Dell PowerSwitch S4128F-ON OS10 Enterprise Edition User Guide Release 10.4.3.0 - Page 1034

14 Virtual Link Trunking Virtual Link Trunking (VLT) is a Layer 2 (L2) aggregate protocol between end devices such as servers connected to different network devices. VLT reduces the role of Spanning Tree Protocols (STPs) by allowing link aggregation group (LAG) terminations on two separate distributions or core switches. VLT: • Allows a single device to use a LAG across two upstream devices • Provides a loop-free topology • Eliminates STP-blocked ports • Optimizes using all available uplink bandwidth • Guarantees fast convergence if either a link or device fails • Enhances optimized forwarding with Virtual Router Redundancy Protocol (VRRP) • Provides link-level resiliency • Assures high availability VLT provides L2 multipathing, creating redundancy through increased bandwidth, enabling multiple parallel paths between nodes and loadbalancing traffic where alternative paths exist. VLT presents a single logical L2 domain from the perspective of attached devices that have a virtual link trunk terminating on separate nodes in the VLT domain. The two VLT nodes are independent Layer2/ Layer3 (L2/L3) switches for devices in the upstream network. L2/L3 control plane protocols and system management features function normally in VLT mode. VLT configurations must be identical on both sides of a trunk. External switches or servers with LACP see the VLT switches as a single virtual switch. VLT physical ports System management protocols 802.1p, 802.1q, LLDP, flow control, port monitoring, and jumbo frames are supported on VLT physical ports. All system management protocols are supported on VLT ports - SNMP, RMON, AAA, ACL, DNS, FTP, SSH, syslog, NTP, RADIUS, SCP, and LLDP. 1034 Virtual Link Trunking