Subject: [ipfix-protocol] Data representation

From: Stewart Bryant <[email-masked]>
Date: Thu, 07 Oct 2004 15:55:02 +0100

There is a problem with the definition of the data-type
representation in the IPFIX protocol specification.

The info model is just that, it concerns itself
with the definition of information, not with its
representation.

The protocol spec deals with the representation
of information elements, but needs to be written in
such a way that it does not have to delve into the
myriad of protocol definitions that exist, and
clearly states how new types will be represented.
In the draft as it stands we started to call out a few
type definitions in detail, but this is essentially
a task without end.

I propose that we simply include the following
statement in the protocol spec and deleted all
other text related to the external representation
of information elements.

"Information elements MUST be sent in canonical format
in network byte order."

NBO is the convention that the IETF uses for all of its
protocol specs. In practical terms it means that an
implementation can just grab data from the wire and
send it back out. The use of the word "canonical"
gives clear direction about what to do with objects
like MAC addresses which have two on the wire formats
(the Token Ring problem).

NBO is big-endian and therefore specifies the
external representation of IPFIX specific numeric
types such as counters etc.

So is the sentence I suggest above the necessary
and sufficient definition for our purposes?

- Stewart

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