In a network where a LAN switch is used, each node gets a direct connection to a switch. That is, a node gets a dedicated connection to the switch which only it (the node or the computer) and the switch use. This dedicated connection makes it possible for one node to maximize use of the bandwidth available to it. After all, no other node is competing with it for bandwidth. This means speedy data transmission.
Moreover, the connection between the node and the switch can be made using cabling which has a separate route for data that the node is sending out and a separate route for data that the switch is forwarding to the node. This eliminates problems of data collision.
The LAN switch is especially a vast improvement over the network hub since it has the ability to “read” the source and destination node of a data packet and forward the packet only to the destination node.
Whenever the node transmits data meant for another node in the local area network, the switch intercepts the data, determines the destination and forwards the transmission to its intended destination. Since a data packet does not get broadcasted to unnecessary segments, network congestion is minimized and network bandwidth is conserved.
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The Local Area Network: Basics
LAN, as you know, is the geographically limited network; it is usually limited to a single office, home, department, or building. In some cases, though, a LAN can exist between neighboring buildings.
It is comprised of various nodes – these are usually desktop computers and computer servers – that are physically connected through LAN cables or through a wireless router and are able to communicate with each other and share common resources (e.g. office printers).
There are many ways of connecting the various nodes in a Local Area Network. Simple networks usually have nodes that are arranged in a bus (straight backbone with segments where nodes are attached) or ring topology (nodes are distributed on a circular backbone and only the node with the ring token can transmit or send data).
They can also be arranged in a star-like arrangement where all nodes have an individual segment connecting them to a hub. The hub is a passive network device; it is simply a place where data packets pass from one node to all the other nodes connected to it (except the port from which the data originally came from). Complex networks are usually a combination of the bus and star typology. Backbones connect multiple hubs.
All these networks have different physical properties (they vary in the way a node can send and receive data to another node), but all these suffer from inefficient bandwidth usage, extremely low speeds and data collision incidence.
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It is comprised of various nodes – these are usually desktop computers and computer servers – that are physically connected through LAN cables or through a wireless router and are able to communicate with each other and share common resources (e.g. office printers).
There are many ways of connecting the various nodes in a Local Area Network. Simple networks usually have nodes that are arranged in a bus (straight backbone with segments where nodes are attached) or ring topology (nodes are distributed on a circular backbone and only the node with the ring token can transmit or send data).
They can also be arranged in a star-like arrangement where all nodes have an individual segment connecting them to a hub. The hub is a passive network device; it is simply a place where data packets pass from one node to all the other nodes connected to it (except the port from which the data originally came from). Complex networks are usually a combination of the bus and star typology. Backbones connect multiple hubs.
All these networks have different physical properties (they vary in the way a node can send and receive data to another node), but all these suffer from inefficient bandwidth usage, extremely low speeds and data collision incidence.
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What are LAN Switches
A LAN switch is a local area networking device that prevents data packet collision, and maximizes transmission speed as well as bandwidth allocation. This is a good replacement to a network hub and solves problems associated with expanding networks.
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How to change a MAC address in Microsoft Windows
Under Windows, the MAC address is stored in a registry key. To change a MAC address, find that key with `regedit` and change it. Of course, Microsoft keeps moving the location of the key around!
Windows XP adds an option to change the MAC address on some network cards under the Advanced tab in the network adapter's Properties menu.
A much easier and more reliable method to change a MAC address under Windows is to use a software utility program designed to do this for you.
Macshift is a free utility that you can use to spoof your MAC address under Microsoft Windows.
What is a MAC address
A MAC address is an address which exists on Layer 2 of the OSI Model.
Layer 2 of the OSI model is the Data Link Layer. The Data Link Layer consists of two sublayers, the Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sublayer controls how a network node gains access to the data and permission to transmit it.
MAC addresses are globally unique addressed that are written into hardware at the time of manufacture. For this reason, MAC addresses are sometimes called Burned In Addresses (BIA).
After manufacture, it is possible in many cases to change the MAC address of a device in software.
MAC addresses are used by many different Layer 2 technologies, including Ethernet, Token Ring, 802.11, Bluetooth, FDDI, ATM, SCSI, and Fibre Channel.
Because MAC addresses originated in the Ethernet specification, the MAC address is sometimes referred to as the Ethernet Address.
A MAC address is 48 bits long. This means that there are 281,474,976,710,656 possible MAC addresses.
A sample MAC address looks like this:
00-0C-F1-56-98-AD
The first three bytes of this address (00-0C-F1) identify the manufacture of this network device, in this case Intel.
These first three bytes are assigned by the IEEE and the database is available online at IEEE OUI and Company_id Assignments.
The last three bytes of this address were assigned by Intel when they device was manufactured.
Posted by: Wasim Javed
Windows XP adds an option to change the MAC address on some network cards under the Advanced tab in the network adapter's Properties menu.
A much easier and more reliable method to change a MAC address under Windows is to use a software utility program designed to do this for you.
Macshift is a free utility that you can use to spoof your MAC address under Microsoft Windows.
What is a MAC address
A MAC address is an address which exists on Layer 2 of the OSI Model.
Layer 2 of the OSI model is the Data Link Layer. The Data Link Layer consists of two sublayers, the Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sublayer controls how a network node gains access to the data and permission to transmit it.
MAC addresses are globally unique addressed that are written into hardware at the time of manufacture. For this reason, MAC addresses are sometimes called Burned In Addresses (BIA).
After manufacture, it is possible in many cases to change the MAC address of a device in software.
MAC addresses are used by many different Layer 2 technologies, including Ethernet, Token Ring, 802.11, Bluetooth, FDDI, ATM, SCSI, and Fibre Channel.
Because MAC addresses originated in the Ethernet specification, the MAC address is sometimes referred to as the Ethernet Address.
A MAC address is 48 bits long. This means that there are 281,474,976,710,656 possible MAC addresses.
A sample MAC address looks like this:
00-0C-F1-56-98-AD
The first three bytes of this address (00-0C-F1) identify the manufacture of this network device, in this case Intel.
These first three bytes are assigned by the IEEE and the database is available online at IEEE OUI and Company_id Assignments.
The last three bytes of this address were assigned by Intel when they device was manufactured.
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DSL
How do I Change a MAC address
Every Ethernet card has a MAC address burned-in at the factory. At times, you may want to change this MAC address to one of your own choosing.
The procedures to change a MAC address are specific to each operating system
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The procedures to change a MAC address are specific to each operating system
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DSL
Switches and Bridges
Switches vs. Bridges
Another piece of network hardware related to the switch is the Bridge. A Bridge is effectively a two-port switch.
Because there is not much market for a two-port switch, bridges are no longer manufactured.
Posted by: Wasim Javed
Another piece of network hardware related to the switch is the Bridge. A Bridge is effectively a two-port switch.
Because there is not much market for a two-port switch, bridges are no longer manufactured.
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DSL
Switches and Hubs
Switches vs. Hubs
Before switches became available, devices called hubs were common.
Hubs were less intelligent network devices that always copied all frames to all ports.
By only copying frames to the destination ports, switches utilize network bandwidth much more effectively than hubs did.
Posted by: Wasim Javed
Before switches became available, devices called hubs were common.
Hubs were less intelligent network devices that always copied all frames to all ports.
By only copying frames to the destination ports, switches utilize network bandwidth much more effectively than hubs did.
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DSL
DSL Modems and DSLAMS
A DSL circuit exists between the DSL modem on the customer premisis and a DSLAM (Digital Subscriber Line Access Multiplier). The DSLAM is usually located in the telco Central Office (CO).
One DSLAM can terminate several hundred DSL connections.
ISDN
ISDN (Integrated Services Digital Network) is a system of digital phone connections that has been designed for sending voice, video, and data simultaneously over digital or ordinary phone lines, with a much faster speed and higher quality than an analog system can provide. ISDN is basically a set of protocol for making and breaking circuit switched connections as well as for advanced call features for the customers. ISDN is the international communication standard for data transmission along telephone lines and has transmission speeds up to 64 Kbps per channel.
Switch
A switch is a network device with multiple ports in one network whose task is to copy frames from one port to another.
Switches operate at Layer 2 of the OSI Model, the Data-Link Layer. This is in contrast to routers, which operate at Layer 3 of the OSI Model, the Network Layer.
A switch stores the MAC Address of every device which is connected to it.
The switch will then evaluate every frame that passes through it. The switch will examine the destination MAC Address in each frame.
Based upon the destination MAC Address, the switch will then decide which port to copy the frame to.
If the switch does not recognize the MAC Address, it will not know which port to copy the frame to. When that happens, the switch will broadcast the frame to all of its ports.
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One DSLAM can terminate several hundred DSL connections.
ISDN
ISDN (Integrated Services Digital Network) is a system of digital phone connections that has been designed for sending voice, video, and data simultaneously over digital or ordinary phone lines, with a much faster speed and higher quality than an analog system can provide. ISDN is basically a set of protocol for making and breaking circuit switched connections as well as for advanced call features for the customers. ISDN is the international communication standard for data transmission along telephone lines and has transmission speeds up to 64 Kbps per channel.
Switch
A switch is a network device with multiple ports in one network whose task is to copy frames from one port to another.
Switches operate at Layer 2 of the OSI Model, the Data-Link Layer. This is in contrast to routers, which operate at Layer 3 of the OSI Model, the Network Layer.
A switch stores the MAC Address of every device which is connected to it.
The switch will then evaluate every frame that passes through it. The switch will examine the destination MAC Address in each frame.
Based upon the destination MAC Address, the switch will then decide which port to copy the frame to.
If the switch does not recognize the MAC Address, it will not know which port to copy the frame to. When that happens, the switch will broadcast the frame to all of its ports.
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DSL Splitters
Some DSL implementations move data traffic over the same pair of wires which carry voice telephone traffic.
Other DSL implementations move date traffic over a dedicated wire pair.
Most American homes have two pairs of wires from the local telephone company. If the home has only one telephone line in use, DSL can be installed on the second pair.
If the home has both telephone lines in use, DSL must share one wire pair with voice traffic. This is done using a DSL splitter.
A DSL splitter is a small box which attaches to the wire pair and splits it into two separate wire pairs, one for voice traffic and the other for DSL traffic.
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Other DSL implementations move date traffic over a dedicated wire pair.
Most American homes have two pairs of wires from the local telephone company. If the home has only one telephone line in use, DSL can be installed on the second pair.
If the home has both telephone lines in use, DSL must share one wire pair with voice traffic. This is done using a DSL splitter.
A DSL splitter is a small box which attaches to the wire pair and splits it into two separate wire pairs, one for voice traffic and the other for DSL traffic.
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DSL
Types of DSL
ADSL (Asynchronous DSL)
ADSL (Asymmetric DSL) is a type of DSL where the upstream and downstream band widths are assigned different amounts of bandwidth. Typical configurations today are 2Mb downstream and 128Kb upstream.
Downstream refers to data which you are downloading across the network to your local systems. Upstream refers to data you are sending from your local systems across the network.
ADSL is the most common flavor of DSL.
HDSL (High bit-rate DSL)
HDSL (High bit-rate Digital Subscriber Line) is a variant of DSL which is not frequently implemented.
IDSL (ISDN over DSL)
IDSL (ISDN over DSL) is a 144Kb standard for DSL. IDSL is available where other forms of DSL, such as ADSL are not available.
IDSL is slow and relatively expensive, but it can sometimes be the best possible option.
RADSL (Rate-adaptive DSL)
RADSL (Rate Adaptive DSL) is an asymmetric DSL variant which can adjust the speed of the DSL connection depending on the distance from the Central Office (CO) and the quality of the connection.
SDSL (Symmetric DSL)
SDSL (Single line DSL) is a DSL variant where the upstream and downstream are both set to the same bandwidth.
SDSL typically operates at 1.5Mbps upstream and downstream.
SDSL is not nearly as common as ADSL.
VDSL (Very high bit-rate DSL)
VDSL (Very high bit-rate DSL) is an asymmetric version of DSL which operates at very high speeds.
VDSL operates at downstream speeds up to 55Mbps, but only at a distance of up to 1000 feet from the Central Office (CO).
At longer distances, VDSL transmission rates drop dramatically
DSL Lite
DSL Lite is an asymmetric variant of DSL which places the DSL splitter at the telco central office instead of in the customer premisis.
G.SHDSL (Single-pair High-speed DSL)
G.SHDSL (Single-pair high-speed Digital Subscriber Line) is a variant of SDSL which is defined by ITU standard G.991.
G.SHDSL supports symmetric speeds from 192Kbps-2304Kbps on a single line pair and 384Kbps-4608Kbps over two pair.
Europeans refer to G.SHDSL as "SDSL", causing confusion with existing SDSL equipment.
Posted by: Wasim Javed
ADSL (Asymmetric DSL) is a type of DSL where the upstream and downstream band widths are assigned different amounts of bandwidth. Typical configurations today are 2Mb downstream and 128Kb upstream.
Downstream refers to data which you are downloading across the network to your local systems. Upstream refers to data you are sending from your local systems across the network.
ADSL is the most common flavor of DSL.
HDSL (High bit-rate DSL)
HDSL (High bit-rate Digital Subscriber Line) is a variant of DSL which is not frequently implemented.
IDSL (ISDN over DSL)
IDSL (ISDN over DSL) is a 144Kb standard for DSL. IDSL is available where other forms of DSL, such as ADSL are not available.
IDSL is slow and relatively expensive, but it can sometimes be the best possible option.
RADSL (Rate-adaptive DSL)
RADSL (Rate Adaptive DSL) is an asymmetric DSL variant which can adjust the speed of the DSL connection depending on the distance from the Central Office (CO) and the quality of the connection.
SDSL (Symmetric DSL)
SDSL (Single line DSL) is a DSL variant where the upstream and downstream are both set to the same bandwidth.
SDSL typically operates at 1.5Mbps upstream and downstream.
SDSL is not nearly as common as ADSL.
VDSL (Very high bit-rate DSL)
VDSL (Very high bit-rate DSL) is an asymmetric version of DSL which operates at very high speeds.
VDSL operates at downstream speeds up to 55Mbps, but only at a distance of up to 1000 feet from the Central Office (CO).
At longer distances, VDSL transmission rates drop dramatically
DSL Lite
DSL Lite is an asymmetric variant of DSL which places the DSL splitter at the telco central office instead of in the customer premisis.
G.SHDSL (Single-pair High-speed DSL)
G.SHDSL (Single-pair high-speed Digital Subscriber Line) is a variant of SDSL which is defined by ITU standard G.991.
G.SHDSL supports symmetric speeds from 192Kbps-2304Kbps on a single line pair and 384Kbps-4608Kbps over two pair.
Europeans refer to G.SHDSL as "SDSL", causing confusion with existing SDSL equipment.
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Labels:
DSL
DSL
What does DSL mean?
DSL stands for Digital Subscriber Line. It is a term used to describe a range of high-speed (broadband) communications services offered over the Public Switched Telephone Network (PSTN). The PSTN uses a pair of copper wires to connect your telephone service to the national telephony network. DSL technology enables high-speed communications over these same copper lines by making use of the frequencies not used by voice communications - the frequency spectrum (range) between 0kHz and 4kHz is used for your telephone service and 20kHz to 2.2MHz for your DSL (ADSL or ADSL2) service.
Posted by: Wasim Javed
DSL stands for Digital Subscriber Line. It is a term used to describe a range of high-speed (broadband) communications services offered over the Public Switched Telephone Network (PSTN). The PSTN uses a pair of copper wires to connect your telephone service to the national telephony network. DSL technology enables high-speed communications over these same copper lines by making use of the frequencies not used by voice communications - the frequency spectrum (range) between 0kHz and 4kHz is used for your telephone service and 20kHz to 2.2MHz for your DSL (ADSL or ADSL2) service.
Posted by: Wasim Javed
Labels:
DSL
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