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     Since time immemorial, I've accepted as a fact of life that routing 
from a nova instance to another instance via floating ip is impossible. 
  We've coped with this via a hack in dnsmasq, setting an alias to 
rewrite public IPs to the corresponding internal IP.

     Right now I'm trying to move our instances off of dnsmasq and onto 
a more robust designate/pdns setup.  Unfortunately, pdns does not 
support split-horizon nor the aliasing scheme that we used in dnsmasq. 
This has me back to square one, wishing that we could just make the 
routing work in the first place.  A recent IRC conversation leads me to 
believe that this issue may actually be fixed in modern nova-network 
versions (with the fix disabled by default), but a day of googling 
hasn't turned up much confirmation.

     Is there a fix for this I'm missing?  If not, what kind of 
solutions are people using to work around it?

     I'm running Icehouse with flatdhcp nova-network and a single 
network node.  Details about the problematic routing can be found in 
this public phabricator task: https://phabricator.wikimedia.org/T96924

     Thanks!

-Andrew