On 24 Nov 2004, at 22:11, admin wrote:
no, orcon told me to use 250 and it seems 1514 is the default in linux.
The MTU usually depends on the frame size that can be accommodated by an interface. There is no useful "default" MTU. I seem to remember hearing from someone that Linux includes the encapsulating frame headers in its calculations when it interprets an MTU, which would make 1514 make sense for Ethernet. Kind of. Except that (MAC dest + MAC source + MAC type + CRC) == 18 bytes. I don't know much about Linux, though. I tend to avoid it in favour of real operating systems. [*] As to 250 bytes, RFC 1122 says: Since nearly all networks in the Internet currently support an MTU of 576 or greater, we strongly recommend the use of 576 for datagrams sent to non-local networks. That seems like reasonable advice, particularly if you expect to have to deal with fragmentation. However, in general, if you reduce your MTU below 1500 bytes you can expect all the inexpertly-firewalled, pMTUd-enabled servers of the world to stop sending you packets, sooner or later. Joe [*] I am running away quickly now.