Value      Value Meaning
        ------    ---------------
         0      No return code
         1      Malformed Echo Request received
         2      One or more of the TLVs is not supported
         3      Replying BFR is the only BFER in header BitString
         4      Replying BFR is one of the BFERs in header BitString
         5      Packet-Forward-Success
         6      Invalid Multipath Info Request
         8      No matching entry in the forwarding table
         9      Set-Identifier Mismatch
        10      DDMAP Mismatch