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Re: [IPFIX] Fwd: I-D ACTION:draft-ietf-ipfix-export-per-sctp-stream-04.txt



Hi Gerhard,

comments inline!

On 04.11.2009, at 09:55, Gerhard Muenz wrote:
Tobias Limmer wrote:
3.1.1. IPFIX Protocol Specifications Limitation:
"Note that a workaround allowed by the IPFIX specifications [RFC5101] is to use only one Template Record per SCTP Transport Session, at the cost of multiplying the number of SCTP Transport Sessions when multiple Template Records are required." This paragraph sounds a little misplaced, as it already mentions the performance impact. After reading it, I was wondering what other method would be proposed in this draft.

Not sure if you got the paragraph right. It talks about SCTP Transport Sessions, not SCTP streams. Using different Transport Sessions requires indeed much more overhead (e.g., multiple sockets) than just having multiple streams in one Transport Session.

Oh right, I misunderstood. But then you should always use the term 'SCTP association' instead of 'SCTP transport session', as you've already done in the rest of the document, except section 2.2. ("[...] active within a single SCTP Transport Session and [...]").

4.2. Template Management:
"Any Data Sets associated with a Template Record MUST be sent on the same SCTP stream on which the Template Record was sent." According to rfc5101, an Options Template Record is a Template Record. Later in the same section you specify: "When the Options Template and associated Data Records are sent in different SCTP streams, [...]".
Isn't this a contradiction, or am I missing something here?

This is a flaw of IPFIX terminology.

In the text, we tried to consistently use "(Options) Template" if we talk about both Options and non-Options Templates. The sentence above is just about non-Options Templates.

Not sure, how we can make this more comprehensible. Maybe a note in the terminology section?

Yes, I agree, as you are using this terminology in the whole document.


Regards,
Tobi

--
Dipl.-Inf. Tobias Limmer
Chair for Computer Networks and Communication Systems
Universität Erlangen-Nürnberg
Martensstr. 3, D-91058 Erlangen, Germany
Phone: +49-9131-8527931  Fax: +49-9131-8527409
eMail: limmer .at. informatik.uni-erlangen.de
URL:   http://www7.informatik.uni-erlangen.de/~limmer