[131831] in North American Network Operators' Group
Re: Emulating a cellular interface
daemon@ATHENA.MIT.EDU (Mikael Abrahamsson)
Sat Nov 6 02:09:46 2010
Date: Sat, 6 Nov 2010 07:09:41 +0100 (CET)
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Saqib Ilyas <msaqib@gmail.com>
In-Reply-To: <AANLkTimM0QFNhy8f4Jf9LLbr0Sryg2YB_32GujkgNww1@mail.gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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
