these tricks you need to short-circuit the pins on the bottom of the phone next to where you plug in you charger.
1. To activate the "Headset" menu, you need to short-circuit pins "3" and "4". After a short time the word "Headset" will be shown in the display. Menu 3-6 is now enabled.
2. To activate the "Car" menu, you need to short-circuit pins "4" and "5". After a short time the word "Car" will be shown in the display. Menu 3-7 is now enabled.
THE REBOOT TRICK
This should work on all software versions of the 6110. 1. Go to the Calendar (Menu-8) 2. Make a note or reminder. 3. Enter some text into the edit box. 4. Hold "Clear" until the whole text is cleared, then press "Back". 5. Press "0". The main screen will now be showing but a space appears on the screen. (you can't see it) 6. Enter 4 digits (e.g. 1234). 7. Use the down arrow to move the cursor to the left side of the numbers and the space (Down arrow twice). 8. Now enter 6 digits and press the call button.
Wait for a few seconds, the screen should start to flash and reboots. It should alsowork on other menus like the "Profiles" menu.
EFR CALL QUALITY
To activate EFR (Enhanced Full Rate) Enter the code- *3370# This improves call quality but decreases batterylife by about 5% To deactivate it, Enter the code- #3370#
THE JAMES BOND TRICK
If you short-circuit theleft middle and right pins on the bottom of the phone with all connections touching each other, the Nokia software hangs! The profile "Headset" will be activated. Before you do this just activate the "Automatic Answer" in the headset profile and set the ringing volume to "Mute". Now you can use your phone for checking out what people are talking about in a room. Just place it under a table in a room and call it. The phone receives the call without ringing and you can listen to what people are saying.
NETWORK MONITOR
There is a hidden menu inside your Nokia phone. If you want to activate it, you'll have to re-program some chips inside of your phone. Check your software version. You can only continue if you have v4.33, v4.73 or v5.24. Take apart the phone. De-solder the EEPROM (ATMEL AT 24C64). Read out the data with an EEPROM programmer and save it to a file (Backup). If you have v.33 or v4.73, change the address "03B8" from "00" to "FF". If you have v5.24 then change the address "0378" from "00" to "FF". Write the new data to the EEPROM and solder it back to the phone, Power on your phone and you should have "Netmonitor" enabled. The Network Monitor gives you the following information.
Carrier number
MS RX Level in DBM Received signal quality MS TX power level C1 (Path loss criterion, used for cell selection and reselection). The range is -99 to 99. RTL (Radio link timeout). Timeslot Indication of the transmitter status Information on the Network parameters. TMSI (Temporary Mobile Subscriber Identity). Cell identification (Cell ID, Number of cells being used). MCC (Mobile country code) MCN (Mobile network code) LAC (Location area code) Ciphering (On/Off) Hopping (On/Off) DTX (On/Off) Discard cell barred information
CHECK SIM-LOCK
Note - If you bought your Nokia on UK Vodafone or UK Cellnet you do not need to check this because they both transmit on GSM900, and they don't lock the phones. However if you bought your phone on UK Orange or UK One2one your phone may be blocked. The reason is that they both transmitt on GSM1800. To make a call on GSM1800 you need what is known as a "Dual band" phone. A dual band phone is able to transmit on both GSM900 and GSM1800, so they lock the phones so you can't use it with any other network simcard. If you find that your phone is locked you can try different software to unlock it. (we havn't found one that works yet), or you can ask your service provider who will gladly exchange the 10 digit code for about £35.
This is how to check the status of the 4 different locks. Aslo don't try entering the wrong number, because after 3 times it will block the phone for good.
The master code is a secret code. The code has 10 digits, To read out the sim-lock status you can enter every combination you want!
"Y" Shows the status of the network-lock. Here you can enter a number from "1" to "4". The "4" is for the sim-card lock.
SIM-LOCK CHECKS
#PW+1234567890+1# = GIVES PROVIDER-LOCK STATUS #PW+1234567890+2# = GIVES NETWORK-LOCK STATUS #PW+1234567890+3# = GIVES COUNTRY-LOCK STATUS #PW+1234567890+4# = GIVES SIM-CARD-LOCK STATUS.
The network module offers classes to make network programming easier and portable. Essentially, there are three sets of classes, first low level classes like QSocket, QServerSocket, QDns, etc. which allow you to work in a portable way with TCP/IP sockets. In addition, there are classes like QNetworkProtocol, QNetworkOperation in the Qt base library, which provide an abstract layer for implementing network protocols and QUrlOperator which operates on such network protocols. Finally the third set of network classes are the passive ones, specifically QUrl and QUrlInfo which do UR
The QSocket classes are not directly related to the QNetwork classes, but QSocket should and will be used for implementing network protocols, which are directly related t
o the QNetwork classes. For example, the QFtp class (which implements the FTP protocol) uses QSockets. But QSockets don't need to be used for protocol implementations, e.g. QLocalFs (which is an implementation of the local filesystem as network protocol) uses QDir and doesn't use QSocket. Using QNetworkProtocols you can implement everything which fits into a hierarchical structure and can be accessed using URLs. This could be, for example, a protocol which can read pictures from a digital camera using a serial connection.
It is quite easy to just use existing network protocol implementations and operate on URLs. For example, downloading a file from an FTP server to the local filesystem can be done with following code:
To see all available operations, look at the QUrlOperator class
documentation.
Since networking works asynchronously, the functi
on call for an operation will normally return before the operation has been completed. This means that the function cannot return a value indicating failure or success. Instead, the return value always is a pointer to a QNetworkOperation, and this object stores all the information about the operation.
For example, QNetworkOperation has a method which returns the state of this operation. Using this you can find out the state of the operation at any time. The object also make
s available the arguments you passed to the QUrlOperator method, the type of the operation and some more information. For more details see the class documentation of QNetworkOperation.
The QUrlOperator emits signals to inform you about the progress of the operations. As you can call many methods which operate on a QUrlOperator's URL, it qu
eues up all the operations. So you can't know which operation the QUrlOperator just processed. Clearly you will want to know which operation just took place, so each signal's last argument is a pointer to the QNetworkOperation object which was just processe
d and which caused the signal to be emitted.
Some of these operations send a start(
) signal at the beginning (if this makes sense), and some of them send some signals during processing. All operations send a finished()
qDebug( "Successfully created directory %s", op->arg( 0 ).latin1() );
break;
// ... and so on
}
}
As mentioned earlier, some operations send other signals too. Let's take the list children operation as an example (e.g. read a directory on a FTP server):
These examples demonstrate now how to use the QUrlOperator and QNetworkOpera
tions. The network extension also contains useful example code.
Implementing your own Network Protocol
QNetworkProtocol provides a base class for implementations of network protocols and an architecture for the a dynamic registration and de-registration of network protocols. If you use this architecture you don't need to care about asynchronous programming, as the architecture hides this and does all the work for you.
Note It is difficult to design a base class for network protocol
s which is useful for all network protocols. The architecture described here is designed to work with all kinds of hierarchical structures, like filesystems. So everything which can be interpreted as hierarchical structure and accessed via URLs, can be implemented as network protocol and easily used in Qt. This is not limited to filesystems only!
To implement a network protocol create a class derived
Some notes on reimplementing these methods: You always g
et a pointer to a QNetworkOperation as argument. This pointer holds all the information about the operation in the current state. If you start processing such an operation, set the state to QNetworkProtocol::StInProgress. If you finished processing the operation, set the state to QNetworkProtocol::StDone if it was successful or QNetworkProtocol::StFailed if an error occurred. If an error occurred you must set an error code (see QNetworkOperation::setErrorCode()) and if you know some details (e.g. an error message) you can also set this message to the operation pointer (see QNetworkOperation::setProtocolDetail()). Also you get all the relevant information (type, arguments, etc.) about the operation from the QNetworkOperation pointer. For details about which arguments you can get and set look at QNetworkOp
If you reimplement an operation function, it's very important to emit the correct signals at the correct time: In general always emit finished() at the end of an operation (when you either successfully finished processing the operation or an error occurred) with the network operation as argument. The whole network architecture relies on correctly emitted f
inished() signals! Then there are some more specialized signals which are specific to operations:
Emit in operationListChildren:
start() just before starting to list the children
newChildren() when new children are read
Emit in operationMkDir:
createdDirectory() after the directory has been created
newChild() (or newChildren()) after the directory has been created (since a new directory is a new child)
Emit in operationRemove:
removed() after a child has been removed
Emit in operationRename:
itemChanged() after a child has been renamed
Emit in operationGet:
data() each time new data has been read
dataTransferProgress() each time new data has been read to indicate ho w much of the data has been read now.
Emit in operationPut:
dataTransferProgress() each time data has been written to indicate how much of the data has been written. Although you know the whole data when this operation is called, it' s suggested not to write the whole data at once, but to do it step by step to avoid blocking the GUI. Doing things incrementally also means that progress can be made visible to the user.
And remember, always emit the finishe
d() signal at the end!
For more details about these signals' arguments look at the QNetworkProtocol class documentation.
Here is a list of which QNetworkOperation arguments you can get and which you must set in which function:
(To get the URL on which you should work, use the QNetworkProtocol::url() method which returns a pointer to the URL operator. Using that you can get the path, ho
st, name filter, etc.)
In operationListChildren:
Nothing.
In operationMkDir:
QNetworkOperation::arg( 0 ) contains the name of the directory which should be created
In operationRemove:
QNetworkOperation::arg( 0 ) contains the name of the file which should be removed. Normally this is a relative name. But it could be absolute. Use QUrl( op->arg( 0 ) ).fileName() to get the filename.
In operationRename:
QNetworkOperation::arg( 0 ) contains the name of the file which should be renamed
QNetworkOperation::arg( 1 ) contains the name to which it should be renamed.
In operationGet:
QNetworkOperation::arg( 0 ) contains the full URL of the file w hich should be retrieved.
In operationPut:
QNetworkOperation::arg( 0 ) contains the full URL o f the file in which the data should be stored.
QNetworkOperation::rawArg( 1 ) contains the data which should be stored in QNetworkOperation::arg( 0 )
In summary: If you reimplement an operation function, you must e
mit some special signals and at the end you must always emit a finished() signal, regardless of success or failure. Also you must change the state of the QNetworkOperation during processing. You can also get and set QNetworkO
It may occur that the network protocol you implement only requires a subset of these operations. In such cases, simply reimplement the operations which are supported by the protocol. Additionally you must specify which operations you support. This is achieved by reimplementing
int QNetworkProtocol::supportedOperations() const;
In your implementation of this method return an int
value which is constructed by OR-ing together the correct values (supported operations) of the following enum (of QNetworkProtocol):
OpListChildren
OpMkDir
OpRemove
OpRename
OpGet
OpPut
For example, if your protocol supports listing children a
nd renaming them, your implementation of supportedOperations() should do this:
Here you must return TRUE, if the connection is up and okay (this means operations on the protocol can be done). If the connection is not okay, return FALSE and start to try opening it. If you cannot open the connection at all (e.g. because the host is not found), emit a finished() signal and set an error code and the QNetworkProtocol::StFailed state to the QNetworkOperation pointer you get here.
Now, you never need to check before doing an operation y
ourself, if the connection is okay. The network architecture does this, which means it uses checkConnection() to see if an operation can be done and if not, it tries it again and again for some time, only calling an operation function if the connection is okay.
To be able to use a network protocol with a QUrlOperator (and so, for example, in the QFileDialog), you must register the network protocol implementation. This can be done like this:
In this case MyProtocol would be a class you implemented as described here (derived from QNetworkProtocol) and the name of the protocol would be "myprot". So to use it, you would do something like
Finally, as example of a network protocol implementation you
could look at the implementation of QLocalFs. The network extension also contains an example implementation of a network protocol.
Error Handling
Error handling is important for both implementing new network protocols for and using them (through QUrlOperator).
After processing an operation has been finished the network operation the QUrlOperator emits the finished() signal. This ha
s as argument a pointer to the processed QNetworkOperation. If the state of this operation is QNetworkProtocol::StFailed, the operation contains some more information about this error. The following error codes are defined in QNetworkProtocol:
QNetworkOperation::errorCode() returns one of these codes or perhaps a different one if you use your an own network protocol implementation which defines additional error codes.
QNetworkOperation::protocolDetails() may also return a string which contains an error message then which might be suitable for display to the user.
If you implement your own network protocol, you must report any errors which occurred. First you always need to be able to access the QNetworkOperation which is being processed at the moment. This is done using QNetworkOperation::operationInProgress(), which returns a pointer to the current network operation or 0 if no operation is processed at the moment.
Now if an error occurred and you need to handle it, do this:
That's all. The connection to the QUrlOperator and so on is done automatically. Additionally, if the error was really bad so that no more operations can be done in the current state (e.g. if the host couldn't be found), call QNetworkProtocol::clearOperationStack()before emitting finished().
Ideally you should use one of the predefined error codes of QNetworkProtocol. If this is not possible, you can add own error codes - they are just normal ints. Just be careful that the value of the error code doesn't conflict with an existing one.
An example to look at is in qt/examples/network/ftpclient. This is the implementation of a fairly complete FTP client, which supports uploading and downloading files, making directories, etc., all done using QUrlOperators.
You might also like to look at QFtp (in qt/src/network/qftp.cpp) or at the example in qt/examples/network/networkprotocol/nntp.cpp.
Network Monitoring Helps You To Optimize Your Network Infrastructure
Network Monitoring is essential for companies of any size and branch, to ensure that their computer systems are running performantly and no outages occur. A network monitoring tool is important to increase the efficency of your network by understanding bandwidth and ressource consumption.
We can devide the Network Monitoring arena into three segments:
Availability (uptime) monitoring
Usage monitoring
Activity montoring
Network uptime monitoring offers the following benefits:
Increased profits: no losses caused by undetected system failures.
Improved customer satisfaction by providing more reliable systems.
Peace of mind: As long as you do not hear from the monitoring tool you know everything is running fine.
Free valuable time to take care of other important busines.
A software for usage monitoring is the key to:
Avoid bandwidth and server performance bottlenecks.
Find out what applications or what servers use up your bandwidth.
Deliver better quality of service to your users by being proactive.
Reduce costs by buying bandwidth and hardware according to actual load.
Activity monitoring enables a precise network behavioural analysis (NBA):
Allow protocols for different roles.
Identify sudden spikes caused by malicious code immediately.
Requirements For a Network Monitoring Solution
A good network monitorig solution should easily be installed and usage should be intuitive so that there is no need for external consultancy and training. Further necessary requirements are:
Remote Management via web browser, PocketPC, or Windows client
Notifications about outages by email, ICQ, pager/SMS, and more.
Comprehensive sensor type selection
Multiple location monitoring
All common methods for network usage data acquisition (SNMP, Packet Sniffing, Xflow) have to be supported.
Merely implementing a network monitoring solution for your network isn't enough. The real work begins after you've chosen and installed a monitoring solution. Yet many IT managers and systems administrators often find themselves unsure of what to monitor after finally selecting and implementing their network monitoring solutions. The key to effective network monitoring is ensuring that a solution is configured to monitor what are essentially a network's vital signs - or triplets: availability, speed and usage.
Users who monitor network availability will ensure that both internal and external parties can access the services within their LANs, including Websites. They can also determine if their mail servers and leased lines are working, as well as if their network service providers are adhering to their SLAs.
Users who monitor network speed will ensure that their websites and network services don't lose visitors or frustrate users due to slow-loading pages, files or images. Users who monitor speed can determine how traffic - or stress - affects performance and how to plan for surges in traffic. Most importantly monitoring speed allows to identify traffic patterns and proactively install network upgrades before slowloading pages test the patience of clients or employees.
Users who monitor usage can accurately assess CPU load and learn just what sort of work their servers are doing at different points in the day. Monitoring usage and spped is also essential for a company to ensure its disparate pieces of hardware are operating at optimum levels - or doing their jobs.
Software Versus Service
There are two options for a network monitoring solution. You can purchase and setup a network monitoring software like PRTG Network Monitor by your own, or you can benefit from network monitoring services provided by an ASP.
Which option (software or service) is the right one for you depends on various factors. You can read more about the on-demand service for network monitoring.
How to Set Up Your Network Monitoring
With PRTG Network Monitor data acquisition technologies and the various infrastructure options in use today it can sometimes get complicated to decide which monitoring technology is right for your problem.
The easiest configuration is to monitor the local traffic of one PC by installing PRTG directly on it. This scenario is used to monitor a single PC in a LAN network or to monitor a PC connected to the Internet via DSL, modem, or cable.
For other network configurations you find detailed setup instructions in our knowledge base.
Interfaces and Modules for Ethernet can also be found under Cisco Network Modules, Cisco Port Adapters, and Cisco Transceiver Modules.
Models (10)
Cisco 3201 Fast Ethernet Switch Mobile Interface Card Cisco 2600/2600 16-Pt 10/100 EtherSwitch NM with 1 GE (1000BaseT) Port Cisco 16-Port 10/100 EtherSwitch NM with In-Line Power and GE Cisco 16-Port 10/100 EtherSwitch NM with In-Line Power Support Cisco Catalyst 6500 48-Port 10/100/1000 Premier WC Ethernet Module Cisco Catalyst 6500 Series 48-Port 10/100/1000 WC Ethernet Module Cisco Catalyst 6500 Series 4-Port 10 Gigabit Ethernet Module Cisco Catalyst 6500 Series Enhanced 16-Port Gigabit Ethernet Module Cisco Gigabit Ethernet Switch Module (CGESM) for HP Cisco IGESM & Cisco Fiber IGESM Switch Module for IBM
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