The ethernet data-module type can be used if you have a C-lan board in your switch.
In V9.5 and up you can assign several port that only were available on serial link before, like management terminal, CDR interface, IP printer,CMS etc..
The unit you are probably looking for is the Avaya IOLAN 104
comcode 700015084, used in combination with C-LAN.
This unit does the same as the datamodule but then using IP
Also see avaya doc 555-233-116_3 from elmodocs library
Rob