Virtual Local Area Networks (vlans)

A switch is an intermediary device which is used to connect multiple end devices within a local area network to share information and also to connect them to network routers to forward information to another network. There are different types of switches’ form factors available and each type is used depending on the network requirements, and these types are:

• Fixed Configuration Switches: these types of switches do not support more features than the ones already configured, for example, a fixed configuration switch has 24 ports configured when bought and more ports cannot be added.
• Modular Configuration Switches: modular configuration switches have more flexibility in their configuration and they are available in different sized chassis that allow them to be configured with modular line cards which contain additional ports.
• Stackable Configuration Switches: these types of switches can be stacked on one on top of another and they are inter connected with a special wire and they operate as one large switch to provide redundancy and high bandwidth and it also provides backup routes in case a switch fails.

Virtual local area networks (VLANs) are logical connections that are configured to reduce the size of a large broadcast domain into smaller broadcast domains. A broadcast domain is a conjunction of devices configured to intercept a broadcast message within a local area network and routers by default don’t forward a broadcast. VLANs are normally configured on a switched LANs but modern implementations can allow them to be configured on a remote network as well. VLANs are used to segment networks to improve security because devices on a particular VLAN act as they are in their own independent network, for example, you can configure a VLAN called engineering and assign only the engineering users to access the information.

Benefits of VLANs:

• Security: a particular department with sensitive data can be separated from the rest of the network improving security as it decreases the chances of confidential information breaches.
• Cost reduction: configuring VLANs eliminates the needs of expensive equipment purchases for efficient use of the network.
• Better performance: by reducing the size of a large broadcast domain, it prevents the unnecessary traffic from circulating the network and consuming bandwidth.
• Broadcast storm mitigation - Dividing a network into VLANs reduces the number of devices that may participate in a broadcast storm.

VLAN Trunks:

Because VLANs are configured in different IP networks, they require a layer 3 device to communicate with each other and that can be expensive as it requires an additional routing device, however there is a solution for that called VLAN trunking. a trunk connection is a point-to-point link between two network devices that connect more than one VLANs. VLAN trunks allow all VLAN traffic to propagate between switches, so that devices which are in the same VLAN, but connected to different switches, can communicate without the intervention of a router. A VLAN trunk does not belong to a specific VLAN; rather, it is a conduit for multiple VLANs between switches and routers.