RFC 9362 | DOTS Robust Block Transmission | February 2023
Boucadair & Shallow | Standards Track | [Page]

Stream:
  Internet Engineering Task Force (IETF)
RFC:
  9362
Category:
  Standards Track
Published:
  February 2023
ISSN:
  2070-1721
Authors:
  M. Boucadair
  Orange
  J. Shallow

# RFC 9362

# Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel Configuration Attributes for Robust Block Transmission

## Abstract

This document specifies new DDoS Open Threat Signaling (DOTS) signal channel configuration parameters that can be negotiated between DOTS peers to enable the use of Q-Block1 and Q-Block2 Constrained Application Protocol (CoAP) options. These options enable robust and faster transmission rates for large amounts of data with less packet interchanges as well as support for faster recovery should any of the blocks get lost in transmission (especially during DDoS attacks).¶

Also, this document defines a YANG data model for representing these new DOTS signal channel configuration parameters. This model augments the DOTS signal YANG module ("ietf-dots-signal-channel") defined in RFC 9132.¶

## Status of This Memo

This is an Internet Standards Track document.¶

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.¶

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9362.¶

## Copyright Notice

Copyright (c) 2023 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶

## 1. Introduction

The Constrained Application Protocol (CoAP) [RFC7252], although inspired by HTTP, was designed to use UDP instead of TCP. The message layer of CoAP over UDP includes support for reliable delivery, simple congestion control, and flow control. The block-wise transfer [RFC7959] introduced the CoAP Block1 and Block2 options to handle data records that cannot fit in a single IP packet, to avoid having to rely on IP fragmentation. The block-wise transfer was further updated by [RFC8323] for use over TCP, TLS, and WebSockets.¶

The CoAP Block1 and Block2 options work well in environments where there are no or minimal packet losses. These options operate synchronously where each individual block has to be requested and can only ask for (or send) the next block when the request for the previous block has completed. Packet rates, and hence block transmission rates, are controlled by Round-Trip Times (RTTs).¶

There is a requirement for these blocks of data to be transmitted at higher rates under network conditions where there may be asymmetrical transient packet loss (e.g., responses may get dropped). An example is when a network is subject to a Distributed Denial of Service (DDoS) attack and there is a need for DDoS mitigation agents relying upon CoAP to communicate with each other (e.g., [RFC9244]). As a reminder, [RFC7959] recommends the use of Confirmable (CON) responses to handle potential packet loss. However, such a recommendation does not work with a "flooded pipe" DDoS situation because the returning ACK packets may not get through.¶

The block-wise transfer specified in [RFC7959] covers the general case but falls short in situations where packet loss is highly asymmetrical. The mechanism specified in [RFC9177] provides features roughly similar to the Block1/Block2 options but also provides additional properties that are tailored towards the intended DDoS Open Threat Signaling (DOTS) transmission. Concretely, [RFC9177] primarily targets applications such as DOTS that can't use Confirmable responses to handle potential packet loss and that support application-specific mechanisms to assess whether the remote peer is able to handle the messages sent by a CoAP endpoint (e.g., DOTS heartbeats as discussed in Section 4.7 of [RFC9132]).¶

[RFC9177] includes guards to prevent a CoAP agent from overloading the network by adopting an aggressive sending rate. These guards are followed in addition to the existing CoAP congestion control as specified in Section 4.7 of [RFC7252] (mainly PROBING_RATE). Table 1 lists the additional CoAP parameters that are used for the guards (Section 7.2 of [RFC9177]). Note that NON in this table refers to Non-confirmable.¶

Table 1: Congestion Control Parameters
Parameter Name | Default Value
--- | ---
MAX_PAYLOADS | 10
NON_MAX_RETRANSMIT | 4
NON_TIMEOUT | 2 s
NON_TIMEOUT_RANDOM | between 2-3 s
NON_RECEIVE_TIMEOUT | 4 s
NON_PROBING_WAIT | between 247-248 s
NON_PARTIAL_TIMEOUT | 247 s

PROBING_RATE and other transmission parameters are negotiated between DOTS peers as discussed in Section 4.5.2 of [RFC9132]. Nevertheless, negotiating the parameters listed in Table 1 is not supported in [RFC9132]. This document defines new DOTS signal channel attributes, corresponding to the parameters in Table 1, that are used to customize the configuration of robust block transmission in a DOTS context.¶

## 2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶

Readers should be familiar with the terms and concepts defined in [RFC7252] and [RFC8612].¶

The terms "payload" and "body" are defined in [RFC7959]. The term "payload" is thus used for the content of a single CoAP message (i.e., a single block being transferred), while the term "body" is used for the entire resource representation that is being transferred in a block-wise fashion.¶

The meanings of the symbols in YANG tree diagrams are defined in [RFC8340] and [RFC8791].¶

## 3. DOTS Attributes for Robust Block Transmission

Section 7.2 of [RFC9177] defines the following parameters that are used for congestion control purposes:¶

MAX_PAYLOADS:
  This parameter represents the maximum number of payloads that can be transmitted at any one time.¶
NON_MAX_RETRANSMIT:
  This parameter represents the maximum number of times a request for the retransmission of missing payloads can occur without a response from the remote peer. By default, NON_MAX_RETRANSMIT has the same value as MAX_RETRANSMIT (Section 4.8 of [RFC7252]).¶
NON_TIMEOUT:
  This parameter represents the maximum period of delay between sending sets of MAX_PAYLOADS payloads for the same body. NON_TIMEOUT has the same value as ACK_TIMEOUT (Section 4.8 of [RFC7252]).¶
NON_TIMEOUT_RANDOM:
  This parameter represents the initial actual delay between sending the first two MAX_PAYLOADS_SETs of the same body. It is a random duration between NON_TIMEOUT and (NON_TIMEOUT * ACK_RANDOM_FACTOR).¶
NON_RECEIVE_TIMEOUT:
  This parameter represents the maximum time to wait for a missing payload before requesting retransmission. By default, NON_RECEIVE_TIMEOUT has a value of twice NON_TIMEOUT.¶
NON_PROBING_WAIT:
  This parameter is used to limit the potential wait needed when using PROBING_RATE.¶
NON_PARTIAL_TIMEOUT:
  This parameter is used for expiring partially received bodies.¶

These parameters are used together with the PROBING_RATE parameter, which in CoAP indicates the average data rate that must not be exceeded by a CoAP endpoint in sending to a peer endpoint that does not respond. The single body of blocks will be subjected to PROBING_RATE (Section 4.7 of [RFC7252]), not the individual packets. If the wait time between sending bodies that are not being responded to based on PROBING_RATE exceeds NON_PROBING_WAIT, then the wait time is limited to NON_PROBING_WAIT.¶

This document augments the "ietf-dots-signal-channel" DOTS signal YANG module defined in Section 5.3 of [RFC9132] with the following additional attributes that can be negotiated between DOTS peers to enable robust and faster transmission:¶

max-payloads:

  This attribute echoes the MAX_PAYLOADS parameter defined in [RFC9177].¶

  This is an optional attribute. If the attribute is supplied in both 'idle-config' and 'mitigating-config', then it MUST convey the same value. If the attribute is only provided as part of 'idle-config' (or 'mitigating-config'), then the other definition (i.e., 'mitigating-config' (or 'idle-config')) MUST be updated to the same value.¶

non-max-retransmit:

  This attribute echoes the NON_MAX_RETRANSMIT parameter defined in [RFC9177]. The default value of this attribute is 'max-retransmit'. Note that DOTS uses a default value of '3' instead of '4' (which is used generically by CoAP for 'max-transmit'; see Section 4.5.2 of [RFC9132] and Section 4.8 of [RFC7252]).¶

  This is an optional attribute.¶

non-timeout:

  This attribute, expressed in seconds, echoes the NON_TIMEOUT parameter defined in [RFC9177]. The default value of this attribute is 'ack-timeout'.¶

  This attribute is also used to compute the NON_TIMEOUT_RANDOM parameter.¶

  This is an optional attribute.¶

non-receive-timeout:

  This attribute, expressed in seconds, echoes the NON_RECEIVE_TIMEOUT parameter defined in [RFC9177]. The default value of this attribute is twice 'non-timeout'.¶

  This is an optional attribute.¶

non-probing-wait:

  This attribute, expressed in seconds, echoes the NON_PROBING_WAIT parameter defined in [RFC9177].¶

  This is an optional attribute.¶

non-partial-timeout:

  This attribute, expressed in seconds, echoes the NON_PARTIAL_TIMEOUT parameter defined in [RFC9177]. The default value of this attribute is 247 seconds.¶

  This is an optional attribute.¶

The tree structure of the "ietf-dots-robust-trans" module (Section 5) is shown in Figure 1.¶

    module: ietf-dots-robust-trans

      augment-structure /dots-signal:dots-signal/dots-signal:message-type
                        /dots-signal:signal-config
                        /dots-signal:mitigating-config:
        +-- max-payloads
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value?   uint16
        |  |     +-- min-value?   uint16
        |  +-- current-value?     uint16
        +-- non-max-retransmit
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value?   uint16
        |  |     +-- min-value?   uint16
        |  +-- current-value?     uint16
        +-- non-timeout
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value-decimal?   decimal64
        |  |     +-- min-value-decimal?   decimal64
        |  +-- current-value-decimal?     decimal64
        +-- non-receive-timeout
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value-decimal?   decimal64
        |  |     +-- min-value-decimal?   decimal64
        |  +-- current-value-decimal?     decimal64
        +-- non-probing-wait
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value-decimal?   decimal64
        |  |     +-- min-value-decimal?   decimal64
        |  +-- current-value-decimal?     decimal64
        +-- non-partial-timeout:
           +-- (direction)?
           |  +--:(server-to-client-only)
           |     +-- max-value-decimal?   decimal64
           |     +-- min-value-decimal?   decimal64
           +-- current-value-decimal?     decimal64

      augment-structure /dots-signal:dots-signal/dots-signal:message-type
                        /dots-signal:signal-config
                        /dots-signal:idle-config:
        +-- max-payloads
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value?   uint16
        |  |     +-- min-value?   uint16
        |  +-- current-value?     uint16
        +-- non-max-retransmit
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value?   uint16
        |  |     +-- min-value?   uint16
        |  +-- current-value?     uint16
        +-- non-timeout
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value-decimal?   decimal64
        |  |     +-- min-value-decimal?   decimal64
        |  +-- current-value-decimal?     decimal64
        +-- non-receive-timeout
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value-decimal?   decimal64
        |  |     +-- min-value-decimal?   decimal64
        |  +-- current-value-decimal?     decimal64
        +-- non-probing-wait
        |  +-- (direction)?
        |  |  +--:(server-to-client-only)
        |  |     +-- max-value-decimal?   decimal64
        |  |     +-- min-value-decimal?   decimal64
        |  +-- current-value-decimal?     decimal64
        +-- non-partial-timeout:
           +-- (direction)?
           |  +--:(server-to-client-only)
           |     +-- max-value-decimal?   decimal64
           |     +-- min-value-decimal?   decimal64
           +-- current-value-decimal?     decimal64

Figure 1: DOTS Fast Block Transmission Tree Structure

These attributes are mapped to Concise Binary Object Representation (CBOR) types as specified in Section 4 and in Section 6 of [RFC9132].¶

DOTS clients follow the procedure specified in Section 4.5 of [RFC9132] to negotiate, configure, and retrieve the DOTS signal channel session behavior (including Q-Block parameters) with DOTS peers.¶

Implementation Note 1:
  'non-probing-wait' ideally should be left having some jitter and so should not be hard-coded with an explicit value. It is suggested to use a base value (using NON_TIMEOUT instead of NON_TIMEOUT_RANDOM); the jitter (ACK_RANDOM_FACTOR - 1) is then added to each time the value is checked.¶
Implementation Note 2:
  If any of the signal channel session configuration parameters is updated, the 'non-probing-wait' and 'non-partial-timeout' values should be recalculated according to the definition algorithms provided in Section 7.2 of [RFC9177] unless explicit values are provided as part of the negotiated configuration.¶

An example of a PUT message to configure Q-Block parameters is depicted in Figure 2. In this example, a non-default value is configured for the 'max-payloads' attribute, while default values are used for 'non-max-retransmit', 'non-timeout', and 'non-receive-timeout' in both idle and mitigation times. Given that 'non-probing-wait' and 'non-partial-timeout' are not explicitly configured in this example, these attributes will be computed following the algorithms provided in Section 7.2 of [RFC9177]. The meanings of the other attributes are detailed in Section 4.5 of [RFC9132].¶

         Header: PUT (Code=0.03)
         Uri-Path: ".well-known"
         Uri-Path: "dots"
         Uri-Path: "config"
         Uri-Path: "sid=123"
         Content-Format: "application/dots+cbor"

         {
           "ietf-dots-signal-channel:signal-config": {
             "mitigating-config": {
               "heartbeat-interval": {
                 "current-value": 30
               },
               "missing-hb-allowed": {
                 "current-value": 15
               },
               "probing-rate": {
                 "current-value": 15
               },
               "max-retransmit": {
                 "current-value": 3
               },
               "ack-timeout": {
                 "current-value-decimal": "2.00"
               },
               "ack-random-factor": {
                 "current-value-decimal": "1.50"
               },
               "ietf-dots-robust-trans:max-payloads": {
                 "current-value": 15
               },
               "ietf-dots-robust-trans:non-max-retransmit": {
                 "current-value": 3
               },
               "ietf-dots-robust-trans:non-timeout": {
                 "current-value-decimal": "2.00"
               },
               "ietf-dots-robust-trans:non-receive-timeout": {
                 "current-value-decimal": "4.00"
               }
             },
             "idle-config": {
               "heartbeat-interval": {
                 "current-value": 0
               },
               "max-retransmit": {
                 "current-value": 3
               },
               "ack-timeout": {
                 "current-value-decimal": "2.00"
               },
               "ack-random-factor": {
                 "current-value-decimal": "1.50"
               },
               "ietf-dots-robust-trans:max-payloads": {
                 "current-value": 15
               },
               "ietf-dots-robust-trans:non-max-retransmit": {
                 "current-value": 3
               },
               "ietf-dots-robust-trans:non-timeout": {
                 "current-value-decimal": "2.00"
               },
               "ietf-dots-robust-trans:non-receive-timeout": {
                 "current-value-decimal": "4.00"
               }
             }
           }
         }

Figure 2: Example of PUT to Convey the Configuration Parameters

The payload of the message depicted in Figure 2 is CBOR-encoded as indicated by the Content-Format set to "application/dots+cbor" (Section 10.4 of [RFC9132]). However, and for the sake of better readability, the example uses JSON encoding of YANG-modeled data following the mapping tables in Section 4 and in Section 6 of [RFC9132]: use the JSON names and types defined in Section 4. These conventions are inherited from [RFC9132].¶

## 4. YANG/JSON Mapping Parameters to CBOR

The YANG/JSON mapping parameters to CBOR are listed in Table 2.¶

Note: Implementers must check that the mapping output provided by their YANG-to-CBOR encoding schemes is aligned with the content of Table 2.¶

Table 2: YANG/JSON Mapping Parameters to CBOR
Parameter Name | YANG Type | CBOR Key | CBOR Major Type & Information | JSON Type
--- | --- | --- | --- | ---
ietf-dots-robust-trans:max-payloads | container | 32776 | 5 map | Object
ietf-dots-robust-trans:non-max-retransmit | container | 32777 | 5 map | Object
ietf-dots-robust-trans:non-timeout | container | 32778 | 5 map | Object
ietf-dots-robust-trans:non-receive-timeout | container | 32779 | 5 map | Object
ietf-dots-robust-trans:non-probing-wait | container | 32780 | 5 map | Object
ietf-dots-robust-trans:non-partial-timeout | container | 32781 | 5 map | Object

## 5. DOTS Robust Block Transmission YANG Module

This module uses the data structure extension defined in [RFC8791].¶

    <CODE BEGINS> file "ietf-dots-robust-trans@2023-02-28.yang"

    module ietf-dots-robust-trans {
      yang-version 1.1;
      namespace "urn:ietf:params:xml:ns:yang:ietf-dots-robust-trans";
      prefix dots-robust;

      import ietf-dots-signal-channel {
        prefix dots-signal;
        reference
          "RFC 9132: Distributed Denial-of-Service Open Threat
                     Signaling (DOTS) Signal Channel Specification";
      }
      import ietf-yang-structure-ext {
        prefix sx;
        reference
          "RFC 8791: YANG Data Structure Extensions";
      }

      organization
        "IETF DDoS Open Threat Signaling (DOTS) Working Group";
      contact
        "WG Web:   <https://datatracker.ietf.org/wg/dots/>
         WG List:  <mailto:dots@ietf.org>

         Author:   Mohamed Boucadair
                   <mailto:mohamed.boucadair@orange.com>;

         Author:   Jon Shallow
                   <mailto:ietf-supjps@jpshallow.com>";
      description
        "This module contains YANG definitions for the configuration
         of parameters that can be negotiated between a DOTS client
         and a DOTS server for robust block transmission.

         Copyright (c) 2023 IETF Trust and the persons identified as
         authors of the code.  All rights reserved.

         Redistribution and use in source and binary forms, with or
         without modification, is permitted pursuant to, and subject
         to the license terms contained in, the Revised BSD License
         set forth in Section 4.c of the IETF Trust's Legal Provisions
         Relating to IETF Documents
         (https://trustee.ietf.org/license-info).

         This version of this YANG module is part of RFC 9362; see the
         RFC itself for full legal notices.";

      revision 2023-02-28 {
        description
          "Initial revision.";
        reference
          "RFC 9362: Distributed Denial-of-Service Open Threat
                     Signaling (DOTS) Configuration Attributes
                     for Robust Block Transmission";
      }

      grouping robust-transmission-attributes {
        description
          "A set of DOTS signal channel session configuration
           parameters that are negotiated between DOTS agents when
           making use of Q-Block1 and Q-Block2 options.";
        container max-payloads {
          description
            "Indicates the maximum number of payloads that
             can be transmitted at any one time.";
          choice direction {
            description
              "Indicates the communication direction in which the
               data nodes can be included.";
            case server-to-client-only {
              description
                "These data nodes appear only in a message sent
                 from the server to the client.";
              leaf max-value {
                type uint16;
                description
                  "Maximum acceptable 'max-payloads' value.";
              }
              leaf min-value {
                type uint16;
                description
                  "Minimum acceptable 'max-payloads' value.";
              }
            }
          }
          leaf current-value {
            type uint16;
            default "10";
            description
              "Current 'max-payloads' value.";
            reference
              "RFC 9177: Constrained Application Protocol (CoAP)
                         Block-Wise Transfer Options Supporting
                         Robust Transmission, Section 7.2";
          }
        }
        container non-max-retransmit {
          description
            "Indicates the maximum number of times a request
             for the retransmission of missing payloads can
             occur without a response from the remote peer.";
          choice direction {
            description
              "Indicates the communication direction in which the
               data nodes can be included.";
            case server-to-client-only {
              description
                "These data nodes appear only in a message sent
                 from the server to the client.";
              leaf max-value {
                type uint16;
                description
                  "Maximum acceptable 'non-max-retransmit' value.";
              }
              leaf min-value {
                type uint16;
                description
                  "Minimum acceptable 'non-max-retransmit' value.";
              }
            }
          }
          leaf current-value {
            type uint16;
            default "3";
            description
              "Current 'non-max-retransmit' value.";
            reference
              "RFC 9177: Constrained Application Protocol (CoAP)
                         Block-Wise Transfer Options Supporting
                         Robust Transmission, Section 7.2";
          }
        }
        container non-timeout {
          description
            "Indicates the maximum period of delay between
             sending sets of MAX_PAYLOADS payloads for the same
             body.";
          choice direction {
            description
              "Indicates the communication direction in which the
               data nodes can be included.";
            case server-to-client-only {
              description
                "These data nodes appear only in a message sent
                 from the server to the client.";
              leaf max-value-decimal {
                type decimal64 {
                  fraction-digits 2;
                }
                units "seconds";
                description
                  "Maximum 'ack-timeout' value.";
              }
              leaf min-value-decimal {
                type decimal64 {
                  fraction-digits 2;
                }
                units "seconds";
                description
                  "Minimum 'ack-timeout' value.";
              }
            }
          }
          leaf current-value-decimal {
            type decimal64 {
              fraction-digits 2;
            }
            units "seconds";
            default "2.00";
            description
              "Current 'ack-timeout' value.";
            reference
              "RFC 9177: Constrained Application Protocol (CoAP)
                         Block-Wise Transfer Options Supporting
                         Robust Transmission, Section 7.2";
          }
        }
        container non-receive-timeout {
          description
            "Indicates the time to wait for a missing payload
             before requesting retransmission.";
          choice direction {
            description
              "Indicates the communication direction in which the
               data nodes can be included.";
            case server-to-client-only {
              description
                "These data nodes appear only in a message sent
                 from the server to the client.";
              leaf max-value-decimal {
                type decimal64 {
                  fraction-digits 2;
                }
                units "seconds";
                description
                  "Maximum 'non-receive-timeout' value.";
              }
              leaf min-value-decimal {
                type decimal64 {
                  fraction-digits 2;
                }
                units "seconds";
                description
                  "Minimum 'non-receive-timeout' value.";
              }
            }
          }
          leaf current-value-decimal {
            type decimal64 {
              fraction-digits 2;
            }
            units "seconds";
            default "4.00";
            description
              "Current 'non-receive-timeout' value.";
            reference
              "RFC 9177: Constrained Application Protocol (CoAP)
                         Block-Wise Transfer Options Supporting
                         Robust Transmission, Section 7.2";
          }
        }
        container non-probing-wait {
          description
            "Used to limit the potential wait needed when
             using 'probing-rate'.";
          choice direction {
            description
              "Indicates the communication direction in which the
               data nodes can be included.";
            case server-to-client-only {
              description
                "These data nodes appear only in a message sent
                 from the server to the client.";
              leaf max-value-decimal {
                type decimal64 {
                  fraction-digits 2;
                }
                units "seconds";
                description
                  "Maximum 'non-probing-wait' value.";
              }
              leaf min-value-decimal {
                type decimal64 {
                  fraction-digits 2;
                }
                units "seconds";
                description
                  "Minimum 'non-probing-wait' value.";
              }
            }
          }
          leaf current-value-decimal {
            type decimal64 {
              fraction-digits 2;
            }
            units "seconds";
            description
              "Current 'non-probing-wait' value.";
            reference
              "RFC 9177: Constrained Application Protocol (CoAP)
                         Block-Wise Transfer Options Supporting
                         Robust Transmission, Section 7.2";
          }
        }
        container non-partial-timeout {
          description
            "Used for expiring partially received bodies.";
          choice direction {
            description
              "Indicates the communication direction in which the
               data nodes can be included.";
            case server-to-client-only {
              description
                "These data nodes appear only in a message sent
                 from the server to the client.";
              leaf max-value-decimal {
                type decimal64 {
                  fraction-digits 2;
                }
                units "seconds";
                description
                  "Maximum 'non-partial-timeout' value.";
              }
              leaf min-value-decimal {
                type decimal64 {
                  fraction-digits 2;
                }
                units "seconds";
                description
                  "Minimum 'non-partial-timeout' value.";
              }
            }
          }
          leaf current-value-decimal {
            type decimal64 {
              fraction-digits 2;
            }
            units "seconds";
            default "247.00";
            description
              "Current 'non-partial-timeout' value.";
            reference
              "RFC 9177: Constrained Application Protocol (CoAP)
                         Block-Wise Transfer Options Supporting
                         Robust Transmission, Section 7.2";
          }
        }
      }

      sx:augment-structure "/dots-signal:dots-signal"
                         + "/dots-signal:message-type"
                         + "/dots-signal:signal-config"
                         + "/dots-signal:mitigating-config" {
        description
          "Indicates DOTS configuration attributes to use for
           robust transmission when a mitigation is active.";
        uses robust-transmission-attributes;
      }
      sx:augment-structure "/dots-signal:dots-signal"
                         + "/dots-signal:message-type"
                         + "/dots-signal:signal-config"
                         + "/dots-signal:idle-config" {
        description
          "Indicates DOTS configuration parameters to use for
           robust transmission when no mitigation is active.";
        uses robust-transmission-attributes;
      }
    }

    <CODE ENDS>

¶

## 6. IANA Considerations

### 6.1. Registry for DOTS Signal Channel CBOR Mappings

This specification registers the following parameters in the IANA "DOTS Signal Channel CBOR Key Values" registry [Key-Map].¶

Table 3: DOTS Robust Block Transmission CBOR Mappings
Parameter Name | CBOR Key Value | CBOR Major Type | Change Controller | Specification Document(s)
--- | --- | --- | --- | ---
ietf-dots-robust-trans:max-payloads | 32776 | 5 | IESG | RFC 9362
ietf-dots-robust-trans:non-max-retransmit | 32777 | 5 | IESG | RFC 9362
ietf-dots-robust-trans:non-timeout | 32778 | 5 | IESG | RFC 9362
ietf-dots-robust-trans:non-receive-timeout | 32779 | 5 | IESG | RFC 9362
ietf-dots-robust-trans:non-probing-wait | 32780 | 5 | IESG | RFC 9362
ietf-dots-robust-trans:non-partial-timeout | 32781 | 5 | IESG | RFC 9362

### 6.2. DOTS Robust Block Transmission YANG Module

IANA has registered the following URI in the "ns" subregistry within the "IETF XML Registry" [RFC3688]:¶

URI:
  urn:ietf:params:xml:ns:yang:ietf-dots-robust-trans¶
Registrant Contact:
  The IESG.¶
XML:
  N/A; the requested URI is an XML namespace.¶

IANA has registered the following YANG module in the "YANG Module Names" subregistry [RFC6020] within the "YANG Parameters" registry.¶

Name:
  ietf-dots-robust-trans¶
Namespace:
  urn:ietf:params:xml:ns:yang:ietf-dots-robust-trans¶
Maintained by IANA?
  N¶
Prefix:
  dots-robust¶
Reference:
  RFC 9362¶

## 7. Security Considerations

The security considerations for the DOTS signal channel protocol are discussed in Section 11 of [RFC9132].¶

CoAP-specific security considerations are discussed in Section 11 of [RFC9177].¶

Consistent with Section 5 of [RFC9132], the "ietf-dots-robust-trans" module is not intended to be used via NETCONF/RESTCONF. It serves as an abstract representation in DOTS signal channel messages. The "ietf-dots-robust-trans" module does not introduce any new vulnerabilities beyond those specified above.¶

## 8. References

### 8.1. Normative References

[RFC2119]
  Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>.
[RFC3688]
  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, <https://www.rfc-editor.org/info/rfc3688>.
[RFC6020]
  Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, <https://www.rfc-editor.org/info/rfc6020>.
[RFC7252]
  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, DOI 10.17487/RFC7252, June 2014, <https://www.rfc-editor.org/info/rfc7252>.
[RFC7959]
  Bormann, C. and Z. Shelby, Ed., "Block-Wise Transfers in the Constrained Application Protocol (CoAP)", RFC 7959, DOI 10.17487/RFC7959, August 2016, <https://www.rfc-editor.org/info/rfc7959>.
[RFC8174]
  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8323]
  Bormann, C., Lemay, S., Tschofenig, H., Hartke, K., Silverajan, B., and B. Raymor, Ed., "CoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets", RFC 8323, DOI 10.17487/RFC8323, February 2018, <https://www.rfc-editor.org/info/rfc8323>.
[RFC8791]
  Bierman, A., Björklund, M., and K. Watsen, "YANG Data Structure Extensions", RFC 8791, DOI 10.17487/RFC8791, June 2020, <https://www.rfc-editor.org/info/rfc8791>.
[RFC9132]
  Boucadair, M., Ed., Shallow, J., and T. Reddy.K, "Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel Specification", RFC 9132, DOI 10.17487/RFC9132, September 2021, <https://www.rfc-editor.org/info/rfc9132>.
[RFC9177]
  Boucadair, M. and J. Shallow, "Constrained Application Protocol (CoAP) Block-Wise Transfer Options Supporting Robust Transmission", RFC 9177, DOI 10.17487/RFC9177, March 2022, <https://www.rfc-editor.org/info/rfc9177>.

### 8.2. Informative References

[Key-Map]
  IANA, "DOTS Signal Channel CBOR Key Values", <https://www.iana.org/assignments/dots/>.
[RFC8340]
  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, <https://www.rfc-editor.org/info/rfc8340>.
[RFC8612]
  Mortensen, A., Reddy, T., and R. Moskowitz, "DDoS Open Threat Signaling (DOTS) Requirements", RFC 8612, DOI 10.17487/RFC8612, May 2019, <https://www.rfc-editor.org/info/rfc8612>.
[RFC9244]
  Boucadair, M., Ed., Reddy.K, T., Ed., Doron, E., Chen, M., and J. Shallow, "Distributed Denial-of-Service Open Threat Signaling (DOTS) Telemetry", RFC 9244, DOI 10.17487/RFC9244, June 2022, <https://www.rfc-editor.org/info/rfc9244>.

## Acknowledgements

Thanks to Tiru Reddy, Meiling Chen, and Kaname Nishizuka for the review.¶

Thanks to Michal Vaško for the yangdoctors review.¶

Thanks to Valery Smyslov for shepherding the document, Paul Wouters for the AD review, Paul Kyzivat for the artart directorate review, Tim Evens for the Gen-ART review, and Jean-Michel Combes for the int-dir review.¶

Thanks to John Scudder, Lars Eggert, Éric Vyncke, Roman Danyliw, Rob Wilton, and Martin Duke for their comments during the IESG review.¶

## Authors' Addresses