Subject: question on negotaited BFD interval

From: "Shahram Davari" <[email-masked]>
Date: Tue, 11 Aug 2009 18:47:41 -0700

Hi,

When the BFD handshake is performed, how is the BFD interval decided and how is the agreed interval communicated between the two end systems?
I don't see any field in the BFD packet that conveys the agreed BFD interval.

Thanks,
Shahram

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From: Vishwas Manral <[email-masked]>
Date: Tue, 11 Aug 2009 19:21:47 -0700

Hi Shahram,

BFD allows different rates in both directions.

Thanks,
Vishwas

On Tue, Aug 11, 2009 at 6:47 PM, Shahram Davari<[email-masked]> wrote:
> Hi,
>
> When the BFD handshake is performed, how is the BFD interval decided and how
> is the agreed interval communicated between the two end systems?

---

From: Arun Gandhi <[email-masked]>
Date: Wed, 12 Aug 2009 07:28:33 -0700

Hi Shahram,

The BFD interval is continuosly negotiated independently in each direction.

Please refer to Section 6.8.2 in the draft: 
http://www.ietf.org/id/draft-ietf-bfd-base-09.txt

6.8.2. Timer Negotiation

   The time values used to determine BFD packet transmission intervals
   and the session Detection Time are continuously negotiated, and thus
   may be changed at any time.  The negotiation and time values are
   independent in each direction for each session.

   Each system reports in the BFD Control packet how rapidly it would
   like to transmit BFD packets, as well as how rapidly it is prepared
   to receive them.  With the exceptions listed in the remainder of this
   section, a system MUST NOT transmit BFD Control packets at an
   interval less than the larger of bfd.DesiredMinTxInterval and
   bfd.RemoteMinRxInterval.  In other words, the system reporting the
   slower rate determines the transmission rate.
 
   [...]

Thanks,
Arun 

On Tue, Aug 11, 2009 at 6:47 PM, Shahram Davari<[email-masked]> wrote:
> Hi,
>
> When the BFD handshake is performed, how is the BFD interval decided 
> and how is the agreed interval communicated between the two end systems?