We have recently started having connectivity problems on our network due to MTU discrepencies across platforms. We currently have a T/R server core which contains varied systems from S/390’s to Win NT Servers to OS/2 Servers. We are currently converting much of our SNA traffic to IP. As we transition to IP and migrate from T/R to Ethernet, we have been experiencing sporadic network problems caused by the seemingly different way MTU and Packet Size is handled across platforms and technologies. We are currently trying to eliminate these problems by standardizing our MTU’s across the board (from the S/390 to the workstations) to eliminate these nagging problems. The trouble we are finding is that MTU seems to be applied differently across platforms and between T/R and Ethernet. Could someome please explain exactly how the MTU is determined for both technologies? What is the optimum setting for MTU on T/R cards to enable them to work seamlessly in the Ethernet world?