Re: [IPFIX] AD Review of draft-ietf-ipfix-export-per-sctp-stream-02 -> impact on performance and capacity

["Romascanu, Dan (Dan)" <[e-mail]>]

Hi Benoit,

Yes, this is the type of information that I was looking for. My reading
of your answer is that the impact of adding SCTP streams in an existing
session versus opening a new SCTP session is minor, with a possible plus
of efficiency at setup time. Processing overhead and message overhead
may potentially be a problem, and care should be exercised in deployment
in order to understand the effects. 

Can we add corresponding text on this? 

Thanks and Regards,

Dan


> -----Original Message-----
> From: Benoit Claise [mailto:[e-mail]] 
> Sent: Tuesday, June 16, 2009 11:52 PM
> To: Romascanu, Dan (Dan)
> Cc: IETF IPFIX Working Group; Randall Stewart; Peter Lei 
> (peterlei); Michael Tuexen
> Subject: Re: [IPFIX] AD Review of 
> draft-ietf-ipfix-export-per-sctp-stream-02 -> impact on 
> performance and capacity
> 
> Dan,
> > Please find below the AD review for
> > draft-ietf-ipfix-export-per-sctp-stream-02. The document is mature 
> > enough to go to IETF Last Call. Unless there are any 
> special comments 
> > or concerns I will send it to IETF Last Call by tomorrow.
> >
> > Please consider the comments below together with the other 
> IETF Last 
> > Call comments. The comments are divided into Technical and Editorial
> >
> > T1. There is not information concerning the impact on 
> performance and 
> > capacity of the reporting and collecting processes. Should 
> we expect 
> > any considerable impact on performance and/or capacity? If any 
> > implementation experience is available I would suggest that 
> we record 
> > it.
> >   
> Collecting information from the authors of 
> draft-stewart-tsvwg-sctpstrrst and 
> draft-ietf-ipfix-export-per-sctp-stream-02, here are the conclusions:
> * We were not too sure what is meant by "performance and 
> capacity" in this context.
> * If the question is about: What's the impact of additional 
> SCTP streams in an existing session versus opening a new SCTP 
> session? The impact is
> minor:
> - You have of course a message exchange to add the streams.
> - You end up adding 16-24 bytes per stream.
> - It is more lightweight to set up additional streams 
> compared to setting up a new association.
> The only thing that comes into my mind is throughput which
> * If the question is about the throughput that could be 
> impaired by processing overhead and message overhead.
> - With respect of processing overhead, I have no idea how the 
> utilization of a large number of streams influences the 
> performance of the SCTP socket. I could imagine that a lot of 
> state information must be stored.
> - With respect of message overhead, we can say that the fact 
> that we discourage multiplexing templates and data records of 
> different template ids may lead to a larger message overhead. 
> If the data record rate is low for a specific template, the 
> exporting process might not be able to optimally fill the 
> IPFIX messages. Hence, we have more overhead due to 
> additional IPFIX message headers and SCTP chunk headers.
> 
> Is this what you have in mind?
> 
> Regards, Benoit.
> 
>