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Date: Sat, 14 Dec 2002 11:25:28 +1300
From: Andrew McGregor <andrew@indranet.co.nz>
To: Nivedita Singhvi <niv@us.ibm.com>
cc: Bogdan Costescu <bogdan.costescu@iwr.uni-heidelberg.de>,
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Subject: Re: R: Kernel bug handling TCP_RTO_MAX?
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--On Friday, December 13, 2002 10:07:01 -0800 Nivedita Singhvi 
<niv@us.ibm.com> wrote:

> 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)..

Things are never that simple.  But I was basically talking about a local 
policy to change the (semantics of the) API in certain cases.  It's 
probably a bad idea and would cause all kinds of breakage, but it is 
interesting to think about.

>
> 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  ;)).

I wasn't aware of the current status.  Ok, that's just where it's at.

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

That's my particular kind of crazy idea.

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

Indeed.

>
> thanks,
> Nivedita
>
>

Andrew
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