< draft-ietf-dtn-bibect-02.txt   draft-ietf-dtn-bibect-03.txt >
Delay-Tolerant Networking Working Group S. Burleigh Delay-Tolerant Networking Working Group S. Burleigh
Internet Draft JPL, Calif. Inst. Of Technology Internet Draft JPL, Calif. Inst. Of Technology
Intended status: Standards Track August 4, 2019 Intended status: Standards Track February 18, 2020
Expires: February 5, 2020 Expires: August 21, 2020
Bundle-in-Bundle Encapsulation Bundle-in-Bundle Encapsulation
draft-ietf-dtn-bibect-02.txt draft-ietf-dtn-bibect-03.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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layer" protocol that tunnels BP "bundles" through encapsulating layer" protocol that tunnels BP "bundles" through encapsulating
bundles. The services provided by the BIBE convergence-layer bundles. The services provided by the BIBE convergence-layer
protocol adapter encapsulate an outbound BP "bundle" in a BIBE protocol adapter encapsulate an outbound BP "bundle" in a BIBE
convergence-layer protocol data unit for transmission as the payload convergence-layer protocol data unit for transmission as the payload
of a bundle. Security measures applied to the encapsulating bundle of a bundle. Security measures applied to the encapsulating bundle
may augment those applied to the encapsulated bundle. The protocol may augment those applied to the encapsulated bundle. The protocol
includes a mechanism for recovery from loss of an encapsulating includes a mechanism for recovery from loss of an encapsulating
bundle, called "custody transfer". This mechanism is adapted from bundle, called "custody transfer". This mechanism is adapted from
the custody transfer procedures described in the experimental Bundle the custody transfer procedures described in the experimental Bundle
Protocol specification developed by the Delay-Tolerant Networking Protocol specification developed by the Delay-Tolerant Networking
Research group of the Internet Research Task Force and documented in Research Group of the Internet Research Task Force and documented in
RFC 5050. RFC 5050.
Table of Contents Table of Contents
1. Introduction...................................................2 1. Introduction...................................................2
2. Conventions used in this document..............................4 2. Conventions used in this document..............................4
3. BIBE Design Elements...........................................4 3. BIBE Design Elements...........................................4
3.1. BIBE Endpoints............................................4 3.1. BIBE Endpoints............................................4
3.2. BIBE Protocol Data Units..................................4 3.2. BIBE Protocol Data Units..................................4
3.3. Custody Signals...........................................6 3.3. Custody Signals...........................................6
3.4. Custody Transfer Status Reports...........................7 3.4. Custody Transfer Status Reports...........................8
4. BIBE Procedures................................................8 4. BIBE Procedures................................................8
4.1. BPDU Transmission.........................................8 4.1. BPDU Transmission.........................................8
4.2. BPDU Reception............................................8 4.2. BPDU Reception............................................9
4.3. Retransmission Timer Expiration..........................10 4.3. Retransmission Timer Expiration..........................10
4.4. Custody Signal Reception.................................10 4.4. Custody Signal Reception.................................10
5. Security Considerations.......................................11 5. Security Considerations.......................................11
6. IANA Considerations...........................................11 6. IANA Considerations...........................................11
7. References....................................................11 7. References....................................................11
7.1. Normative References.....................................11 7.1. Normative References.....................................11
7.2. Informative References...................................11 7.2. Informative References...................................12
8. Acknowledgments...............................................11 8. Acknowledgments...............................................12
Appendix A. For More Information.................................13 Appendix A. For More Information.................................13
Appendix B. CDDL expression......................................14 Appendix B. CDDL expression......................................14
1. Introduction 1. Introduction
This document describes Bundle-in-Bundle Encapsulation (BIBE), a This document describes Bundle-in-Bundle Encapsulation (BIBE), a
Delay-Tolerant Networking (DTN) Bundle Protocol (BP) [BP] Delay-Tolerant Networking (DTN) Bundle Protocol (BP) [BP]
"convergence layer" protocol that tunnels BP "bundles" through "convergence layer" protocol that tunnels BP "bundles" through
encapsulating bundles. encapsulating bundles.
Conformance to the bundle-in-bundle encapsulation (BIBE) Conformance to the bundle-in-bundle encapsulation (BIBE)
specification is OPTIONAL for BP nodes. Each BP node that conforms specification is OPTIONAL for BP nodes. Each BP node that conforms
to the BIBE specification provides a BIBE convergence-layer adapter to the BIBE specification provides a BIBE convergence-layer adapter
(CLA) that is implemented within the administrative element of the (CLA) that is implemented by the administrative element of the BP
BP node's application agent. Like any convergence-layer adapter, node's application agent. Like any convergence-layer adapter, the
the BIBE CLA provides: BIBE CLA provides:
. A transmission service that sends an outbound bundle (from the . A transmission service that sends an outbound bundle (from the
bundle protocol agent) to a peer CLA. In the case of BIBE, the bundle protocol agent) to a peer CLA. In the case of BIBE, the
sending CLA and receiving peer CLA are both BP nodes. sending CLA and receiving peer CLA are both BP nodes.
. A reception service that delivers to the bundle protocol agent . A reception service that delivers to the bundle protocol agent
an inbound bundle that was sent by a peer CLA (itself a BP an inbound bundle that was sent by a peer CLA (itself a BP
node) via the BIBE convergence layer protocol. node) via the BIBE convergence layer protocol.
The BIBE CLA performs these services by: The BIBE CLA performs these services by:
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. Moreover, in the event that no single point of egress from an . Moreover, in the event that no single point of egress from an
insecure region of network topology can be determined at the insecure region of network topology can be determined at the
moment a bundle is to be encapsulated, multiple copies of the moment a bundle is to be encapsulated, multiple copies of the
bundle may be encapsulated individually and forwarded to all bundle may be encapsulated individually and forwarded to all
candidate points of egress. candidate points of egress.
The protocol includes a mechanism for recovery from loss of an The protocol includes a mechanism for recovery from loss of an
encapsulating bundle, called "custody transfer". This mechanism is encapsulating bundle, called "custody transfer". This mechanism is
adapted from the custody transfer procedures described in the adapted from the custody transfer procedures described in the
experimental Bundle Protocol specification developed by the Delay- experimental Bundle Protocol specification developed by the Delay-
Tolerant Networking Research group of the Internet Research Task Tolerant Networking Research Group of the Internet Research Task
Force and documented in RFC 5050 [RFC5050]. Custody transfer is a Force and documented in RFC 5050 [RFC5050]. Custody transfer is a
convention by which the loss or corruption of BIBE encapsulating convention by which the loss or corruption of BIBE encapsulating
bundles can be mitigated by the exchange of other bundles, which are bundles can be mitigated by the exchange of other bundles, which are
termed "custody signals". termed "custody signals".
2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119]. document are to be interpreted as described in RFC-2119 [RFC2119].
In this document, these words will appear with that interpretation In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance. interpreted as carrying RFC-2119 significance.
3. BIBE Design Elements 3. BIBE Design Elements
3.1. BIBE Endpoints 3.1. BIBE Endpoints
BIBE convergence-layer protocol endpoints, also known as BIBE BIBE convergence-layer protocol endpoints, also known as BIBE
convergence-layer adapters (BCLAs), are the Administrative Elements convergence-layer adapters (BCLAs), are implemented by the
of Bundle Protocol nodes that conform to the BIBE protocol administrative elements of the application agents of BP nodes that
specification. The node of which a given BCLA is one component is conform to the BIBE protocol specification. The node of which a
termed the BCLA's "local node". given BCLA is one component is termed the BCLA's "local node". A BP
node that includes a BCLA is termed a "BIBE node".
3.2. BIBE Protocol Data Units 3.2. BIBE Protocol Data Units
A BIBE Protocol Data Unit (BPDU) for which custody transfer is
requested is termed a "custodial BPDU".
Notionally, a BCLA is assumed to implement in some way, for each Notionally, a BCLA is assumed to implement in some way, for each
custodial node to which the local node issues BIBE Protocol Data BIBE node to which the local node issues custodial BPDUs, the
Units (BPDUs), the following two data resources: following two data resources:
1. A "custodial transmission count" (CTC). A CTC is a 1. A "custodial transmission count" (CTC). A CTC is a
monotonically increasing integer indicating the number of monotonically increasing integer indicating the number of
"custodial" BPDUs - that is, BPDUs for which custody transfer custodial BPDUs that have been issued to this BIBE node by the
was requested - that have been issued to the custodial node by local node since instantiation of the local node.
the local node since instantiation of the local node.
2. A "custodial transmission database" (CTDB), a notional array of 2. A "custodial transmission database" (CTDB), a notional array of
"custodial transmission items" (CTIs). The CTDB contains one "custodial transmission items" (CTIs). The CTDB contains one
CTI for each custodial BPDU issued to the custodial node, by CTI for each custodial BPDU issued to this BIBE node, by the
the local node, for which (a) no custody disposition has yet local node, for which (a) no custody disposition has yet been
been received in any custody signal (as discussed later) and received in any custody signal (as discussed later) and (b) the
(b) the bundle encapsulated in that BPDU has not yet been bundle encapsulated in that BPDU has not yet been destroyed due
destroyed due to, e.g., time-to-live expiration. Each CTI to, e.g., time-to-live expiration. Each CTI notionally
notionally contains: contains:
a. A reference to the bundle encapsulated in the a. A reference to the bundle encapsulated in the
corresponding BPDU. corresponding BPDU.
b. The "transmission ID" of the corresponding BPDU, as b. The "transmission ID" of the corresponding BPDU, as
discussed below. discussed below.
c. A "retransmission time" indicating the time by which c. A "retransmission time" indicating the time by which
custody disposition for the corresponding BDPU is custody disposition for the corresponding BDPU is
expected. expected.
A BIBE protocol data unit is a Bundle Protocol administrative record A BIBE protocol data unit is a Bundle Protocol administrative record
whose record type code is 3 (i.e., bit pattern 0011), constructed as whose record type code is 3 (i.e., bit pattern 0011) and whose
follows. representation conforms to the Bundle Protocol specification for
administrative record representation. The content of the record
SHALL be a BPDU message represented as follows.
Each BPDU SHALL be represented as a CBOR array. The number of Each BPDU message SHALL be represented as a CBOR array. The number
elements in the array SHALL be 3. of elements in the array SHALL be 3.
The first item of the BPDU array SHALL be the "transmission ID" for The first item of the BPDU array SHALL be the "transmission ID" for
the BPDU, represented as a CBOR unsigned integer. The transmission the BPDU, represented as a CBOR unsigned integer. The transmission
ID for a BPDU for which custody transfer is NOT requested SHALL be ID for a BPDU for which custody transfer is NOT requested SHALL be
zero. The transmission ID for a BPDU for which custody transfer IS zero. The transmission ID for a BPDU for which custody transfer IS
requested SHALL be the current value of the local node's custodial requested SHALL be the current value of the local node's custodial
transmission count, plus 1. transmission count, plus 1.
The second item of the BPDU array SHALL be the BPDU's retransmission The second item of the BPDU array SHALL be the BPDU's retransmission
time (i.e., the time by which custody disposition for this BPDU is time (i.e., the time by which custody disposition for this BPDU is
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scope of this specification and may be dynamically responsive to scope of this specification and may be dynamically responsive to
changes in connectivity. changes in connectivity.
The third item of the BPDU array SHALL be a single BP bundle, termed The third item of the BPDU array SHALL be a single BP bundle, termed
the "encapsulated bundle", represented as a CBOR byte string of the "encapsulated bundle", represented as a CBOR byte string of
definite length. definite length.
3.3. Custody Signals 3.3. Custody Signals
A "custody signal" is a Bundle Protocol administrative record whose A "custody signal" is a Bundle Protocol administrative record whose
record type code is 4 (i.e., bit pattern 0100) and whose content is record type code is 4 (i.e., bit pattern 0100) and whose
constructed as follows. representation conforms to the Bundle Protocol specification for
administrative record representation. The content of the record
shall be a Custody message represented as follows.
The content of each custody signal SHALL be represented as a CBOR Each custody message SHALL be represented as a CBOR array. The
array. The number of elements in the array SHALL be 2. number of elements in the array SHALL be 2.
The first item of the custody signal content array SHALL be a The first item of the custody signal content array SHALL be a
disposition code represented as a CBOR unsigned integer. Valid disposition code represented as a CBOR unsigned integer. Valid
disposition codes are defined as follows: disposition codes are defined as follows:
+---------+--------------------------------------------+ +---------+--------------------------------------------+
| Value | Meaning | | Value | Meaning |
+=========+============================================+ +=========+============================================+
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| 3 | Redundant (reception by a node that | | 3 | Redundant (reception by a node that |
| | already has a copy of this bundle). | | | already has a copy of this bundle). |
+---------+--------------------------------------------+ +---------+--------------------------------------------+
| 4 | Depleted storage. | | 4 | Depleted storage. |
+---------+--------------------------------------------+ +---------+--------------------------------------------+
| 5 | Destination endpoint ID unintelligible. | | 5 | Destination endpoint ID unintelligible. |
+---------+--------------------------------------------+ +---------+--------------------------------------------+
| 6 | No known route destination from here. | | 6 | No known route destination from here. |
+---------+--------------------------------------------+ +---------+--------------------------------------------+
| 7 | No timely contact with next node on route. | | 7 | No timely contact with next node on route. |
+---------+--------------------------------------------+ +---------+--------------------------------------------+
| 8 | Block unintelligible. | | 8 | Block unintelligible. |
+---------+--------------------------------------------+ +---------+--------------------------------------------+
| (other) | Reserved for future use. | | (other) | Reserved for future use. |
+---------+--------------------------------------------+ +---------+--------------------------------------------+
Figure 1: Disposition Codes Figure 1: Disposition Codes
The second item of the custody signal content array SHALL be a The second item of the custody signal content array SHALL be a
"disposition scope report", represented as a CBOR indefinite-length "disposition scope report", represented as a CBOR array of definite
array. Each item of the disposition scope report array SHALL be a length. Each item of the disposition scope report array SHALL be a
"disposition scope sequence", represented as a CBOR array of two "disposition scope sequence", represented as a CBOR array of two
elements. The first element of each disposition scope sequence elements. The first element of each disposition scope sequence
array SHALL be the first transmission ID in a sequence of 1 or more array SHALL be the first transmission ID in a sequence of 1 or more
consecutive transmission IDs corresponding to BPDUs to which the consecutive transmission IDs corresponding to BPDUs to which the
custody signal's disposition is declared to apply; the second custody signal's disposition is declared to apply; the second
element of each disposition scope sequence array SHALL be the number element of each disposition scope sequence array SHALL be the number
of transmission IDs in that sequence. Both are represented as CBOR of transmission IDs in that sequence. Both are represented as CBOR
unsigned integers. unsigned integers.
A custody signal constitutes an assertion by the source of that A custody signal constitutes an assertion by the source of that
administrative bundle that the indicated disposition code applies to administrative record that the indicated disposition code applies to
all BPDUs identified by the transmission IDs enumerated in the all BPDUs identified by the transmission IDs enumerated in the
custody signal's disposition scope report. If the disposition code custody signal's disposition scope report. If the disposition code
is zero, then the source of the custody signal has accepted custody is zero, then the source of the custody signal has accepted custody
of all bundles that were encapsulated in the indicated BPDUs. of all bundles that were encapsulated in the indicated BPDUs.
Otherwise the source of the custody signal has refused custody of Otherwise the source of the custody signal has refused custody of
all bundles that were encapsulated in the indicated BPDUs, for the all bundles that were encapsulated in the indicated BPDUs, for the
indicated reason. indicated reason.
3.4. Custody Transfer Status Reports 3.4. Custody Transfer Status Reports
A "custody transfer status report" is a bundle status report with A "custody transfer status report" is a bundle status report with
the "reporting node attempted custody transfer" flag set to 1. the "reporting node attempted custody transfer" flag set to 1.
4. BIBE Procedures 4. BIBE Procedures
4.1. BPDU Transmission 4.1. BPDU Transmission
When a BCLA is requested by the bundle protocol agent to send a When a BCLA is requested by the bundle protocol agent to send a
bundle to the peer BCLA(s) included in the BP endpoint identified by bundle to the peer BCLA(s) included in the destination BP endpoint
a specified BP endpoint ID: identified by a specified BP endpoint ID:
. The BCLA SHALL generate, as defined in Section 6.2 of the . The BCLA SHALL generate, as defined in Section 6.2 of the
Bundle Protocol specification (a work in progress), a BPDU for Bundle Protocol specification, a BPDU for which the third
which the third element of the content array is the bundle that element of the content array is the bundle that is to be
is to be transmitted. The destination of the bundle whose transmitted. The destination of the bundle whose payload is the
payload is the BPDU (termed the "encapsulating bundle") SHALL BPDU (termed the "encapsulating bundle") SHALL be the specified
be the specified BP endpoint. Selection of the values of the destination BP endpoint. Selection of the values of the
parameters governing the forwarding of the encapsulating parameters governing the forwarding of the encapsulating
bundle, other than the destination endpoint ID, is an bundle, other than the destination endpoint ID, is an
implementation matter. The parameter values governing the implementation matter. The parameter values governing the
forwarding of the BPDU's encapsulated bundle MAY be consulted forwarding of the BPDU's encapsulated bundle MAY be consulted
for this purpose. for this purpose.
. Note that any transmission request presented to a BCLA MAY . Note that any transmission request presented to a BCLA MAY
request that the transmission be subject to Custody Transfer, request that the transmission be subject to Custody Transfer,
provided that the destination EID of the request identifies a provided that the destination EID of the request identifies a
singleton endpoint. singleton endpoint.
. If Custody Transfer is requested: . If Custody Transfer is requested:
o The first element of the BPDU's content array MUST be the o The first element of the BPDU's content array MUST be the
BPDU's transmission ID, which SHALL be 1 more than the BPDU's transmission ID, which SHALL be 1 more than the
current value of the BCLA's CTC for the node that is the current value of the BCLA's CTC for the node that is the
sole occupant of the BPDU's destination endpoint. sole occupant of the BPDU's destination endpoint.
o The second element of the BPDU's content array MUST be the o The second element of the BPDU's content array MUST be the
BPDU's retransmission time as discussed in 3.2 above. BPDU's retransmission time as discussed in 3.2 above.
o The bundle protocol agent MUST add the retention constraint o The bundle protocol agent MUST add the retention constraint
"Custody accepted" to the encapsulated bundle. "Custody accepted" to the encapsulated bundle.
o The BCLA MAY establish a retransmission timer for the o The BCLA MAY establish a retransmission timer for the
encapsulated bundle. If a retransmission timer is corresponding CTI. If a retransmission timer is
established, it MUST be set to expire at the BPDU's established, it MUST be set to expire at the
retransmission time. retransmission time indicated in the BPDU.
. Otherwise, the first two elements of the BPDU's content array . Otherwise:
MUST both be zero. o The first two elements of the BPDU's content array MUST
both be zero.
o Upon completion of step 2 of Section 6.2 of the Bundle
Protocol specification (i.e., a request for transmission
of the encapsulating bundle has been presented to the
bundle protocol agent), the BCLA SHOULD notify the bundle
protocol agent that transmission of the encapsulated
bundle succeeded.
Note that the custody transfer retransmission timer mechanism Note that the custody transfer retransmission timer mechanism
provides a means of recovering from loss of an encapsulating bundle provides a means of recovering from loss of an encapsulating bundle
as indicated by non-arrival of a responding custody signal. as indicated by non-arrival of a responding custody signal.
4.2. BPDU Reception 4.2. BPDU Reception
When a BCLA receives a BPDU from the bundle protocol agent (that is, When a BCLA receives a BPDU from the bundle protocol agent (that is,
upon delivery of the payload of an encapsulating bundle): upon delivery of the payload of an encapsulating bundle):
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reception". reception".
o Otherwise, if the BCLA determines that its local node can o Otherwise, if the BCLA determines that its local node can
neither deliver nor forward the encapsulated bundle for neither deliver nor forward the encapsulated bundle for
any of the reasons listed in Figure 1, then custody any of the reasons listed in Figure 1, then custody
transfer has failed. Custody transfer failure SHALL be transfer has failed. Custody transfer failure SHALL be
handled as follows: handled as follows:
. The BCLA SHALL add the BPDU's transmission ID to the . The BCLA SHALL add the BPDU's transmission ID to the
disposition scope report of a pending outbound disposition scope report of a pending outbound
custody signal, destined for the node that was the custody signal, destined for the node that was the
source of the encapsulating bundle, whose disposition source of the encapsulating bundle, whose disposition
is the reason code from Figure 2 that indicates the is the reason code from Figure 1 that indicates the
reason for the custody transfer failure. reason for the custody transfer failure.
o Otherwise, custody transfer has succeeded: o Otherwise, custody transfer has succeeded:
. The BCLA SHALL add the BPDU's transmission ID to the . The BCLA SHALL add the BPDU's transmission ID to the
disposition scope report of a pending outbound disposition scope report of a pending outbound
custody signal, destined for the node that was the custody signal, destined for the node that was the
source of the encapsulating bundle, whose disposition source of the encapsulating bundle, whose disposition
is zero (indicating that custody was accepted). is zero (indicating that custody was accepted).
o In each of these three cases: o In each of these three cases:
. The pending outbound custody signal MAY then be . The pending outbound custody signal MAY then be
issued immediately, but alternatively it MAY be issued immediately, but alternatively it MAY be
issued at some time in the future, possibly enabling issued at some time in the future, possibly enabling
additional BPDUs' transmission IDs to be added to the additional BPDUs' transmission IDs to be added to the
same disposition scope report. same disposition scope report.
. If the "request reporting of custody transfer
attempted" flag in the encapsulating bundle's status
report request field is set to 1, and status
reporting is enabled, a custody transfer status
report whose reason code is the same as the pending
outbound custody signal's disposition SHOULD be
generated, destined for the report-to endpoint of the
encapsulating bundle.
. If Custody Transfer was NOT requested for this BPDU, or if . If Custody Transfer was NOT requested for this BPDU, or if
Custody Transfer was requested for this BPDU and custody Custody Transfer was requested for this BPDU and custody
transfer succeeded, then the encapsulated bundle SHALL be transfer succeeded, then the encapsulated bundle SHALL be
delivered from the convergence layer adapter to the bundle delivered from the BCLA to the bundle protocol agent, whereupon
protocol agent, whereupon bundle reception SHALL be performed reception of the encapsulated bundle SHALL be performed as
as defined in section 5.6 of the Bundle Protocol specification defined in section 5.6 of the Bundle Protocol specification in
(a work in progress) as usual: the encapsulated bundle may be the usual manner: the encapsulated bundle may be forwarded,
forwarded, delivered, etc. delivered, etc.
Note that the manner in which pending outbound custody signals are Note that the procedures by which pending outbound custody signals
managed, disposition scope reports are aggregated, and custody are managed, disposition scope reports are aggregated, and custody
signal transmission is initiated is an implementation matter that signal transmission is initiated are implementation matters that
is beyond the scope of this specification. Note, however, that are beyond the scope of this specification. Note, however, that
failure to deliver a custody signal prior to the earliest value of failure to deliver a custody signal prior to the earliest value of
retransmission time among all BPDUs enumerated in the custody retransmission time among all BPDUs enumerated in the custody
signal's disposition scope report may result in unnecessary signal's disposition scope report may result in the unnecessary
retransmission of one or more BPDUs. re-forwarding of one or more encapsulated bundles.
4.3. Retransmission Timer Expiration 4.3. Retransmission Timer Expiration
Upon expiration of a retransmission timer, the BCLA SHOULD remove Upon expiration of a retransmission timer, the BCLA SHOULD remove
the corresponding CTI from the CTDB (destroying the associated the corresponding CTI from the CTDB (destroying the associated
retransmission timer, if any) and notify the bundle protocol agent retransmission timer, if any) and notify the bundle protocol agent
that custodial transmission of the indicated bundle failed. This that transmission failed for the encapsulated bundle referenced by
notification may cause the indicated bundle to be re-forwarded that CTI. Note that this notification may cause the encapsulated
(possibly on a different route). bundle to be re-forwarded (possibly on a different route).
4.4. Custody Signal Reception 4.4. Custody Signal Reception
When a BCLA receives a custody signal from the bundle protocol agent When a BCLA receives a custody signal from the bundle protocol agent
(that is, upon delivery of the payload of a custody-signal-bearing (that is, upon delivery of the payload of a custody-signal-bearing
bundle): bundle):
. If the custody signal's disposition is 0 (custody acceptance), . If the custody signal's disposition is 0 (custody acceptance),
then for each transmission ID in the custody signal's then for each transmission ID in the custody signal's
disposition scope report: disposition scope report:
o The bundle protocol agent MUST remove the retention o The bundle protocol agent MUST remove the retention
constraint "Custody accepted" on the bundle referenced by constraint "Custody accepted" on the encapsulated bundle
the corresponding CTI. referenced by the corresponding CTI.
o The corresponding CTI MUST be removed from the CTDB o The corresponding CTI MUST be removed from the CTDB
(destroying the associated retransmission timer, if any). (destroying the associated retransmission timer, if any).
o The BCLA SHOULD notify the bundle protocol agent that
transmission succeeded for the encapsulated bundle
referenced by the corresponding CTI.
. Otherwise (custody refusal), for each transmission ID in the . Otherwise (custody refusal), for each transmission ID in the
custody signal's disposition scope report: custody signal's disposition scope report:
o The corresponding CTI MUST be removed from the CTDB o The corresponding CTI MUST be removed from the CTDB
(destroying the associated retransmission timer, if any). (destroying the associated retransmission timer, if any).
o Any further action taken by the BCLA is implementation- o Any further action taken by the BCLA is implementation-
specific and may depend on the reason code cited for the specific and may depend on the reason code cited for the
refusal. For example, if the custody signal's reason code refusal. For example, if the custody signal's reason code
was "Depleted storage", the BCLA might choose to notify was "Depleted storage", the BCLA might choose to notify
the bundle protocol agent that custodial transmission of the bundle protocol agent that transmission failed for the
the indicated bundle failed. If the reason code was encapsulated bundle referenced by the corresponding CTI.
"Redundant reception", on the other hand, this might cause If the reason code was "Redundant reception", on the other
the BCLA simply to instruct the bundle protocol agent to hand, the BCLA might simply instruct the bundle protocol
remove the retention constraint "Custody accepted" on the agent to remove the retention constraint "Custody
bundle referenced by the corresponding CTI and to revise accepted" on the encapsulated bundle referenced by the
its algorithm for computing retransmission time. corresponding CTI and to revise its algorithm for
computing retransmission time.
5. Security Considerations 5. Security Considerations
An adversary on a DTN-based network that can delete bundles could An adversary on a DTN-based network that can delete bundles could
delete a BIBE custody signal in transit. This could result in delete a BIBE custody signal in transit. This could result in
unnecessary custodial retransmission, degrading network performance. custody transfer failure and the possible re-forwarding of
encapsulated bundles, degrading network performance.
Alternatively, an adversary on a DTN-based network that can reorder Alternatively, an adversary on a DTN-based network that can reorder
bundles could cause bundles to be delivered to a BCLA in an order bundles could cause bundles to be delivered to a BCLA in an order
that complicates the efficient construction of disposition scope that complicates the efficient construction of disposition scope
reports in pending outbound custody signals. This could result in reports in pending outbound custody signals. This could result in
inefficient custody transfer communications, again degrading network inefficient custody transfer communications, again degrading network
performance. performance.
Custody transfer in BIBE may be contraindicated in environments Custody transfer in BIBE may be contraindicated in environments
characterized by such attacks. characterized by such attacks.
skipping to change at page 11, line 37 skipping to change at page 11, line 49
6. IANA Considerations 6. IANA Considerations
The BIBE specification requires IANA registration of the new BIBE The BIBE specification requires IANA registration of the new BIBE
administrative records (type codes 3 and 4) defined above. administrative records (type codes 3 and 4) defined above.
7. References 7. References
7.1. Normative References 7.1. Normative References
[BP] Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol [BP] Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol
Version 7", Work In Progress, August 2019. Version 7", draft-ietf-dtn-bpbis, February 2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References 7.2. Informative References
[RFC5050] Scott, K. and S. Burleigh, "Bundle Protocol [RFC5050] Scott, K. and S. Burleigh, "Bundle Protocol
Specification", RFC 5050, November 2007. Specification", RFC 5050, November 2007.
8. Acknowledgments 8. Acknowledgments
skipping to change at page 13, line 10 skipping to change at page 13, line 10
(draft-irtf-dtnrg-bundle-encapsulation-06, 2009), the influence of (draft-irtf-dtnrg-bundle-encapsulation-06, 2009), the influence of
that earlier document is gratefully acknowledged. that earlier document is gratefully acknowledged.
This document was prepared using 2-Word-v2.0.template.dot. This document was prepared using 2-Word-v2.0.template.dot.
Appendix A. For More Information Appendix A. For More Information
Please refer comments to dtn@ietf.org. The Delay Tolerant Networking Please refer comments to dtn@ietf.org. The Delay Tolerant Networking
Research Group (DTNRG) Web site is located at http://www.dtnrg.org. Research Group (DTNRG) Web site is located at http://www.dtnrg.org.
Copyright (c) 2019 IETF Trust and the persons identified as authors Copyright (c) 2020 IETF Trust and the persons identified as authors
of the code. All rights reserved. of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without Redistribution and use in source and binary forms, with or without
modification, is permitted pursuant to, and subject to the license modification, is permitted pursuant to, and subject to the license
terms contained in, the Simplified BSD License set forth in Section terms contained in, the Simplified BSD License set forth in Section
4.c of the IETF Trust's Legal Provisions Relating to IETF Documents 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info). (http://trustee.ietf.org/license-info).
Appendix B. CDDL expression Appendix B. CDDL expression
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