[clue] a networking riddle

Mike Bean beandaemon at gmail.com
Mon Oct 14 15:15:05 MDT 2013


So I've been scratching my head for a long time trying to understand this,
and it makes no sense to me.   We have to discrete OU's.   SCP
transmissions of any real size tend to fail from A to B, but not from B to
A.

My colleagues have been arguing that the fix is to set the MTU at side B to
1500.  And Lo, and behold, when we do, it works, increase the MTU to 9000,
and it fails again.

http://unix.stackexchange.com/questions/14187/why-does-scp-hang-on-copying-files-larger-than-1405-bytes

What I have difficulty understanding, is if a jumbo frame carries, say,
9000 bytes, and hypothetically, if it's a 5,000 bytes file + your MTU =
1500, which means you split it up into 3 transmissions.

Same size transmission; capped packet size,  more packets.   So I would
naturally conclude that at an MTU of 9000 it could get done in 1 what an
MTU of 1500 would do in 3?

(scratches head)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://cluedenver.org/pipermail/clue/attachments/20131014/4c0d7688/attachment.html 


More information about the clue mailing list