TrunkLinks

TrunkLinks is a networking term used to describe high-capacity inter-switch links that carry traffic for multiple VLANs between network devices such as switches, routers, or data-center devices. The concept emphasizes the aggregation and management of multiple VLANs across a single logical path through VLAN tagging, typically using 802.1Q encapsulation.

Purpose and scope: TrunkLinks enable VLANs to span devices in a scalable manner, allowing centralized policy enforcement and efficient use of link bandwidth. They are commonly used on core-to-distribution links, between switches in campus networks, and in data centers where large VLAN topologies exist.

Implementation: TrunkLinks are configured by enabling trunk ports on connected devices, enabling VLAN tagging, and, where needed, applying link aggregation to increase bandwidth and provide redundancy. Common configurations include selecting the encapsulation type (802.1Q), designating a native VLAN, and restricting which VLANs are permitted on the trunk. To increase resilience, trunks are often placed in link aggregation groups (LAGs) using protocols such as LACP.

Management and considerations: Proper monitoring of trunk usage, spanning-tree topology, and VLAN pruning helps prevent misconfigurations and loops. Security considerations include avoiding unnecessary exposure of the native VLAN, limiting allowed VLANs on trunks, and ensuring consistent configuration across devices. Some environments disable dynamic trunk negotiation to reduce the risk of misconfiguration.

Limitations and alternatives: In large or complex networks, extensive trunking can complicate troubleshooting and change management. Alternatives include segmenting traffic with separate physical paths, using routed interfaces for interbuilding traffic, or employing fabric architectures that decouple trunking from policy enforcement. See also VLAN, 802.1Q, trunk link, link aggregation, LACP.