This document provides an overview of switches, including: 1. Switches come in manageable and non-manageable varieties and can use cut-through or store-and-forward switching techniques. 2. Switches learn device MAC addresses through address learning and forward frames according to their MAC tables. Spanning Tree Protocol (STP) prevents network loops. 3. Switches have components like processors, memory, and ports that can be configured as access or trunk ports to carry one or multiple VLANs respectively. VLANs virtualize the network into multiple broadcast domains.

1. SWITCHING
• Switch is a layer 2 Device
• Two types of switches:-
1. Manageable
• Switches which has a console port
• It is costly
• Ex: Cisco catalyst 2950
1. Non-manageable-
• Switches which does not have console port
• Less expensive
• Ex: D-link, Net gear

2. FURTHER CLASSIFICATION
1. Cut through
 Cut through switch is one which has no error checking on incoming
frame
 Ex: Normal Switch
2. Store and Forward
 Store and forward has a buffer (small memory) in which the incoming
frame is saved in it , checks the error and transmits

3. FUNCTIONS OF SWITCH
• Address Learning
• No entries are in MAC table initially
• Each port broad cast to find its device for communication
• The frame contains SMAC and source port no:
• It is entered into the MAC table
• After finding its device , the details are entered into the MAC table

4. • Forwarding
• Forwarding is the process in which the frames are transferred according to
MAC table
• Loop avoidance
• Two links are connected to two switches.
• A loop occurs between the loops

5. STP (SPANNING TREE PROTOCOL)
• Provides a loop-free redundant network topology by
placing certain ports in the blocking state.
• It is to avoid Looping in switches

6. BRIDGE ID
• It is an address used to identify switches
• It is a combination of priority value + MAC address
• Ex: 32768:aa:bb:cc:dd

7. ROUTE BRIDGE
• The highest priority switch among network of switch.
• It controls the other ones.
• Only one Route Bridge is in a network
• The other switches are called non-Route Bridge

8. DESIGNATED PORT
• The forwarding port of frame is called DP
• All ports in Route Bridge are Designated ports
• All ports in a non-Route Bridge are non- Designated ports

9. ROOT PORT
• The ports in which designated and Non-Designated ports
communicate.

10. STP OPERATION
• BPDU (Bridge Protocol Data Unit), with the help of this packet, Root
Bridge is elected.
• The Root Bridge is elected with comparing Bridge ID and Root ID.
• The lowest BPDU Root ID is the Root Bridge.
• Initially BPDU packets are sent to all switches.
• A Root Port is selected with the help of Path Cost.
• The port in which Path cost having lowest value is the Root port.

11. SWITCH COMPONENTS
• Processor
• Motherboard
• SMPS
• RAM
• NVRAM
• FLASH
• Switches typically have no power switch to turn them on and off.
They simply connect or disconnect from a power source.

12. COMMAND LINE INTERFACE
• The command line interface of switch is same as that of a Router
• The Port interface is automatically assigned with IP and by default the
status is up.

13. SWITCH PORT TYPES
1. Trunk
 A Switch to Switch connections are Trunk
2. Access
 PC- Switch connections are Access

14. SETTING ACCESS & TRUNK PORT
Switch(config)#interface fastethernet 0/1
Switch(config-if)#switchport mode access (For Access Port)
Switch(config-if)#switchport mode trunk

15. PORT SECURITY
Switch(config)#interface fastethernet 0/1
Switch(config-if)#switchport mode access
Switch(config-if)# switchport port-security
Switch(config-if)#switchport port-security maximum 1
Switch(config-if)# switchport port-security mac address sticky
Switch(config-if)# switchport port-security violation shutdown
Switch# show port-security (To Verify)

16. VLAN
• Switch is a single broadcast domain
• Converting a single broadcast domain into multiple broadcast
domain is called Vlan.
• It is a virtual LAN created in a switch.
• Two types:-
• 1- 1005 standard
• 1006 – 4096 extended
• All ports in a switch comes under Vlan 1 or administrative vlan by
default (name default)
• Mainly Vlan is implemented for logical grouping
• A device under one Vlan area will not communicate with other Vlan
area
• Implements security

17. CREATING VLAN
Switch(config)#vlan 100
Switch(config-vlan)#name vlan100
• Assigning a port to vlan:-
Switch(config)#interface fastethernet 0/1
Or
Switch(config)#interface range fastethernet 0/1 – 10
Switch(config-if)#switchport access vlan 100
• To remove:-
Switch(config)#no vlan 100
Switch(config-if)#no switchport access vlan 100

18. ASSIGNING IP
Switch(config)#interface vlan 100
Switch(config-if)#ip address 192.168.1.1 255.255.255.0
Switch(config-if)#no shut down

19. VLAN IDENTIFICATION OR FRAME
TAGGING
• Adding Vlan ID to each frame containing the details of destination
Vlan ID is called Vlan Identification
• Trunk port is used to connect two switch which passes multiple Vlan
information
• Access port is used to connect PC and switch which passes single
Vlan information
• Types:-
• ISL (Interlink Switch)- Encapsulation method of CISCO
• IEEE 802.1Q or dot1Q- Open support all switches

20. ROUTER ON STICK
In Router:-
Router(config)#interface fastethernet f0/0.1
Router(config-if)#encapsulation dot1q 100
Router(config-if)#ip address 10.0.0.1 255.0.0.0
Router(config)#interface fastethernet f0/0.2
Router(config-if)#encapsulation dot1q 200
Router(config-if)#ip address 20.0.0.1 255.0.0.0
Router(config)#interface fastethernet f0/0.3
Router(config-if)#encapsulation dot1q 200
Router(config-if)#ip address 30.0.0.1 255.0.0.0
Router(config)#interface fastethernet f0/0
Router(config-if)no shut down
In Switch:-
Switch(config)interface fastethernet 0/1
Switch(config-if)switchport mode trunk
Switch#show interface trunk

21. VTP (VLAN TRUNKING PROTOCOL)
• VTP is used to create domain environment in a switching network
• VTP modes:-
• Server
• Client
• Transparent

22. • Cannot create,
change, or delete
VLANs
• Forwards
advertisements
• Synchronizes
VLAN
configurations
• Does not save in
NVRAM
• Creates, modifies, and deletes
VLANs
• Sends and forwards
advertisements
• Synchronizes VLAN
configurations
• Saves configuration in NVRAM
• Creates, modifies, and
deletes VLANs locally
only
• Forwards
advertisements
• Does not
synchronize VLAN
configurations
• Saves configuration in
NVRAM

23. VTP DOMAIN
• VTP updates will not be received in switch which is having different
domain name.
• It receives when domain name is same
Switch(config)#vtp domain NS (To create domain)
Switch(config)#vtp mode ? (To change the VTP mode)

24. CONFIGURATION REVISION
NUMBER
• A switch having higher revision number database overwrites to
another switch having lower revision number.
• To avoid this we make the switch which has higher revision number
into transparent mode.

25. VTP PRUNING MODE
• This mode controls transferring unwanted updates from server to un
manual switch.