Port Forwarding

MSTP and RSTP use rapid forwarding mechanisms to get ports to the forwarding state. However, there is a difference in forwarding time between user ports and inter-switch links (ISLs). If a user port is defined as adminedge TRUE using the set spantree adminedge command, it will forward as soon as the port becomes operational. An ISL will forward based on an exchange of BPDUs. By default, autoedge is set to TRUE and adminedge is set to FALSE. These settings satisfy most requirements. Autoedge allows a port defined as adminedge FALSE to discover in a short period of time that it is an edge port. The only time it is necessary to set adminedge to TRUE is when the attached user device cannot tolerate the several seconds required for auto-detection to detect the port as a user port and move it to forwarding. Setting an ISL to adminedge TRUE should be avoided because it can lead to transient data loops.