On 06/26/2013 11:58 PM, Michael Solberg wrote:
 Hi list.
 
 I'm having some trouble with my network setup and I thought maybe the
 group could help.  I have three compute nodes with two network
 interfaces.  There's a private 192.168.32.0/24 network (fixed range) on
 eth1 and a 10.17.12.128/25 network (floating range) on eth0 on these nodes.
 
 Networking works as expected.  Connectivity is good on the 192 network
 and traffic is forwarded from the floating range inbound to the fixed
 range correctly.  That is, I can ssh into an instance from the outside
 world using the floating address.  However, when traffic is leaving the
 instance, it doesn't seem to get translated.  Here's a concrete example:
 
 Instance has a fixed address of 192.168.32.4.
 Instance is assigned a floating address of 10.17.12.139.
 Instance is running on a hypervisor with the address 10.17.12.12.
 
 Pings from the instance to 10.17.12.12 return fine, but pings from the
 instance out to the internet don't work.  When I run a tcpdump, I see
 that the pings reach the destination with the source address set to
 192.168.32.4:
 
 [root(a)10.17.12.11 ~]# tcpdump -n -i eth0 icmp
 tcpdump: WARNING: eth0: no IPv4 address assigned
 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
 listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
 23:55:38.238739 IP 192.168.32.4 > 10.17.12.11: ICMP echo request, id
 45321, seq 1, length 64
 23:55:38.238774 IP 10.17.12.11 > 192.168.32.4: ICMP echo reply, id
 45321, seq 1, length 64
 
 Is this expected?  If so, is there any way to get nova-network to
 translate the outbound traffic so that it looks like it's coming from
 10.17.12.139 instead of 192.168.32.4? 
Can you provide more information on your network topology?  What
nova-network mode are you using?
Your example is for "pings from the instance out to the internet", but
you're pinging an address (10.17.12.11) that's on the same private
network as the compute node (10.17.12.12).  My guess is that is
confusing things.
-- 
Russell Bryant