On Mon, Sep 10, 2012 at 11:34 AM, Steve Thompson smt@vgersoft.com wrote:
A CentOS 6.3 box ("host") runs several KVM virtual machines, each of which has two interfaces attached to the two bridges br1 and br2 (and each thus has two IP's; one on 192.168.0.0/22 and one on 192.168.4.0/22); net.ipv4.ip_forward on the host is 1. Simplified diagram:
host +---------------+ | |net1 = 192.168.0.0/22 | | net2 = 192.168.4.0/22 -----------------------+ br1 br2 +--------------------------------- | | | | | | | | Client A +---------------+ Client B (hosts KVM1, KVM2, etc)
Each client uses the bridge's IP address on the same side as default gateway. Client A can successfully ping or ssh (for example) to a KVM machine by IP address by using the KVM machine's net1 IP address. Client B can likewise communicate using the KVM machine's net2 IP address. However, neither client can communicate by using the address on the opposing segment (eg, Client A using KVM1_net2_IP); I can see from tcpdump that the packets are received by the virtual machine but no reply is ever made. Any clue?
Routing problem? What are the response to each of the commands below on all five systems: host, Client A and B, KVM1 and 2:
# ip addr show # ip route show