[e2e] Types Of Service
David P. Reed
dpreed at reed.com
Mon Jul 28 12:25:41 PDT 2003
I disagree - the protocols are defined to optimize a particular type of
TCP provides high reliability end-to-end. Modifying the size of its
checksum and encrypting its payload including a virtual header is all that
you would need to increase its reliability to an arbitrary level.
RTP provides lowest jitter for a data stream where loss is not a problem
(error correction adds jitter by definition).
UDP has no QoS goals - it exists to enable protocols like RTP to be
dispatched at the endpoints to the right process that implements the protocol.
Luby's Digital Fountain (over UDP) provides most efficient goodput on a
noisy channel for messages that occupy many packets (efficiency =
goodput/total_transmitted; for Digital Fountain efficiency ~ 1 - packet
error rate, which is optimal).
At 03:42 PM 7/28/2003 -0300, Fernando Gont wrote:
>In the same paper (David Clark's) as that of my previous post, it's stated
>that "The second goal of the Internet architecture is that it should
>support, at the transport service level, a variety of types of service.".
>However, only TCP, UDP, and RTP (which is built over UDP) come to my mind,
>they don't guarantee any specific type of service (for example, "low
>delay", "high throughput", etc.) by themselves.
>Besides that, for example, TCP provides a "realiable" byte stream.
>However, there are some errors that TCP won't catch, so if reliability is
>a real issue, then another layer of error control must be built up on top
>Have there been any efforts (I *do* think so) in developing transport
>protocols that focus on providing different types of service ("low delay",
>"high throughput", "true (?) reliability", etc. ) ?
>Pointers to any papers discussing the problems and efforts around this
>will be appreciated, too.
>e-mail: fernando at gont.com.ar || fgont at acm.org
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