Portfast

Portfast is a feature on Cisco switches that places a port directly into the forwarding state when an end device is connected. Without this feature, a port first passes through the listening and learning states of the spanning tree protocol, causing a delay of around 30 seconds. This waiting period can cause DHCP requests or network boot processes to fail. Portfast is enabled only on access ports with connected end devices such as PCs, printers or IP phones. It must not be used on uplinks to other switches, as this could create loops. As a safeguard, portfast is usually combined with BPDU guard, which disables the port as soon as unexpected spanning tree messages are received. Switches from other manufacturers offer comparable features under different names.