[LARTC] How to do network emulation on incoming traffic?

[kevin-lartc at horizon.com]

> Somebody will probaby correct me quickly here but I dont think there is
> a way of creating jitter and latency and packet loss easily in linux.

Er... excuse me?  The network emulator module ("netem") does it very nicely.

The problem is, it's a traffic control queue discipline, and thus
only works on egress traffic.


Actually, after having found some more docs, the whole business
of nested qdiscs is starting to make more sense.

A classful qdisc just chooses among a number of sub-queues when a
"dequeue" request from the device for more data to send arrives.

The result is a tree of qdiscs, with classless qdiscs at the leaves.


But this means that it makes no sense to have a child of a classless
qdisc.  And yet the netem examples are full of such things, e.g.:
ttp://linux-net.osdl.org/index.php/Netem#Rate_control

When does netem ever pull from the "child" queue?