[c-nsp] rancid and inventory with "^"

[Alexander Clouter]

Hi,

* john heasley <heas at shrubbery.net> [2010-09-07 13:35:26-0700]:
>
> Tue, Sep 07, 2010 at 09:39:00AM +0100, Alexander Clouter:
> > >   !NAME: "temperature outlet 9 ", DESCR: "module 9 outlet temperature Sensor"
> > >   !NAME: "temperature inlet 9 ",  DESCR: "module 9 inlet temperature Sensor"
> > > + !NAME: "temperature device-1 9 ", DESCR: "module 9 device-1 temperature Sensor"
> > > + !NAME: "temperature device-2 9 ", DESCR: "module 9 device-2 temperature Sensor"
> > >   !opv1^T^LB
> 
> fwiw, this would strike me a either failing hardware (SMbuss or sensor)
> or a s/w bug thats reading outside of device ID buffer range or an
> improperly flashed device ID.  if it flaps, its probably not the latter.
> 
Cisco said "there might be an I2C glitch".  Makes me wonder if Cisco 
bitbang the I2C bus off some GPIO pins and much up the timing if the 
router is under load.

> it could also be a s/w bug that is just writing junk to the tty when this
> command is run.  you can speculate based upon the bahavior.
> 
Indeed, you could speculate pretty much anything regarding an opaque 
box.  :)  

> > Anyway, there was a thread here that kicked this off into life:
> > 
> > http://marc.info/?l=cisco-nsp&m=126780984709176&w=2
> 
> and that could be the s/w just not being patient enough for those devices.
> if the command returns an error when it fails to reach devices it knows to
> exist, then rancid can be altered to fail and retry.
>
There is no error.  To me that looks like either a buffer length not 
being properly checked, a NULL byte at the end of a string going AWOL 
(think 'strncpy') or there is crud just coming off the I2C bus (for 
whatever reason) and IOS is trying it's best to make the output usable; 
even if that means removing unusable guff.

To be frank, it's rare that the vendor ever does the right thing so I 
doubt it's IOS trying to do the Right Thing(tm) :)

Cheers

-- 
Alexander Clouter
.sigmonster says: Use at own risk.