Subject: [ipfix-protocol] Generalisation of the Reduced Size Encoding

From: "STEPHAN Emile RD-CORE-LAN" <[email-masked]>
Date: Mon, 2 May 2005 12:11:22 +0200

Dear Bryant, Benoit

Protocol-v12 does not generalise the size encoding reduction to string and array. This should be added because such kinds of fields are defined with a length longer that those used (e.g. wlanSsid).

Regards
Emile

> -----Message d'origine-----
> De : Stewart Bryant [mailto:[email-masked]]
> Envoyé : jeudi 7 avril 2005 13:15
> À : STEPHAN Emile RD-CORE-LAN
> Cc : Benoit Claise; [email-masked]
> Objet : Re: [ipfix-protocol] draft-ietf-ipfix-protocol-11.txt: 6.2 Reduced
> Size Encoding of Integer Types
> 
> 
> 
> STEPHAN Emile RD-CORE-LAN wrote:
> > Dear Benoit,
> >
> > This section says that an exporter MAY use shorter IE length than in the
> > info model but does not clearly say that in this case it is mandatory to
> > declare these length in the template.
> 
> That is already stated in section 3.2
> 
> "Field Length
>      The length of the corresponding encoded Information Element,
>      in octets.  Refer to [IPFIX-INFO].  The field length may be
>      smaller than the definition in [IPFIX-INFO] if reduced size
>      encoding is used (see section 7.2)."
> 
> 
> 
> >
> > I propose to replace the beginning of this section with:
> >
> > "Information Elements containing integer types in the information
> > model MAY be encoded using fewer octets than those implied by their
> > type in the information model definition [IPFIX-INFO], in this case the
> > exporter MUST indicate these lengths in the template ...
> >
> 
> I don't think that your added text "in this case the
> exporter MUST indicate these lengths in the template"
> 
> is needed since you have to send exactly the number of octets
> that you declared in the template.
> 
> BTW - the reduction would also apply to a fixed length string
> object, say a name, that might be defined as an IE of max length
> X (to tell the collector DB the max size it needs to store)
> but which the exporter knew woud only ever take Y<X to describe.
> We should therefore increase the scope to include any
> primative type where the collector can figure out the semantics
> of a reduced size export.
> 
> Regards
> 
> Stewart
> 
> >
> > Regards
> > Emile
> >
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