I believe you mean the random linear network coding (RLNC) stuff? By default, ns-3 does not have RLNC. There are several projects available for using RLNC in the application layer, i.e., data traffic packets are encoded using RLNC (or its sparse variants). One such example using it on top of UDP is by myself at:
https://github.com/yeliqseu/sparsenc, see the exampels in ns-3 folder. You may also take a look at Steinwurf's repository (you might need permission):
https://github.com/steinwurf, where they have ns-3 examples for using the KODO network coding library. I'm not aware of any (open-source) RLNC implementation in ns-3's transport or other layers. You may need to implement it by yourself.
Hope it helps.