Network Bridge
Network Device:Bridge
Ø A network bridge is a networking device that generate a single aggregate network from multiple communication networks or network segments.
Ø
A network
bridge joins two separate networks. This function is
called network bridging.
Ø
The
main function of bridge is to reduce the amount of traffic on LAN by dividing
into two segments (Solving congestion problem)-Two collision domain, Two Parts
Ø It is also used for interconnecting two LANs
working on the same protocol. It has a single input
and single output port, thus
making it a 2-port device.
Ø
Bridges are similar
to — but more intelligent than — simple repeaters,
which also extend signal range.
Ø
A bridge is a
repeater, with add on the functionality of filtering data frame at network boundary by
reading the MAC addresses of source and destination.
Ø
Bridge devices
inspect
incoming network traffic and determine whether to forward or discard the
traffic according to its intended destination.
Ø
An Ethernet bridge, for
example, inspects
each incoming Ethernet frame including the source and destination
MAC addresses — and sometimes the frame size — when it
processes individual forwarding decisions.
Transparent
Bridge
Ø
As
the name suggests, it is an invisible bridge
in the computer network.
Ø
The
main function of this bridge is to block
or forward the data depending on the MAC address.
Ø
The
other devices within the network are unaware
of the existence of bridges.
Ø
Transparent
bridging uses a table (similar to a routing table) called the forwarding
information base to regulate the forwarding
of frames between network segments.
Ø
The
table starts empty and entries are added because
the bridge receives frames.
Ø
If
a destination address entry isn't found within
the table, the frame is flooded to all or any other ports of the bridge, except
the one from which it was received.
Ø
By
means of those flooded frames, a number on the destination
network will respond and a forwarding database
entry are going to be created.
Ø
These
bridges are implemented mainly in Ethernet networks.
Translational
Bridge
Ø A translational bridge plays a key
role in changing a networking system from one type to another.
Ø These bridges are used to
connect two different networks like token ring & Ethernet.
Ø This bridge can add or remove the traffic
based on the traveling direction, and forward
the frames of the data link layer in between
LANs which uses various types of network protocols.
Ø The different network connections
are Ethernet to Token ring otherwise Ethernet
on UTP (unshielded twisted pair) to coaxial Cable
& in between FOC and copper wiring.
Source-route
Bridge
Ø Source-route Bridge is one type of technique used
for Token Ring networks and it
is designed by IBM.
Ø In this bridge, the total frame route is
embedded in one frame. routing operation is performed by source station and the
frame specifies which route to follow (making precise decisions of how the
frame is forwarding using the network.)
Ø The hot can discover frame by
sending a special frame called discovery frame,
which spreads through the entire network using all possible paths to
destination.
Ø By using this method, two
similar network segments are connected to the
data link layer.
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