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Re: [Linux-cluster] two nodes can't see eachother.

On Thu, Feb 26, 2009 at 12:53 PM, Antonio Dias <accdias+cluster gmail com> wrote:

On Thu, Feb 26, 2009 at 17:39, Vincent VIAL <vincent vial tv> wrote:
> I checked what you suggested but according to cman man page, broadcast is
> used by default and multicast is only used if a multicast parameter is given
> in the cluster.conf file.

I'm not sure but I believe that now the default is multicast. And if
so, the problem can be in the switch not letting igmp version packages
pass through.

I had this problem when deploying a RHEL5 cluster in a environment
using Cisco switches. Since I didn't have access to the switches
configuration, the workaround was to force my Linux boxes speaks igmp
version 2. You can try this on your boxes. Edit /etc/sysctl.conf e put
a line like this:

net.ipv4.conf.all.force_igmp_version = 2

And issue a "sysctl -p" or reboot your boxes.

Antonio Dias


I'm also trying to understand this problem. Is both cluster nodes are not in same network?, if both nodes are pinging with each other through your gateway router (may be your managed switch ). as cluster uses multicast so you have to increase the TTL value of your outgoing packets.
for e.g. you can try out this iptables command
#iptables -t mangle -I OUTPUT -j TTL --ttl-set 60
I know this is not best rule, you can customize to suite your own setup and requirement.
If doesn't help this then let us know your setup architecture.
Rajveer Singh

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