Spanning Tree Commands

[nawas]

I'm trying to enable some Cisco STP features in our network environment after we had STP loop issus this week. I'm confused with these two commands:

1. Set spantree bpdu-guard mod/port enable

2. Set spantree portfast bpdu-guard enable

For the command it appears that one is per port and one is global but when I do

switch> (enable) sh spantre portfast

Global Portfast BPDU guard is enabled.

Global Portfast BPDU filter is disabled.

And

switch> (enable) sh spantree bpdu-guard

Global BPDU Guard is enabled on the switch. (but that I had to do by using the first command with mod/port option.

Port BPDU-Guard

------------------------ ----------

1/1 Default

1/2 Default

2/1 Enable

2/2 Enable

2/3 Enable

2/4 Enable

2/5 Enable

2/6 Enable

2/7 Enable

Can anyone explain me th difference between spantree bpdu-guard and portfast bpdu-guard aslo any other suggestion in preventing STP loop.

Thank you all in advance.

[Prashanth Krishnappa]

"Set spantree portfast bpdu-guard enable" is a global command which affects all ports which have portfast enabled while "Set spantree bpdu-guard mod/port enable" is per port.

Follow best practices to avoid STP issues

http://www.cisco.com/warp/public/473/185.html

http://www.cisco.com/warp/public/473/103.html

[nawas]

Hi Prkrishan

I have to disagree with you on that, yes from the command it appears that one is global and one is per port but it appears that both have different functionaly, one is used for any portfast enabled port but the other one is used for more non trunk port. Can someone else explain this to me?

Thanks

[milan.kulik]

Hi,

my understanding is:

"Set spantree portfast bpdu-guard enable" is a global command which enables bpdu-guard on all portfast enabled ports.

"Set spantree bpdu-guard mod/port enable" is a port command which enables bpdu-guard on a port no matter if the port has portfast enabled or not.

Regards,

Milan