? What are Metacard's UDP (datagram) Limits

[Dar Scott]

On Monday, April 29, 2002, at 09:12 PM, Sparticus Zarris, Cross 
Country Communications wrote:

> Why can't I find this documented anywhere?

You can find this in your TCP/IP references or the RFCs.

I responded earlier, but that may be incomplete.  What you are 
seeing is the maximum number that can fit in the total size field 
of 16 bits less 20 bytes of the minimum IP header less 8 bytes for 
the UDP header.

However some environments potentially have security requirements 
that do not allow the minimum header.

The UDP datagrams you are sending are broken into many small 
packets.  If any part gets lost, the whole thing is lost.  This 
fragmenting (which applies to all IP packets) is based on the MTU 
of the media encountered along the way.

For LAN communications, I would limit datagram sizes to about 8K.

Some firewalls will not allow fragmented IP packets.  Maybe some 
routers.  In those environments you might want to limit your 
datagram size to about 1200 bytes.  I have never run across this 
problem, so I'm not sure what would be appropriate as far as size.

Some instruments and DOS applications also have size limitations.

Dar Scott