[Oberon] MTU, MaxPkt, EthernetFrameSize & etc.

PETER EASTHOPE peasthope at shaw.ca
Thu Oct 2 23:18:46 MEST 2008


Since a few weeks ago, the Native Oberon system at 
home has had a problem sending large files by FTP 
and large messages by SMTP.  Small files and 
messages transmit OK to any destination and large 
files transmit OK to my Debian Lenny based router.

A possible explanation is that the ISP installed 
a router which imposes a smaller MTU than previously 
existed.  This I can test with ping.

Also I see that Net3Com509.Mod has MaxPkt = 1514;
Net3Com90x.Mod has EthernetFrameSize = 1514; 
and NetTCP.Mod has MaxSMSS = 1420;
Whereas the table in 
has Ethernet (802.3) (RFC 1191)  MTU 1492.

Can anyone comment or advise regarding the MTU setting in the 
Ethernet drivers? 

If the Ethernet MaxPkt is reduced, I guess that  
the MaxSMSS should be reduced by the same 

Would MaxSMSS = "Maximum Send Maximum Segment Size"?

Thanks for any ideas,       ... Peter E.

http://carnot.yi.org/ = http://carnot.pathology.ubc.ca/

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