LANswitches

LAN switches are network devices that connect multiple devices within a local area network (LAN) and forward data frames between them based on MAC addresses. They operate mainly at Layer 2 of the OSI model, though some switches include Layer 3 features for routing between networks. Switches learn the MAC addresses of connected devices by listening to frames on each port and build a MAC address table that maps addresses to specific ports. When a frame arrives, the switch forwards it only to the port associated with the destination address, reducing unnecessary traffic. Some switches use store-and-forward forwarding, while others use cut-through or adaptive methods.

Common varieties include unmanaged switches, which are plug-and-play with no configuration; managed switches, which offer configuration options for VLANs, QoS, security, and monitoring; and smart or smart-managed switches, which provide mid-range management capabilities. Many LAN switches also offer Power over Ethernet (PoE), enabling devices such as IP phones and wireless access points to receive power through the data cables.

Deployment typically places switches at the access layer to connect end devices, with uplinks to distribution or other switches. VLANs enable network segmentation, while link aggregation (LACP) increases bandwidth and redundancy. Spanning Tree Protocol (STP) helps prevent switching loops. Speeds range from 10/100/1000 Mbps on entry models to 10 Gbps and higher on enterprise devices, with port counts from a few up to 48 or more.

Management and security considerations include secure interfaces, strong authentication, and regular firmware updates. VLANs, access control lists (ACLs), and private management networks improve security. Relevant standards include IEEE 802.1Q for VLAN tagging, IEEE 802.3 for Ethernet, and STP variants such as RSTP or MSTP.