On Sat, 6 Nov 2010, Saqib Ilyas wrote:
A friend of mine is doing some testing where he wishes to emulate a cellular-like interfaces with random drops and all, out of an ethernet interface. Since we have plenty of network and system ops on the list, I
I would say that a cellular interface doesn't really have random drops, then there is something wrong with it (at least if it's UMTS). A UMTS network has RLC re-transmits all the way between the RNC and the mobile terminal. This means that a UMTS network has more characteristics of packet flow, stalls for hundreds of milliseconds or seconds (or even minutes, my record is 240 seconds), and then a burst of packets. Very jittery, but very low rate of packet loss. Also, the terminal might go down in "idle", meaning that if you send a packet to it, it'll take 1-2 seconds for it to come out of idle, cellular resources allocated, and then the packets start flowing. I don't have a good idea how to emulate this, the tools I've seen so far usually just emulate jitter, delay and packet loss, and not really the above behaviours. -- Mikael Abrahamsson email: swmike@swm.pp.se