checking portfast from a Linux host

[HelloNair]

Hi,

I would like to query from a Linux host to see whether my network port has portfast enabled or not. I do not want to login to network switch and would like the query to be based on my Linux host ( egs. tcpdump ) . Ant suggestions ?

Regards
H.Nair

 

[ADB100]

Unplug the LAN cable, plug it back in and immediately from a shell prompt ping something you know is reachable. If it replies immediately or after a couple of packets you have portfast enabled. If it takes 50-seconds or so then it is normal STP.

 

[HelloNair]

Thanks ADB100

I am doing an automated check. Instead of unplug the cable, I can bring down the NIC from the Linux host. And then enable it again. Now I have another query. What is the minimum time that I have to wait if STP ? Is it 50 seconds always

Thanks
H.Nair

 

[ADB100]

The STP protocol is widely documented -

http://www.proprofs.com/mwiki/index.php/Spanning_Tree_Protocol

When a port becomes active it will go through three timers - Max Age whilst it listens for BPDU's on the interface to see if it is already part of the Tree, it then puts the port in Listening State for the Forward Delay time (default 15-seconds) and then in the Learning State for the Forward Delay time. During this period the port will not forward any packets that are received. Add them up and its 50-seconds. PortFast fast-forwards these states and moves a port to the forwarding state after a second or so.

Andy