Ubuntu
network-manager package

  1. Bug #291085
  2. Comment #6

Comment 6 for bug 291085

Revision history for this message
Mikel Ward (mikelward) wrote :

The optimal MTU was 1492. Anything higher would fail.

It turns out my ADSL router was configured with an MTU of 1500, but should have been set to 1492.

For some reason (I'm assuming a poorly designed router), ping with don't fragment and a fixed packet size didn't reveal this.

With eth0 mtu=1500, ADSL mtu=1500, ping -M do -s 1470 www.slashdot.org just hangs. With eth0 mtu=1500, ADSL mtu=1492, it prints lines like this:
From www.routerlogin.com (192.168.1.254) icmp_seq=2 Frag needed and DF set (mtu = 1492)

So setting my ADSL modem's MTU to 1492 appears to be the correct fix, but it does make me wonder why CentOS 5, NetBSD, and Windows have all been working fine, all connected via Ethernet.