You can have up to a 4Gbit 'pipe' to a single controller with the right setup. You'll want to use 4 subnets for sure, and definitely use decent to good (dedicated) switches for iSCSI. To get an idea of which switches are decent, check Dell Equallogic's support matrix, available from en.community.dell.com/.../2661.equallogic-compatibility-matrix-06192013.aspx.
Hello all I have a MD3200i with dual raid modules and 2 hosts, I want to achieve the maximum connection speed I can with the 8x 1GB iSCSI ports on the MD3200i. If both of my hosts were to have 8 NIC ports each, with switches in between could I theoreticly achive 2x 4GB links for each host to the MD3200i? (1x 4gb using MPIO to each raid controller module per host) If the raid controller module 0 port 0 has the IP address 192.168.130.101, can it serve 2 seperate iSCSI initiators from different hosts with IP's 192.168.130.103 and 192.168.130.104? hope this makes sense. Thank                 
MD3200i iSCSI config question