The Empty

I have been setting up 3 new Linux servers at work.  Two of them are on gigabit, so I set their MTU's to 9000 to increase the throughput of the gigabit interfaces.  During certain parts of setting the servers up, I saw issues.  I couldn't rsync from one of the gigabit servers to the other.  I couldn't scp files.  Well, I could scp files, but only tiny ones.  I was perplexed.  I could scp and rsync between either of the gigabit servers and the one on fast Ethernet.  I could ssh into any of the servers from any other.  Heck, the gigabit servers were even on the same subnet.  I asked friends and coworkers.  I got onto IRC.  No one had a hint.  Then I crafted a better google search and found this.  Basically, my packets were getting fragmented since the switch probably has the MTU set to 1500, which is the "normal" Ethernet MTU.  While the info at that URL blames a firewall or NAT, I found some other posts around the 'net from people that also experience it without any firewall or NAT in the way.

Anyway, I cranked the MTU back down to 1500 on all interfaces and everything now works fine.  Grr.