Nizar
To really answer your question we need to consider not only the hardware platform of the 1841 but more importantly the particular version and feature set of the IOS software running on it. I have checked the feature navigator on the Cisco web site and I find that the 1841 running the Advanced Enterprise Services feature set does have support for DLSW and for SDLC.
So to answer your question, yes the 1841 does support IBM SNA technology.
HTH
Rick
HTH
Rick