– For creating multiple distinct broadcast domains, a single 2 layer network might be divided in computer networking. – The domains thus created exist in mutual isolation with each other and therefore the data packets can pass between them through the routers only.
– These domains are nothing but VLANs or virtual local networks.
– This can be achieved through router or switch devices.
– This is difficult to achieve with simpler devices since they can support partitioning only on the level of port (if they do).
– Thus, sharing of VLANs across various devices needs a dedicated cable for each of these domains.
– Tagging is another technique used by sophisticated devices for marking the packets.
– Using this, a single trunk can be used for transporting the data to various domains.
– A common set of requirements might be used for grouping the hosts without concerning to their physical location through VLAN and this simplifies the network design to a great extent.
– The attributes of a VLAN are similar to that of the physical LAN with only exception.
– In VLAN, end stations can be grouped very easily that are not even located on the same network switch.
– The configuration of the membership of a virtual LAN can be done via software rather than having physical relocation of the connections and other devices.
– The VLAN concept is today used by a number of enterprise level networks.
– In a normal physical LAN all the interfaces are considered to be laying the same domain by a switch.
The functions of a VLAN can be physically replicated but it would require the following:
1. A parallel as well as separate collection of network cables and
2. Equipment that has been set separate from the primary network.
Issues addressed by the VLANs include:
3. Network management
Following services are provided by the routers implemented in VLAN topology:
2. Broadcast filtering
3. Address summarization
4. Traffic – flow management
Uses of VLAN
– The IP traffic between the domains cannot be bridged by the switches and doing so would lead to violation of the VLAN domains.
– VLANs are also helpful in creating multiple layer 3 networks using the same switch on layer 2.
– Using VLANs one can split up the network so its DHCP server would not be used by the hosts.
– In its place they would obtain address from some other server.
– VLANs are constructs of the 2nd layer when compared to the IP subnets i.e., layer 3 constructs.
– In a VLAN environment, relationships existing between IP subnets and VLANs are often one–to–one.
– Having a number of subnets on one VLAN is also possible.
– Mapping between these two constructs is important in network designing process.
– Responding to re-locations and controlling the traffic patterns becomes easy by employing VLANs.
– They offer the flexibility required for adapting to the changes in the network and also simplify the administration. – In some cases, VLANs might be employed in work environments and schools for making the access to local networks and administration easier and to avoid network disruption.
– When it comes to cloud computing VLANs, the resources are the mac addresses and IP addresses that can be managed by the users themselves.
– A default VLAN can enable them and then the devices connected to its ports can exchange data packets among themselves.
– VLAN groups can be used for separating ports which in turn separates the traffic also.
– VLANs help in grouping the networks in such a way that the location of the users matters no more to the network location.
– With following technologies, VLANs can be implemented:
1. Fiber distributed data interface or FDDI
3. Asynchronous transfer mode