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<p style="margin-bottom: 0cm;"><font size="2">Hi,</font></p>
<p style="margin-bottom: 0cm;"><font size="2">I'm trying to run a J2EE
application server cluster in OpenVZ. Each J2EE application server
instance in the cluster relies on multicast to find the other cluster
members, so I need to get multicast working with OpenVZ. To start
with, I'm working with a two node cluster, consisting of two VEs,
each hosting a single J2EE server node. I've got multicast working
when the VEs are both on the same HN, and so the cluster works fine
in this situation. However, if the VEs are on separate HNs, multicast
does not work between the VEs, and so the cluster members do not find
each other. Note that all works fine if the two J2EE application
server instances are on the HNs themselves (i.e. not running in VEs)
- i.e. multicast is working fine between the two HNs. So, I'd be
grateful for some help in trying to get multicast working when the
VEs are on different HNs.</font></p>
<p style="margin-bottom: 0cm;"><font size="2">To clarify, current
working configuration, with both VEs on the same HN:</font></p>
<p style="margin-bottom: 0cm;"><font size="2">|| HN1 [VE1] <---
multicast via bridge (vzbr0) ---> [VE2] ||</font></p>
<p style="margin-bottom: 0cm;"><font size="2">And desired configuration,
with VEs on separate HNs:</font></p>
<p style="margin-bottom: 0cm;"><font size="2">|| HN1 [VE1] || <--
-multicast ---> || HN2 [VE2] ||</font></p>
<p style="margin-bottom: 0cm;"></p><p style="margin-bottom: 0cm;"><font size="2"><br></font></p><p style="margin-bottom: 0cm;"><font size="2">Environment details:</font></p>
<p style="margin-bottom: 0cm;"><font size="2">Host Kernel =
ovzkernel-smp-2.6.9-023stab044.11.x86_64 (RHEL4 based kernel for
x86_64).<br>Guest Operating System =
centos-4-x86_64-minimal .</font></p>
<p style="margin-bottom: 0cm;"></p><font size="2">Following the thread at
<a href="http://forum.openvz.org/index.php?t=msg&goto=21090">http://forum.openvz.org/index.php?t=msg&goto=21090</a> , the VEs are
configured to use veth, with the veths connected using a bridge
(vzbr0).</font><font size="2"><br>The routing tables are
setup so that the (unicast) IPs for the VEs are routed via the
bridge. This all works fine for unicast in all scenarios - i.e.
between the VEs, between the hosting HN and VEs, and between other
nodes and the VEs. It also works fine for multicast between the VEs
if they are on the same HN. However, it does not work for multicast
from the HNs to the VEs they are hosting, or from other nodes
(including VEs on other nodes) to the VEs.<br><br> </font><p style="margin-bottom: 0cm;">
</p>
<p style="margin-bottom: 0cm;"><font size="2">Steps carried out so far:</font></p><p style="margin-bottom: 0cm;"><font size="2">In attempting to get
multicast working between VEs on separate machines (HNs), so far,
I've carried out the following:</font></p>
<p style="margin-bottom: 0cm;"><font size="2">1. Added a route for the
Class D multicast address to the bridge (vzbr0). This enabled
multicast from the hosting HN to the VE it was hosting (verified this
using ping). However, other nodes, including the VE on the other HN
still could not send / receive multicast traffic from the VE.<br>2. Attempted to enable
multicast forwarding by echo 1>
/proc/sys/net/ipv4/conf/vzbr0/mc_forwarding . However, this was
denied ("Operation not permitted"). Perhaps the OpenVZ
RHEL4 kernel does not allow this by default ? However, unsure if this is
required to get multicast to work.</font></p>
<p style="margin-bottom: 0cm;"><font size="2">Questions:</font></p>
<p style="margin-bottom: 0cm;"></p>
<p style="margin-bottom: 0cm;"><font size="2">So, no luck with the
above. Does anyone have any suggestions as to how I could get this to
work ?<br>In particular, is enabling
the mc_forwarding setting required ? If so, is a RHEL4 kernel
available with this enabled ?<br>Or is there something else
I'm missing ?</font></p>
<p style="margin-bottom: 0cm;"><font size="2">Many thanks for any help
on this.</font></p>