Frédéric, In RFC 879, it says "HOSTS MUST NOT SEND DATAGRAMS LARGER THAN 576 OCTETS UNLESS THEY HAVE SPECIFIC KNOWLEDGE THAT THE DESTINATION HOST IS PREPARED TO ACCEPT LARGER DATAGRAMS."
However, since you say you are sending/receiving on an Ethernet network, you can assume that you can use the full Ethernet MTU. Another RFC maximum size would be around 64KB, the maximum length of an IP packet. If you are using TCP, the MSS option allows the two endpoints to communicate their local MTUs, which makes efficient use of the network. I did an isolated experiment recently with a Linux box and an unknown box on the Internet and discovered that they negotiated to using around 1500 byte packets, and there was no IP fragmentation. Therefore, the Internet core in this case was able to handle packets of that size. However this was only a single test, and was not comprehensive. I hope this helps, -David Vos On 8/1/07, Frédéric BERNON <[EMAIL PROTECTED]> wrote: > Hi group, > > Is someone can tell me if there is any RFC restricting the size of a datagram > in broadcast and in multicast on a ethernet network (other than the MTU)? > > I have in mind 512 bytes for broadcast datagrams, but I'm not sure if it's a > "RFC requirement", or a "known good practice"... > > ==================================== > Frédéric BERNON > HYMATOM SA > Chef de projet informatique > Microsoft Certified Professional > Tél. : +33 (0)4-67-87-61-10 > Fax. : +33 (0)4-67-70-85-44 > Email : [EMAIL PROTECTED] > Web Site : http://www.hymatom.fr > ==================================== > P Avant d'imprimer, penser à l'environnement > > _______________________________________________ > lwip-users mailing list > [email protected] > http://lists.nongnu.org/mailman/listinfo/lwip-users > > _______________________________________________ lwip-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/lwip-users
