Matt and I have invented a way of expanding our Treno page to be far more useful to the US ISP community. This note is a brief description of what we have in mind; we'd like to hear comments from providers on whether they would be interested in this capability. The current Treno server uses treno in an attempt to emulate TCP behavior on a straight path from the PSC to an end site somewhere in the Internet. This feature, while useful, is somewhat limited in that all of the benchmarking tests start with our single provider, MCInet. We have found that, by using GRE tunnels, the vBNS, and some smoke and mirrors, we can offer a Treno-type test starting at any router at any NAP, traversing the Internet to a host of your choice, which then returns ACKs to the Treno server via the NAP of your choice. We believe that this very general capability, not rooted in any provider or NAP, will be very useful to debugging Internet performance problems. More details on how this could work: We would attach the Treno server directly to the vBNS, where is would have a clear path to each of the NAPs. A GRE tunnel (RFC1701 & 1702 if you are unfamiliar) would be set up between the Treno server and NAP routers owned by ISPs interested in participating. The Treno server would encapsulate probes inside of GRE packets and deliver them to the appropriate exit router. This router strips off the outer headers, and forwards the probes to their destination. These packets use a source address based on the NAP desired for return traffic. For example, a provider wishing to test their infrastructure could launch a Treno test which originates at the Sprint NAP and traverses their infrastructure to the PacBell NAP. The test would indicate the overall throughput for the path. The reverse test could be done independently, allowing the isolation of assymetric problems. Another example, a user seeing poor performance to a remote site. The user could indepently test performance from their closest NAP to each of their site and the remote site. If they wished, they could also look at the view from another NAP or a third provider not related to their site or the destination site. After this analysis, it would be trivial to file a trouble ticket with the provider who owns the problem. (An aside -- providers who participate would have access to the logs, so the user filing the trouble report could simply send a URL with the Treno summary indicating the problem. This might greatly aid the communication process between end-users and providers. Heck, we could even add a mailto: button to the page...) We have tested the GRE tunneling capability on a local Cisco 7507, and have found that the load placed on the router to de-encapsulate GRE packets is about the same as what treno currently places on Cisco 7500 class routers. If there is interest, and we procede with this idea, we would include a rate throttle which would automatically stop a treno test running at rates which would put more than a minimal load on the routers performing the GRE tunneling. For example, 100 pps puts about a 5% load on our 7507. If we throttled at this rate, people would still be able to run tests up to speeds to 3.2 Mb/s at FDDI size packets, or 1.2 Mb/s at ethernet sized packets. It is in principle possible for each GRE tunnel to define a different throttle, so that heavily loaded NAP routers could be more protected than less loaded routers. In addition to rate throttling, we plan to update the Treno code to run tests in reverse (starting at the end point and reducing the TTL, rather than the current algorithm) and also to emulate, rather precisely, the proposed TCP SACK (draft-ietf-tcplw-sack-00.txt) behavior. During the implemention of this plan, we would use a phased testing period to give providers a chance to test and use the new server on their infrastructure prior to openning it up to the general public. It might also be feasible to keep separate provider access which allows providers to do things to themselves (in order to debug problems) which normal mortals using the server would not be able to do. The question we would like to pose to the provider community is, "Is this interesting and useful?" If the answer is yes, we will proceed with our work. For all you non-US people who have patiently read this far, don't necessarily think you will be left out in the cold. If the first phase of this tool works, we are interested in exploring ways to expand this capability to include non-US sites. Please send us your feedback on these ideas. Matt will also be at the NANOG meeting tomorrow if you want to ask us questions directly. --Jamshid & Matt PS. The current Treno server is at http://www.psc.edu/~pscnoc/treno.html