--- 1/draft-ietf-dtn-tcpclv4-10.txt 2019-02-28 22:13:36.754686814 -0800 +++ 2/draft-ietf-dtn-tcpclv4-11.txt 2019-02-28 22:13:36.858689339 -0800 @@ -1,22 +1,22 @@ Delay Tolerant Networking B. Sipos Internet-Draft RKF Engineering Obsoletes: 7242 (if approved) M. Demmer Intended status: Standards Track UC Berkeley -Expires: May 9, 2019 J. Ott +Expires: September 1, 2019 J. Ott Aalto University S. Perreault - November 5, 2018 + February 28, 2019 Delay-Tolerant Networking TCP Convergence Layer Protocol Version 4 - draft-ietf-dtn-tcpclv4-10 + draft-ietf-dtn-tcpclv4-11 Abstract This document describes a revised protocol for the TCP-based convergence layer (TCPCL) for Delay-Tolerant Networking (DTN). The protocol revision is based on implementation issues in the original TCPCL Version 3 of RFC7242 and updates to the Bundle Protocol contents, encodings, and convergence layer requirements in Bundle Protocol Version 7. Specifically, the TCPCLv4 uses CBOR-encoded BPv7 bundles as its service data unit being transported and provides a @@ -32,25 +32,25 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on May 9, 2019. + This Internet-Draft will expire on September 1, 2019. Copyright Notice - Copyright (c) 2018 IETF Trust and the persons identified as the + Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as @@ -69,50 +69,50 @@ 3.4. Example Message Exchange . . . . . . . . . . . . . . . . 17 4. Session Establishment . . . . . . . . . . . . . . . . . . . . 19 4.1. TCP Connection . . . . . . . . . . . . . . . . . . . . . 19 4.2. Contact Header . . . . . . . . . . . . . . . . . . . . . 19 4.3. Contact Validation and Negotiation . . . . . . . . . . . 20 4.4. Session Security . . . . . . . . . . . . . . . . . . . . 21 4.4.1. TLS Handshake Result . . . . . . . . . . . . . . . . 22 4.4.2. Example TLS Initiation . . . . . . . . . . . . . . . 22 4.5. Message Type Codes . . . . . . . . . . . . . . . . . . . 23 4.6. Session Initialization Message (SESS_INIT) . . . . . . . 24 - 4.6.1. Session Extension Items . . . . . . . . . . . . . . . 26 - 4.7. Session Parameter Negotiation . . . . . . . . . . . . . . 27 + 4.7. Session Parameter Negotiation . . . . . . . . . . . . . . 26 + 4.8. Session Extension Items . . . . . . . . . . . . . . . . . 27 5. Established Session Operation . . . . . . . . . . . . . . . . 28 5.1. Upkeep and Status Messages . . . . . . . . . . . . . . . 28 5.1.1. Session Upkeep (KEEPALIVE) . . . . . . . . . . . . . 28 5.1.2. Message Rejection (MSG_REJECT) . . . . . . . . . . . 29 5.2. Bundle Transfer . . . . . . . . . . . . . . . . . . . . . 30 - 5.2.1. Bundle Transfer ID . . . . . . . . . . . . . . . . . 30 - 5.2.2. Transfer Initialization (XFER_INIT) . . . . . . . . . 31 - 5.2.3. Data Transmission (XFER_SEGMENT) . . . . . . . . . . 34 - 5.2.4. Data Acknowledgments (XFER_ACK) . . . . . . . . . . . 35 - 5.2.5. Transfer Refusal (XFER_REFUSE) . . . . . . . . . . . 36 + 5.2.1. Bundle Transfer ID . . . . . . . . . . . . . . . . . 31 + 5.2.2. Data Transmission (XFER_SEGMENT) . . . . . . . . . . 31 + 5.2.3. Data Acknowledgments (XFER_ACK) . . . . . . . . . . . 33 + 5.2.4. Transfer Refusal (XFER_REFUSE) . . . . . . . . . . . 34 + 5.2.5. Transfer Extension Items . . . . . . . . . . . . . . 37 6. Session Termination . . . . . . . . . . . . . . . . . . . . . 38 - 6.1. Session Termination Message (SESS_TERM) . . . . . . . . . 38 + 6.1. Session Termination Message (SESS_TERM) . . . . . . . . . 39 6.2. Idle Session Shutdown . . . . . . . . . . . . . . . . . . 41 7. Implementation Status . . . . . . . . . . . . . . . . . . . . 41 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . 41 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . 42 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 43 9.1. Port Number . . . . . . . . . . . . . . . . . . . . . . . 43 - 9.2. Protocol Versions . . . . . . . . . . . . . . . . . . . . 43 + 9.2. Protocol Versions . . . . . . . . . . . . . . . . . . . . 44 9.3. Session Extension Types . . . . . . . . . . . . . . . . . 44 - 9.4. Transfer Extension Types . . . . . . . . . . . . . . . . 44 - 9.5. Message Types . . . . . . . . . . . . . . . . . . . . . . 45 + 9.4. Transfer Extension Types . . . . . . . . . . . . . . . . 45 + 9.5. Message Types . . . . . . . . . . . . . . . . . . . . . . 46 9.6. XFER_REFUSE Reason Codes . . . . . . . . . . . . . . . . 46 9.7. SESS_TERM Reason Codes . . . . . . . . . . . . . . . . . 47 9.8. MSG_REJECT Reason Codes . . . . . . . . . . . . . . . . . 48 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 49 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 49 11.1. Normative References . . . . . . . . . . . . . . . . . . 49 - 11.2. Informative References . . . . . . . . . . . . . . . . . 49 + 11.2. Informative References . . . . . . . . . . . . . . . . . 50 Appendix A. Significant changes from RFC7242 . . . . . . . . . . 50 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51 1. Introduction This document describes the TCP-based convergence-layer protocol for Delay-Tolerant Networking. Delay-Tolerant Networking is an end-to- end architecture providing communications in and/or through highly stressed environments, including those with intermittent connectivity, long and/or variable delays, and high bit error rates. @@ -233,21 +233,21 @@ transferred segment. Transmission Failure The TCPCL supports positive indication of certain reasons for bundle transmission failure, notably when the peer entity rejects the bundle or when a TCPCL session ends before transferr success. The TCPCL itself does not have a notion of transfer timeout. Reception Initialized The TCPCL supports indication to the reciver just before any transmssion data is sent. This corresponds to - reception of the XFER_INIT message. + reception of the XFER_SEGMENT message with the START flag set. Interrupt Reception The TCPCL allows a BP agent to interrupt an individual transfer before it has fully completed (successfully or not). Interruption can occur any time after the reception is initialized. Reception Success The TCPCL supports positive indication when a bundle has been fully transferred from a peer entity. Reception Intermediate Progress The TCPCL supports positive @@ -430,27 +430,26 @@ Once negotiated, the parameters of a TCPCL session cannot change and if there is a desire by either peer to transfer data under different parameters then a new session must be established. This makes CL logic simpler but relies on the assumption that establishing a TCP connection is lightweight enough that TCP connection overhead is negligable compared to TCPCL data sizes. Once the TCPCL session is established and configured in this way, bundles can be transferred in either direction. Each transfer is - performed by an initialization (XFER_INIT) message followed by one or - more logical segments of data within an XFER_SEGMENT message. - Multiple bundles can be transmitted consecutively on a single TCPCL - connection. Segments from different bundles are never interleaved. - Bundle interleaving can be accomplished by fragmentation at the BP - layer or by establishing multiple TCPCL sessions between the same - peers. + performed by an sequence of logical segments of data within + XFER_SEGMENT messages. Multiple bundles can be transmitted + consecutively in a single direction on a single TCPCL connection. + Segments from different bundles are never interleaved. Bundle + interleaving can be accomplished by fragmentation at the BP layer or + by establishing multiple TCPCL sessions between the same peers. A feature of this protocol is for the receiving node to send acknowledgment (XFER_ACK) messages as bundle data segments arrive . The rationale behind these acknowledgments is to enable the sender node to determine how much of the bundle has been received, so that in case the session is interrupted, it can perform reactive fragmentation to avoid re-sending the already transmitted part of the bundle. In addition, there is no explicit flow control on the TCPCL layer. @@ -638,48 +637,48 @@ V [SESSTERM] Figure 10: Processing of Session Initiation (PSI) Transfers can occur after a session is established and it's not in the ending state. Each transfer occurs within a single logical transfer stream between a sender and a receiver, as illustrated in Figure 11 and Figure 12 respectively. - +--Send XFER_DATA--+ + +--Send XFER_SEGMENT--+ +--------+ | | | Stream | +-------------+ | - | Idle |---Send XFER_INIT-->| In Progress |<---------+ + | Idle |---Send XFER_SEGMENT-->| In Progress |<------------+ +--------+ +-------------+ | - +------All segments sent-------+ + +---------All segments sent-------+ | V +---------+ +--------+ | Waiting |---- Receive Final---->| Stream | - | for Ack | Ack | IDLE | + | for Ack | XFER_ACK | IDLE | +---------+ +--------+ Figure 11: Transfer sender states Notes on transfer sending: Pipelining of transfers can occur when the sending entity begins a new transfer while in the "Waiting for Ack" state. - +-Receive XFER_DATA-+ - +--------+ | Send Ack | + +-Receive XFER_SEGMENT-+ + +--------+ | Send XFER_ACK | | Stream | +-------------+ | - | IDLE |--Receive XFER_INIT-->| In Progress |<----------+ + | IDLE |--Receive XFER_SEGMENT-->| In Progress |<-------------+ +--------+ +-------------+ | - +---------Sent Final Ack---------+ + +--------Sent Final XFER_ACK--------+ | V +--------+ | Stream | | IDLE | +--------+ Figure 12: Transfer receiver states 3.3. Transfer Segmentation Policies @@ -729,48 +728,43 @@ and transfer extension types can apply further nuance to transfer policies and policy negotiation. 3.4. Example Message Exchange The following figure depicts the protocol exchange for a simple session, showing the session establishment and the transmission of a single bundle split into three data segments (of lengths "L1", "L2", and "L3") from Entity A to Entity B. - Note that the sending node MAY transmit multiple XFER_SEGMENT - messages without necessarily waiting for the corresponding XFER_ACK - responses. This enables pipelining of messages on a transfer stream. - Although this example only demonstrates a single bundle transmission, - it is also possible to pipeline multiple XFER_SEGMENT messages for + Note that the sending node can transmit multiple XFER_SEGMENT + messages without waiting for the corresponding XFER_ACK responses. + This enables pipelining of messages on a transfer stream. Although + this example only demonstrates a single bundle transmission, it is + also possible to pipeline multiple XFER_SEGMENT messages for different bundles without necessarily waiting for XFER_ACK messages to be returned for each one. However, interleaving data segments from different bundles is not allowed. No errors or rejections are shown in this example. Entity A Entity B ======== ======== +-------------------------+ | Contact Header | -> +-------------------------+ +-------------------------+ <- | Contact Header | +-------------------------+ +-------------------------+ | SESS_INIT | -> +-------------------------+ +-------------------------+ <- | SESS_INIT | +-------------------------+ +-------------------------+ - | XFER_INIT | -> - | Transfer ID [I1] | - | Total Length [L1] | - +-------------------------+ - +-------------------------+ | XFER_SEGMENT (start) | -> | Transfer ID [I1] | | Length [L1] | | Bundle Data 0..(L1-1) | +-------------------------+ +-------------------------+ +-------------------------+ | XFER_SEGMENT | -> <- | XFER_ACK (start) | | Transfer ID [I1] | | Transfer ID [I1] | | Length [L2] | | Length [L1] | |Bundle Data L1..(L1+L2-1)| +-------------------------+ @@ -851,21 +845,23 @@ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +---------------+---------------+---------------+---------------+ | magic='dtn!' | +---------------+---------------+---------------+---------------+ | Version | Flags | +---------------+---------------+ Figure 14: Contact Header Format See Section 4.3 for details on the use of each of these contact - header fields. The fields of the contact header are: + header fields. + + The fields of the contact header are: magic: A four-octet field that always contains the octet sequence 0x64 0x74 0x6e 0x21, i.e., the text string "dtn!" in US-ASCII (and UTF-8). Version: A one-octet field value containing the value 4 (current version of the protocol). Flags: A one-octet field of single-bit flags, interpreted according to the descriptions in Table 1. @@ -1011,121 +1007,166 @@ Message Type: Indicates the type of the message as per Table 2 below. Encoded values are listed in Section 9.5. +--------------+----------------------------------------------------+ | Type | Description | +--------------+----------------------------------------------------+ | SESS_INIT | Contains the session parameter inputs from one of | | | the entities, as described in Section 4.6. | | | | - | XFER_INIT | Contains the length (in octets) of the next | - | | transfer, as described in Section 5.2.2. | - | | | | XFER_SEGMENT | Indicates the transmission of a segment of bundle | - | | data, as described in Section 5.2.3. | + | | data, as described in Section 5.2.2. | | | | | XFER_ACK | Acknowledges reception of a data segment, as | - | | described in Section 5.2.4. | + | | described in Section 5.2.3. | | | | | XFER_REFUSE | Indicates that the transmission of the current | | | bundle SHALL be stopped, as described in Section | - | | 5.2.5. | + | | 5.2.4. | | | | | KEEPALIVE | Used to keep TCPCL session active, as described in | | | Section 5.1.1. | | | | | SESS_TERM | Indicates that one of the entities participating | | | in the session wishes to cleanly terminate the | | | session, as described in Section 6. | | | | | MSG_REJECT | Contains a TCPCL message rejection, as described | | | in Section 5.1.2. | +--------------+----------------------------------------------------+ Table 2: TCPCL Message Types 4.6. Session Initialization Message (SESS_INIT) Before a session is established and ready to transfer bundles, the session parameters are negotiated between the connected entities. The SESS_INIT message is used to convey the per-entity parameters - which are used together to negotiate the per-session parameters. + which are used together to negotiate the per-session parameters as + described in Section 4.7. The format of a SESS_INIT message is as follows in Figure 17. +-------------------------------+ | Message Header | +-------------------------------+ | Keepalive Interval (U16) | +-------------------------------+ | Segment MRU (U64) | +-------------------------------+ | Transfer MRU (U64) | +-------------------------------+ | EID Length (U16) | +-------------------------------+ | EID Data (variable) | +-------------------------------+ - | Session Extension Length (U64)| + | Session Extension Length (U32)| +-------------------------------+ | Session Extension Items (var.)| +-------------------------------+ Figure 17: SESS_INIT Format - A 16-bit unsigned integer indicating the interval, in seconds, - between any subsequent messages being transmitted by the peer. - The peer receiving this contact header uses this interval to - determine how long to wait after any last-message transmission and - a necessary subsequent KEEPALIVE message transmission. + The fields of the SESS_INIT message are: - A 64-bit unsigned integer indicating the largest allowable single- - segment data payload size to be received in this session. Any - XFER_SEGMENT sent to this peer SHALL have a data payload no longer - than the peer's Segment MRU. The two entities of a single session - MAY have different Segment MRUs, and no relation between the two - is required. + Keepalive Interval: A 16-bit unsigned integer indicating the + interval, in seconds, between any subsequent messages being + transmitted by the peer. The peer receiving this contact header + uses this interval to determine how long to wait after any last- + message transmission and a necessary subsequent KEEPALIVE message + transmission. - A 64-bit unsigned integer indicating the largest allowable total- - bundle data size to be received in this session. Any bundle - transfer sent to this peer SHALL have a Total Bundle Length - payload no longer than the peer's Transfer MRU. This value can be - used to perform proactive bundle fragmentation. The two entities - of a single session MAY have different Transfer MRUs, and no + Segment MRU: A 64-bit unsigned integer indicating the largest + allowable single-segment data payload size to be received in this + session. Any XFER_SEGMENT sent to this peer SHALL have a data + payload no longer than the peer's Segment MRU. The two entities + of a single session MAY have different Segment MRUs, and no relation between the two is required. - Together these fields represent a variable-length text string. - The EID Length is a 16-bit unsigned integer indicating the number - of octets of EID Data to follow. A zero EID Length SHALL be used - to indicate the lack of EID rather than a truly empty EID. This - case allows an entity to avoid exposing EID information on an - untrusted network. A non-zero-length EID Data SHALL contain the - UTF-8 encoded EID of some singleton endpoint in which the sending - entity is a member, in the canonical format of :. This EID encoding is consistent - with [I-D.ietf-dtn-bpbis]. + Transfer MRU: A 64-bit unsigned integer indicating the largest + allowable total-bundle data size to be received in this session. + Any bundle transfer sent to this peer SHALL have a Total Bundle + Length payload no longer than the peer's Transfer MRU. This value + can be used to perform proactive bundle fragmentation. The two + entities of a single session MAY have different Transfer MRUs, and + no relation between the two is required. - Together these fields represent protocol extension data not - defined by this specification. The Session Extension Length is - the total number of octets to follow which are used to encode the - Session Extension Item list. The encoding of each Session - Extension Item is within a consistent data container as described - in Section 4.6.1. The full set of Session Extension Items apply - for the duration of the TCPCL session to follow. The order and - mulitplicity of these Session Extension Items MAY be significant, - as defined in the associated type specification(s). + EID Length and EID Data: Together these fields represent a variable- + length text string. The EID Length is a 16-bit unsigned integer + indicating the number of octets of EID Data to follow. A zero EID + Length SHALL be used to indicate the lack of EID rather than a + truly empty EID. This case allows an entity to avoid exposing EID + information on an untrusted network. A non-zero-length EID Data + SHALL contain the UTF-8 encoded EID of some singleton endpoint in + which the sending entity is a member, in the canonical format of + :. This EID encoding is + consistent with [I-D.ietf-dtn-bpbis]. -4.6.1. Session Extension Items + Session Extension Length and Session Extension Items: Together these + fields represent protocol extension data not defined by this + specification. The Session Extension Length is the total number + of octets to follow which are used to encode the Session Extension + Item list. The encoding of each Session Extension Item is within + a consistent data container as described in Section 4.8. The full + set of Session Extension Items apply for the duration of the TCPCL + session to follow. The order and mulitplicity of these Session + Extension Items MAY be significant, as defined in the associated + type specification(s). + +4.7. Session Parameter Negotiation + + An entity calculates the parameters for a TCPCL session by + negotiating the values from its own preferences (conveyed by the + contact header it sent to the peer) with the preferences of the peer + node (expressed in the contact header that it received from the + peer). The negotiated parameters defined by this specification are + described in the following paragraphs. + + Transfer MTU and Segment MTU: The maximum transmit unit (MTU) for + whole transfers and individual segments are idententical to the + Transfer MRU and Segment MRU, respectively, of the recevied + contact header. A transmitting peer can send individual segments + with any size smaller than the Segment MTU, depending on local + policy, dynamic network conditions, etc. Determining the size of + each transmitted segment is an implementation matter. + + Session Keepalive: Negotiation of the Session Keepalive parameter is + performed by taking the minimum of this two contact headers' + Keepalive Interval. The Session Keepalive interval is a parameter + for the behavior described in Section 5.1.1. + + Enable TLS: Negotiation of the Enable TLS parameter is performed by + taking the logical AND of the two contact headers' CAN_TLS flags. + A local security policy is then applied to determine of the + negotated value of Enable TLS is acceptable. It can be a + reasonable security policy to both require or disallow the use of + TLS depending upon the desired network flows. If the Enable TLS + state is unacceptable, the node SHALL terminate the session with a + reason code of "Contact Failure". Note that this contact failure + is different than a failure of TLS handshake after an agreed-upon + and acceptable Enable TLS state. If the negotiated Enable TLS + value is true and acceptable then TLS negotiation feature + (described in Section 4.4) begins immediately following the + contact header exchange. + + Once this process of parameter negotiation is completed (which + includes a possible completed TLS handshake of the connection to use + TLS), this protocol defines no additional mechanism to change the + parameters of an established session; to effect such a change, the + TCPCL session MUST be terminated and a new session established. + +4.8. Session Extension Items Each of the Session Extension Items SHALL be encoded in an identical Type-Length-Value (TLV) container form as indicated in Figure 18. + The fields of the Session Extension Item are: Flags: A one-octet field containing generic bit flags about the Item, which are listed in Table 3. If a TCPCL entity receives a Session Extension Item with an unknown Item Type and the CRITICAL flag set, the entity SHALL close the TCPCL session with SESS_TERM reason code of "Contact Failure". If the CRITICAL flag is not set, an entity SHALL skip over and ignore any item with an unknown Item Type. @@ -1133,24 +1174,23 @@ the extension item. This specification does not define any extension types directly, but does allocate an IANA registry for such codes (see Section 9.3). Item Length: A 32-bit unsigned integer field containing the number of Item Value octets to follow. Item Value: A variable-length data field which is interpreted according to the associated Item Type. This specification places no restrictions on an extension's use of available Item Value - data. Extension specification SHOULD avoid the use of large data - exchanges within the TCPCL contact header as no bundle transfers - can begin until the full contact exchange and negotiation has been - completed. + data. Extension specifications SHOULD avoid the use of large data + lengths, as no bundle transfers can begin until the full extension + data is sent. 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +---------------+---------------+---------------+---------------+ | Item Flags | Item Type | Item Length...| +---------------+---------------+---------------+---------------+ | length contd. | Item Value... | +---------------+---------------+---------------+---------------+ | value contd. | +---------------+---------------+---------------+---------------+ @@ -1161,62 +1201,20 @@ | Name | Code | Description | +----------+--------+-----------------------------------------------+ | CRITICAL | 0x01 | If bit is set, indicates that the receiving | | | | peer must handle the extension item. | | | | | | Reserved | others | +----------+--------+-----------------------------------------------+ Table 3: Session Extension Item Flags -4.7. Session Parameter Negotiation - - An entity calculates the parameters for a TCPCL session by - negotiating the values from its own preferences (conveyed by the - contact header it sent to the peer) with the preferences of the peer - node (expressed in the contact header that it received from the - peer). The negotiated parameters defined by this specification are - described in the following paragraphs. - - Transfer MTU and Segment MTU: The maximum transmit unit (MTU) for - whole transfers and individual segments are idententical to the - Transfer MRU and Segment MRU, respectively, of the recevied - contact header. A transmitting peer can send individual segments - with any size smaller than the Segment MTU, depending on local - policy, dynamic network conditions, etc. Determining the size of - each transmitted segment is an implementation matter. - - Session Keepalive: Negotiation of the Session Keepalive parameter is - performed by taking the minimum of this two contact headers' - Keepalive Interval. The Session Keepalive interval is a parameter - for the behavior described in Section 5.1.1. - - Enable TLS: Negotiation of the Enable TLS parameter is performed by - taking the logical AND of the two contact headers' CAN_TLS flags. - A local security policy is then applied to determine of the - negotated value of Enable TLS is acceptable. It can be a - reasonable security policy to both require or disallow the use of - TLS depending upon the desired network flows. If the Enable TLS - state is unacceptable, the node SHALL terminate the session with a - reason code of "Contact Failure". Note that this contact failure - is different than a failure of TLS handshake after an agreed-upon - and acceptable Enable TLS state. If the negotiated Enable TLS - value is true and acceptable then TLS negotiation feature - (described in Section 4.4) begins immediately following the - contact header exchange. - - Once this process of parameter negotiation is completed (which - includes a possible completed TLS handshake of the connection to use - TLS), this protocol defines no additional mechanism to change the - parameters of an established session; to effect such a change, the - TCPCL session MUST be terminated and a new session established. - 5. Established Session Operation This section describes the protocol operation for the duration of an established session, including the mechanism for transmitting bundles over the session. 5.1. Upkeep and Status Messages 5.1.1. Session Upkeep (KEEPALIVE) @@ -1238,26 +1236,25 @@ choose a keepalive interval no longer than 10 minutes (600 seconds). Note: The Keepalive Interval SHOULD NOT be chosen too short as TCP retransmissions MAY occur in case of packet loss. Those will have to be triggered by a timeout (TCP retransmission timeout (RTO)), which is dependent on the measured RTT for the TCP connection so that KEEPALIVE messages MAY experience noticeable latency. The format of a KEEPALIVE message is a one-octet message type code of KEEPALIVE (as described in Table 2) with no additional data. Both - sides SHOULD send a KEEPALIVE message whenever the negotiated - interval has elapsed with no transmission of any message (KEEPALIVE - or other). + sides SHALL send a KEEPALIVE message whenever the negotiated interval + has elapsed with no transmission of any message (KEEPALIVE or other). If no message (KEEPALIVE or other) has been received in a session - after some implementation-defined time duration, then the node SHOULD + after some implementation-defined time duration, then the node SHALL terminate the session by transmitting a SESS_TERM message (as described in Section 6.1) with reason code "Idle Timeout". If configurable, the idle timeout duration SHOULD be no shorter than twice the keepalive interval. If not configurable, the idle timeout duration SHOULD be exactly twice the keepout interval. 5.1.2. Message Rejection (MSG_REJECT) If a TCPCL node receives a message which is unknown to it (possibly due to an unhandled protocol mismatch) or is inappropriate for the @@ -1330,301 +1327,209 @@ 5.2.1. Bundle Transfer ID Each of the bundle transfer messages contains a Transfer ID which is used to correlate messages (from both sides of a transfer) for each bundle. A Transfer ID does not attempt to address uniqueness of the bundle data itself and has no relation to concepts such as bundle fragmentation. Each invocation of TCPCL by the bundle protocol agent, requesting transmission of a bundle (fragmentary or otherwise), results in the initiation of a single TCPCL transfer. - Each transfer entails the sending of a XFER_INIT message and some - number of XFER_SEGMENT and XFER_ACK messages; all are correlated by - the same Transfer ID. + Each transfer entails the sending of a sequence of some number of + XFER_SEGMENT and XFER_ACK messages; all are correlated by the same + Transfer ID. Transfer IDs from each node SHALL be unique within a single TCPCL session. The initial Transfer ID from each node SHALL have value zero. Subsequent Transfer ID values SHALL be incremented from the prior Transfer ID value by one. Upon exhaustion of the entire 64-bit Transfer ID space, the sending node SHALL terminate the session with SESS_TERM reason code "Resource Exhaustion". For bidirectional bundle transfers, a TCPCL node SHOULD NOT rely on any relation between Transfer IDs originating from each side of the TCPCL session. -5.2.2. Transfer Initialization (XFER_INIT) - - The XFER_INIT message contains the total length, in octets, of the - bundle data in the associated transfer. The total length is - formatted as a 64-bit unsigned integer. - - The purpose of the XFER_INIT message is to allow entities to - preemptively refuse bundles that would exceed their resources or to - prepare storage on the receiving node for the upcoming bundle data. - See Section 5.2.5 for details on when refusal based on XFER_INIT - content is acceptable. - - The Total Bundle Length field within a XFER_INIT message SHALL be - treated as authoritative by the receiver. If, for whatever reason, - the actual total length of bundle data received differs from the - value indicated by the XFER_INIT message, the receiver SHOULD treat - the transmitted data as invalid. - - The format of the XFER_INIT message is as follows in Figure 20. - - +-----------------------------+ - | Message Header | - +-----------------------------+ - | Transfer ID (U64) | - +-----------------------------+ - | Total Bundle Length (U64) | - +-----------------------------+ - | Transfer Extension | - | Length (U64) | - +-----------------------------+ - | Transfer Extension Items... | - +-----------------------------+ - - Figure 20: Format of XFER_INIT Messages - - The fields of the XFER_INIT message are: - - Transfer ID: A 64-bit unsigned integer identifying the transfer - about to begin. - - Total Bundle Length: A 64-bit unsigned integer indicating the size - of the data-to-be-transferred. - - Transfer Extension Length and Transfer Extension Items: Together - these fields represent protocol extension data not defined by this - specification. The Transfer Extension Length is the total number - of octets to follow which are used to encode the Transfer - Extension Item list. The encoding of each Transfer Extension Item - is within a consistent data container as described in - Section 5.2.2.1. The full set of transfer extension items apply - only to the assoicated single transfer. The order and - mulitplicity of these transfer extension items MAY be significant, - as defined in the associated type specification(s). - - An XFER_INIT message SHALL be sent as the first message in a transfer - sequence, before transmission of any XFER_SEGMENT messages for the - same Transfer ID. XFER_INIT messages MUST NOT be sent unless the - next XFER_SEGMENT message has the 'START' bit set to "1" (i.e., just - before the start of a new transfer). - -5.2.2.1. Transfer Extension Items - - Each of the Transfer Extension Items SHALL be encoded in an identical - Type-Length-Value (TLV) container form as indicated in Figure 21. - The fields of the Transfer Extension Item are: - - Flags: A one-octet field containing generic bit flags about the - Item, which are listed in Table 5. If a TCPCL node receives a - Transfer Extension Item with an unknown Item Type and the CRITICAL - flag set, the node SHALL refuse the transfer with an XFER_REFUSE - reason code of "Extension Failure". If the CRITICAL flag is not - set, an entity SHALL skip over and ignore any item with an unknown - Item Type. - - Item Type: A 16-bit unsigned integer field containing the type of - the extension item. This specification does not define any - extension types directly, but does allocate an IANA registry for - such codes (see Section 9.4). - - Item Length: A 32-bit unsigned integer field containing the number - of Item Value octets to follow. - - Item Value: A variable-length data field which is interpreted - according to the associated Item Type. This specification places - no restrictions on an extension's use of available Item Value - data. Extension specification SHOULD avoid the use of large data - exchanges within the XFER_INIT as the associated transfer cannot - begin until the full initialization message is sent. - - 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 - +---------------+---------------+---------------+---------------+ - | Item Flags | Item Type | Item Length...| - +---------------+---------------+---------------+---------------+ - | length contd. | Item Value... | - +---------------+---------------+---------------+---------------+ - | value contd. | - +---------------+---------------+---------------+---------------+ - - Figure 21: Transfer Extension Item Format - - +----------+--------+-----------------------------------------------+ - | Name | Code | Description | - +----------+--------+-----------------------------------------------+ - | CRITICAL | 0x01 | If bit is set, indicates that the receiving | - | | | peer must handle the extension item. | - | | | | - | Reserved | others | - +----------+--------+-----------------------------------------------+ - - Table 5: Transfer Extension Item Flags - -5.2.3. Data Transmission (XFER_SEGMENT) +5.2.2. Data Transmission (XFER_SEGMENT) Each bundle is transmitted in one or more data segments. The format - of a XFER_SEGMENT message follows in Figure 22. + of a XFER_SEGMENT message follows in Figure 20. +------------------------------+ | Message Header | +------------------------------+ | Message Flags (U8) | +------------------------------+ | Transfer ID (U64) | +------------------------------+ + | Transfer Extension | + | Length (U32) | + | (only for START segment) | + +------------------------------+ + | Transfer Extension | + | Items (var.) | + | (only for START segment) | + +------------------------------+ | Data length (U64) | +------------------------------+ | Data contents (octet string) | +------------------------------+ - Figure 22: Format of XFER_SEGMENT Messages + Figure 20: Format of XFER_SEGMENT Messages The fields of the XFER_SEGMENT message are: Message Flags: A one-octet field of single-bit flags, interpreted - according to the descriptions in Table 6. + according to the descriptions in Table 5. Transfer ID: A 64-bit unsigned integer identifying the transfer being made. + Transfer Extension Length and Transfer Extension Items: Together + these fields represent protocol extension data for this + specification. The Transfer Extension Length and Transfer + Extension Item fields SHALL only be present when the 'START' flag + is set on the message. The Transfer Extension Length is the total + number of octets to follow which are used to encode the Transfer + Extension Item list. The encoding of each Transfer Extension Item + is within a consistent data container as described in + Section 5.2.5. The full set of transfer extension items apply + only to the assoicated single transfer. The order and + mulitplicity of these transfer extension items MAY be significant, + as defined in the associated type specification(s). + Data length: A 64-bit unsigned integer indicating the number of octets in the Data contents to follow. Data contents: The variable-length data payload of the message. +----------+--------+-----------------------------------------------+ | Name | Code | Description | +----------+--------+-----------------------------------------------+ | END | 0x01 | If bit is set, indicates that this is the | | | | last segment of the transfer. | | | | | | START | 0x02 | If bit is set, indicates that this is the | | | | first segment of the transfer. | | | | | | Reserved | others | +----------+--------+-----------------------------------------------+ - Table 6: XFER_SEGMENT Flags + Table 5: XFER_SEGMENT Flags The flags portion of the message contains two optional values in the - two low-order bits, denoted 'START' and 'END' in Table 6. The + two low-order bits, denoted 'START' and 'END' in Table 5. The 'START' bit MUST be set to one if it precedes the transmission of the first segment of a transfer. The 'END' bit MUST be set to one when transmitting the last segment of a transfer. In the case where an entire transfer is accomplished in a single segment, both the 'START' and 'END' bits MUST be set to one. Once a transfer of a bundle has commenced, the node MUST only send segments containing sequential portions of that bundle until it sends a segment with the 'END' bit set. No interleaving of multiple transfers from the same node is possible within a single TCPCL session. Simultaneous transfers between two entities MAY be achieved using multiple TCPCL sessions. -5.2.4. Data Acknowledgments (XFER_ACK) +5.2.3. Data Acknowledgments (XFER_ACK) Although the TCP transport provides reliable transfer of data between transport peers, the typical BSD sockets interface provides no means to inform a sending application of when the receiving application has processed some amount of transmitted data. Thus, after transmitting some data, the TCPCL needs an additional mechanism to determine whether the receiving agent has successfully received the segment. To this end, the TCPCL protocol provides feedback messaging whereby a receiving node transmits acknowledgments of reception of data segments. - The format of an XFER_ACK message follows in Figure 23. + The format of an XFER_ACK message follows in Figure 21. +-----------------------------+ | Message Header | +-----------------------------+ | Message Flags (U8) | +-----------------------------+ | Transfer ID (U64) | +-----------------------------+ | Acknowledged length (U64) | +-----------------------------+ - Figure 23: Format of XFER_ACK Messages + Figure 21: Format of XFER_ACK Messages The fields of the XFER_ACK message are: Message Flags: A one-octet field of single-bit flags, interpreted - according to the descriptions in Table 6. + according to the descriptions in Table 5. Transfer ID: A 64-bit unsigned integer identifying the transfer being acknowledged. Acknowledged length: A 64-bit unsigned integer indicating the total number of octets in the transfer which are being acknowledged. A receiving TCPCL node SHALL send an XFER_ACK message in response to each received XFER_SEGMENT message. The flags portion of the XFER_ACK header SHALL be set to match the corresponding DATA_SEGMENT message being acknowledged. The acknowledged length of each XFER_ACK contains the sum of the data length fields of all XFER_SEGMENT messages received so far in the course of the indicated transfer. - The sending node MAY transmit multiple XFER_SEGMENT messages without - necessarily waiting for the corresponding XFER_ACK responses. This + The sending node SHOULD transmit multiple XFER_SEGMENT messages + without waiting for the corresponding XFER_ACK responses. This enables pipelining of messages on a transfer stream. For example, suppose the sending node transmits four segments of bundle data with lengths 100, 200, 500, and 1000, respectively. After receiving the first segment, the node sends an acknowledgment of length 100. After the second segment is received, the node sends an acknowledgment of length 300. The third and fourth acknowledgments are of length 800 and 1800, respectively. -5.2.5. Transfer Refusal (XFER_REFUSE) +5.2.4. Transfer Refusal (XFER_REFUSE) The TCPCL supports a mechanism by which a receiving node can indicate to the sender that it does not want to receive the corresponding - bundle. To do so, upon receiving a XFER_INIT or XFER_SEGMENT - message, the node MAY transmit a XFER_REFUSE message. As data - segments and acknowledgments MAY cross on the wire, the bundle that - is being refused SHALL be identified by the Transfer ID of the - refusal. + bundle. To do so, upon receiving an XFER_SEGMENT message, the node + MAY transmit a XFER_REFUSE message. As data segments and + acknowledgments MAY cross on the wire, the bundle that is being + refused SHALL be identified by the Transfer ID of the refusal. There is no required relation between the Transfer MRU of a TCPCL node (which is supposed to represent a firm limitation of what the node will accept) and sending of a XFER_REFUSE message. A XFER_REFUSE can be used in cases where the agent's bundle storage is temporarily depleted or somehow constrained. A XFER_REFUSE can also be used after the bundle header or any bundle data is inspected by an agent and determined to be unacceptable. - A receiver MAY send an XFER_REFUSE message as soon as it receives a - XFER_INIT message without waiting for the next XFER_SEGMENT message. - The sender MUST be prepared for this and MUST associate the refusal - with the correct bundle via the Transfer ID fields. + A receiver MAY send an XFER_REFUSE message as soon as it receives any + XFER_SEGMENT message. The sender MUST be prepared for this and MUST + associate the refusal with the correct bundle via the Transfer ID + fields. - The format of the XFER_REFUSE message is as follows in Figure 24. + The format of the XFER_REFUSE message is as follows in Figure 22. +-----------------------------+ | Message Header | +-----------------------------+ | Reason Code (U8) | +-----------------------------+ | Transfer ID (U64) | +-----------------------------+ - Figure 24: Format of XFER_REFUSE Messages + Figure 22: Format of XFER_REFUSE Messages The fields of the XFER_REFUSE message are: Reason Code: A one-octet refusal reason code interpreted according - to the descriptions in Table 7. + to the descriptions in Table 6. Transfer ID: A 64-bit unsigned integer identifying the transfer being refused. +------------+------------------------------------------------------+ | Name | Semantics | +------------+------------------------------------------------------+ | Unknown | Reason for refusal is unknown or not specified. | | | | | Extension | A failure processing the Transfer Extension Items ha | @@ -1635,78 +1540,160 @@ | | received. | | | | | No | The receiver's resources are exhausted. The sender | | Resources | SHOULD apply reactive bundle fragmentation before | | | retrying. | | | | | Retransmit | The receiver has encountered a problem that requires | | | the bundle to be retransmitted in its entirety. | +------------+------------------------------------------------------+ - Table 7: XFER_REFUSE Reason Codes + Table 6: XFER_REFUSE Reason Codes The receiver MUST, for each transfer preceding the one to be refused, have either acknowledged all XFER_SEGMENTs or refused the bundle transfer. The bundle transfer refusal MAY be sent before an entire data segment is received. If a sender receives a XFER_REFUSE message, the sender MUST complete the transmission of any partially sent XFER_SEGMENT message. There is no way to interrupt an individual TCPCL message partway through sending it. The sender MUST NOT commence transmission of any further segments of the refused bundle subsequently. Note, however, that this requirement does not ensure that an entity will not receive another XFER_SEGMENT for the same bundle after transmitting a XFER_REFUSE message since messages MAY cross on the wire; if this happens, subsequent segments of the bundle - SHOULD also be refused with a XFER_REFUSE message. + SHALL also be refused with a XFER_REFUSE message. Note: If a bundle transmission is aborted in this way, the receiver MAY not receive a segment with the 'END' flag set to '1' for the aborted bundle. The beginning of the next bundle is identified by the 'START' bit set to '1', indicating the start of a new transfer, and with a distinct Transfer ID value. +5.2.5. Transfer Extension Items + + Each of the Transfer Extension Items SHALL be encoded in an identical + Type-Length-Value (TLV) container form as indicated in Figure 23. + + The fields of the Transfer Extension Item are: + + Flags: A one-octet field containing generic bit flags about the + Item, which are listed in Table 7. If a TCPCL node receives a + Transfer Extension Item with an unknown Item Type and the CRITICAL + flag set, the node SHALL refuse the transfer with an XFER_REFUSE + reason code of "Extension Failure". If the CRITICAL flag is not + set, an entity SHALL skip over and ignore any item with an unknown + Item Type. + + Item Type: A 16-bit unsigned integer field containing the type of + the extension item. This specification allocates an IANA registry + for such codes (see Section 9.4). + + Item Length: A 32-bit unsigned integer field containing the number + of Item Value octets to follow. + + Item Value: A variable-length data field which is interpreted + according to the associated Item Type. This specification places + no restrictions on an extension's use of available Item Value + data. Extension specifications SHOULD avoid the use of large data + lengths, as the associated transfer cannot begin until the full + extension data is sent. + + 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +---------------+---------------+---------------+---------------+ + | Item Flags | Item Type | Item Length...| + +---------------+---------------+---------------+---------------+ + | length contd. | Item Value... | + +---------------+---------------+---------------+---------------+ + | value contd. | + +---------------+---------------+---------------+---------------+ + + Figure 23: Transfer Extension Item Format + + +----------+--------+-----------------------------------------------+ + | Name | Code | Description | + +----------+--------+-----------------------------------------------+ + | CRITICAL | 0x01 | If bit is set, indicates that the receiving | + | | | peer must handle the extension item. | + | | | | + | Reserved | others | + +----------+--------+-----------------------------------------------+ + + Table 7: Transfer Extension Item Flags + +5.2.5.1. Transfer Length Extension + + The purpose of the Transfer Length extension is to allow entities to + preemptively refuse bundles that would exceed their resources or to + prepare storage on the receiving node for the upcoming bundle data. + + Multiple Transfer Length extension items SHALL NOT occurr within the + same transfer. The lack of a Transfer Length extension item in any + transfer SHALL NOT imply anything about the potential length of the + transfer. The Transfer Length extension SHALL be assigned transfer + extension type ID 0x0001. + + The format of the Transfer Length data is as follows in Figure 24. + + +----------------------+ + | Total Length (U64) | + +----------------------+ + + Figure 24: Format of Transfer Length data + + The fields of the Transfer Length extension are: + + Total Length: A 64-bit unsigned integer indicating the size of the + data-to-be-transferred. The Total Length field SHALL be treated + as authoritative by the receiver. If, for whatever reason, the + actual total length of bundle data received differs from the value + indicated by the Total Length value, the receiver SHALL treat the + transmitted data as invalid. + 6. Session Termination This section describes the procedures for ending a TCPCL session. 6.1. Session Termination Message (SESS_TERM) To cleanly shut down a session, a SESS_TERM message SHALL be transmitted by either node at any point following complete transmission of any other message. When sent to initiate a termination, the REPLY bit of a SESS_TERM message SHALL NOT be set. Upon receiving a SESS_TERM message after not sending a SESS_TERM - message in the same session, an entity SHOULD send an acknowledging + message in the same session, an entity SHALL send an acknowledging SESS_TERM message. When sent to acknowledge a termination, a SESS_TERM message SHALL have identical data content from the message being acknowledged except for the REPLY bit, which is set to indicate acknowledgement. After sending a SESS_TERM message, an entity MAY continue a possible in-progress transfer in either direction. After sending a SESS_TERM message, an entity SHALL NOT begin any new outgoing transfer (i.e. - send an XFER_INIT message) for the remainder of the session. After - receving a SESS_TERM message, an entity SHALL NOT accept any new - incoming transfer for the remainder of the session. + send an XFER_SEGMENT message) for the remainder of the session. + After receving a SESS_TERM message, an entity SHALL NOT accept any + new incoming transfer for the remainder of the session. Instead of following a clean shutdown sequence, after transmitting a SESS_TERM message an entity MAY immediately close the associated TCP connection. When performing an unclean shutdown, a receiving node SHOULD acknowledge all received data segments before closing the TCP - connection. When performing an unclean shutodwn, a transmitting node - SHALL treat either sending or receiving a SESS_TERM message (i.e. - before the final acknowledgment) as a failure of the transfer. Any - delay between request to terminate the TCP connection and actual - closing of the connection (a "half-closed" state) MAY be ignored by - the TCPCL node. + connection. Not acknowledging received segments can result in + unnecessary retransmission. When performing an unclean shutodwn, a + transmitting node SHALL treat either sending or receiving a SESS_TERM + message (i.e. before the final acknowledgment) as a failure of the + transfer. Any delay between request to terminate the TCP connection + and actual closing of the connection (a "half-closed" state) MAY be + ignored by the TCPCL node. The format of the SESS_TERM message is as follows in Figure 25. +-----------------------------+ | Message Header | +-----------------------------+ | Message Flags (U8) | +-----------------------------+ | Reason Code (U8) | +-----------------------------+ @@ -1755,35 +1742,35 @@ Table 9: SESS_TERM Reason Codes A session shutdown MAY occur immediately after transmission of a contact header (and prior to any further message transmit). This MAY, for example, be used to notify that the node is currently not able or willing to communicate. However, an entity MUST always send the contact header to its peer before sending a SESS_TERM message. If reception of the contact header itself somehow fails (e.g. an - invalid "magic string" is recevied), an entity SHOULD close the TCP + invalid "magic string" is recevied), an entity SHALL close the TCP connection without sending a SESS_TERM message. If the content of the Session Extension Items data disagrees with the Session Extension Length (i.e. the last Item claims to use more octets than are present in the Session Extension Length), the reception of the contact header is considered to have failed. If a session is to be terminated before a protocol message has completed being sent, then the node MUST NOT transmit the SESS_TERM - message but still SHOULD close the TCP connection. Each TCPCL - message is contiguous in the octet stream and has no ability to be - cut short and/or preempted by an other message. This is particularly - important when large segment sizes are being transmitted; either - entire XFER_SEGMENT is sent before a SESS_TERM message or the - connection is simply terminated mid-XFER_SEGMENT. + message but still SHALL close the TCP connection. Each TCPCL message + is contiguous in the octet stream and has no ability to be cut short + and/or preempted by an other message. This is particularly important + when large segment sizes are being transmitted; either entire + XFER_SEGMENT is sent before a SESS_TERM message or the connection is + simply terminated mid-XFER_SEGMENT. 6.2. Idle Session Shutdown The protocol includes a provision for clean shutdown of idle sessions. Determining the length of time to wait before closing idle sessions, if they are to be closed at all, is an implementation and configuration matter. If there is a configured time to close idle links and if no TCPCL messages (other than KEEPALIVE messages) has been received for at @@ -1967,29 +1954,31 @@ specification. IANA will create, under the "Bundle Protocol" registry, a sub- registry titled "Bundle Protocol TCP Convergence-Layer Version 4 Transfer Extension Types" and initialize it with the contents of Table 12. The registration procedure is RFC Required within the lower range 0x0001--0x7fff. Values in the range 0x8000--0xffff are reserved for use on private networks for functions not published to the IANA. - +----------------+--------------------------+ + +----------------+---------------------------+ | Code | Message Type | - +----------------+--------------------------+ + +----------------+---------------------------+ | 0x0000 | Reserved | | | | - | 0x0001--0x7fff | Unassigned | + | 0x0001 | Transfer Length Extension | + | | | + | 0x0002--0x7fff | Unassigned | | | | | 0x8000--0xffff | Private/Experimental Use | - +----------------+--------------------------+ + +----------------+---------------------------+ Table 12: Transfer Extension Type Codes 9.5. Message Types EDITOR NOTE: sub-registry to-be-created upon publication of this specification. IANA will create, under the "Bundle Protocol" registry, a sub- registry titled "Bundle Protocol TCP Convergence-Layer Version 4 @@ -2004,25 +1993,23 @@ | 0x01 | XFER_SEGMENT | | | | | 0x02 | XFER_ACK | | | | | 0x03 | XFER_REFUSE | | | | | 0x04 | KEEPALIVE | | | | | 0x05 | SESS_TERM | | | | - | 0x06 | XFER_INIT | - | | | - | 0x07 | MSG_REJECT | + | 0x06 | MSG_REJECT | | | | - | 0x08--0xf | Unassigned | + | 0x07--0xf | Unassigned | +-----------+--------------+ Table 13: Message Type Codes 9.6. XFER_REFUSE Reason Codes EDITOR NOTE: sub-registry to-be-created upon publication of this specification. IANA will create, under the "Bundle Protocol" registry, a sub- @@ -2115,22 +2102,23 @@ 11.1. Normative References [BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 2015. [I-D.ietf-dtn-bpbis] - Fall, K. and E. Birrane, "Bundle Protocol Version 7", - draft-ietf-dtn-bpbis-11 (work in progress), May 2018. + Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol + Version 7", draft-ietf-dtn-bpbis-12 (work in progress), + November 2018. [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, DOI 10.17487/RFC0793, September 1981, . [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC 1122, DOI 10.17487/RFC1122, October 1989, . @@ -2151,22 +2139,22 @@ 11.2. Informative References [github-dtn-bpbis-tcpcl] Sipos, B., "TCPCL Example Implementation", . [I-D.ietf-dtn-bpsec] Birrane, E. and K. McKeever, "Bundle Protocol Security - Specification", draft-ietf-dtn-bpsec-08 (work in - progress), October 2018. + Specification", draft-ietf-dtn-bpsec-09 (work in + progress), February 2019. [RFC2595] Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595, DOI 10.17487/RFC2595, June 1999, . [RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst, R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant Networking Architecture", RFC 4838, DOI 10.17487/RFC4838, April 2007, . @@ -2199,30 +2187,31 @@ length. o Changed contact header content to limit number of negotiated options. o Added contact option to negotiate maximum segment size (per each direction). o Added session extension capability. - o Added transfer extension capability. + o Added transfer extension capability. Moved transfer total length + into an extension item. o Defined new IANA registries for message / type / reason codes to allow renaming some codes for clarity. o Expanded Message Header to octet-aligned fields instead of bit- packing. o Added a bundle transfer identification number to all bundle- - related messages (XFER_INIT, XFER_SEGMENT, XFER_ACK, XFER_REFUSE). + related messages (XFER_SEGMENT, XFER_ACK, XFER_REFUSE). o Use flags in XFER_ACK to mirror flags from XFER_SEGMENT. o Removed all uses of SDNV fields and replaced with fixed-bit-length fields. o Renamed SHUTDOWN to SESS_TERM to deconflict term "shutdown". o Removed the notion of a re-connection delay parameter.