A VLAN (Virtual Local Area Network) is used to logically segment a single physical network into multiple virtual networks. It allows network administrators to group devices logically, regardless of their physical location, into separate broadcast domains. This segmentation enhances network security, efficiency, and management by isolating traffic within specified VLANs and controlling communication between them.
VLANs are used to improve network performance, security, and manageability. By dividing a large network into smaller VLANs, administrators can reduce broadcast traffic, improve network performance by limiting the scope of broadcast domains, and enhance security by isolating sensitive or critical devices from other parts of the network.
The function of VLAN in a router involves assigning VLAN tags to network packets as they traverse the router. Routers with VLAN support can route traffic between different VLANs based on VLAN tags, allowing them to separate and manage traffic from different VLANs within a single physical interface or across multiple interfaces. This capability enables routers to enforce security policies, control traffic flow between VLANs, and optimize network resource allocation.
In Cisco networking, VLANs are configured and managed using Cisco switches and routers. Cisco devices support VLANs through IEEE 802.1Q trunking, which allows multiple VLANs to be carried over a single physical link between switches or routers. VLAN configuration involves assigning VLAN IDs (tags) to switch ports, defining VLAN membership for devices connected to those ports, and configuring VLAN interfaces on routers to route traffic between VLANs. Cisco switches and routers provide robust VLAN management capabilities, including VLAN creation, deletion, modification, and VLAN trunking protocols like ISL (Inter-Switch Link) and 802.1Q, ensuring efficient VLAN deployment and operation in enterprise networks.
