[c-nsp] OSPF fast hellos

[Curtis Doty]

And beware the showstopper in 12.2S and 12.4T where BFD causes an NMI 
reset. Doh!

It haunted me for many moons before my stubborness prevailed. And a sharp 
Escalations Engineer at Cisco sleuthed it out and eventually generated bug 
ID CSCek75694 with a fix that is supposed to wind back into the mainline 
trains by EOY.

../C

Yesterday Frank Bulk said:

> If you can get BFD support worked into the 3750ME, we wouldn't have to mess
> with OSPF fast hellos. =)
>
> Frank
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Rodney Dunn
> Sent: Thursday, October 30, 2008 12:30 PM
> To: Ben Steele
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] OSPF fast hellos
>
> On Thu, Oct 30, 2008 at 08:06:36AM +1030, Ben Steele wrote:
>> Because I couldn't see bfd support for 3750's, best it can do is UDLD,
>> otherwise that would be my preferred method.
>>
>> Are you advising against fast hello's?
>
> No totally.
>
> Have you seen many issues with people
>> using them?
>
> Yes. They have to be scheduled on the CPU as a process and that is more
> variable because IOS is run to completion, except for psuedo preemption
> added for BFD.
>
> Even that isn't 100% bullet proof but it's better than OSPF fast hellos
> from that perspective.
>
>
>
>>
>> -----Original Message-----
>> From: Rodney Dunn [mailto:rodunn at cisco.com]
>> Sent: Wednesday, 29 October 2008 11:41 PM
>> To: Ben Steele
>> Cc: cisco-nsp at puck.nether.net
>> Subject: Re: [c-nsp] OSPF fast hellos
>>
>> Why don't you use BFD instead. It's designed with something called
>> pseudo preemption from an OS scheduler perspective that helps
>> reduce false positives and the fact that BFD frames are handled
>> under interrupt and not process scheduled for rx/tx.
>>
>> Rodney
>>
>> On Wed, Oct 29, 2008 at 04:09:45PM +1030, Ben Steele wrote:
>>> Anyone currently using this in a fairly demanding environment? Ie
> 5-10Gbs+
>>> Campus/DC model.
>>>
>>>
>>>
>>> Curious as to whether you've had any/many false dead peers with such a
>> short
>>> interval, subsecond dead peer detection does sound very temping though.
>>>
>>>
>>>
>>> Cheers
>>>
>>>
>>>
>>> Ben
>>>
>>>
>>>
>>>
>>>
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