Re: [rtcweb] PseudoTCP implementation (Re: realiable data service)

On Wed, Jul 20, 2011 at 9:15 AM, Harald Alvestrand <harald@alvestrand.no>wrote:

> On 07/20/11 03:13, Cullen Jennings wrote:
>
>> On Jul 18, 2011, at 15:11 , Randell Jesup wrote:
>>
>>  All that said - yes, there are complexity issues to consider, which was
>>> why I was suggesting leveraging
>>> an existing tunneled protocol like SCTP or even TCP-over-UDP.
>>>
>> I agree with bunch of what you are saying but the previous several times
>> I've seen the use SCTP over UDP conversation, it usually ends about the
>> point the we ask for a user land implementation. Whatever we do more or less
>> has to be user land or already exist in the OS that people run browsers on.
>>
>> If someone has a user land implementation of SCTP or TCP, I imagine that
>> might change the outcome a bit from previous times. I have not looked at the
>> TCP over UPD library Justin mentioned but, at casual glance, I noticed is
>> around 400 lines of code which is very small, which is cool. But given the
>> lines of code in say the BSD TCP stack, it does make me wonder what's
>> missing. That said, I don't think we need something with the perforce of the
>> BSD TCP stack as long as what is there is TCP friendly and robust.
>>
> I believe this is the current URL:
>
> http://code.google.com/p/**libjingle/source/browse/trunk/**
> talk/session/tunnel/**pseudotcpchannel.cc<http://code.google.com/p/libjingle/source/browse/trunk/talk/session/tunnel/pseudotcpchannel.cc>(500 or so lines).
>
> The real protocol implementation is here:
> http://code.google.com/p/**libjingle/source/browse/trunk/**
> talk/p2p/base/pseudotcp.cc<http://code.google.com/p/libjingle/source/browse/trunk/talk/p2p/base/pseudotcp.cc>
> which is another 1000 lines (not counting the various .h files).
>
> We're not THAT good at writing compact code :-)
>

Yes, I was going to send a similar email. There are some
deficiencies/optimizations for the fact it runs over ICE-UDP - doesn't do
path MTU discovery, no checksum, no OOB data - but it is based on TCP and
implements slow start and other congestion avoidance mechanisms, and is
actively used by a number of applications where reliable transfer is
important, such as file transfer and remote desktop applications.

>
>>
>>
>>
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