Run-time address creation in AWS

[Alex Rousskov]

On 05/04/2016 05:00 PM, unjc email wrote:

> In normal Linux machine, (correct me if I am wrong) the IP addresses of
> IP-alias could be recognized by other machines in the same subnet via
> broadcasting multicast packets.

I believe such "recognition" is usually done via regular ARP traffic,
not IP broadcast or multicast, but this is not my area of expertise.
More importantly, using [large number of] IP aliases on external
interfaces is often a bad idea because it may cause various networking
problems, including ARP floods and table overflows.


> I am able to create the aliases on the loopback interfaces using
> polygraph-aka tool with no error; 

Great.


> but TCP packets are not able to be
> routed back to the EC2 instance that runs web-polygraph client.  

If all TCP pairs (client+server) in your test are on the same subnet,
then you should have no problem setting up routes for loopback-bound
robots to reach loopback-bound servers (via the proxy if you are testing
a proxy). The old PolyMix-4 workload documentation explains how that can
be done (notice how all robots and servers use lo0 interface):
http://www.measurement-factory.com/docs/PolyMix-4/#Sect:3

Polygraph cannot setup routes automatically (yet?), but they usually
boil down to one or two "route" commands per drone and are easily
scripted if needed because the routes are usually "stable" across tests
even if the exact set of robot or server IP addresses changes.


HTH,

Alex.