Chapter 2 : Network components.
Lecture 5
Network interconnection devices
- Network interconnection devices :
1- Repeater.
2- Hub.
3- Bridge.
4- Switch.
5- Router.
Network interconnection devices
1- Repeater:
- A repeater : is a device used in a network to strengthen a
signal as it is passed along the network cable.
- Repeaters can only be used to regenerate signals between
similar network segments.
- A repeater forwards every signal; it has no filtering capability.
- The main disadvantage is that they just amplify signals. These
signals not only include the network signals, but any noise on
the wire as well.
1-Repeater:
Network interconnection devices
2- Hub.
- Hubs are devices used to link several computers together.
- They retransmitted any signal that comes in on one port and
copy it to the other ports (a process that is also called
broadcasting).
- Hubs can be either active or passive.
- An active hub has its own power supply, and regenerates
incoming signals before retransmitting them.
- Passive hubs simply relay the signal without regenerating it.
2- Hub:
Network interconnection devices
3- Switch.
- Switches are devices used to link several computers together.
- A switch uses an internal address table to route incoming data
frames via the port associated with their destination MAC
address.
- Network switches are capable of inspecting data packets as
they are received, determining the source and destination
device of that packet, and forwarding it appropriately by
delivering each message only to the connected device it was
intended for.
- A switch offers generally better performance than a hub.
3- Switch.
Network interconnection devices
4- Bridge.
- A bridge is a device that used to create a connection between
network segments.
- Sometimes it is necessary to divide network into subnets to
reduce the amount of traffic on a network. Once divided, the
bridge connects the two subnets and manages the traffic flow
between them.
-A bridge monitors the information traffic on both sides of the
network so that it can pass packets of information to the
correct location.
Network interconnection devices
- When the bridge first becomes operational, the routing table is
blank, but as data is transmitted back and forth, the bridge
adds the source MAC address of any incoming frame to the
routing table and associates the address with the port on
which the frame arrives. In this way, the bridge quickly builds
up a complete picture of the network topology.
- If the bridge does not know the destination segment for an
incoming frame, it will forward the frame to all attached
segments except the segment on which the frame was
transmitted.
4- Bridge.
4- Bridge.
Network interconnection devices
5- Router.
- Routers are highly intelligent devices that connect multiple
network types and determine the best path for sending data.
- Like bridges, they can segment large networks and can filter out
noise.
- Routers are network devices that literally route data around
the network. By examining data as it arrives, the router can
determine the destination address for the data; then, by using
tables of defined routes, the router determines the best way
for the data to continue its journey.
Network interconnection devices
- Routers are normally used to connect one LAN to another.
- Typically, when a WAN is set up, there will be at least two
routers used.
** Basic concepts :
Unicast:
Is the process of sending information from one computer to one
computer only.
Multicast:
Is the process of sending information from one computer to
some devices.
Broadcast:
Is the process of sending information from one computer to all
devices.