Basic information about network devices.

1. Network Devices
By Rahul Kushwaha

2. Hubs
• Intelligent hubs have console ports, to
allow monitoring of the hubs status and
port activity.
• Passive hubs just repeat any incoming
signals to every port available, therefore
does not act as a line repeater.
• Passive hubs just split signals to multiple
ports but do not regenerate the signals,
which means that they do not extend a
cable’s length. They only allow two or
more hosts to connect to the same cable
segment.
• Active hubs regenerate signals.
• Hubs utilise star topology.

3. Hub Pros & Cons
Disadvantages
• Bandwidth is shared by all hosts i.e. 10Mbs shared by 25 ports/users.
• Can create bottlenecks when used with switches.
• Have no layer 3 switching capability.
• Most Hubs are unable to utilise VLANS.
Advantages
• As an active hubs regenerate signals, it increases the distance that can be
spanned by the LAN (up to 100 meters per segment).
• Hubs can also be connected locally to a maximum of two other hubs, thereby
increasing the number of devices that can be attached to the LAN.
• Active hubs are usually used against attenuation, which is a decrease in the
strength of the signal over distance.

4. Switches
• A switch is a multi-port bridge.
• It operates at OSI data link layer 2.
• It stores MAC addresses in an
internal lookup table.
• Temporary switched paths are
created between the frame’s source
destination.
• Some Switches have limited layer 3
IP routing capabilities.
• Switches can be configured to use
VLANS.
• Switches support spanning tree
protocol to create resilient
networks.

5. Example Topology
Switch
Hub
UTP
10Mbs
Fibre
100Mbs

6. Transceiver Modules
• Connects to any Auxiliary Unit
Interface port (AUI).
• Operates at OSI layer 1.
• Allows multiple media types to
connect to an Ethernet device. i.e.
fibre ST/SC,Co-ax cable, and UTP.
UTP
Co-axial

7. Routers
• Routers are OSI network layer 3
devices
• Using interface modules can
connect different layer 2
technologies e.g. Ethernet, FDDI,
token ring etc…
• Routers have the capability to
interconnect network segments or
entire networks (WANS/MANS).
• These devices examine incoming
packets to determine the
destination address of the data. It
then examines its internal routing
table to choose the best path for
the packet through the network,
and switches them to the proper
outgoing port.

8. Example Router Topology

9. THE END!!