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Date: Fri, 13 Dec 2002 10:07:01 -0800
From: Nivedita Singhvi <niv@us.ibm.com>
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To: Andrew McGregor <andrew@indranet.co.nz>
CC: Bogdan Costescu <bogdan.costescu@iwr.uni-heidelberg.de>,
       "David S. Miller" <davem@redhat.com>, dlstevens@us.ibm.com,
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       stefano.andreani.ap@h3g.it, linux-kernel@vger.kernel.org,
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Subject: Re: R: Kernel bug handling TCP_RTO_MAX?
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Andrew McGregor wrote:

> In a closed network, why not have SOCK_STREAM map to something faster than
> TCP anyway?  That is, if I connect(address matching localnet), SOCK_STREAM
> maps to (eg) SCTP.  That would be a far more dramatic performance hack!
> 
> Andrew

Not that simple. SCTP (if that is what Matti was referring to) is 
a SOCK_STREAM socket, with a protocol of IPPROTO_SCTP. I'm just
getting done implementing a testsuite against the SCTP API.

i.e. You have to know you want an SCTP socket at the time you
open the socket. You certainly have no idea whether youre on
a closed network or not, for that matter, the app may want to talk
on multiple interfaces etc. (Most hosts will have one interface
on a public net)..

Currently, Linux SCTP doesn't yet support TCP style i.e SOCK_STREAM
sockets, we only do udp-style sockets (SOCK_SEQPACKET).  We will be
putting in SOCK_STREAM support next, but understand that performance
is not something that has been addressed yet, and a performant SCTP
is still some ways away (though I'm sure Jon and Sridhar will be 
working their tails off to do so  ;)). 

But dont expect SCTP to be the surreptitious underlying layer
carrying TCP traffic, if thats an expectation that anyone has :)

Solving this problem without application involvement is a 
more limited scenario..

thanks,
Nivedita
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