Hi, my impression from several presentations seen this week at the IETF as well as at the ISOC Panel on "Improving Internet Experience" is that we probably need to do something on reducing the number of _broken_ middleboxes (or their implementations respectively) - I'm not focusing on NAT boxes here. We all know that it's actually hard to engineer new innovative protocols around those broken boxes in the path. I think it's clear that we will not get rid of them, but if I hear about boxes that try to do "clever optimization" or "security" by rewriting TCP sequence numbers (w/o considering them in SACK), bundling segments and so on, I'm wondering who actually engineered those boxes; aren't the vendors/engineers participating in the IETF? Who buys and deploys such boxes, esp. if you consider that todays short- sighted optimization may prevent usage of a newer transport protocol that actually may provide a much larger performance improvement than this middlebox? It's really sad that we still have many problems due to such broken implementations that break the Internet transparency and hinder innovations like SCTP, ECN, various TCP enhancements, and many others. What could be IETF efforts to get a better situation for the deployment of future innovations or do we simply accept that (a few) broken middleboxes dictate the future level of innovation in the Internet? Regards, Roland Some prior related work: https://tools.ietf.org/html/rfc2775 Internet Transparency https://tools.ietf.org/html/rfc3724 The Rise of the Middle and the Future of End-to-End: Reflections on the Evolution of the Internet Architecture https://tools.ietf.org/html/rfc4924 Reflections on Internet Transparency