Subject: Re: [ipfix-reqs] Flow definition

From: Benoit Claise <[email-masked]>
Date: Mon, 14 Jul 2003 17:22:07 +0200

Simon Leinen wrote:

>Ganesh Sadasivan writes:
>  
>
>>Thanks David. I re-read the charter & agree that the charter does
>>not mention about MPLS flows. But the question is if flow collection
>>is done on MPLS encapsulated IP packet ? If so should we not
>>explicitly include them in the flow definition.
>>    
>>
The charter doesn't speak about MPLS but the requirement draft does:

2.1.  IP Traffic Flow

   There are several definitions of the term 'flow' being used by the
   Internet community. Within this document we use the following one:

   A flow is defined as a set of IP packets passing an observation point
   in the network during a certain time interval. All packets belonging
   to a particular flow have a set of common properties. Each property
   is defined as the result of applying a function to the values of:

      1. one or more packet header field (e.g. destination IP address),
         transport header field (e.g. destination port number), or
         application header field (e.g. RTP header fields [RFC1889])

      2. one or more characteristics of the packet itself (_e.g. number
         of MPLS labels_, etc...)

4.4.  MPLS Label

   If the observation point is located at a device supporting
   Multiprotocol Label Switching (MPLS, see [RFC3031]) then the metering
   process MUST be able to separate flows by the MPLS label.

>I would say no, we shouldn't.
>

What's next? So maybe the proposal #2 from Ganesh (below) makes sense?

 From I have the following proposal:
1. "A flow is defined as a set of IP packets or a sub-IP encapsulated IP
packets passing an observation point in the network during a certain 
time interval."
2.
In the section on MPLS there should be  a statement telling that for
MPLS packets, the  metering process has to dig into the packet or by 
some other means
find out if the encapsulated packet is an IP packet.

Regards, Benoit.