Here is Matt's full table and descriptive text: "Note that there is no specific reason to require any particular MTU at any particular rate. As a general principle, we prefer declining packet times (and declining worst case jitter) as you go to higher rates. Actual Vision Alternate 1 Alternate 2 Rate MTU Time MTU Time MTU Time MTU Time 10 Mb/s 1.5kB 1200uS 100 Mb/s 1.5kB 120uS 12kB 960uS 9kB 720uS 4.3kB 433uS 1 Gb/s 1.5kB 12uS 96kB 768uS 64kB 512uS 9kB 72uS 10 Gb/s 1.5kB 1.2uS 750kB 600uS 150kB 120uS 64kB 51.2uS 100 Gb/s 6MB 480uS 1.5MB 120uS 64kB 5.12uS 1 Tb/s 50MB 400uS 15MB 120uS 64kB 0.512uS The above numbers are very speculative about what MTUs might make sense in the market. We keep updating them as we learn more about how MTU affects the balance between switching costs and end-system costs vs. end-to-end performance." If you wish, you can also consider Alternate 3 for 9kB: 72us@1Gbps, 7.2us@10Gbps, .72us@100Gbps, .072us@1Tbps. Fred fred.l.templin@boeing.com