Hello Jajah,
Coincidentally, I answered this question yesterday. SAP Note 1142930 explains that "in transaction SBIW, you can specify a particular server using the 'Maintain Control Parameters for Data Transfer' Customizing activity (table ROIDOCPRMS)" at the source system side. Furthermore, you can optionally restrict the extraction job to a certain server group after implementing the code from SAP Note 1488762.
Regards,
Roger