ResolutionVirtuozzo for Linux 3.0 SP1 support two networking modes - 'venet' and 'veth'.
In 'venet' mode (default mode) you could just set correct source for packets.
E.g. I have the node with two NICs - eth0 192.168.10.1/24 and eth1 172.16.0.3/24 and VE on this node with two IP addresses - 192.168.10.2 and 172.16.0.4.
Virtuozzo will try to set correct source if IP in VE match the network configured on the node, if it fail Virtuozzo will set IP of the first interface in VE as a source.
But if I set inside of VE source of packets addressed to network 172.16.0.0/24, packets will pass through eth1:
ip r a 172.16.0.0/24 dev venet0 scope link src 172.16.0.4
You may want to add this command to /etc/rc.local inside VE so that it will be configured on each VE startup.
In 'veth' mode you may configure gateway and any other parameters for each veth interface in VE. Please read the file 'ftp://downloads.swsoft.com/Rel300sp1/README.30sp1' for more
information about 'veth' mode - "VIRTUOZZO NETWORKING MODES" section. This file is shipped with Virtuozzo 3.0 SP1 distrib.