[c-nsp] OIR on 7600s: Pretty much evil?

[Benjamin Lovell]

It's not deterministic as it starts when first longest pin touches backplane and ends when shortest pin connects. As a practical matter assume 100ms on the low side and reboot on the high side. :)

Most protocol timers will be long enough that the low side is not a concern exceptions being BFD and OSPF fast hellos. OSPF fast hellos are just a bad idea for many more reasons than OIR so I will ignore this case. If you are doing BFD at min timers like 50x3 then OIR could be an issue. if you are somewhere north of 200x3 then you should be ok as if you stall longer than this you are probably on your way to a reboot anyway. 

-Ben

On Nov 11, 2010, at 10:16 AM, chip wrote:

> What's the time length on the bus stall?  Working on re working lots of
> timers, hadn't thought of this.  Something to add to the tests.
> 
> --chip
> 
> On Thu, Nov 11, 2010 at 9:55 AM, Geoffrey Pendery <geoff at pendery.net> wrote:
> 
>> I'll second Gert - I've personally performed close to 100 OIRs on a
>> variety of 6500 chassis, and never had it cause a problem.
>> 
>> There was a previous thread almost exactly like this, BTW - if you
>> feel like searching the archive.  It was half-filled with "OIR always
>> fails, I call it Online Insert and Reboot!" and half-filled with "I've
>> never had a problem, ever.  Works like a charm."  A couple people
>> explained the bus stall behavior:
>> As you're sliding the blade in, it stalls the bus when it first makes
>> contact, then releases the stall once it's all the way in.
>> 
>> My take-away from that thread was that it's a self-fulfilling
>> prophecy:  The techs who approach it confidently, expecting no
>> problems, slide the blade in quickly and experience none.  The techs
>> who are worried and skeptical, slide the blade in slowly and
>> cautiously - and their caution leads to a reboot.
>> 
>> That said, the others in this thread are also correct - if your RP is
>> doing stuff on tight timers, especially BFD, even a very short bus
>> stall can still be service impacting.  And of course, it's better to
>> plan a maintenance window expecting problems and be pleasantly
>> surprised than to assume it's no big deal and get hit with an outage.
>> 
>> 
>> -Geoff
>> 
>> 
>> On Thu, Nov 11, 2010 at 2:00 AM, Gert Doering <gert at greenie.muc.de> wrote:
>>> Hi,
>>> 
>>> On Wed, Nov 10, 2010 at 03:01:21PM -0700, John Neiberger wrote:
>>>> I'm just curious to hear your thoughts on OIR on this platform. Is
>>>> this something that you prefer to avoid? Do you have any OIR-related
>>>> horror stories you'd like to share?
>>> 
>>> On 6500/7600 (and 7200), we *never* had any issues.
>>> 
>>> On 7500, the "R" in "OIR" translates to "Reboot".
>>> 
>>> gert
>>> --
>>> USENET is *not* the non-clickable part of WWW!
>>>                                                          //
>> www.muc.de/~gert/
>>> Gert Doering - Munich, Germany
>> gert at greenie.muc.de
>>> fax: +49-89-35655025
>> gert at net.informatik.tu-muenchen.de
>>> 
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>> 
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> 
> 
> 
> -- 
> Just my $.02, your mileage may vary,  batteries not included, etc....
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