Jon, Do you have something blocking MTU Path Discovery? Unless I'm off base on this, shouldn't that be taking care of your issue? -Richard -----Original Message----- From: Jon Meek [mailto:meekjt@gmail.com] Sent: Friday, November 26, 2010 12:17 PM To: nanog@nanog.org Subject: Re: Jumbo frame Question I have the "opposite problem". I use iperf to test WAN and VPN throughput and packet loss, but find that the sending Linux system starts out with the expected MTU / MSS but then ramps up the packet size to way beyond 1500. The result is that network equipment must fragment the packets. On higher bandwidth circuits there are a lot of re-transmits that mask any real packet loss that might exist in the path. I have tried multiple methods to clamp the MTU, but nothing has worked so far. This leads me to wonder how often real bulk transfer applications start using jumbo packets that just end up getting fragmented downstream. The jumbo packets from iperf occur on various versions of the Linux kernel and different distributions. It might only happen on GigE. Suggestions on clamping the MTU are welcome. Thanks, Jon On Thu, Nov 25, 2010 at 7:13 PM, Harris Hui <harris.hui@hk1.ibm.com> wrote:
Hi
Does anyone have experience on design / implementing the Jumbo frame enabled network?