[Cluster-devel] Re: [PATCH] [DLM] Bind connections from known local address when using TCP

[Patrick Caulfield <pcaulfie@redhat.com>]

Steven Whitehouse wrote:
> Hi,
> 
> On Thu, 2007-10-25 at 18:49 -0400, Lon Hohberger wrote:
>> A common problem occurs when multiple IP addresses within the same
>> subnet are assigned to the same NIC.  If we make a connection attempt to
>> another address on the same subnet as one of those addresses, the
>> connection attempt will not necessarily be routed from the address we
>> want.
>>
>> In the case of the DLM, the other nodes will quickly drop the connection
>> attempt, causing problems.
>>
>> This patch makes the DLM bind to the local address it acquired from the
>> cluster manager when using TCP prior to making a connection, obviating
>> the need for administrators to "fix" their systems or use clever routing
>> tricks.
>>
> 
> I'm happy to apply the patch, but I wonder why not just set the prefsrc
> for the route? That will fix it for all applications not just the DLM.
> Also if there are multiple NICs in the system with the same IP address
> set assigned to them, then this solution may fail whereas the prefsrc
> solution will continue to work as that allows specification of a device
> too (amoung other things),

I think it's appropriate to fix this in the DLM code. DLM doesn't work without
it in this situation and there night (possibly!?) be applications that don't
want prefsrc setting.

-- 
Patrick