[sctp-dev] Stream Count Overhead

[Chris Hegarty]

Hi Ray,

I am not aware of any additional overhead of using such a number of 
streams, at least not by the Java implementation.

There may be a small accountancy overhead in the native kernel SCTP 
implementation, but it shouldn't be much. The Java implementation (built 
on top of the kernel impl) adds very little too. That said, I haven't 
experimented too much with large numbers of streams.

Your project sounds interesting, and your experiences would be very welcome.

-Chris.

On 10/13/11 08:23 PM, Ray Racine wrote:
> Need some guidance.
>
> Intent is to use SCTP as the means to send ProtocolBuffer msgs in an
> asynch request / response manner between internal systems in a datacenter.
>
> Another option I looked at was possibly leveraging SPDY over TCP to
> frame the protocolbuffer msgs.   But I'd be stuck with TCP
> head-of-line-blocking and seems SCTP would be a much better way to go.
>
> SPDY uses what it calls stream ids as basically a one time use request /
> response identifier.  i.e. Send requests async on stream N, N+1, N+2,
> ... (they really use even / odd but you get the idea).  So if you get a
> response back on stream N+M you know that was the response for the N+M'd
> request. IF one were to replicate this behavior over SCTP and used a
> standard STCPChannel connect/accept approach then the MAX IN/OUT streams
> are negotiated at connection time.
>
> In SPDY this approach is cost free.  I don't have an intuition for the
> per-stream cost of a (JVM) SCTP connection.  Say I have a server with
> 100 SCTP client connections where each connection is negotiated at the
> maximum permitted IN/OUT streams and where each stream is used once
> until rollover, and then progress through the streams again.  (SPDY
> would require the connection to be reestablished.)
>
> Normally I wouldn't even think about going this route and would say set
> up 2 streams per SCTP connection, one for control msgs and one for data
> msgs.  However, I did a google search for SCTP and SPDY and I actually
> found a study by of SPDY over SCTP by a knowledgeable SCTP expert that
> appears to have taken this approach.  Any substantive problem with
> maxing the streams on a SCTP connection?
>
> Advice?
>
> Thanks in advance,
>
> Ray
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