request APC for 'Service Zone'

Wed Oct 25 23:06:29 EDT 2000

There is the "real" answer, and the practical answer.

The real answer is that depending on what kind of network you are on,
you could see, in theory, packets of up to 64K bytes.  4K bytes can actually
seen in some Gig-E systems.  Whether you will find a video codec using such
large packets sizes or not is uncertain; I've never seen one.

It used to be that we thought 1510-odd bytes was the biggest practical
packet you
see on a LAN, but that's no longer the case.  There is a lot of code around
fails above that 1500 ish number.


> -----Original Message-----
> From: Chris Farmer [mailto:cfarmer at]
> Sent: Wednesday, October 25, 2000 9:05 PM
> To: ITU-SG16 at
> Subject: Sanity check on Packet Sizes....
> Okay,
> I was researching an arcane fact on the theoretical and
> practical sizes for
> RTP packet sizes for
> video conferencing.
> What I have come up with is:
> There is specific RFC's about implimenting H.263, H.261,
> G.723, but I'm
> looking for just an overall
> practical size to check input buffer sizes.
> RFC 1889 RTP packet structure referes to 768, RFC 791
> RFC 768 UDP refers to obsolete RFC 760.
> RFC 791 states in the Glossory,
>     ARPANET messages max size is about 1012 octets (8096)bits.
>    ARPANET packet max size is about 126 octets (1008) bits.
> As a client side EP, should I be concerned about the ARPANET
> message size or
> the ARPANET packet size?
> RFC 760 states:
>         65,536 octets theoretically, put not practical
>             Page 22, every destination should be able to
> receive a datagram
> of 576 octets in one piece or as fragments to be reassembled
> so my guess here is 4608 bits max?  Or is this too low level
> and there is
> another RFC that I should reference?
> Any help in this direction?
> Thanks,
> Christopher B. Farmer
> Software Engineer
> Smith Micro Software, Inc.
> (503) 641-1221 ext 28
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