Evaluation

Evaluation Result
      Method |a)  b)   c)  d)
      -------+-----------------
      Layer2 |NG  OK   NG  NG
      Layer3 |OK  OK*  NG  OK*
      Tunnel |OK  OK   NG  OK
      Policy |OK  OK*  OK  NG

      a)Removal of Previous Connectivity,  b)Anti-spoofing
      c)Encrypted Communication Management, d)Operation Cost

      OK = state-of-the-art technology/implementation is enough
      OK* =  same as above, but some operational hack is required.
      NG = need a development/implementation of some new protocol.