2011-03-24 2026-02-19 Specification Required Scott Burleigh, Fred Templin none 0 Reserved 6,7 1 Bundle Payload Block 6 2 Bundle Authentication Block 6 3 Payload Integrity Block 6 4 Payload Confidentiality Block 6 5 Previous-Hop Insertion Block 7 6 Previous node (proximate sender) 7 7 Bundle age (in milliseconds) 6 8 Metadata Extension Block 6 9 Extension Security Block 7 10 Hop count (#prior xmit attempts) 7 11 Block Integrity 7 12 Block Confidentiality 7 13 Custody Transfer Extension Block CCSDS-734.6-O-1 7 14 Compressed Status Reporting Extension Block CCSDS-734.6-O-1 7 15-191 Unassigned 6,7 192-255 Reserved for Private and/or Experimental Use RFC Required 0-5 Reserved 6 Assigned 7 Assigned 8-255 Unassigned Specification Required Scott Burleigh, Fred Templin 6,7 0 Bundle is a fragment 6,7 1 ADU is an administrative record 6,7 2 Bundle must not be fragmented 6 3 Custody transfer is requested 6 4 Destination endpoint is a singleton 6,7 5 Acknowledgement by application is requested 7 6 Status time requested in reports 6 7-8 Class of service: priority 6 9-13 Class of service: reserved 6,7 14 Request reporting of bundle reception 6 15 Request reporting of custody acceptance 6,7 16 Request reporting of bundle forwarding 6,7 17 Request reporting of bundle delivery 6,7 18 Request reporting of bundle deletion 6,7 19 Reserved 6,7 20 Reserved 21-63 Unassigned Specification Required Scott Burleigh, Fred Templin 6,7 0 Block must be replicated in every fragment 6,7 1 Transmit status report if block can't be processed 6,7 2 Delete bundle if block can't be processed 6 3 Last block 6,7 4 Discard block if it can't be processed 6 5 Block was forwarded without being processed 6 6 Block contains an EID-reference field 7-63 Unassigned RFC Required 00000000 Reserved 00000001 Reporting node received bundle 00000010 Reporting node accepted custody of bundle 00000100 Reporting node forwarded the bundle 00001000 Reporting node delivered the bundle 00010000 Reporting node deleted the bundle 00100000 Unassigned 01000000 Unassigned 10000000 Unassigned Specification Required Scott Burleigh, Fred Templin 6,7 0 No additional information 6,7 1 Lifetime expired 6,7 2 Forwarded over unidirectional link 6,7 3 Transmission canceled 6,7 4 Depleted storage 6,7 5 Destination endpoint ID unavailable 6,7 6 No known route to destination from here 6,7 7 No timely contact with next node on route 6,7 8 Block unintelligible 7 9 Hop limit exceeded 7 10 Traffic pared 7 11 Block unsupported 7 12 Missing security operation 7 13 Unknown security operation 7 14 Unexpected security operation 7 15 Failed security operation 7 16 Conflicting security operation 17-254 Unassigned 6,7 255 Reserved Specification Required Scott Burleigh, Fred Templin 0 No additional information 1-2 Unassigned 3 Redundant reception (reception by a node that is a custodial node for this bundle) 4 Depleted storage 5 Destination endpoint ID unintelligible 6 No known route to destination from here 7 No timely contact with next node on route 8 Block unintelligible 9-126 Unassigned 127 Reserved Specification Required Rick Taylor 0 Reserved 1 URI 2-191 Unassigned 192-255 Private and/or Experimental Use Specification Required Stephen Farrell, Edward Birrane 0 Unassigned 1 BAB-HMAC 2 PIB-RSA-SHA256 3 PCB-RSA-AES128-PAYLOAD-PIB-PCB 4 ESB-RSA-AES128-EXT values greater than 4 Reserved Specification Required Stephen Farrell, Edward Birrane 0 Block contains results 1 Block contains correlator 2 Block contains parameters 3 Destination EIDref present 4 Source EIDref present values greater than 4 Reserved Specification Required Stephen Farrell, Edward Birrane 0 Reserved 1 initialization vector (IV) 2 reserved 3 key-information 4 fragment-range (pair of SDNVs) 5 integrity signature 6 unassigned 7 salt 8 PCB integrity check value (ICV) 9 reserved 10 encapsulated block 11 block type of encapsulated block 12-191 reserved 192-250 private use 251-255 reserved Specification Required Marc Blanchet, Keith Scott 6,7 0 Reserved 6,7 1 Bundle status report 6 2 Custody signal 3 Unassigned 6 4 Aggregate Custody Signal CCSDS-BP 5-12 Unassigned 7 13 Compressed Custody Signal CCSDS-734.6-O-1 7 14 Compressed Reporting Signal CCSDS-734.6-O-1 15 Unassigned 7 16-254 Unassigned 7 255 ACME Node ID Validation 7 256-64383 Unassigned 7 64384-64511 Reserved for Experimental Use 7 64512-65535 Reserved for Private Use Renamed "'ipn' Scheme URI Default Allocator Node Numbers" and moved to per . Marc Blanchet, Keith Scott 0-63 Specification Required 1024-65535 Specification Required 0 Bundle Protocol Administrative Record 1 CCSDS File Delivery Service CCSDS 727.0-B-4 2 Reserved 3-63 Unassigned 64-1023 Allocated to the Space Assigned Numbers Authority (SANA) for use by Consultative Committee for Space Data Systems (CCSDS) missions. 1024-65535 Unassigned >=65535 Reserved for Private or Experimental Use RFC Required 0 Reserved 1 Reserved 2 Reserved 3 TCPCL 4 TCPCLv4 5-255 Unassigned RFC Required 0x0 Reserved DATA_SEGMENT 0x1 Indicates the transmission of a segment of bundle data, as described in Section 5.2. ACK_SEGMENT 0x2 Acknowledges reception of a data segment, as described in Section 5.3. REFUSE_BUNDLE 0x3 Indicates that the transmission of the current bundle shall be stopped, as described in Section 5.4. KEEPALIVE 0x4 KEEPALIVE message for the connection, as described in Section 5.6. SHUTDOWN 0x5 Indicates that one of the nodes participating in the connection wishes to cleanly terminate the connection, as described in Section 6. LENGTH 0x6 Contains the length (in bytes) of the next bundle, as described in Section 5.5. 0x7-0xf Unassigned RFC Required 0x0 Reason for refusal is unknown or not specified. 0x1 The receiver now has the complete bundle. The sender may now consider the bundle as completely received. 0x2 The receiver's resources are exhausted. The sender SHOULD apply reactive bundle fragmentation before retrying. 0x3 The receiver has encountered a problem that requires the bundle to be retransmitted in its entirety. 0x4-0x7 Unassigned 0x8-0xf Reserved for future usage. RFC Required 0x00 Idle timeout The connection is being closed due to idleness. 0x01 Version mismatch The node cannot conform to the specified TCPCL protocol version. 0x02 Busy The node is too busy to handle the current connection. 0x03-0xff Unassigned Expert Review Brian Sipos, Rick Taylor 0x0000 Reserved 0x0001-0x7FFF Unassigned 0x8000-0xFFFF Reserved for Private or Experimental Use Expert Review Brian Sipos, Rick Taylor 0x0000 Reserved 0x0001 Transfer Length Extension 0x0002-0x7FFF Unassigned 0x8000-0xFFFF Reserved for Private or Experimental Use RFC Required 0x00 Reserved 0x01 XFER_SEGMENT 0x02 XFER_ACK 0x03 XFER_REFUSE 0x04 KEEPALIVE 0x05 SESS_TERM 0x06 MSG_REJECT 0x07 SESS_INIT 0x08-0xEF Unassigned 0xF0-0xFF Reserved for Private or Experimental Use Specification Required Brian Sipos, Rick Taylor 0x00 Unknown 0x01 Completed 0x02 No Resources 0x03 Retransmit 0x04 Not Acceptable 0x05 Extension Failure 0x06 Session Terminating 0x07-0xEF Unassigned 0xF0-0xFF Reserved for Private or Experimental Use Specification Required Brian Sipos, Rick Taylor 0x00 Unknown 0x01 Idle timeout 0x02 Version mismatch 0x03 Busy 0x04 Contact Failure 0x05 Resource Exhaustion 0x06-0xEF Unassigned 0xF0-0xFF Reserved for Private or Experimental Use Specification Required Brian Sipos, Rick Taylor 0x00 Reserved 0x01 Message Type Unknown 0x02 Message Unsupported 0x03 Message Unexpected 0x04-0xEF Unassigned 0xF0-0xFF Reserved for Private or Experimental Use Standards Action 0 Reserved n/a 1 dtn 2 ipn 3-254 Unassigned n/a 255-65535 Reserved n/a >65535 Reserved for Private Use n/a Specification Required Ken McKeever, Edward Birrane -32768 to -1 Reserved 0 Reserved 1 BIB-HMAC-SHA2 2 BCB-AES-GCM 3 COSE (TEMPORARY - registered 2024-11-12, extension registered 2025-10-01, expires 2026-11-12) 4-32767 Unassigned Specification Required Ken McKeever, Edward Birrane 0 Include primary block flag 1 Include target header flag 2 Include security header flag 3-7 Reserved 8-15 Unassigned Specification Required Ken McKeever, Edward Birrane 0 Include primary block flag 1 Include target header flag 2 Include security header flag 3-7 Reserved 8-15 Unassigned