Re: Timer Manipulation

[Dave Katz <dkatz at juniper.net>]

I believe the spec is clear--it is a MUST that the end changing  
parameters sends a Poll Sequence (and also a MUST that P and F not be  
set simultaneously.)
It is a MAY that the new parameters are carried in F packets so that  
the old values don't have to be kept around (it doesn't hurt anything.)

Do what it says, and it works.

I don't see that this requires any further text in the spec.

--Dave

On Aug 14, 2009, at 5:50 PM, Vishwas Manral wrote:

> Hi Shahram,
>
> If I understand you right, you are correct. I raised this issue on the
> list about what needs to be done when both sides change parameters
> symultaneously.
>
> It seems we will put this in a later version of the RFC.
>
> Thanks,
> Vishwas
>
> On Fri, Aug 14, 2009 at 2:14 PM, Shahram Davari<davari at broadcom.com>  
> wrote:
> > Hi Satyam,
> >
> > But section 6.5 says " A BFD Control packet MUST NOT have both the  
> > Poll (P)
> > and Final (F) bits set.".
> >
> > Regards,
> > Shahram
> > ________________________________
> > From: Satyam Sinha [mailto:satyamsinha at live.com]
> > Sent: Friday, August 14, 2009 1:57 PM
> > To: Shahram Davari; rtg-bfd at ietf.org
> > Subject: RE: Timer Manipulation
> >
> > Hi Shahram,
> >
> > The MAY here means that BFD allows an endpoint to set both (P) and  
> > (F) bits
> > together in the same packet. The endpoint "MAY" initiate the poll  
> > sequence
> > even while it is responding to a poll sequence. It is not mandatory  
> > for it
> > to wait for the poll sequence to complete before initiating it's  
> > own poll
> > sequence.
> >
> > In case of change in local parameters while the endpoint is  
> > receiving a poll
> > sequence, the endpoint could either use new parameters and set both  
> > (P) &
> > (F) bits or use old parameters with only the (F) bit set and then  
> > start a
> > poll sequence following the final transmissions. In both cases the  
> > endpoint
> > has to wait for a Final packet from the other end.
> >
> > Regards,
> >
> > Satyam
> >
> > ________________________________
> > From: davari at broadcom.com
> > To: rtg-bfd at ietf.org
> > Date: Fri, 14 Aug 2009 12:44:24 -0700
> > Subject: Timer Manipulation
> >
> > Hi,
> >
> > Section 6.8.3 of base draft says :
> >
> > "If either bfd.DesiredMinTxInterval is changed or  
> > bfd.RequiredMinRxInterval
> > is changed, a Poll Sequence MUST be initiated (see section 6.5). If  
> > the
> > timing is such that a system receiving a Poll Sequence wishes to  
> > change the
> > parameters described in this paragraph, the new parameter values  
> > MAY be
> > carried in packets with the Final (F) bit set, even if the Poll  
> > Sequence has
> > not yet been sent."
> >
> > It seems that the above mentioned MAY requirement is not a good idea,
> > because if a Poll receiver updates any parameter in the Final  
> > packet, then
> > how can the Poll receiver verify that those Parameters are Received  
> > by the
> > Poll sender?
> >
> > Regards,
> > Shahram
> >
> > ________________________________
> > Get your vacation photos on your phone! Click here.