FRIENDS FIRST WE HAVE TO READ SOME MOST IMPORTANT THEORY TO BECOME A GOOD CISCO CERTIFIED NETWORK ASSOCIATE. SO PLEASE READ IT CAREFULLY.
Network Topology
• Network topology defines the structure of the network.
• physical topology means the actual layout of the wire or media
• logical topology defines how the media is accessed by the hosts for sending data.
Physical Topology
• A bus topology uses a single backbone cable that is terminated at both ends. All the hosts connect directly to this backbone
• A ring topology connects one host to the next and the last host to the first. This creates a physical ring of cable.
• A star topology connects all cables to a central point.
Physical Topology (Contd.)
• An extended star topology links individual stars together by connecting the hubs or switches.
• A hierarchical topology is similar to an extended star. However, instead of linking the hubs or switches together, the system is linked to a computer that controls the traffic on the topology
• A mesh topology is implemented to provide as much protection as possible from interruption of service. For example, each host has its own connections to all other hosts.
Logical Topology
• Broadcast topology
• Each host sends its data to all other hosts on the network medium
• There is no order that the stations must follow to use the network
• It is first come, first serve. Ethernet works this way.
Logical Topology (Contd.)
• Token passing
• An electronic token is passed sequentially to each host
• When a host receives the token, that host can SEND data on the network
• If the host has no data to send, it passes the token to the next host and the process repeats itself
• Examples: Token Ring and Fiber Distributed Data Interface (FDDI), Token Passing in Bus Topology (Arcnet)
Networking Devices
• Equipment that connects directly to a network segment is referred to as a networking device.
• These devices are broken up into two classifications.
v end-user devices
v network devices
End User Devices
• Provide services directly to the user.
• Examples:
computers, printers, scanners, and other devices.
Network Devices
• They connect the end-user devices together to allow them to communicate.
• Examples:
Hub, repeaters, Bridge, Switch,
router etc.
Repeater
• Used to regenerate a signal.
• It regenerates analog or digital signals that are distorted by transmission loss due to attenuation
• Does NOT make intelligent decision concerning forwarding packets like a router or bridge
Hub
• Hubs concentrate connections
• In other words, they take a group of hosts and allow the network to see them as a single unit
• This is done passively, without any other effect on the data transmission
• Active hubs concentrate hosts and also regenerate signals.
Bridge
• Bridges convert network data formats and perform basic data transmission management
• Bridges provide connections between LANs
• Bridges also check data to determine if it should cross the bridge
• This makes each part of the network more efficient.
Switch
• Switches add more intelligence to data transfer management
• They can determine if data should remain on a LAN and transfer data only to the connection that needs it
• Another difference between a bridge and switch is that a switch does NOT convert data transmission formats
Router
• Has all the capabilities listed above
• Can regenerate signals, concentrate multiple connections, convert data transmission formats, and manage data transfers
• They can also connect to a WAN, which allows them to connect LANs that are separated by great distances
• None of the other devices can provide this type of connection
LAN Segmentation with Bridges
LAN Segmentation with Switches
LAN Segmentation with Routers
LAN Segmentation
Segmentation allows network congestion to be significantly reduced within each segment.
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