Re: [Idr] Hold Negotiation

["Vishwas Manral" <[e-mail]>]

Hi Jeff,

Thanks for the reply. I needed one last clarification again:

>  : If the negotiated hold time value is zero, then the HoldTimer and
>  : KeepaliveTimer are not started.
The point that I raise is the value that is negotiated. If my
configured HoldTime is 0 and the received Hold time is 90. What is the
smaller HoldTime? Is it 0 (which is just a place holder which implies
infinity Hold Time as the timers are not started at all - so in
practice is a larger Hold Time than 90) or is it 90 (numerically
bigger than 0 - but in practice a smaller value).

By the logic of it, the negotiated value should be 90 seconds and not
0 seconds, shouldn't it? As the RFC also states that:

         Upon
         receipt of an OPEN message, a BGP speaker MUST calculate the
         value of the Hold Timer by using the smaller of its configured
         Hold Time and the Hold Time received in the OPEN message.

I agree to the other part of the text you quote, it does seem to clarify this.

Thanks,
Vishwas

On Mon, Mar 10, 2008 at 5:07 AM, Jeffrey Haas <[e-mail]> wrote:
>
> On Fri, Mar 07, 2008 at 06:17:57PM -0800, Vishwas Manral wrote:
>  > I found an ambiguity in the Hold Time negotiation for the value of 0 received.
>  >
>  > The idea of negotiation of the Hold time is that if we will use the
>  > smaller of the two values of Hold time to be the actual Hold Time. A
>  > value of 0, actually means the Maximum Hold time. So in case we get a
>  > value of 0 from the neighbor, should we use the value of Hold time as
>  > 0(a smaller numeric value - but a bigger  value as such) or should we
>  > use the value of (x > 0) as it is logically lesser than the value of 0
>  > Hold time.
>  >
>  > I would think we want the latter. Do let me know what you think?
>
>  RFC 4271 says the following:
>  : If the negotiated hold time value is zero, then the HoldTimer and
>  : KeepaliveTimer are not started.
>
>  This is supported at various points throughout the FSM documentation
>  calling out the case of non-zero and zero.  For example:
>
>  :         - if the HoldTimer initial value is non-zero,
>  :             - starts the KeepaliveTimer with the initial value and
>  :             - resets the HoldTimer to the negotiated value,
>  :           else, if the HoldTimer initial value is zero,
>  :             - resets the KeepaliveTimer and
>  :             - resets the HoldTimer value to zero,
>  :         - and changes its state to OpenConfirm.
>
>  So, while non-zero values are a negotiated timer the zero case is
>  intended to shut off the timers.
>
>  -- Jeff
>
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