19 gre_error (UNKNOWN_PROTOCOL, "unknown protocol")
20 gre_error (UNSUPPORTED_VERSION, "unsupported version")
21 gre_error (PKTS_DECAP, "GRE input packets decapsulated")
22 gre_error (PKTS_ENCAP, "GRE output packets encapsulated")
23 gre_error (NO_SUCH_TUNNEL, "GRE input packets dropped due to missing tunnel")
gre_error(NONE,"no error") gre_error(UNKNOWN_PROTOCOL