Showing posts with label Computer Networking. Show all posts
Showing posts with label Computer Networking. Show all posts
Thursday, October 1, 2015
Cisco Wireless LAN Controller Configuration Guide PDF Ebook
This chapter describes the controller components and features. It contains these sections:
•Cisco Unified Wireless Network Solution Overview.
•Operating System Software.
•Operating System Security.
•Layer 2 and Layer 3 Operation.
•Cisco Wireless LAN Controllers.
•Controller Platforms.
•Cisco UWN Solution Wired Connections.
•Cisco UWN Solution WLANs.
•File Transfers,.
•Power Over Ethernet.
•Cisco Wireless LAN Controller Memory.
•Cisco Wireless LAN Controller Failover Protection.
•Network Connections to Cisco Wireless LAN Controllers.
Cisco Wireless LAN Controller Configuration Guide Ebook
Wednesday, September 16, 2015
Cisco CCNA VTP - VLAN Trunking Protocol
On Cisco Devices, VTP (VLAN Trunking Protocol) maintains VLAN configuration consistency across the entire network. VTP uses Layer 2 trunk frames to manage the addition, deletion, and renaming of VLANs on a network-wide basis from a centralized switch in the VTP server mode. VTP is responsible for synchronizing VLAN information within a VTP domain and reduces the need to configure the same VLAN information on each switch.
VTP minimizes the possible configuration inconsistencies that arise when changes are made. These inconsistencies can result in security violations, because VLANs can cross connect when duplicate names are used. They also could become internally disconnected when they are mapped from one LAN type to another, for example, Ethernet to ATM LANE ELANs or FDDI 802.10 VLANs. VTP provides a mapping scheme that enables seamless trunking within a network employing mixed-media technologies.
Cisco CCNA VTP - VLAN Trunking Protocol pkt Sample
How to calculate wildcard mask? [Easy Way]
Some students of Computer Networking especially those appearing in Certification exams such as Cisco Certification Exams or Juniper Certification Exams have problem in calculating wildcard mask. Some know the concept but their method is difficult that might result in wastage of time which may prove to be a problem in certification exams. Also, the wildcard mask is used in extensively in Access Control Lists (ACLs), EIGRP and OSPF, so learning how to calculate wildcard mask is important. We have decided to share a very simple method to calculate the wildcard mask efficiently and hopefully you will not have any ‘how to calculate wildcard mask?’ afterwards.
The method is: first calculate the subnet mask for the network for which you want to find the wildcard mask. Then subtract that subnet mask from 255.255.255.255
An example will explain this method more efficiently. Consider you have a network of 172.16.1.0/24 and you want to calculate the wildcard mask for it. We know that the subnet mask for this network is 255.255.255.0 Now we subtract this subnet mask from 255.255.255.255 as follow:
255.255.255.255
– 255.255.255.0
————————
0.0.0.255
As you can see, 0.0.0.255 is our required wildcard mask. Using this method we can find any wildcard mask easily.
Take another example, if you have network address of 172.16.0.0/20. We know that the subnet mask for this network address is 255.255.240.0
Using the above mentioned method, wildcard mask is:
255.255.255.255
– 255.255.240.0
————————
0.0.15.255
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Fiber Optic Network
In the telcos, singlemode fiber is used to connect long distance switches, central offices and SLCs (subscriber loop carriers, small switches in pedestals in subdivisions or office parks or in the basement of a larger building). Practically every telco's network is now fiber optics except the connection to the home. Fiber to the home is not yet cost effective - especially since most homes do not want (nor are willing to pay) for the high speed services that would justify fiber optics.
CATV companies "overbuild" with fiber. They lash fiber cable onto the aerial "hardline" coax used for the rest of the network or pull it in the same conduit underground. The fiber allows them to break their network into smaller service areas that prevent large numbers of customers from being affected in an outage, making for better service and customer relations. The fiber also gives them a return path which they use for Internet and telephone connections, increasing their revenue potential.
LANs (local area networks) use fiber optics primarily in the backbone but increasingly to the desk. The LAN backbone often needs longer distance than copper cable (Cat 5/5e/6) can provide and of course, the fiber offers higher bandwidth for future expansion. Most large corporate LANs use fiber backbones with copper wire to the desktop. Fiber to the desk can be cost effective if properly designed.
Lots of other networks use fiber. CCTV is often on fiber for it's distance capability. Industrial plants use lots of fiber or distance and noise immunity. Utilities use it for network management, liking its immunity to noise also. The military uses it because it's hard to tap or jam. Airplanes use it for that reason too, but also like the lighter weight of fiber.
Designing Cable Networks
Industrial Networks
Centralized Fiber LANs
CATV companies "overbuild" with fiber. They lash fiber cable onto the aerial "hardline" coax used for the rest of the network or pull it in the same conduit underground. The fiber allows them to break their network into smaller service areas that prevent large numbers of customers from being affected in an outage, making for better service and customer relations. The fiber also gives them a return path which they use for Internet and telephone connections, increasing their revenue potential.
LANs (local area networks) use fiber optics primarily in the backbone but increasingly to the desk. The LAN backbone often needs longer distance than copper cable (Cat 5/5e/6) can provide and of course, the fiber offers higher bandwidth for future expansion. Most large corporate LANs use fiber backbones with copper wire to the desktop. Fiber to the desk can be cost effective if properly designed.
Lots of other networks use fiber. CCTV is often on fiber for it's distance capability. Industrial plants use lots of fiber or distance and noise immunity. Utilities use it for network management, liking its immunity to noise also. The military uses it because it's hard to tap or jam. Airplanes use it for that reason too, but also like the lighter weight of fiber.
Designing Cable Networks
I guess this is too big a topic for a overview! But we'll pass along some hints to make life easier. First and foremost, visit the work site and check it out thoroughly. Know the "standards" but use common sense in designing the installation. Don't cut corners which may affect performance or reliability. Consider what are the possible problems and work around or prevent them. There ain't no substitute for common sense here!
Fiber's extra distance capability makes it possible to do things not possible with copper wire. For example, you can install all the electronics for a network in one communications closet for a building and run straight to the desktop with fiber. With copper, you can only go about 90 meters (less than 300 feet), so you need to keep the electronics close to the desk. With fiber, you only need passive patch panels locally to allow for moves. Upgrades are easy, since the fiber is only loafing at today's network speed!
Is Copper Really Cheaper Than Fiber?
Fiber's extra distance capability makes it possible to do things not possible with copper wire. For example, you can install all the electronics for a network in one communications closet for a building and run straight to the desktop with fiber. With copper, you can only go about 90 meters (less than 300 feet), so you need to keep the electronics close to the desk. With fiber, you only need passive patch panels locally to allow for moves. Upgrades are easy, since the fiber is only loafing at today's network speed!
Is Copper Really Cheaper Than Fiber?
When it comes to costs, fiber optics is always assumed to be much more expensive than copper cabling. Whatever you look at - cable, terminations or networking electronics - fiber costs more, although as copper gets faster (e.g. Cat 6) it gets more expensive, almost as much as fiber. So isn't it obvious that fiber networks are more expensive than copper? Maybe not! There is more to consider in making the decision.
Why Use Fiber?
Why Use Fiber?
If fiber is more expensive, why have all the telephone networks been converted to fiber? And why are all the CATV systems converting to fiber too? Are their networks that different? Is there something they know we don't? Telcos use fiber to connect all their central offices and long distance switches because it has thousands of times the bandwidth of copper wire and can carry signals hundreds of times further before needing a repeater. The CATV companies use fiber because it give them greater reliability and the opportunity to offer new services, like phone service and Internet connections. Both telcos and CATV operators use fiber for economic reasons, but their cost justification requires adopting new network architectures to take advantage of fiber's strengths. A properly designed premises cabling network can also be less expensive when done in fiber instead of copper. There are several good examples of fiber being less expensive, so lets examine them.
Industrial Networks
In an industrial environment, electromagnetic interference (EMI) is often a big problem. Motors, relays, welders and other industrial equipment generate a tremendous amount of electrical noise that can cause major problems with copper cabling, especially unshielded cable like Cat 5. In order to run copper cable in an industrial environment, it is often necessary to pull it through conduit to provide adequate shielding. With fiber optics, you have complete immunity to EMI. You only need to choose a cable type that is rugged enough for the installation, with breakout cable being a good choice for it's heavy-duty construction. The fiber optic cable can be installed easily from point to point, passing right next to major sources of EMI with no effect. Conversion from copper networks is easy with media converters, gadgets that convert most types of systems to fiber optics. Even with the cost of the media converters, the fiber optic network will be less than copper run in conduit.
Long Cable Runs
Long Cable Runs
Most networks are designed around structured cabling installed per EIA/TIA 568 standards. This standard calls for 90 meters (295 feet) of permanently installed unshielded twisted pair (UTP) cable and 10 meters (33 feet) of patchcords. But suppose you need to connect two buildings or more? The distance often exceeds the 90 meters by the time you include the runs between the buildings plus what you need inside each building. By the time you buy special aerial or underground waterproof copper cable and repeaters, you will usually spend more than if you bought some outside plant fiber optic cable and a couple of inexpensive media converters. It's guaranteed cheaper if you go more than two links (180 meters.)
Centralized Fiber LANs
When most contractors and end users look at fiber optics versus Cat 5e cabling for a LAN, they compare the same old copper LAN with fiber directly replacing the copper links. The fiber optic cable is a bit more expensive than Cat 5e and terminations are a little more too, but the big difference is the electronics which are $200 or more per link extra for fiber. However, the real difference comes if you use a centralized fiber optic network - shown on the right of the diagram above. Since fiber does not have the 90 meter distance limitation of UTP cable, you can place all electronics in one location in or near the computer room. The telecom closet is only used for passive connection of backbone fiber optic cables, so no power, UPS, ground or air conditioning is needed. These auxiliary services, necessary with Cat 5 hubs, cost a tremendous amount of money in each closet. In addition, having all the fiber optic hubs in one location means better utilization of the hardware, with fewer unused ports. Since ports in modular hubs must be added in modules of 8 or 16, it's not uncommon with a hub in a telecom closet to have many of the ports in a module empty . With a centralized fiber system, you can add modules more efficiently as you are supporting many more desktop locations but need never have more than a one module with open ports.
High Speed Networking
High Speed Networking
It was over a year after Gigabit Ethernet (GbE) became available on fiber optics that it finally become available on Cat 5e. It took another couple of years before GbE on copper became significantly less expensive. In order to get GbE to work over Cat 5e, the electronics must be very complicated, and consequently as expensive as fiber. A newer version is in the wings, awaiting a Cat 6 standard, but that means the version running over Cat 5e will be obsolete before it even gets started! Finally, we went to a major distributor's seminar on advanced cabling recently and the copper marketing guy told us to go fiber for GbE.
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Graphical Network Simulator 3 With IOS Download
Graphical Network Simulator-3 is a software emulator for networks. It allows the combination of virtual devices and real devices, and so can be used to simulate complex networks. It uses Dynamips emulation software to simulate Cisco IOS
Transmission Media in Computer Networks
It is the transmission media in which signals are confined to a specific path using wire or cable.
A. Twisted Pair Cable
Twisted Pair is of two types :
1. Unshielded Twisted Pair Cable
It is the most common type of telecommunication when compared with Shielded Twisted Pair Cable which consists of two conductors usually copper, each with its own colour plastic insulator. Identification is the reason behind coloured plastic insulation.
UTP cables consist of 2 or 4 pairs of twisted cable. Cable with 2 pair use RJ-11 connector and 4 pair cable useRJ-45 connector.
Advantages :
It consists of two insulating copper wires (1mm thick). The wires are twisted together in a helical form to reduce electrical interference from similar pair.
Disadvantages :
2. Shielded Twisted Pair Cable
This cable has a metal foil or braided-mesh covering which encases each pair of insulated conductors. Electromagnetic noise penetration is prevented by metal casing. Shielding also eliminates crosstalk (explained in KEY TERMS Chapter).
It has same attenuation as unshielded twisted pair. It is faster the unshielded and coaxial cable. It is more expensive than coaxial and unshielded twisted pair.
Advantages :
B. Coaxial Cable
Coaxial is called by this name because it contains two conductors that are parallel to each other. Copper is used in this as centre conductor which can be a solid wire or a standard one. It is surrounded by PVC installation, a sheath which is encased in an outer conductor of metal foil, barid or both.
Outer metallic wrapping is used as a shield against noise and as the second conductor which completes the circuit. The outer conductor is also encased in an insulating sheath. The outermost part is the plastic cover which protects the whole cable.
Here the most common coaxial standards.
There are two types of Coaxial cables :
1. BaseBand
This is a 50 ohm (Ω) coaxial cable which is used for digital transmission. It is mostly used for LAN’s. Baseband transmits a single signal at a time with very high speed. The major drawback is that it needs amplification after every 1000 feet.
2. BroadBand
This uses analog transmission on standard cable television cabling. It transmits several simultaneous signal using different frequencies. It covers large area when compared with Baseband Coaxial Cable.
Advantages :
C. Fiber Optic Cable
These are similar to coaxial cable. It uses electric signals to transmit data. At the centre is the glass core through which light propagates.
Advantages :
This cable is the most commonly used and is cheaper than others. It is lightweight, cheap, can be installed easily, and they support many different types of network. Some important points :
Its frequency range is 0 to 3.5 kHz.
Typical attenuation is 0.2 dB/Km @ 1kHz.
Typical delay is 50 µs/km.
Repeater spacing is 2km.
Its frequency range is 0 to 3.5 kHz.
Typical attenuation is 0.2 dB/Km @ 1kHz.
Typical delay is 50 µs/km.
Repeater spacing is 2km.
Twisted Pair is of two types :
- Unshielded Twisted Pair (UTP)
- Shielded Twisted Pair (STP)
1. Unshielded Twisted Pair Cable
It is the most common type of telecommunication when compared with Shielded Twisted Pair Cable which consists of two conductors usually copper, each with its own colour plastic insulator. Identification is the reason behind coloured plastic insulation.
UTP cables consist of 2 or 4 pairs of twisted cable. Cable with 2 pair use RJ-11 connector and 4 pair cable useRJ-45 connector.
Advantages :
- Installation is easy
- Flexible
- Cheap
- It has high speed capacity,
- 100 meter limit
- Higher grades of UTP are used in LAN technologies like Ethernet.
It consists of two insulating copper wires (1mm thick). The wires are twisted together in a helical form to reduce electrical interference from similar pair.
Disadvantages :
- Bandwidth is low when compared with Coaxial Cable
- Provides less protection from interference.
2. Shielded Twisted Pair Cable
This cable has a metal foil or braided-mesh covering which encases each pair of insulated conductors. Electromagnetic noise penetration is prevented by metal casing. Shielding also eliminates crosstalk (explained in KEY TERMS Chapter).
It has same attenuation as unshielded twisted pair. It is faster the unshielded and coaxial cable. It is more expensive than coaxial and unshielded twisted pair.
Advantages :
- Easy to install
- Performance is adequate
- Can be used for Analog or Digital transmission
- Increases the signalling rate
- Higher capacity than unshielded twisted pair
- Eliminates crosstalk
Disadvantages :
- Difficult to manufacture
- Heavy
B. Coaxial Cable
Coaxial is called by this name because it contains two conductors that are parallel to each other. Copper is used in this as centre conductor which can be a solid wire or a standard one. It is surrounded by PVC installation, a sheath which is encased in an outer conductor of metal foil, barid or both.
Outer metallic wrapping is used as a shield against noise and as the second conductor which completes the circuit. The outer conductor is also encased in an insulating sheath. The outermost part is the plastic cover which protects the whole cable.
Here the most common coaxial standards.
- 50-Ohm RG-7 or RG-11 : used with thick Ethernet.
- 50-Ohm RG-58 : used with thin Ethernet
- 75-Ohm RG-59 : used with cable television
- 93-Ohm RG-62 : used with ARCNET.
There are two types of Coaxial cables :
1. BaseBand
This is a 50 ohm (Ω) coaxial cable which is used for digital transmission. It is mostly used for LAN’s. Baseband transmits a single signal at a time with very high speed. The major drawback is that it needs amplification after every 1000 feet.
2. BroadBand
This uses analog transmission on standard cable television cabling. It transmits several simultaneous signal using different frequencies. It covers large area when compared with Baseband Coaxial Cable.
- Bandwidth is high
- Used in long distance telephone lines.
- Transmits digital signals at a very high rate of 10Mbps.
- Much higher noise immunity
- Data transmission without distortion.
- The can span to longer distance at higher speeds as they have better shielding when compared to twisted pair cable
Disadvantages :
- Single cable failure can fail the entire network.
- Difficult to install and expensive when compared with twisted pair.
- If the shield is imperfect, it can lead to grounded loop.
C. Fiber Optic Cable
These are similar to coaxial cable. It uses electric signals to transmit data. At the centre is the glass core through which light propagates.
In multimode fibres, the core is 50microns, and In single mode fibres, the thickness is 8 to 10 microns.
The core in fiber optic cable is surrounded by glass cladding with lower index of refraction as compared to core to keep all the light in core. This is covered with a thin plastic jacket to protect the cladding. The fibers are grouped together in bundles protected by an outer shield.
Fiber optic cable has bandwidth more than 2 gbps (Gigabytes per Second)
The core in fiber optic cable is surrounded by glass cladding with lower index of refraction as compared to core to keep all the light in core. This is covered with a thin plastic jacket to protect the cladding. The fibers are grouped together in bundles protected by an outer shield.
Fiber optic cable has bandwidth more than 2 gbps (Gigabytes per Second)
Advantages :
- Provides high quality transmission of signals at very high speed.
- These are not affected by electromagnetic interference, so noise and distortion is very less.
- Used for both analog and digital signals.
- It is expensive
- Difficult to install.
- Maintenance is expensive and difficult.
- Do not allow complete routing of light signals.
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Transmission Modes in Computer Networks
Transmission mode means transferring of data between two devices. It is also called communication mode. These modes direct the direction of flow of information. There are three types of transmission mode. They are :
1. SIMPLEX Mode
In this type of transmission mode data can be sent only through one direction i.e. communication is unidirectional. We cannot send a message back to the sender. Unidirectional communication is done in Simplex Systems.
Examples of simplex Mode is loudspeaker, television broadcasting, television and remote, keyboard and monitor etc.
2. HALF DUPLEX Mode
In half duplex system we can send data in both directions but it is done one at a time that is when the sender is sending the data then at that time we can’t send the sender our message. The data is sent in one direction.
Example of half duplex is a walkie- talkie in which message is sent one at a time and messages are sent in both the directions.
3. FULL DUPLEX Mode
In full duplex system we can send data in both directions as it is bidirectional. Data can be sent in both directions simultaneously. We can send as well as we receive the data.
Example of Full Duplex is a Telephone Network in which there is communication between two persons by a telephone line, through which both can talk and listen at the same time.
In full duplex system there can be two lines one for sending the data and the other for receiving data.
- Simplex Mode
- Half duplex Mode
- Full duplex Mode
1. SIMPLEX Mode
In this type of transmission mode data can be sent only through one direction i.e. communication is unidirectional. We cannot send a message back to the sender. Unidirectional communication is done in Simplex Systems.
Examples of simplex Mode is loudspeaker, television broadcasting, television and remote, keyboard and monitor etc.
2. HALF DUPLEX Mode
In half duplex system we can send data in both directions but it is done one at a time that is when the sender is sending the data then at that time we can’t send the sender our message. The data is sent in one direction.
Example of half duplex is a walkie- talkie in which message is sent one at a time and messages are sent in both the directions.
3. FULL DUPLEX Mode
In full duplex system we can send data in both directions as it is bidirectional. Data can be sent in both directions simultaneously. We can send as well as we receive the data.
Example of Full Duplex is a Telephone Network in which there is communication between two persons by a telephone line, through which both can talk and listen at the same time.
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What is a Default Routing
A Default Route (also known as the gateway of last resort) is a special type of static route. Where a static route specifies a path a router should use to reach a specific destination, a default route specifies a path the router should use if it doesn’t know how to reach the destination.
Default Route is the network route used by a router when there is no other known route exists for a given IP datagram's destination address. All the IP datagrams with unknown destination address are sent to the default route.
How to configure Default Routes Watch This Video
Default Route is the network route used by a router when there is no other known route exists for a given IP datagram's destination address. All the IP datagrams with unknown destination address are sent to the default route.
Default Routing pkt file download Click Here
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Network Topology
Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer network. Essentially, it is thetopological structure of a network and may be depicted physically or logically.
Types of Network Topology
1. BUS Topology
Bus topology is a network type in where every computer and network device is connected to single cable.
2. RING Topology
It is called ring topology because it forms a ring as each computer is connected to another computer, with the last one connected to the first. Exactly two neighbours for each device.
Features of Ring Topology
3. STAR Topology
In this type of topology all the computers are connected to a single hub through a cable. This hub is the central node and all others nodes are connected to the central node.
Features of Star Topology
4. MESH Topology
It is a point-to-point connection to other nodes or devices. Traffic is carried only between two devices or nodes to which it is connected. Mesh has n (n-2)/2 physical channels to link hn devices.
Types of Mesh Topology
1. Partial Mesh Topology : In this topology some of the systems are connected in the same fashion as mesh topology but some devices are only connected to two or three devices.
2. Full Mesh Topology : Each and every nodes or devices are connected to each other.
5. TREE Topology
It has a root node and all other nodes are connected to it forming a hierarchy. It is also called hierarchical topology. It should at least have three levels to the hierarchy.
Features of Tree Topology
6. HYBRID Topology
It is two different types of topologies which is a mixture of two or more topologies. For example if in an office in one department ring topology is used and in another star topology is used, connecting these topologies will result in Hybrid Topology (ring topology and star topology).
Features of Hybrid Topology
1. BUS Topology
Bus topology is a network type in where every computer and network device is connected to single cable.
Features of Bus Topology
- It transmits data only in one direction.
- Every device is connected to a single cable
Advantages of Bus Topology
- It is cost effective.
- Cable required is least compared to other network topology.
- Used in small networks.
- It is easy to understand.
- Easy to expand joining two cables together.
Disadvantages of Bus Topology
- Cables fails then whole network fails.
- If network traffic is heavy or nodes are more the performance of the network decreases.
- Cable has a limited length.
- It is slower than the ring topology.
2. RING Topology
It is called ring topology because it forms a ring as each computer is connected to another computer, with the last one connected to the first. Exactly two neighbours for each device.
Features of Ring Topology
- A number of repeaters are used and the transmission is unidirectional.
- Date is transferred in a sequential manner that is bit by bit.
Advantages of Ring Topology
- Transmitting network is not affected by high traffic or by adding more nodes, as only the nodes having tokens can transmit data.
- Cheap to install and expand
Disadvantages of Ring Topology
- Troubleshooting is difficult in ring topology.
- Adding or deleting the computers disturbs the network activity.
- Failure of one computer disturbs the whole network.
3. STAR Topology
In this type of topology all the computers are connected to a single hub through a cable. This hub is the central node and all others nodes are connected to the central node.
Features of Star Topology
- Every node has its own dedicated connection to the hub.
- Acts as a repeater for data flow.
- Can be used with twisted pair, Optical Fibre or coaxial cable.
Advantages of Star Topology
- Fast performance with few nodes and low network traffic.
- Hub can be upgraded easily.
- Easy to troubleshoot.
- Easy to setup and modify.
- Only that node is affected which has failed rest of the nodes can work smoothly.
Disadvantages of Star Topology
- Cost of installation is high.
- Expensive to use.
- If the hub is affected then the whole network is stopped because all the nodes depend on the hub.
- Performance is based on the hub that is it depends on its capacity
It is a point-to-point connection to other nodes or devices. Traffic is carried only between two devices or nodes to which it is connected. Mesh has n (n-2)/2 physical channels to link hn devices.
Types of Mesh Topology
1. Partial Mesh Topology : In this topology some of the systems are connected in the same fashion as mesh topology but some devices are only connected to two or three devices.
2. Full Mesh Topology : Each and every nodes or devices are connected to each other.
Features of Mesh Topology
- Fully connected.
- Robust.
- Not flexible.
Advantages of Mesh Topology
- Each connection can carry its own data load.
- It is robust.
- Fault is diagnosed easily.
- Provides security and privacy.
Disadvantages of Mesh Topology
- Installation and configuration is difficult.
- Cabling cost is more.
- Bulk wiring is required.
5. TREE Topology
It has a root node and all other nodes are connected to it forming a hierarchy. It is also called hierarchical topology. It should at least have three levels to the hierarchy.
Features of Tree Topology
- Ideal if workstations are located in groups.
- Used in Wide Area Network.
Advantages of Tree Topology
- Extension of bus and star topologies.
- Expansion of nodes is possible and easy.
- Easily managed and maintained.
- Error detection is easily done.
Disadvantages of Tree Topology
- Heavily cabled.
- Costly.
- If more nodes are added maintenance is difficult.
- Central hub fails, network fails.
6. HYBRID Topology
It is two different types of topologies which is a mixture of two or more topologies. For example if in an office in one department ring topology is used and in another star topology is used, connecting these topologies will result in Hybrid Topology (ring topology and star topology).
Features of Hybrid Topology
- It is a combination of two or topologies
- Inherits the advantages and disadvantages of the topologies included
Advantages of Hybrid Topology
- Reliable as Error detecting and trouble shooting is easy.
- Effective.
- Scalable as size can be increased easily.
- Flexible.
Disadvantages of Hybrid Topology
- Complex in design.
- Costly.
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Classless Inter-Domain Routing (CIDR)
CIDR (Classless Inter-Domain Routing, sometimes known as supernetting) is a way to allocate and specify the Internet addresses used in inter-domain routing more flexibly than with the original system of Internet Protocol (IP) address classes. As a result, the number of available Internet addresses has been greatly increased. CIDR is now the routing system used by virtually all gateway hosts on the Internet's backbone network. The Internet's regulating authorities now expect every Internet service provider (ISP) to use it for routing.
Using CIDR, each IP address has a network prefix that identifies either an aggregation of network gateways or an individual gateway. The length of the network prefix is also specified as part of the IP address and varies depending on the number of bits that are needed (rather than any arbitrary class assignment structure). A destination IP address or route that describes many possible destinations has a shorter prefix and is said to be less specific. A longer prefix describes a destination gateway more specifically. Routers are required to use the most specific or longest network prefix in the routing table when forwarding packets.
CIDR is supported by the Border Gateway Protocol, the prevailing exterior (interdomain) gateway protocol. (The older exterior or interdomain gateway protocols, Exterior Gateway Protocol and Routing Information Protocol, do not support CIDR.) CIDR is also supported by the OSPF interior or intradomain gateway protocol.
Classless Inter-Domain Routing examples
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How to setup Dlink wifi Router in Hindi
DLink wifi Router Setup Video Series in Hindi Shows How to setup D-link wifi router.
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Windows 7 Printer Sharing
Printer Sharing in Windows 7 in hindi by Jagvinder Thind Shows How to add a network printer using Windows 7 or How To Connect Your Printer To Your Network.
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Computer Knowledge
How To Use Network Cable Tester
Network Cable Tester :
Not sure what the network problem? Costly alternative before buying a router or cable modem, test your cables! Wires are broken (and the cables around the house that you know how to slip) if the tester will detect it. If you have your own patch cables and wires are properly assigned to the case if you want to test, you need to! Your twisted pair, Straight, Crossover RJ-11, RJ-45 connectors, CAT 5 / Cat 5E / Cat 6 cable / UTP test. Insert the battery, turn on the tester and the remote end of the main part of the other end connected to one end of the light cable wire (if present) indicates that there is a problem. Very useful item for the networking enthusiast!SHARE BY GK
Computer Knowledge
Cisco CCNA Routing Metrics
This Video in Hindi by Jagvinder Thind Explains What is Routing Metrics. CCNA Training Video. Metrics is a property of a route in computer networking, consisting of any value used by a routing protocol to determine whether one particular route should be chosen over another. CCNA 200-120
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Computer Knowledge
Ethernet
Ethernet is a family of computer networking technologies for local area networks (LANs) and metropolitan area networks (MANs). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3, and has since been refined to support higher bit rates and longer link distances. Over time, Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI, and ARCNET. The primary alternative for contemporary LANs is not a wired standard, but instead a wireless LAN standardized as IEEE 802.11 and also known as Wi-Fi.
The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet. The original 10BASE5 Ethernet used coaxial cable as a shared medium. Later the coaxial cables were replaced with twisted pair and fiber optic links in conjunction with hubs or switches. Over the course of its history, Ethernet data transfer rates have been increased from the original 3 megabits per second (Mbit/s) to the latest 100 gigabits per second (Gbit/s), with 400 Gbit/s expected by early 2017.
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This Video Series in Hindi explains Basics of IP Address, IP Addressing, Subnet, Subnetting and VLSM in Hindi. VLSM is important topic in Cisco CCNA CCNP Exam
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Networking Devices Repeaters, Hubs, Bridges, Switches working in Hindi
All Videos Networking Devices Repeaters, Hubs, Bridges, Switches working in Hindi
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