Subject: [ipfix-req] Requirements draft issues - Reinaldo 3

From: "Reinaldo Penno" <[email-masked]>
Date: Tue, 1 Oct 2002 17:28:32 -0700

Issue Number : Reinaldo 3

Issue:

I'm looking to understand/really clarify this requirement. It seems
ambiguous...at least to me. I do not understand what is the meaning/purpose
of "-->abscence<-- of reliability....MUST be indicated". Shouldn't we just
rephrase that by just saying that the protocol MUST be reliable, provide
in-sequence delivery and retransmission? 

It seems to me we should have 2 options: 

1. The IPfix protocol runs over TCP or SCTP 
2. The ipfix protocol does not run over TCP or TCP but provide a service
equal or in excess to what is provided by TCP/SCTP in terms of reliability,
congestion awareness and in-sequence delivery.

Reading this text I feel there is a third option which is: 

3. "the protocol should run over TCP or SCTP, but you can sidestep this
requirement by putting a sequence number on the application layer and/or
providing 'abscence' of reliability"...

Or maybe one should ask what's the definition of a reliable protocol as far
as the ipfix protocol is concerned... 

"6.3.2.  Reliability 

   Absence of reliability of the data transfer, for example caused by 
   loss or reordering of packets containing flow information, MUST be 
   indicated. 

   Please note that if an unreliable transport protocol is used, 
   reliability can be provided by higher layers. In such a case only 
   lack of overall reliability MUST be indicated. For example reordering 
   could be dealt with by adding a sequence number to each packet." 

Proposed Solution:

clean up the text, clarify what is a reliable protocol/what to expect from
one, possibly incorporate the two options suggested above.