VLAN: CONCEPT: WHAT, CREATION, KEY POINTS



TOPICS

WHAT IS VLAN?

VLAN CREATION

KEY POINTS


 

WHAT IS VLAN?

VLAN (Virtual Local Area Network) Definition:

VLAN is the logical grouping of ports on same or different devices, which becomes separate broadcast domain.

The devices can be located at the same location or different location. VLANs are based on logical instead of physical connections.

 

Meaning of Broadcast domain:

In a new switch, all the ports are part of a single broadcast domain

If traffic comes from any port of the switch to any destination in the switch, searching process for destination will be done across all the ports.

Technically, ARP request will go to every port to find out the destination

By creating VLAN’s means, we are dividing single broadcast domain into multiple broadcast domain.

 

In simple words,

We have a switch with 10 ports.

Two VLAN’s are created, VLAN 5 & 6.

1-5 ports are assigned to VLAN 5 and 6-10 ports are assigned to VLAN 6

If traffic comes from any port in-between port 1-5, searching process will be done in ports 1-5,

To find out the destination port

Similarly, if traffic comes from any port in-between port 6-10, searching process will be done in ports

6-10, to find out the destination port

If there are no VLAN’s, if traffic comes from any port of the switch, searching process will be done in

All the ports of the switch, there is no division

 Port Types:

  1. Access Port: It can carry traffic of one VLAN
  2. Trunk port: It can carry traffic of more than one VLAN

 

VLAN CREATION

How to create VLAN’s?

There are two types of VLAN: L2 and L3 VLAN

 

Configuration for L2 VLAN:

Switch#conf t

Switch#vlan 10    Created

Switch#sh running-config vlan 10    Verified

/IP cannot be provided to L2 VLAN/

 

Configuration for L3 VLAN:

Switch#conf t

Switch# interface vlan 10    Created

Switch#sh running-config  interface vlan 10    Verified

/IP can be provided to L3 VLAN/


 

KEY POINTS

  1. 1 VLAN=1 Broadcast Domain
  2. 1 Subnet or Network is assigned to one VLAN. Separate VLAN means separate subnet or network
  3. In a new switch, all ports are access ports and assigned to the same VLAN, Default VLAN (VLAN 1)
  4. If further division is required into the VLAN, we have the option of Private VLAN.Private VLAN will be discussed in some other post
  5. IP cannot be provided to L2 VLAN
  6. IP can be provided to L3 VLAN

 

 

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