[e2e] application layer -SCTP!!!!

[Ian McDonald]

On 2/28/06, Srinivas Krishnan <shrin.krishnan at gmail.com> wrote:
> SCTP does seem to provide on the outside a very nice interface
> borrowing congestion control from TCP and the concept of various
> streams. However, the experiences we had with SCTP are not too good,
> especially with the PR-SCTP. We at UNC-CH wanted a protocol that lets
> choose on the application layer conditions whether we wanted a fully
> reliable protocol or just a best-effort protocol. Unfortunately the 2
> implementations of SCTP: SCTPLIB (a user level package) or the kernel
> level implementation in Linux do not fully support partial reliability
> or a way of making per packet/object decision of whether we wanted
> full reliability, partial etc.
>
> In the end we rolled out our own protocol based on UDP using TFRC as a
> congestion control algorithm (based it on the sender side). The
> protocol lets us choose whether we wanted to provide full reliability,
> partial reliability based on the application. We even have a module
> which does a form of congestion control in the application itself.
> This is for a video adaptation and hence based on latency we always do
> not need to send the next packet as the time for display on the client
> might have passed.

I am doing a similar thing but basing it in the transport layer. It
will check whether the packet is past expiry time before sending and
will also weight control packets higher than audio with video being
the lowest.

I am working with using DCCP CCID3 on Linux at present which is
similar in performance I would assume to UDP using TFRC as CCID3 is
TFRC based. Have you looked at DCCP? You might be able to choose
whether you want reliable or unreliable using a mixture of switching
between TCP and DCCP or were you wanting to switch midstream?
>
> I will describe some more of our work on video adaptation on a separate post.

Will be interested in seeing.

Ian
--
Ian McDonald
Web: http://wand.net.nz/~iam4
Blog: http://imcdnzl.blogspot.com
WAND Network Research Group
Department of Computer Science
University of Waikato
New Zealand