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?
Steve
On Mon, Sep 10, 2012 at 11:34 AM, Steve Thompson <smt at 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 -- Dale Dellutri
On Mon, Sep 10, 2012 at 11:34 AM, Steve Thompson <smt at vgersoft.com> wrote:> > > Each client uses the bridge's IP address on the same side as default > gateway.What does that mean? A bridge shouldn't have an address and a gateway needs to be the IP of something capable of routing. -- Les Mikesell lesmikesell at gmail.com