Moe Trin
Guest
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 Posted:
Sat Oct 15, 2005 8:20 am Post subject:
Re: UDP packets greater than minimum link MTU for IPv4 (68 b |
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In the Usenet newsgroup comp.dcom.modems, in article
<1129246063.016289.121530@f14g2000cwb.googlegroups.com>, Satya wrote:
| Quote: | For some reason UDP packets greater than 68 bytes is not getting
across...so this has left me wondering if it has got to do anything
with minimum link MTU for IPv4 (68 bytes).
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I don't see why - it's perfectly legal to send a UDP packet with zero
bytes of data - which means 20 bytes of IP header, and 8 bytes of UDP
header for a total of 28 bytes. The IP packet should be padded up to
the minimum link size what-ever that may be. At the other extreme, you
could have what-ever the maximum link size - as long as it's less than
65535 _total_ bytes - in theory a UDP packet could be 65507 bytes. As a
specific yardstick, DNS queries/replies over UDP are limited to 512
bytes, but NFS uses block sizes up to 8192 bytes in normal setups.
Those would be fragmented on Ethernet, unless you are using Jumbo frames.
| Quote: | Its a simple p2p application that I am coding...
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on an unknown operating system over an unspecified link. Try again.
Old guy |
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