SSIS 2008 and SSIS 2012

Nothing wrong, unlike other SQL Server services SSIS is not instance-aware.  So you can only have one instance (the "default" instance) of each SQL Server version on the same machine.

In your case, to connect to SSIS 2012 you need to use SSMS 2012 and to connect to SSIS 2008 you'd use SSMS 2008.

More info: Interoperability and Coexistence (Integration Services)

"So you can only have one instance (the "default" instance) of each SQL Server version on the same machine.
"

I am already doing this kind of thing but it seems that it can find out the SSIS of one SQL edition.

I have one SSIS for SQL 2008 and one for SQL 2012.

"In your case, to connect to SSIS 2012 you need to use SSMS 2012 and to connect to SSIS 2008 you'd use SSMS 2008."

so use SSMS 2012 to connect to SIS2012 and SIS 2008 R2 using SSMS 2008 R2  ?

both edition install on my local machine.

but one thing is, SQL Server 2012 Integration Services (SSIS) can also connect to SSIS 2008 R2, how can we separate it?

so use SSMS 2012 to connect to SIS2012 and SIS 2008 R2 using SSMS 2008 R2  ?

Correct.

but one thing is, SQL Server 2012 Integration Services (SSIS) can also connect to SSIS 2008 R2, how can we separate it?

Normally not by default.  The following is an excerpt from the link I mentioned earlier:

You cannot connect to an instance of the SQL Server 2005 or the SQL Server 2008 version of the Integration Services service from the SQL Server 2012 version of Management Studio. You can use the SQL Server 2012 version of Management Studio to manage Integration Services packages that are stored in an instance of SQL Server 2008 or SQL Server 2012. You need to modify the service configuration file to add the instance of SQL Server 2008 to the list of locations managed by the service.

The choice of words is a bit confusing, but as far as I understand it unless you've modified the configuration file, SSMS 2012 will only connect to SSIS 2012.

"You need to modify the service configuration file to add the instance of SQL Server 2008 to the list of locations managed by the service."

here come a much interesting concept ! but how to modify the configuration files ?

I just verify that I can connect to SSIS 2008 R2 using SSMS 2008 and SSIS 2012 using SMS 2012, the version number tell this!

but one thing, if we are architecting that from SSDT - BI tools for VS 2010 / SSDT - BT Tools for VS2012, can we connect or deploy package to both version of SSIS ?

but one thing, if we are architecting that from SSDT - BI tools for VS 2010 / SSDT - BT Tools for VS2012, can we connect or deploy package to both version of SSIS ?

No, packages developed with SSDT will not be compatible with 2008.  If your packages need to run on 2008 you'll need to use BIDS 2008 to develop them.

" If your packages need to run on 2008 you'll need to use BIDS 2008 to develop them. "

oh shit ! my BIDS 2008 can't start at all, it just keep saying SSDT is not installed and cna't start the workspace, which in fact the SSDT installed with all patches instlaled.

any idea on how to solve this?

my BIDS 2008 can't start at all, it just keep saying SSDT is not installed and cna't start the workspace, which in fact the SSDT installed with all patches instlaled.

any idea on how to solve this?

No idea, I'd recommend to open a separate question for that issue...

"Please note that you will still not be able to actually "connect" to the 2008 SSIS instance.  But you will get an additional node in the Object Explorer when connecting to SSIS 2012.  This node will be called The2008Instance and will show the packages deployed to the 2008 MSDB.

Also note that you'll need to restart the 2012 SSIS service after changing the config file."

you mean I can't even modify it ?

Modify what exactly?  The name of the additional node?  That can be modified if you want, just change the Name property to what you prefer...

"Modify what exactly? "

config file, MsDtsSrvr.ini.xml

so just open it and edit it?

Yes, it's a text file (XML)...  But take a copy of the file first so you can always put that back to undo your changes if needed.

"But take a copy of the file first so you can always put that back to undo your changes if needed. "

yes, how to remark/comment the XML file? then I don't need to backup at all.

Why would you want to do that?  I'm not sure that it's supported but if you really insist, XML comments go like this:

<!-- comment -->

Select allOpen in new window

But I seriously recommend you to take a copy instead: CTRL+C, CTRL+V with the file selected and you've got a backup...

yeah ok !