What is the bpdu optimization ?

[hyukin.kwon]

Hi all,

I have a Cat 6509 with SUP 720 and There is a configuration about BPDU Optimization.

My question is, What is the meaning of below ?

" no spanning-tree bpdu optimization "

TIA

[Francois Tallet]

Hi,

This is an engineering command that is appearing on the sup720 because of the bug. If possible, try to re-enable the feature (you might need to upgrade for that). This only has an impact in pvst mode anyway (RSTP and MST don't use this).

Regards,

Francois

[hyukin.kwon]

Thanks ftallet,

I don't exactly follow you, You mean 'no spanning-tree bpdu optimize' is a bug, So I should re-enable 'spanning-tree bpdu optimize' ?

and Do U have any Document on this ?

TIA

[Francois Tallet]

There is a bug ID (CSCeh96795), but I don't think it is externally visible. The command itself is normally hidden. The optimization has always been the default, but it has to be allowed on a per platform basis. The sup720 was lacking this authorization in its first release, which explains why the command was showing up and could not be removed. If you can remove it, then it means that the problem is fixed in the IOS you are running. Else, it's no big deal anyway.

[hyukin.kwon]

Many thanks for you information...

There is one thing further I'd lik to ask.

Actually What is BPDU Optimization ?

TIA

[Francois Tallet]

Hi,

I've had the opportunity to give some information about this in an earlier post. I've attempted to paste the long link below. Let me know if it works.

http://forums.cisco.com/eforum/servlet/NetProf;jsessionid=34744F374E98703C97916700339258B7.SJ3B?page=netprof&forum=Archive&topic=Network%20Infrastructure&CommCmd=MB%3Fcmd%3Ddisplay_location%26location%3D.1ddaa3a3

Regards,

Francois

[bjw]

As I recall,

bpdu optimization allows bpdu processing at the interrupt level and saves CPU cycles. I really haven't run into a situation where I had a production switch operating at a regular CPU usage above 25%. Leaving it on or off is a mute point in my case.

I would only use it in voluminous and busy L2 environments

B White

City of Henderson, Nevada, USA