From: "Gregg N" 

Geo wrote:
> "John Beckett" 
wrote in message
> news:428c5a34.2637812{at}216.144.1.254...
>
>> Interesting point. Actually, UDP just uses an underlying IP datagram
>> to send its payload, so the limit is due to IP. An IP datagram can
>> carry 64K bytes (including headers), so a single UDP packet can
>> carry just less than 64K bytes of payload.
>
> Are you sure it's 64K "Bytes" and not "Bits"? That
seems like kind of
> a huge packet.
>
> Geo.

The "total length" field in the IP header is 16 bits, and
specifies the length in octets of the whole packet, including the header. A
16-bit length field allows for up to 65535 octets (when bits are on the
wire, groups of eight are referred to as "octets" rather than
"bytes").

http://www.freesoft.org/CIE/Course/Section3/7.htm

The limiting factor will not be the maximum length allowed by the IP
header, but the maximum length allowed by the Ethernet frame into which it
is inserted.

Gregg

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