On 07/12/2011 09:38 AM, Igor Smolyar wrote: >> This topology is invalid. When the MTU is set to 1200 it is expected that >> the maximum frame size received will not be greater than 1214. As such when >> the system with a 1200 MTU receives a frame larger than 1214 it will be >> dropped as an invalid packet and will be reported as an RX length error. >> >> Thanks, >> >> Alex >> > Hi Alex, > > Large icmp request is being fragmented and received icmp reply is not > exceeding the mtu. > Exactly the same topology is working with different hardware (I think > same driver but copper NIC, I will have to check exact model it > again). > > Thanks, Igor.
Well, as I stated MTU 1200 matched up with MTU 1500 is expected not to work. You can verify this by setting both sides to 1200 MTU to verify that the combination at this lower size works. In my experience when you set the MTU to 1500 it typically means you will send 1514 byte frames. The easiest way to verify what is going on would be to run tcpdump or wireshark on both sides of the connection. You should see that the transmitter with the 1200 MTU will fragment the packets and send frames that are 1214 in size. The system with the 1500 MTU will likely send 1514 byte frames from it's end, and the system with the 1200 MTU will report the rx_length_errors and not receive the frames. Thanks, Alex ------------------------------------------------------------------------------ AppSumo Presents a FREE Video for the SourceForge Community by Eric Ries, the creator of the Lean Startup Methodology on "Lean Startup Secrets Revealed." This video shows you how to validate your ideas, optimize your ideas and identify your business strategy. http://p.sf.net/sfu/appsumosfdev2dev _______________________________________________ E1000-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
