Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements
Webcast-Catalyst9k
New Member

spanning-tree portfast question

This may sound like a dumb question but here goes: Is it correct to enable spanning-tree portfast on a switch port that is connected to a router. I know that this port should be a trunk port and it should not have to listen to the BPDU's so there should be no reason that it cant go directly from blocking to forwarding correct??? Never mind I found my answer below. This operates at layer 2 so the router doesnt matter. Thanks anyway

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: spanning-tree portfast question

portfast is a good idea to have enabled for router ports. if you were to issue a shutdown command on the router interface, it would take about 45 seconds for the switchport to come back up after you brought the router interface back up from admin down. This is because each part of the stp state is about 15 seconds. having port fast enabled would allow you to shutdown a router port, renable and immediatly start routing traffic.

2 REPLIES
New Member

Re: spanning-tree portfast question

portfast is a good idea to have enabled for router ports. if you were to issue a shutdown command on the router interface, it would take about 45 seconds for the switchport to come back up after you brought the router interface back up from admin down. This is because each part of the stp state is about 15 seconds. having port fast enabled would allow you to shutdown a router port, renable and immediatly start routing traffic.

Cisco Employee

Re: spanning-tree portfast question

Yes, you can enable spanning-tree portfast on a router port connected to a switch.

-amit singh

120
Views
10
Helpful
2
Replies
CreatePlease to create content