The document discusses concepts related to network bridging, detailing how bridges connect different LANs and operate at both the physical and data link layers. It covers types of bridges including Ethernet, Wi-Fi, and power line bridges, along with their functions, advantages, and disadvantages. The document concludes by highlighting the increasing awareness of network bridging and its importance in future secure network communication.

1. BRIDGE
PRESENTED BY-
Jagrata Das(Roll No-18),
Kaushik Jha (Roll No.-19),
Madhushree Ghosh(Roll No.-20),
Mrinmoyee Rana(Roll No.-21)
OF B-TECH(IT), 3RD YR, 6TH SEMESTER

2. CONTENTS
• INTRODUCTION
• BRIDGES
• HOW BRIDGE WORK
• CHARECTERISTIC OF BRIDGING
• TYPES OF BRIDGING
• ADVANTAGE AND DISADVANTAGE
• WHAT IS ETHERNET BRIDGE
• TYPE OF ETHERNET BRIDGE
• FUNCTION OF ETHERNET BRIDGE
• ROUTER VS BRIDGE
• BROUTER

3. INTRODUCTION
• In telecommunication networks, a bridge is a
product that connects a local area network
(LAN) to another local area network.
• Operates in both the PHYSICAL and the
DATALINK layer.
• A bridge has a table used in filtering
decisions.
• A bridge has a table that maps address to
ports.
• Passing messages known to be within the
same LAN.
• Forwarding messages known to be on the
other interconnected LANs.

4. BRIDGES
• As a PHYSICAL layer device, it regenerates the
signal it receives.
• As a datalink layer device, the bridge can check
the PHYSICAL/MAC addresses (source and
destination)contained in the frame.
• It can check the destination address of a frame
and decide if the frame should be forwarded or
dropped.
• If the frame is to be forwarded, the decision must
specify the port.
• Bridge isolates collision domains since it buffers
frames

5. BRIDGES
Link Layer devices:Link
Operate on Ethernet frames, examining frame header and
selectively forwarding frame based on its destination
Operate on

6. HOW BRIDGE WORKS
• Bridges work at the Media
Access Control Sub-layer of
the OSI model
• Routing table is built to record
the segment no. of address
• If destination address is in the
same segment as the source
address, stop transmit
• Otherwise, forward to the
other segment

7. A BRIDGE
CONNECTING
TWO LANs

8. CHARECTERISTIC OF BRIDGE
• Routing Table:
-Contains one entry per station of network to
which bridge is connected.
• Filtering:
-Is used by bridge to allow only those packets
destined to the remote network.
• Forwarding:
-the process of passing a packet from one
network to another.
• Learning algorithm:
-the process by which the bridge learns how to
reach stations on the internetwork.

9. Simple Bridging :
• A simple bridge connects two network
segments.
• Typically by operating transparently and
deciding on a frame-by-frame.
• A store and forward technique is
typically used so, during forwarding
• Bridges reduce collisions by partitioning
the collision domain.

10. Multiport Bridging:
• A multiport bridge connects
multiple networks and
operates transparently to
decide on a frame-by-frame.
• It works on the basis whether
and where to forward traffic.
• It also uses store and forward
operation.
• The multiport bridge function
serves as the basis for network
switches.

11. Transparent Bridge:
Also called learning bridges
• Build a table of MAC addresses as
frames arrive
• Ethernet networks use transparent
bridge
• Duties of transparent bridge are :
Filtering frames, forwarding and
blocking

12. Source Routing Bridge:
Used in Token Ring networks
• Each station should determine the
route to the destination.
• Addresses of these bridges are
included in the frame.
• Frame contains the source and
destination address.
• Frame also contains the bridge
addresses.

13. ADVANTAGES AND DISADVANTAGES OF BRIDGE
Advantage:
• Extend Physical network
• Reduce network traffic with minor segmentation
• Creates separate collision domains
• Reduce collisions
• Connect different architecture
Disadvantages of using bridges:
• –Slower that repeaters due to filtering
• –Do not filter broadcasts
• –More expensive than repeaters

14. what is an Ethernet bridge?
• Device that connects two different local area
networks together.
• Both networks must connect using the same
Ethernet protocol.
• Bridges can also be used to add remote
computers to a LAN.
• Many bridges can connect multiple
computers or other compatible devices with
or without wires.

15. TYPES
ETHERNET BRIDGE
WI-FI BRIDGE POWER LINE
BRIDGE

16. WIRELESS BRIDGE
• Type of networking hardware
device.
• Enables connection of two
different LAN segments by
bridging a wireless connection
between them.
• Works much like a wired
network bridge.
• Used to connect LANs that are
logically separated or located
in different locations.

17. POWER LINE BRIDGE
• Also known as power line Ethernet Adapter.
• Device that allow data to travel through
already existing power lines within a building.
• A bridge plugged into an AC outlet is
connected to the router using a network
cable.
• Another bridge plugs into the outlet to
provide an Ethernet port for another router.

18. FUNCTIONS
• Uses Data Layer of the OSI Reference Model to
find computers on network.
• Finds devices using Media Access
Control(MAC)addresses.
• They can’t find internet protocol addresses.

19. • Addressing
– Routers are explicitly addressed.
– Bridges are not addressed.
• Availability
– Routers can handle failures in links, stations, and other
routers.
– Bridges use only source and destination MAC address.
• Message Size
» Routers can perform fragmentation on packets and thus
handle different packet sizes.
» Bridges cannot do fragmentation .
• Forwarding
» Routers forward a message to a specific destination.
» Bridges forward a message to an outgoing network.

20. ROUTER VS BRIDGE
• Priority
» Routers can treat packets according to priorities
» Bridges treat all packets equally.
• Error Rate
» Network layers have error-checking algorithms
that examines each received packet.
» The MAC layer provides a very low undetected
bit error rate.
• Security
» Both bridges and routers provide the ability to
put “security walls” around specific stations.
» Routers generally provide greater security than
bridges because
– they can be addressed directly and
– they use additional data for implementing
security.

21. BROUTER
• A network device that works
as Bridge and as a Router.
• Capable of establishing a
bridge between two networks
as well as routing some
messages from the bridge
networks to other networks.
• Are sometimes called (Layer
2/3) switches and are a
combination of bridge/router
hardware and software

22. Conclusion:
• The awareness for network bridging issues is slowly rising.
• A possible future holds network zones that communicate with each other on well
defined paths.
• Bridging zones is only possible by design at security gateways that link zones each
other.
• Security will be essential part of every member in each zone down to the single
client.