Subject: Re: Poll sequence for Echo

From: Satyam Sinha <[email-masked]>
Date: Mon, 8 Dec 2008 22:17:24 -0800

Hi Vishwas,
 
>From 6.8.3 (Timer manipulation):
 
   If bfd.DesiredMinTxInterval is increased and bfd.SessionState is Up,
   the actual transmission interval used MUST NOT change until the Poll
   Sequence described above has terminated.  This is to ensure that the
   remote system updates its Detection Time before the transmission
   interval increases.
 
   If bfd.RequiredMinRxInterval is reduced and bfd.SessionState is Up,
   the previous value of bfd.RequiredMinRxInterval MUST be used when
   calculating the Detection Time for the remote system until the Poll
   Sequence described above has terminated.  This is to ensure that the
   remote system is transmitting packets at the higher rate (and those
   packets are being received) prior to the Detection Time being
   reduced.
 
A poll sequence ensures graceful handling of parameter change on an already established session by having a two way handshake. Without the poll seq. an established session can flap.
 
However, on changing the bfd.RequiredMinEchoRxInterval, an invocation of poll seq. should not be mandatory as an acknowledgement from the peer is not needed. The peer can be informed of the change as part of subsequent messages. I don't think a "MUST" needs to apply to bfd.RequiredMinEchoRxInterval change. 
 
Regards,
 
Satyam
 
-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Vishwas Manral
Sent: Monday, December 08, 2008 2:56 PM
To: [email-masked]; David Ward
Subject: Poll sequence for Echo
Hi,
The BFD base specification states that:
   If either bfd.DesiredMinTxInterval is changed or
   bfd.RequiredMinRxInterval is changed, a Poll Sequence MUST be
   initiated.
Is there a reason it does not state the same for bfd.RequiredMinEchoRxInterval? I think the Poll sequence needs to be required for this too.
Thanks,
Vishwas
_________________________________________________________________
You live life online. So we put Windows on the web. 
http://clk.atdmt.com/MRT/go/127032869/direct/01/