Networking devices like hubs, switches, routers, and gateways interconnect networks and manage data flow. Hubs operate at the physical layer and connect segments but do not filter traffic. Switches operate at the data link layer and can direct traffic to specific ports for better performance than hubs. Routers operate at the network layer and can connect networks across LANs, MANs, and WANs using IP addressing to route packets. Gateways can operate at multiple layers and act as connections between different network protocols or applications.

1. Internetworking
Devices

2. Introducing Network Elements
• Networking devices interconnects networks
• Manage data flow and network traffic

3. Repeaters
• Operate at Physical Layer of the OSI model
 Reshape the weak signal
 Connect two segments of the same LAN

4. Hubs - I
 Simplest and low cost device
 Also known as Multi-port Repeater
 Operates at Physical Layer like Repeater
 Data transfer to all the ports
 Hub types:
 Active hub – Provides signal regeneration
 Passive hub – No signal regeneration
 Intelligent hub – Provides management of each port

5. Operation of Hub

6. Hubs Configurations
 Hub configurations can be used to expand
networks.

7. Bridges - I
 Layer 2 devices
as it works at
Data Link Layer
of the OSI model
 Interconnect
multiple LANs
and manages
data flow

8. Bridges - II
Working of a bridge

9. Bridges - III
• Capable of passing a frame
• Check Physical address
• Pass frame to the specified segment
• Perform error checking on the frame

10. Types of Bridge
• Transparent Bridge – common in ethernet
network
• Translational bridge – used to connect two
different network such as ethernet and token
ring
• Source-route Bridge – found in token ring
technology

11. Bridges - IV
• Features
– Easy to use as just plug in device
– Helps in network expansion
– Divides large network into small segments
– Used for increasing network reliability
Disadvantages
– Frames are buffered so provides network delay
– During high traffic may overload network
– Does not filter broadcast packets
– Expensive than Repeaters

12. Switches
 Provide signal flow management
 Replace slower hub
 Being a Data Link Layer device uses MAC address
for data transfer
 Data transfer to specific port

13. Multispeed Switches
• Having number of ports such as 100 Base T
and one or two gigabit ports
• Port detects the speed of NIC and runs at that
speed is called auto sensing
• Port runs at 10, 100 or gigabit is referred to as
10/100/1000 port

14. Routers - I
 Operate at Network Layer of the OSI model
 Can connect nearer or far network segments

15. Routers - II
• Works in LAN, MAN and WAN environments
• Having LAN and WAN ports
• WAN port connects to regular phone line or
more advanced telephone connection like
ISDN, ADSL, T1 or may be a cable modem
• Route the packets seeing the IP address
stored in the packet
• Comes in variety shapes, sizes and functions

16. Routers - III
 Decide the best route with the help of network layer
address
 Responsible for Source to Destination delivery of
packet
 For routing decisions routers use routing algoritm
 Router types:
 Static router – Routing tables are manually configured
 Dynamic router – Routing tables are automatically
configured

17. Routing Protocols - I
Router considers number of hops, time delay and link cost to
find the best path
An autonomous system (AS) consists of network groups and
routers which are managed by a single organisation

18. Gateways - I
 Operate at all layers of the OSI model
 Act as gate to other networks
 A default gateway is on the same subnet as your
computer

19. Gateways - II
 Address Gateway – Interconnects same protocol
networks
 Protocol Gateway – Interconnects different protocol
networks
 Application Gateway – Connects two parts of
applications
 Transport Gateway – Connects networks at
transport layer

20. Other Devices - I
 Multi-protocol router supports multiple
communication protocols
 Like router, it operates at Network Layer

21. Other Devices - II
 Brouter provides combined functions of Bridge and
Router
 Works at two layers, Data Link and Network
 Can operate only as bridge or only as router
 High performance switch operating at network layer
is Layer 3 Switch