EXPERIMENT NO 2
The various components used in networking are :-
• Every network architecture has a maximum cable length beyond which signals cannot
• Repeaters are used to reconstruct signal and thus extend the reach of a network.
• When the signal is reconstructed, they are able to reach the maximum length of the
cable, thus reducing the interference of electrical signal.
• Repeaters operate in the physical layers of the OSI model.
• These are analog devices that are connected to two cable segments.
• Repeaters do not understand packets, frames, or headers. They understand volts.
• Repeaters works in co-axial environment.
They are multiport repeaters and also work on physical layer.
• These are devices used to join two or more network segments acting like a repeater
with an added advantage of monitoring address of data packets. In this way, it filters
data packets that don’t need to be sent. This causes a delay in transfer rate, as each
address of the packets has to be monitored.
• In data link layers we find bridges.
• When frames arrive, software in the bridge extracts the destination address from the
header and looks it up in the table to see where to send the frame. For Ethernet this
address is the 48bit destination address. Like a hub, a modern bridge has line cards,
usually for four or eight inputs lines of certain types. A line card for Ethernet cannot
handle token ring frames. But, a bridge may have line card for different network types
and different speeds.
• With a bridge each line is its own collision domain, in contrast to Hub.
• It is similar to bridge in that both route on frame address. It is mostly used to connect
individual computers. If A wants to send a frame to host B, the switch actively
forward the frame from A to B, but bridge cannot. Each switch port goes to single
computer; switch must have space for many more line cards. Each line card provides
buffer space for frames arriving on its port since each port is it’s own collision
domain, switch never lose frames to collisions. However, if frames come in faster
than they can be retransmitted, the switch may run out of buffer space and have to
• To eliminate this problem slightly, modern switches start forwarding frames as soon
as the destination header field has come in. these switches don’t use store-and –
forward switching. This is called cut through switches (CUTS). It is handled entirely
in hardware, but bridge use CPU that did store-and–switching in software. But all the
modern bridges and switches contain special integrated cut for switching; there is
almost no technical difference.
• Router is like intelligent bridge that can be programmed for passing or not passing
either data of a particular nature or to a particular user.
• Router use information within packets to determine the best route through a network
• Router supports multiple alternate paths between locations and can select best path
based on traffic loads, line speeds and cost.
• Some routers are capable of linking dissimilar networks, such as an Ethernet segment
to a token ring network.
• It operates in the network layer.
• When packets come in to a router, the frame header mad trailer area stripped off and
the packet located in the frame’s payload field is passed to the routing software. This
software uses the packet header to choose an output line. The routing software does
not see the frame address and does not even know whether the packet came in LAN
or a point-to-point line.
• Gateways connects between different networks (for example, PC networks in offices
connected to an ISPs network)
• Gateways operate from the transport layer to the application layer of the OSI model.