2009-03-18 2009-06-18 Standards Action 0 Reserved 1 I1 (first establishment message from the initiator) 2 R1 (first establishment message from the responder) 3 I2 (2nd establishment message from the initiator) 4 R2 (2nd establishment message from the responder) 5 R1bis (Reply to reference to non-existent context) 6 I2bis (Reply to a R1bis message) 7-59 Unassigned 60-63 Reserved for Experimental Use 64 Update Request 65 Update Acknowledgement 66 Keepalive 67 Probe Message 68 Error Message 69-123 Unassigned 124-127 Reserved for Experimental Use Standards Action 0 Reserved 1 Responder Validator 2 Locator List 3 Locator Preferences 4 CGA Parameter Data Structure 5 CGA Signature 6 ULID Pair 7 Forked Instance Identifier 8-9 Unassigned 10 Keepalive Timeout Option 11-16383 Unassigned 16384-32767 Reserved for Experimental Use Standards Action 0 Unknown Shim6 message type 1 Critical Option not recognized 2 Locator verification method failed 3 Locator List Generation number out of sync 4 Error in the number of locators 5-119 Unassigned 120-127 Reserved for debugging purposes Standards Action 0 Reserved 1 HBA 2 CGA 3-200 Unassigned 201-254 Reserved for Experimental Use 255 Reserved