Jun 24 • Notes • 2301 Views • 1 Comment on VIRTUAL LANs and NETWORK LAYER


The virtual LANs can be classified as the type of the LAN with the property to help out to group the users.The group of the users need not be in the  physical location but in the logical manner.It can be demonstrated as the standard which helps to  transfer the data without any restraints.It also helps to attain the traffic separation and the better utilization of the bandwidth.




VIRTUAL LAN Membership

Basically there are two common ways for the VLAN



The Static VLANs are generally created by assigning the ports to the VLANs and this is the reason that it is also known as the port-based VLANs.The device in the network by default is assumed as the VLAN of the port.If somehow any changes are made in the ports and the same VLAN is to be asccessed then manually the port to VLAN connection is to be made.

The Dynamic VLANs are generally based on the information such as the source.In this the VLAN management policy server assigns the switch ports to the VLANs.Mac address of the device which is connected to the port is used to log onto the device

Configuration of the VLANs

Step 1:Virtual interface is to be defined

Go to system> configure Network >Manage Interface and then finally click on the Add VLAN Interface button to open up the create page.


step 1 stage

step 1 stage

Now the page appears which requires the following data.

step 1 stage 2

step 1 stage 2



Physical interface:In this section the interface is selected for which the virtual subinterface is to be defined.

VLAN ID: The VLAN ID can be the number between 2 and 4094.

IP address:the netmask and the IP address for the virtual subinterfaces is to be assigned.Only the static IP address is to be assigned.

Zone :here the virtual subinterface zone is to be selected.The virtual subinterface will be the member of the selected zone.

On the successful completion of the interface details,a newly defined virtual subinterface under the selected physical interface will be displayed.


step 1 stage 3

step 1 stage 3


Step 2:Now restart the management service from the CLI console

Log on to the CLI console through the Telnet and select the option Restart Management services.


step 2

step 2

Once the Virtual Interface is defined and is included in the zone,it will be treated exactly same as the physical interface.customization of the firewall rules that govern the traffic between the VLANs and other interfaces can be performed the same way as done with the physical interface.


Communicaton between VLANs is accomplished through routing, and the traditional securityand filtering functions of the router can be used.Cisco IOS software provides network services such as security filtering, quality of services and accounting on a per VLAN basis.

The following helps in the communication between the switches:

Relaying Function

• Native VLAN

• PVST +

• Intergrated Routing and Bridging

Network Layer-Logical Addressing

Each and every network device has the physical address known as the MAC address which is basically assigned to the device at the factory.The logical address lets us access the network device by using the address assigned by us.The logical addresses are created and used by the network layer protocols such as the IP or IPX.The network layer protocols changes the logical addresses to the MAC address.

In the network layer a global addressing system that identifies every host and the router necessary for the delivery of the packet from network to the network..The internet address or the IP address is of 32 bits that defines the a host or router on the internet.The portion of the Internet protocol that identifies the network is known as the Netid.The portion of the  address that identifies the host or router on the network is called hostid.There are 5 classes in the address.The classes A,B,C differ in the number of the hosts allowed per network.Class D is for multicasting and the class E is reserved.

1)uni cast communication is the one source sending the packet of the data to the destination

2)multicast communication is the one source sending the packet of data to the multiple number of the destination.

Sub netting divides the one large network to the smaller ones.In supernetting combines several networks to large one.


Q.What do you mean by Virtual LANs??
virtual LANs which is the type of the LAN with the property to help out to group out the users that to in the logical manner.It helps to attain the traffic separation and better utilization of band width.

Q.What are the ways for Virtual LAN membership??

There are two ways for the membership of Virtual LAN

1)STATIC Virtual LAN


GATE Syllabus

1. Gate syllabus for Computer Science and Information Technology

2. Gate syllabus for Electronics and Communication Engineering


1. IES Syllabus for Electronics and Telecomm

2. IES Syllabus for General Ability

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