[Pacemaker] Corosync using unicast instead of multicast

[Steven Dake]

On 11/05/2010 01:30 AM, Dan Frincu wrote:
> Hi,
>
> Alan Jones wrote:
>> This question should be on the openais list, however, I happen to know
>> the answer.
>> To get up and running quickly you can configure broadcast with the
>> version you have.
>>
> I've done that already, however I was a little concerned as to what
> Steven Dake said on the openais mailing list about using broadcast
> "Broadcast and redundant ring probably don't work to well together.".
>
> I've also done some testing and saw that the broadcast address used is
> 255.255.255.255, regardless of what the bindnetaddr network address is,
> and quite frankly, I was hoping to see a directed broadcast address.
> This wasn't the case, therefore I wonder whether this was the issue that
> Steven was referring to, because by using the 255.255.255.255 as a
> broadcast address, there is the slight chance that some application
> running in the same network might send a broadcast packet using the same

This can happen with multicast or unicast modes as well.  If a third 
party application communicates on the multicast/port combo or unicast 
port of a cluster node, there is conflict.

With encryption, corosync encrypts and authenticates all packets, 
ignoring packets without a proper signature.  The signatures are 
difficult to spoof.  Without encryption, bad things happen in this 
condition.

For more details, read "SECURITY" file in our source distribution.

> port as configured on the cluster. How would the cluster react to that,
> would it ignore the packet, would it wreak havoc?
>
> Regards,
>
> Dan
>
> That's my main concern right now.
>> Corosync can distinguish separate clusters with the multicast address
>> and port that become payload to the messages.
>> The patch you referred to can be applied to the top of tree for
>> corosync or you can wait for a new release 1.3.0 planned for the end
>> of November.
>> Alan
>>
>> On Thu, Nov 4, 2010 at 1:02 AM, Dan Frincu<dfrincu at streamwide.ro>  wrote:
>>
>>> Hi all,
>>>
>>> I'm having an issue with a setup using the following:
>>> cluster-glue-1.0.6-1.6.el5.x86_64.rpm
>>> cluster-glue-libs-1.0.6-1.6.el5.x86_64.rpm
>>> corosync-1.2.7-1.1.el5.x86_64.rpm
>>> corosynclib-1.2.7-1.1.el5.x86_64.rpm
>>> drbd83-8.3.2-6.el5_3.x86_64.rpm
>>> kmod-drbd83-8.3.2-6.el5_3.x86_64.rpm
>>> openais-1.1.3-1.6.el5.x86_64.rpm
>>> openaislib-1.1.3-1.6.el5.x86_64.rpm
>>> pacemaker-1.0.9.1-1.el5.x86_64.rpm
>>> pacemaker-libs-1.0.9.1-1.el5.x86_64.rpm
>>> resource-agents-1.0.3-2.el5.x86_64.rpm
>>>
>>> This is a two-node HA cluster, with the nodes interconnected via bonded
>>> interfaces through the switch. The issue is that I have no control of the
>>> switch itself, can't do anything about that, and from what I understand the
>>> environment doesn't allow enabling multicast on the switch. In this
>>> situation, how can I have the setup functional (with redundant rings,
>>> rrp_mode: active) without using multicast.
>>>
>>> I've seen that individual network sockets are formed between nodes, unicast
>>> sockets, as well as the multicast sockets. I'm interested in knowing how
>>> will the lack of multicast affect the redundant rings, connectivity,
>>> failover, etc.
>>>
>>> I've also seen this page
>>> https://lists.linux-foundation.org/pipermail/openais/2010-October/015271.html
>>> And here it states using UDPU transport mode avoids using multicast or
>>> broadcast, but it's a patch, is this integrated in any of the newer versions
>>> of corosync?
>>>
>>> Thank you in advance.
>>>
>>> Regards,
>>>
>>> Dan
>>>
>>> --
>>> Dan FRINCU
>>> Systems Engineer
>>> CCNA, RHCE
>>> Streamwide Romania
>>>
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>>>
>>>
>>>
>>
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>>
>> Project Home:http://www.clusterlabs.org
>> Getting started:http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>> Bugs:http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
>>
>
> --
> Dan FRINCU
> Systems Engineer
> CCNA, RHCE
> Streamwide Romania
>
>
>
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>
> Project Home: http://www.clusterlabs.org
> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
> Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker