In an effort to port a Performance Enhancing Proxy (PEP, see scps.org) to OpenBSD, I am looking at ways to simulate radio channels at IP level with loss rate, delay and jitter. Has anyone worked on, for example, extending ALTQ to add delay and/or jitter capability to OpenBSD? Would I waste my time diving into the source of ALTQ?
Two years back, I wrote an extension plugin for m0n0wall.ch which uses ipfw and dummynet in FreeBSD for traffic shaping. Actually, dummynet started off as an IP channel simulator that provides delay and jitter options besides loss rate, and then was also used for shaping/queuing. A search of the archives revealed that others asked also about extended IP channel simulation in OpenBSD. But I could not find anything ready to use yet. OpenBSD's IP stack parameter setting for high bandwidth-delay satellite channels were apparently tested using externally supplied simulation data. Apparently, others also worked on porting the SCPS (TP?) PEP to OpenBSD, but I am unclear if they ever succeeded to make it work, and if they published their work. I am grateful for any pointers towards IP channel simulation and/or PEPs such as SCPS TP in OpenBSD. Thanks, Rolf
