lpwan Working Group D. Barthel Internet-Draft Orange SA Intended status: Informational L. Toutain Expires: 4 January 2024 IMT Atlantique A. Kandasamy Acklio D. Dujovne Universidad Diego Portales JC. Zuniga Cisco 3 July 2023 OAM for LPWAN using Static Context Header Compression (SCHC) draft-barthel-schc-oam-schc-01 Abstract This document describes ICMPv6 compression with SCHC and how basic OAM is performed on Low Power Wide Area Networks (LPWANs) by compressing ICMPv6/IPv6 headers and by protecting the LPWAN network and the Device from undesirable ICMPv6 traffic. With IP protocols now generalizing to constrained networks, users expect to be able to Operate, Administer and Maintain them with the familiar tools and protocols they already use on less constrained networks. OAM uses specific messages sent into the data plane to measure some parameters of a network. Most of the time, no explicit values are sent is these messages. Network parameters are obtained from the analysis of these specific messages. This can be used: * To detect if a host is up or down. * To measure the RTT and its variation over time. * To learn the path used by packets to reach a destination. OAM in LPWAN is a little bit trickier since the bandwidth is limited and extra traffic added by OAM can introduce perturbation on regular transmission. Three main scenarios are investigated: Barthel, et al. Expires 4 January 2024 [Page 1] Internet-Draft SCHC OAM for LPWAN July 2023 * OAM reachability messages coming from internet. In that case, the SCHC core should act as a proxy and handle specifically the OAM traffic. * OAM messages initiated by LPWAN devices: They can be anticipated by the core SCHC. * OAM error messages coming from internet. In that case, the SCHC core may forward a compressed version to the device. The primitive functionalities of OAM are achieved with the ICMPv6 protocol. ICMPv6 defines messages that inform the source of IPv6 packets of errors during packet delivery. It also defines the Echo Request/ Reply messages that are used for basic network troubleshooting (ping command). ICMPv6 messages are transported on IPv6. This document also introduces the notion of actions in a SCHC rule, to perform locally some operations. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. 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 4 January 2024. 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 Barthel, et al. Expires 4 January 2024 [Page 2] Internet-Draft SCHC OAM for LPWAN July 2023 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Detailed behavior . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Device does a ping . . . . . . . . . . . . . . . . . . . 5 4.1.1. Rule example . . . . . . . . . . . . . . . . . . . . 6 4.2. Device is ping'ed . . . . . . . . . . . . . . . . . . . . 7 4.2.1. Rule example . . . . . . . . . . . . . . . . . . . . 7 4.3. Device is the source of an ICMPv6 error message . . . . . 8 4.4. Device is the destination of an ICMPv6 error message . . 9 4.4.1. ICMPv6 error message compression. . . . . . . . . . . 10 5. YANG identities and tree . . . . . . . . . . . . . . . . . . 13 6. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 14 7. Security considerations . . . . . . . . . . . . . . . . . . . 18 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 9.1. Normative References . . . . . . . . . . . . . . . . . . 18 9.2. Informative References . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 1. Introduction The primitive functionalities of OAM [RFC6291] are achieved with the ICMPv6 protocol. ICMPv6 [RFC4443] is a companion protocol to IPv6 [RFC8200]. [RFC4443] defines a generic message format. This format is used for messages to be sent back to the source of an IPv6 packet to inform it about errors during packet delivery. More specifically, [RFC4443] defines 4 error messages: Destination Unreachable, Packet Too Big, Time Exceeded and Parameter Problem. [RFC4443] also defines the Echo Request and Echo Reply messages, which provide support for the ping application. Other ICMPv6 messages are defined in other RFCs, such as an extended format of the same messages [RFC4884] and other messages used by the Neighbor Discovery Protocol [RFC4861]. Barthel, et al. Expires 4 January 2024 [Page 3] Internet-Draft SCHC OAM for LPWAN July 2023 This document focuses on using Static Context Header Compression (SCHC) to compress [RFC4443] messages that need to be transmitted over the LPWAN network, and on having the LPWAN gateway proxying the Device to save it the unwanted traffic. LPWANs’ salient characteristics are described in [RFC8376]. 2. Terminology This draft re-uses the Terminology defined in [RFC8724]. 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. 3. Use cases In the LPWAN architecture, we can distinguish the following cases: * the Device is the originator of an Echo Request message, and therefore the destination of the Echo Reply message. This message is compressed by the device through SCHC rules specifying ICMPv6 fields. * the Device is the destination of an Echo Request message, and therefore the purported source of an Echo Reply message. The core SCHC can either send a compressed SCHC message, or proxy the answer to avoid sending data on the constrained link. The proxy answer can be related to the device activity. * the Device is the (purported) source of an ICMP error message, mainly in response to an incorrect incoming IPv6 message, or in response to a ping request. In this case, as much as possible, the core SCHC C/D should act as a proxy and originate the ICMP Destination Unreachable message, so that the Device and the LPWAN network are protected from this unwanted traffic. * the Device is the destination of the ICMP message, mainly in response to a packet sent by the Device to the network that generates an error. In this case, we want the ICMP message to reach the Device, and this document describes in Section 4.4.1 what SCHC compression should be applied. These cases are further described in Section 4. Barthel, et al. Expires 4 January 2024 [Page 4] Internet-Draft SCHC OAM for LPWAN July 2023 4. Detailed behavior 4.1. Device does a ping A Device may send some Echo Request message to check the availability of the network or the host running the Application. If a ping request is generated by a Device, then SCHC compression applies. The format of an ICMPv6 Echo Request message is described in Figure 1, with Type=128 and Code=0. 0 1 2 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Data ... +-+-+-+-+- Figure 1: ICMPv6 Echo Request message format If we assume that one rule will be devoted to compressing Echo Request messages, then Type and Code are known in the rule to be 128 and 0 and can therefore be elided with the not-sent CDA. Checksum can be reconstructed with the compute-checksum CDA and therefore is not transmitted. [RFC4443] states that Identifier and Sequence Number are meant to “aid in matching Echo Replies to this Echo Request” and that they “may be zero”. Data is “zero or more bytes of arbitrary data”. For constrained devices or networks, we recommend that Identifier be zero, Sequence Number be a counter on 3 bits, and Data be zero bytes (absent). Therefore, Identifier is elided with the not-sent CDA, Sequence Number is transmitted on 3 bits with the LSB CDA and no Data is transmitted. The transmission cost of the Echo Request message is therefore the size of the Rule Id + 3 bits. The rule ID length can be chosen to avoid adding padding. Barthel, et al. Expires 4 January 2024 [Page 5] Internet-Draft SCHC OAM for LPWAN July 2023 When the destination receives the Echo Request message, it will respond back with a Echo Reply message. This message bears the same format as the Echo Request message but with Type = 129 (see Figure 1). [RFC4443] states that the Identifier, Sequence Number and Data fields of the Echo Reply message shall contain the same values as the invoking Echo Request message. Therefore, a rule shall be used similar to that used for compressing the Echo Request message. 4.1.1. Rule example The following rule gives an example of a SCHC compression. The type can be elided if the direction is taken into account. Identifier is ignored and generated as 0 at decompression. This implies that only one single ping can be launched at any given time on a device. Finally, only the least significant 8 bits of the sequence number are sent on the LPWAN, allowing a serie of 255 consecutive pings. +============+==+====+====+========+==========+===========++======+ | Field |FL| FP | DI | Target | Matching | CDA || Sent | | | | | | Value | Operator | || bits | +============+==+====+====+========+==========+===========++======+ | _IPv6 Headers description_ | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |8 | 1 | Up | 128 | equal | not-sent || | | Type | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |8 | 1 | Dw | 129 | equal | not-sent || | | Type | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |8 | 1 | Bi | 0 | equal | not-sent || | | Code | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |16| 1 | Bi | | ignore | compute-* || | | Checksum | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |16| 1 | Bi | 0 | ignore | not-sent || | | Identifier | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |16| 1 | Bi | 0 | MSB(8) | LSB || 8 | | Sequence | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ Table 1: Example of compression rule for a ping from the device Barthel, et al. Expires 4 January 2024 [Page 6] Internet-Draft SCHC OAM for LPWAN July 2023 4.2. Device is ping'ed If the Device is ping’ed (i.e., is the destination of an Echo Request message), the device receives the compress message and generate an Echo. In that case, the fields sequence number and identifier cannot be compressed if the source is not aware of the compression scheme. But the default behavior is to avoid propagating the Echo Request message over the LPWAN. This is done by proxying the ping request on the core SCHC C/D. This requires to introduce a new processing when the rule is selected. The selection of a compression rule triggers the compression and sends the SCHC packet to the other end. Specifying an Action, change this behavior. In our case, being processed by the compressor, the packet description is processed by a ping proxy. Since the rule is used for the selection, so CDAs are not necessary and set to "not- sent". The ping-proxy takes a parameter in second, gives the interval during which the device is considered active. During this interval, the proxy-ping echoes ping requests, after this duration, the ping request will be discarded. The resulting behavior is shown on Figure 2 and described below: Device NGW core SCHC C/D Internet Host SCHC packet ---|~~~~~~~~~~~~~~~~~~~~~~~>| Echo Request, Code=0 | l t | | | |<---------------------------| i i | | | | | f m | | | |--------------------------->| e e X | | | Echo Reply, Code=0 | r | | | | | | | | | | | Echo Request, Code=0 | | | |O---------------------------| | | | | | | | | Figure 2: Examples of ICMPv6 Echo Request/Reply 4.2.1. Rule example The following rule shows an example of a compression rule for pinging a device. Barthel, et al. Expires 4 January 2024 [Page 7] Internet-Draft SCHC OAM for LPWAN July 2023 +============+==+====+====+========+==========+===========++======+ | Field |FL| FP | DI | Target | Matching | CDA || Sent | | | | | | Value | Operator | || bits | +============+==+====+====+========+==========+===========++======+ | *Action: proxy-ping(300)* | +-----------------------------------------------------------------+ | _IPv6 Headers description_ | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |8 | 1 | Dw | 128 | equal | not-sent || | | Type | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |8 | 1 | Dw | 0 | equal | not-sent || | | Code | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |16| 1 | Dw | | ignore | compute-* || | | Checksum | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |16| 1 | Dw | | ignore | not-sent || | | Identifier | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ | ICMPv6 |16| 1 | Dw | | ignore | not-sent || 8 | | Sequence | | | | | | || | +------------+--+----+----+--------+----------+-----------++------+ Table 2: Example of compression rule for a ping to a device In this example, type and code are elided, the identifer has to be sent, and the sequence number is limited to one byte. 4.3. Device is the source of an ICMPv6 error message As stated in [RFC4443], a node should generate an ICMPv6 message in response to an IPv6 packet that is malformed or which cannot be processed due to some incorrect field value. The general intent of this document is to spare both the Device and the LPWAN network this un-necessary traffic. The incorrect packets should be caught at the core SCHC C/D and the ICMPv6 notification should be sent back from there. Barthel, et al. Expires 4 January 2024 [Page 8] Internet-Draft SCHC OAM for LPWAN July 2023 Device NGW core SCHC C/D Internet Host | | | Destination Port=XXX | | | |<---------------------------| | | | | | | |--------------------------->| | | | ICMPv6 Port Unreachable | | | | | | | | | Figure 3: Example of ICMPv6 error message sent back to the Internet Figure 3 shows an example of an IPv6 packet trying to reach a Device. Let's assume that no rule matches the incoming packet (i.e. there is no co-compression rule) Instead of sending the packet over the LPWAN and having this packet rejected by the Device, the core SCHC C/D issues an ICMPv6 error message “Destination Unreachable” (Type 1) with Code 1 (“Port Unreachable”) on behalf of the Device. In that case the SCHC C/D MAY act as a router (i.e. it MUST have a routable IPv6 address to generate an ICMPv6 message). When compressing a packet containing an IPv6 header, no compression rules are found and: * if a rule contains some extension headers, a parameter problem may be generated (type 4), * no rule contains the IPv6 device address found in the incoming packet, a no route to destination ICMPv6 message (type 0, code 3) may be generated, * a device IPv6 address is found, but no port matches, a port unreachable ICMPv6 message (type 0, code 4) may be generated, 4.4. Device is the destination of an ICMPv6 error message In this situation, we assume that a Device has been configured to send information to a server on the Internet. If this server becomes no longer accessible, an ICMPv6 message will be generated back towards the Device by either an intermediate router or the destination. This information can be useful to the Device, for example for reducing the reporting rate in case of periodic reporting of data. Therefore, we compress the ICMPv6 message using SCHC and forward it to the Device over the LPWAN. We also introduce new MO and CDA that can be used to test the presence and/or compress the returning payload. Barthel, et al. Expires 4 January 2024 [Page 9] Internet-Draft SCHC OAM for LPWAN July 2023 Device NGW core SCHC C/D Internet Server | | | | | SCHC compressed IPv6 | | |~~~~~~~~~~~|----------->|----------------------X | | | |<--------------------- | |<~~~~~~~~~~|------------| ICMPv6 Host unreachable | |SCHC compressed ICMPv6 | payload: IPv6 packet | |payload: compressed IPv6| | | | | | Figure 4: Example of ICMPv6 error message sent back to the Device Figure 4 illustrates this behavior. The ICMPv6 error message is compressed as described in Section 4.4.1 and forwarded over the LPWAN to the Device. The SCHC returning message contains the SCHC residue of the ICMPv6 message and MAY contain the compressed original message contained in the ICMP message. The compression can be done by the core SCHC by reversing the direction as if this message was issued by the device. 4.4.1. ICMPv6 error message compression. The ICMPv6 error messages defined in [RFC4443] contain the fields shown in Figure 5. 0 1 2 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value/Unused | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | As much of invoking packet | + as possible without the ICMPv6 packet + | exceeding the minimum IPv6 MTU | Figure 5: ICMPv6 Error Message format [RFC4443] states that Type can take the values 1 to 4, and Code can be set to values between 0 and 6. Value is unused for the Destination Unreachable and Time Exceeded messages. It contains the MTU for the Packet Too Big message and a pointer to the byte causing the error for the Parameter Error message. Therefore, Value is never expected to be greater than 1280 in LPWAN networks. Barthel, et al. Expires 4 January 2024 [Page 10] Internet-Draft SCHC OAM for LPWAN July 2023 The payload is viewed as a field. An unsued field MUST not appear in the compressoin rules. The source address of the message SHOULD be ignore, since it can be initiated by any router on the path. The following generic rule can therefore be used to compress all ICMPv6 error messages as defined today. More specific rules can also be defined to achieve better compression of some error messages. The Type field can be associated to a matching list [1, 2, 3, 4] and is therefore compressed down to 2 bits. Code can be reduced to 3 bits using the LSB CDA. Value can be sent on 11 bits using the LSB CDA, but if the Device is known to send smaller packets, then the size of this field can be further reduced. The first rule example Table 3 just sends the ICMP type and code as residue to the device. +========+===+==+==+===============+=============+============++====+ |Field |FL |FP|DI|Target Value |Matching |CDA ||Sent| | | | | | |Operator | ||bits| +========+===+==+==+===============+=============+============++====+ | _IPv6 | | Headers | | descript | | ion_ | +--------+---+--+--+---------------+-------------+------------++----+ |ICMPv6 |8 |1 |Dw|1 |equal |not-sent || | |Type | | | | | | || | +--------+---+--+--+---------------+-------------+------------++----+ |ICMPv6 |8 |1 |Dw|[0,1,2,3,4,5,6]|match-mapping|mapping-sent||3 | |Code | | | | | | || | +--------+---+--+--+---------------+-------------+------------++----+ |ICMPv6 |16 |1 |Dw| |ignore |compute-* || | |Checksum| | | | | | || | +--------+---+--+--+---------------+-------------+------------++----+ |ICMPv6 |var|1 |Dw| |ignore |not-sent || | |Payload | | | | | | || | +--------+---+--+--+---------------+-------------+------------++----+ Table 3: Example of compression rule for a ICMP error to a device The second rule example Table 4 also only sends the ICMP type and code as residue to the device, but it introduces the new MO "rev- rule-match". This MO will check if a rule matches the payload. Barthel, et al. Expires 4 January 2024 [Page 11] Internet-Draft SCHC OAM for LPWAN July 2023 +========+===+==+==+=================+===========+===========++====+ |Field |FL |FP|DI| Target Value | Matching | CDA ||Sent| | | | | | | Operator | ||bits| +========+===+==+==+=================+===========+===========++====+ | _IPv6 Headers description_ | +--------+---+--+--+-----------------+-----------+-----------++----+ |ICMPv6 |8 |1 |Dw| 1 | equal | not-sent || | |Type | | | | | | || | +--------+---+--+--+-----------------+-----------+-----------++----+ |ICMPv6 |8 |1 |Dw| [0,1,2,3,4,5,6] | match- | mapping- || | |Code | | | | | mapping | sent || | +--------+---+--+--+-----------------+-----------+-----------++----+ |ICMPv6 |16 |1 |Dw| | ignore | compute-* || | |Checksum| | | | | | || | +--------+---+--+--+-----------------+-----------+-----------++----+ |ICMPv6 |var|1 |Dw| | rev-rule- | not-sent || | |Payload | | | | | match | || | +--------+---+--+--+-----------------+-----------+-----------++----+ Table 4: Example of compression rule for a ICMP error to a device By [RFC4443], the rest of the ICMPv6 message must contain as much as possible of the IPv6 offending (invoking) packet that triggered this ICMPv6 error message. This information is used to try and identify the SCHC rule that was used to decompress the offending IPv6 packet. If the rule can be found then the Rule Id is added at the end of the compressed ICMPv6 message. Otherwise the compressed packet ends with the compressed Value field. The third rule example Table 5 also sends the ICMP type, code and the compresssed payload as residue. It can be noted that this field is identified as "variable" in the rule which will introduce a size before the IPv6 compressed header. Barthel, et al. Expires 4 January 2024 [Page 12] Internet-Draft SCHC OAM for LPWAN July 2023 +========+===+==+==+===============+========+=========++===========+ |Field |FL |FP|DI|Target Value |Matching|CDA ||Sent bits | | | | | | |Operator| || | +========+===+==+==+===============+========+=========++===========+ | _IPv6 Headers description_ | +--------+---+--+--+---------------+--------+---------++-----------+ |ICMPv6 |8 |1 |Dw|128 |equal |not-sent || | |Type | | | | | | || | +--------+---+--+--+---------------+--------+---------++-----------+ |ICMPv6 |8 |1 |Dw|[0,1,2,3,4,5,6]|match- |mapping- || | |Code | | | | |mapping |sent || | +--------+---+--+--+---------------+--------+---------++-----------+ |ICMPv6 |16 |1 |Dw| |ignore |compute-*|| | |Checksum| | | | | | || | +--------+---+--+--+---------------+--------+---------++-----------+ |ICMPv6 |var|1 |Dw| |rev- |rev- ||(compressed| |Payload | | | | |rule- |compress-||IPv6 | | | | | | |match |sent ||header*8) +| | | | | | | | ||4 or +12 | | | | | | | | ||(for | | | | | | | | ||variable | | | | | | | | ||length) | +--------+---+--+--+---------------+--------+---------++-----------+ Table 5: Example of compression rule for a ICMP error to a device LT: do we add packet too big, for instance if a fragmentation rule cannot handle a size larger than 1280? 5. YANG identities and tree Figure 6 shows the augmentation of the Data Model defined in [RFC9363] This YANG module extends Field ID identities to includes fields contained in ICMPv6 header. Note that the ICMPv6 payload is parsed to the specific field "fid-icmpv6-payload" It also defines two new Most identities: * mo-rev-rule-match: The value contained in the Field Value matches a rule. The direction used for matching isthe opposite of the incoming message: UP becomes DOWN and DOWN becomes UP. This MO can be used to test if the Payload contained in the ICMPv6 message matches a rule. This means that the original packet, at the origine of the ICMPv6 message, may have been generated from the SCHC decompression. Barthel, et al. Expires 4 January 2024 [Page 13] Internet-Draft SCHC OAM for LPWAN July 2023 * mo-rule-match: The value contained in the Target Value matches a rule. The direction is the one of the incoming message. This MO is not used for ICMPv6 messages, but since it can be used in other situations, it has been included in the Data Model. The Field Value may be compressed by a rule. The result SHOULD be included in the SCHC message as a variable length residue. It contains the Rule ID used by the compression, the residue, the payload and some padding bits since the variable length init is in bytes. * cda-rev-compress-sent: The direction used for compression is the opposite of the incoming message: UP becomes DOWN and DOWN becomes UP. * cda-compress-sent: The direction used for compression is the same as for the incoming message. module: ietf-schc-oam augment /schc:schc/schc:rule/schc:nature/schc:compression: +--rw proxy-behavior? schc-oam:proxy-type +--rw proxy-behavior-value* [index] +--rw index uint16 +--rw value? binary Figure 6: YANG tree 6. YANG Module module ietf-schc-oam { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-schc-oam"; prefix schc-oam; import ietf-schc { prefix schc; } organization "IETF IPv6 over Low Power Wide-Area Networks (lpwan) working group"; contact "WG Web: WG List: Editor: Laurent Toutain Editor: Ana Minaburo "; Barthel, et al. Expires 4 January 2024 [Page 14] Internet-Draft SCHC OAM for LPWAN July 2023 description " Copyright (c) 2021 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 Simplified 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 XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. 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 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here. ************************************************************************* This module extends the ietf-schc module to include the compound-ack behavior for Ack On Error as defined in RFC YYYY. It introduces a new leaf for Ack on Error defining the format of the SCHC Ack and add the possibility to send several bitmaps in a single answer."; revision 2023-06-26 { description "Initial version for RFC YYYY "; reference "RFC YYYY: OAM"; } identity fid-icmpv6-base-type { base schc:fid-base-type; description "Field IP base type for ICMPv6 headers described in RFC 4443"; reference "RFC 4443 Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification"; } // ICMPv6 Fields Barthel, et al. Expires 4 January 2024 [Page 15] Internet-Draft SCHC OAM for LPWAN July 2023 identity fid-icmpv6-type { base schc:fid-icmpv6-base-type; description "ICMPv6 type field"; } identity fid-icmpv6-code { base schc:fid-icmpv6-base-type; description "ICMPv6 code field"; } identity fid-icmpv6-checksum { base schc:fid-icmpv6-base-type; description "ICMPv6 checksum field"; } identity fid-icmpv6-mtu { base schc:fid-icmpv6-base-type; description "ICMPv6 MTU (see draft OAM)"; } identity fid-icmpv6-pointer { base schc:fid-icmpv6-base-type; description "ICMPv6 field (see draft OAM)"; } identity fid-icmpv6-identifier { base schc:fid-icmpv6-base-type; description "ICMPv6 identifier field"; } identity fid-icmpv6-sequence { base schc:fid-icmpv6-base-type; description "ICMPv6 sequence number field"; } identity fid-icmpv6-payload { base schc:fid-icmpv6-base-type; description "payload in the ICMPv6 message"; } Barthel, et al. Expires 4 January 2024 [Page 16] Internet-Draft SCHC OAM for LPWAN July 2023 // MO and CDA identity mo-rule-match { base schc:mo-base-type; description "Macthing operator return true, if the TV matches a rule keeping UP and DOWN direction." ; } identity mo-rev-rule-match { base schc:mo-base-type; description "Macthing operator return true, if the TV matches a rule reversing UP and DOWN direction." ; } identity cda-compress-sent { base schc:mo-base-type; description "Send a compressed version of TV keeping UP and DOWN direction." ; } identity cda-rev-compress-sent { base schc:mo-base-type; description "Send a compressed version of TV reversing UP and DOWN direction." ; } // Proxy actions identity proxy-schc-message{ description "Define how the message is proxied after compression"; } identity proxy-none { base proxy-schc-message; description "The message is not proxied and sent to L2, default behavior of RFC 8724"; } identity proxy-pingv6 { base proxy-schc-message; description Barthel, et al. Expires 4 January 2024 [Page 17] Internet-Draft SCHC OAM for LPWAN July 2023 "The message is processed by an ping6 proxy"; } typedef proxy-type { type identityref { base proxy-schc-message; } description "type used in rules"; } // SCHC rule augment "/schc:schc/schc:rule/schc:nature/schc:compression" { leaf proxy-behavior { type schc-oam:proxy-type; default "schc-oam:proxy-none"; description "Entity proxying the SCHC message."; } list proxy-behavior-value { key "index"; uses schc:tv-struct; description "Parameters associated to the proxy action."; } description "added to SCHC rules"; } } Figure 7: YANG module 7. Security considerations flood the return path with ICMP error messages. 8. IANA Considerations TODO 9. References 9.1. Normative References Barthel, et al. Expires 4 January 2024 [Page 18] Internet-Draft SCHC OAM for LPWAN July 2023 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", STD 89, RFC 4443, DOI 10.17487/RFC4443, March 2006, . [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI 10.17487/RFC4861, September 2007, . [RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro, "Extended ICMP to Support Multi-Part Messages", RFC 4884, DOI 10.17487/RFC4884, April 2007, . [RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu, D., and S. Mansfield, "Guidelines for the Use of the "OAM" Acronym in the IETF", BCP 161, RFC 6291, DOI 10.17487/RFC6291, June 2011, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, . [RFC8724] Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC. Zuniga, "SCHC: Generic Framework for Static Context Header Compression and Fragmentation", RFC 8724, DOI 10.17487/RFC8724, April 2020, . [RFC9363] Minaburo, A. and L. Toutain, "A YANG Data Model for Static Context Header Compression (SCHC)", RFC 9363, DOI 10.17487/RFC9363, March 2023, . 9.2. Informative References Barthel, et al. Expires 4 January 2024 [Page 19] Internet-Draft SCHC OAM for LPWAN July 2023 [RFC8376] Farrell, S., Ed., "Low-Power Wide Area Network (LPWAN) Overview", RFC 8376, DOI 10.17487/RFC8376, May 2018, . Authors' Addresses Dominique Barthel Orange SA 28 chemin du Vieux Chene BP 98 38243 Meylan Cedex France Email: dominique.barthel@orange.com Laurent Toutain IMT Atlantique 2 rue de la Chataigneraie CS 17607 35576 Cesson-Sevigne Cedex France Email: laurent.toutain@imt-atlantique.fr Arunprabhu Kandasamy Acklio 1137A avenue des Champs Blancs 35510 Cesson-Sevigne Cedex France Email: arun@ackl.io Diego Dujovne Universidad Diego Portales Vergara 432 Santiago Chile Email: diego.dujovne@mail.udp.cl Juan Carlos Zuniga Cisco Montreal QC Canada Email: juzuniga@cisco.com Barthel, et al. Expires 4 January 2024 [Page 20]