Re: Add-CID and large_CID

RFC 4995, section 5.2.1.3:

    When the ROHC channel is configured with a large CID space:

       o  The large CID is always present and is represented using the
          encoding scheme of Section 5.3.2, limited to two octets.  In
          this case, the Header starts with a packet type indication.

So no, there cannot be an Add-CID octet there in this case; don't send  
them.
While there may not be a technical problem for a decopressor in  
accepting an Add-CID octet in large-CID mode, it is not quite clear  
what that means, there is no need, and this goes beyond any reasonable  
concept of robustness.

Gruesse, Carsten