[Openais] Re: Use of unicast socket

Steven Dake sdake at mvista.com
Fri Jul 16 15:48:10 PDT 2004

On Fri, 2004-07-16 at 15:20, Sabharwal, Atul wrote:
> Hi Steve,
> I noticed that the GMI library listens to a unicast as well as a
> multicast socket
> As given in Bindnet and McastPort.  Why does it listen to the unicast
> socket ?
> There is no unicast messaging API. Also, if its for internal use, should
> there
> Not be a UnicastPort.
The unicast socket is used for the token.  They could be the same
socket.  At one time, I seperated them because I thought it was
necessary to get the socket to bind to the correct ports.  I have since
figured out how all that stuff works and a seperate socket isn't

> Also, noticed that both the SrcPort & DstPort for multicast messages are
> set to
> McastPort. This is a bug and would not allow for multiple instances of
> apps
> Using GMI. Also, if GMI was configured for a cluster which had a NAT
> module

Multiple apps could use gmi if they passed in a different port number. 
The port number may only be used once per host because of the unicast

> In the middle, this would be a problem. Although, I am not aware of use
> or
> Feasibility of IP multicast across NAT modules but theoretically, it
> should
> Be possible.

I think it is unlikely anyone would use network address translation
between networks.  The performance would be pretty slow and would likely
cause gmi to operate poorly with lots of remulticast errors and token

An interesting possiblity is a router, however.  Did you ever get the
router configuration to work?  I don't have a router to test with, so I
am not sure if this would work correctly or not.

Thanks Atul

> Thanks,
> Atul
> -------------------------------------------------------------
> P.S:  All opinions are my personal opinion(s) & responsibility and do
> not represent the view of my employer ( Intel Corporation ).

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