A network switch is a telecommunication device that connects network segments, processes incoming messages, and forwards data to targeted devices at various OSI layers. Switches play a crucial role in modern LANs, facilitating data management and connectivity while offering different functionalities based on their layer specification. They have advantages such as reduced broadcast domains and efficient traffic handling, but require proper design for optimal performance.

2. NETWORK SWITCH
 A network switch is a device used to connect network
segments or network devices.
 Network switch receive messages and send them to the
targeted audience.
 It is a telecommunication device that uses the packet
switching to receive,process and forward data to the
destination address.

3. NETWORK SWITCH

4. Contd..
 Network switch forwards data to one or multiple
devices that need to receive it.
 Switches are the multiport network bridges that
process and forward data at the data link layer(layer 2
of OSI model).
 The switches that process data at the network layer or
above it, known as layer 3 switches or multi-layer
switches.

5. APPLICATIONS OF SWITCHES
 A switch can manage the flow of data across the
network.
 A network switch plays an integeral part in most
modern Ethernet LANs.Mid to large sized LANs
contain a number of linked managed switches.
 Switches are also used in SOHO(Small Office/Home
Office) applications that typically uses a single switch
to access the various broadband servioces an d the
services like voice over internet protocol.

6. Contd…
 A switch is a device used in a computer network to
physically connect the devices together.
 Each network device is connected to a switch is
identified using a MAC address or a hardware
address.Therefore,a switch is also considered as a
intelligent network hub.
 A switch can trensfer data to any of the other devices at
a time using half duplex mode or full duplex mode.

7. FUNCTIONS & ROLE
 A switch may operate at one or more layers of the OSI
model as data link layer,network layer,transport
layer,etc.A device that operate simultaneously at more
than one of these layers,called as Multilayer switch.
 Devices that interconnect at layer 3 are called
Routers,that’s why layer 3 switches are also known as
Routers.
 For commercial use,it is possible to connect different
types of networks such as Ethernet,Fibre
Channel,RapidIO,ATM,etc.This connectivity can be at
any layers.

8. Contd,..
 Generally,switches do not provide any network
security.Therefore,some vendors provide firewall and
network intrusion detection system to provide more
security.
 Switch is used to create a mirror image of data that can
go to external device.Ince most switch port mirroring
provides only one mirrored stream,network hubs can
be useful for fanning out data to several read-only
analyzers,such as intrusion detection system and
packet sniffers.

9. TYPES/LAYER-SPECIFIC
FUNCTIONALITY
 Layer 1 Switch or Hub
 Layer 2 switch
 Layer 3 switch
 Layer 4-7 switch(multi-layered switch)

10. N/W DEVICES & OSI LAYER
ASSOCIATION

11. LAYER1 SWITCH
 A network hub is simply a network device that does
not manage any of the traffic coming through it.Any
packet entering through a port is repeated on every
other port.So the packet collissions effect the entire
network.
 Can not filter messages,propagate to all connected
devices.
 Not intelligent to find out best path for data packets.

12. PORT MIRRORING
 Layer 1 switches perform function called port
mirroring.
 This helps to send network packets from one switch
port to another switch port.

13. LAYER 2 SWITCH
 A network bridge,operating at the data link layer,may
interconnect a small number of devices in a home or
the office.The bridges learn the MAC addrwess of eac
connected device.
 Single bridges also can provide exteremly high
performance in specialized applications such as
storage area networks.

14. 4 forwarding methods
 Store and Forward :- The switch buffers and verifies
each frame before forwarding it.
 Perform error-checking before sending network frames.
 Highly reliable and slow.
 Cut Through :- The switch reads only up to the
frame’s hardware address before starting to forward
it.
 No error checking performed.
 Look up destination and forward it.
 Performance penalty.

15. Contd…
 Fragment Free :- It checks the first 64 bytes of the
frame,where addressing information is
stored.Collisions shuld be detected and tehn that
frames will not be forwarded.
 It attempts to retain the benefits of both store &
froward and cut through.
 Error checking is left for the end device.

16. Contd…
 Adaptive Switching :- A method of automatically
selecting between the other three modes.

17. LAYER 3 SWITCH
 Most the fuctions are performed by a router.
 The most common capability of layer 3 is awareness of
IP multicast through IGMP snooping.
 In this layer,switch can increase their efficiency by
delivering more traffic.


18. LAYER 4 SWITCH
 Layer-4 switch is vendor-dependent.
 It may contain firewall,VPN concentrator and IP
Security gateway.
 It is responsible for the analysis and control of network
traffic at transport layer.
 Eg. Cisco 3560 L4 switch

19. Contd..

20. LAYER 7 SWITCH
 This may distribute loads based on Uniform Resource
Locator .
 It may include a web cache and participate in a content
delivery network.

21. Contd…

22. ADVANTAGES
 The number of broadcast domains gets decreased.
 Unlike hub,switches are more hardware oriented.
 It can make use of CAM table for port to MAC
mapping.
 Unlike router,multi ports of switches are available in
lower cost.
 It helps in logical segmentation by supporting VLAN.

23. DISADVANTAGE
 Proper designing and configuration is required if
multicast packets are being handled.
 While limiting broadcasts,switches are not as good as
routers.

24. CONCLUSION