ured as trunk ports. All ports must be the same speed and duplex as well. In
other words, all the ports must be configured the same or PAgP will
not work.
the speed or duplex of one port, all ports will then run that speed or duplex.
Because most of the ports connect to workstations, printers, servers, routers,
and so on, it's basically a waste of resources for these point-to-point ports to
be running the Spanning Tree Protocol. When a device, let's say a worksta-
tion, powers up, it takes up to 50 seconds before the switch will forward data
on the port because the STP is making sure no loops are going to occur when
the port is in forwarding mode. Not only is this a waste of time (because a
loop will not occur with point-to-point links), but some protocols or appli-
cations could time out.
states. This is very helpful for switch ports that have workstations or servers
attached because these devices will connect immediately instead of waiting
for the STP to converge. If you connect a hub to a port configured with Port-
Fast and then accidentally connect another port into the switch from the
hub, you will have a network loop and STP will not stop it. It is important
to make sure that PortFast is used only on point-to-point links connected
only to workstations or servers.
mand. The following switch output shows how to configure ports 2/1-12
with PortFast: