marek-sezemsky / coreemu

Automatically exported from code.google.com/p/coreemu
BSD 2-Clause "Simplified" License
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link effects between hub/switch and node only have downstream effect #233

Open GoogleCodeExporter opened 9 years ago

GoogleCodeExporter commented 9 years ago
1. Draw a link between a node and a switch and another node.
2. Configure 3ms delay on one link.
3. The round-trip delay will be 3ms, not 6ms as the GUI seems to indicate, as 
one would expect.

The netem queues only effect outbound traffic. For a link to a switch there is 
only one veth pair. For an upstream effect, a tc netem queue can be placed on 
the veth installed in the namespace container. Drawback here is that this is 
exposed to the "user" inside the container, and any queuing an app or daemon 
may apply. Another option is to try using the Intermediate Functional Block 
pseudo-device IFB, described here:

http://www.linuxfoundation.org/collaborate/workgroups/networking/netem#How_can_I
_use_netem_on_incoming_traffic.3F

Described in blog entry here:
http://coreemu.blogspot.com/2013/12/asymmetric-links-and-jitter.html

Original issue reported on code.google.com by ahrenh...@gmail.com on 3 Dec 2013 at 10:19