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CONNECTING DEVICES 9.3 - Coggle Diagram
CONNECTING DEVICES 9.3
definition
Connecting devices can be divided into five categories
based on the layer in which they operate in a network.
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passive hubs
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In a star topology Ethernet LAN, a passive hub is just a point where the signals coming from different stations collide; the hub is the collision point.
repeaters
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A repeater receives a signal and, before it becomes too weak or corrupted, regenerates the original bit pattern.
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A repeater must be placed so that a signal reaches it before any noise changes the meaning of any of its bits.
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active hubs
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Used to createconnections between stations in a physical star topology.EG: used in some Ethernet implementations, 10BaseT.
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bridges
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Physical layer - it regenerates the signal it receives;
data link layer - checl the physical (MAC) addresses ( source and destination) containe in the frame.
filtering
A bridge has filtering capability - can check the destination address of a frame and decide if the frame should be forwarded or dropped.
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transparent bridges
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If a bridge is added or deleted from the system , reconiguration of the stations is unnecessary.
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a dynamic table
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The destination address- for forwarding decision ; the source address - for adding entries to the table and for updating purposes
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two-layer switches
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A two-layer switch - a abridge with many ports and a design that allows better ( faster ) performance .
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routers
A router - a three layer device that routes packets based on their logical addresses ( host-to-host addressing).
A router normally connects LANs and WANs in the Internet and has a routing table that is used for making decisions about the route.
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gateway
A gateway normally a computer that operates in all five layers of the Internet or seven layers of OSI model.
A gateway takes an application message , reads it, and interprets it - can be used as a connectting device between two internetworks that use different models.
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backbone networks
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In a backbone network, no station is directly connected to the backbone ; the stations are part of LAN, and the backbone connects the LANs.
The backbone is itself a LAN that uses a LAN protocol such as Ethernet ; each connection to the backbone is itself another LAN.
virtual LANs
A virtual local area network (VLAN) is a local area network configured by software, not by physical wiring.
The idea of VLAN technology is to divide a LAN into logical , instead of physical , segments.
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VLANs create domains - VLANs group stations belonging to one or more physical LANs into broadcast domains.
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