wow ..that's ancient ..can you try to upgrade those to 5.x ?   Home > Support > Software Downloads and Licensing > Downloads C > Connectrix Firmware B Series  they only list ds16b3  ..not sure if 5.2.3c would work on ds16b2.  So if McData is in open fabric mode, you will need to set ds16 to initerop mode 1 (on code 5.x) and set domain id between 97-127.  When you change interop mode on Brocade ..it will wipe it clean. You don't need to mess with port mode type, typically it should auto negotiate to E-port.
It's been a long time since I worked with comparable switches. We have a subsidiary that has 2 ds4400m switches currently in use and inherited two ds16b2 switches. they want to ISL the ds16b2's to the ds4400m's and I don't recall if I need to change the ds16b2's from Native mode to a different mode to enable this.  I haven't found any documentation to provide me with the answer.  Hopefully, someone can assist me here.  thanks.  Jim 
legacy ds16b2 isl to legacy ds4400m switch