--- 1/draft-ietf-roll-turnon-rfc8138-14.txt 2020-09-18 07:14:00.806161618 -0700 +++ 2/draft-ietf-roll-turnon-rfc8138-15.txt 2020-09-18 07:14:00.830162223 -0700 @@ -1,43 +1,43 @@ ROLL P. Thubert, Ed. Internet-Draft L. Zhao -Updates: 8138 (if approved) Cisco Systems -Intended status: Standards Track September 8, 2020 -Expires: March 12, 2021 +Updates: 6550, 8138 (if approved) Cisco Systems +Intended status: Standards Track 18 September 2020 +Expires: 22 March 2021 A RPL DODAG Configuration Option for the 6LoWPAN Routing Header - draft-ietf-roll-turnon-rfc8138-14 + draft-ietf-roll-turnon-rfc8138-15 Abstract This document updates RFC 8138 by defining a bit in the RPL DODAG Configuration Option to indicate whether compression is used within the RPL Instance, and specify the behavior of RFC 8138-capable nodes - when the bit is set and reset. + when the bit is set and unset. 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 March 12, 2021. + This Internet-Draft will expire on 22 March 2021. Copyright Notice Copyright (c) 2020 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 @@ -46,56 +46,56 @@ as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. References . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 3 2.3. Requirements Language . . . . . . . . . . . . . . . . . . 4 - 3. The RPL DODAG Configuration Option . . . . . . . . . . . . . 4 + 3. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 4 4. Updating RFC 8138 . . . . . . . . . . . . . . . . . . . . . . 5 5. Transition Scenarios . . . . . . . . . . . . . . . . . . . . 5 5.1. Coexistence . . . . . . . . . . . . . . . . . . . . . . . 6 5.2. Inconsistent State While Migrating . . . . . . . . . . . 6 5.3. Rolling Back . . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 9. Normative References . . . . . . . . . . . . . . . . . . . . 8 10. Informative References . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction The design of Low Power and Lossy Networks (LLNs) is generally focused on saving energy, which is the most constrained resource of all. The routing optimizations in the "Routing Protocol for Low Power and Lossy Networks" [RFC6550] (RPL) such as routing along a Destination-Oriented Directed Acyclic Graph (DODAG) to a Root Node - and the associated packet compression technique [RFC8138] derive from - that primary concern. + and the associated routing header compression and forwarding + technique specified in [RFC8138] derive from that primary concern. - Enabling [RFC8138] requires a Flag Day where the network is upgraded - and rebooted. Otherwise, if acting as a Leaf, a node that does not - support the compression would fail to communicate; if acting as a - router it would drop the compressed packets and black-hole a portion - of the network. This specification enables a hot upgrade where a - live network is migrated. During the migration, the compression - remains inactive, until all nodes are upgraded. + Enabling [RFC8138] on a running network requires a Flag Day where the + network is upgraded and rebooted. Otherwise, if acting as a Leaf, a + node that does not support the compression would fail to communicate; + if acting as a router it would drop the compressed packets and black- + hole a portion of the network. This specification enables a hot + upgrade where a live network is migrated. During the migration, the + compression remains inactive, until all nodes are upgraded. - This document complements [RFC8138] and dedicates a flag in the RPL - DODAG Configuration Option to indicate whether the [RFC8138] - compression should be used within the RPL DODAG. The setting of this - new flag is controlled by the Root and propagates as is in the whole - network as part of the normal RPL signaling. + This document complements [RFC8138] and signals whether it should be + used within a RPL DODAG with a new flag in the RPL DODAG + Configuration Option. The setting of this new flag is controlled by + the Root and propagates as is in the whole network as part of the + normal RPL signaling. The flag is cleared to maintain the compression inactive during the migration phase. When the migration is complete (e.g., as known by network management and/or inventory), the flag is set and the compression is globally activated in the whole DODAG. 2. Terminology 2.1. References @@ -128,76 +128,77 @@ 2.2. Glossary This document often uses the following acronyms: 6LoWPAN: IPv6 over Low-Power Wireless Personal Area Network 6LoRH: 6LoWPAN Routing Header DIO: DODAG Information Object (a RPL message) DODAG: Destination-Oriented Directed Acyclic Graph LLN: Low-Power and Lossy Network RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks - SubDAG: Subset of a DAG that is a child of a node + SubDAG: A DODAG rooted at a node which is a child of that node and a + subset of a larger DAG MOP: RPL Mode of Operation RPI: RPL Packet Information RAL: RPL-Aware Leaf RAN: RPL-Aware Node RUL: RPL-Unaware Leaf SRH: Source Routing Header 2.3. Requirements Language 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. The RPL DODAG Configuration Option +3. Updating RFC 6550 The DODAG Configuration Option is defined in Section 6.7.6 of - [RFC6550]. - - The RPL DODAG Configuration Option is typically placed in a DODAG - Information Object (DIO) message. The DIO message propagates down - the DODAG to form and then maintain its structure. The DODAG - Configuration Option is copied unmodified from parents to children. - - As shown in Figure 1, the DODAG Configuration Option was designed - with 4 bit positions reserved for future use as Flags. + [RFC6550]. Its purpose is extended to distribute configuration + information affecting the construction and maintenance of the DODAG, + as well as operational parameters for RPL on the DODAG, through the + DODAG. As shown in Figure 1, the Option was originally designed with + 4 bit positions reserved for future use as Flags. 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 = 0x04 |Opt Length = 14| | |T| |A| ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + - | <- Flags -> ... | Figure 1: DODAG Configuration Option (Partial View) This specification defines a new flag "Enable RFC8138 Compression" - (T). The "T" flag is set to turn-on the use of the compression of - RPL artifacts with [RFC8138] within the DODAG. The new "T" flag is - encoded in position 2 of the reserved Flags field in the RPL DODAG - Configuration Option, and set to 0 in legacy implementations as - specified in Section 6.7.6 of [RFC6550]. + (T). The "T" flag is set to turn-on the use of [RFC8138] within the + DODAG. The "T" flag is encoded in position 2 of the reserved Flags + in the DODAG Configuration Option (counting from bit 0 as the most + significant bit) and set to 0 in legacy implementations as specified + respectively in Sections 20.14 and 6.7.6 of [RFC6550]. - [RFC6550] states, when referring to the DODAG Configuration Option, - that "Nodes other than the DODAG Root MUST NOT modify this - information when propagating the DODAG Configuration option". - Therefore, a legacy parent propagates the "T" flag as set by the Root - whether it supports this specification or not. So when the "T" flag - is set, it is transparently flooded to all the nodes in the DODAG. + The RPL DODAG Configuration Option is typically placed in a DODAG + Information Object (DIO) message. The DIO message propagates down + the DODAG to form and then maintain its structure. The DODAG + Configuration Option is copied unmodified from parents to children. Section 6.3.1 of [RFC6550] defines a 3-bit Mode of Operation (MOP) in the DIO Base Object. This specification applies to MOP values 0 to - 6. For a MOP value of 7, the compression MUST be used by default - regardless of the setting of the "T" flag. + 6. For a MOP value of 7, the bit in position 2 is considered + unallocated and [RFC8138] MUST be used by default. + + [RFC6550] states that "Nodes other than the DODAG Root MUST NOT + modify this information when propagating the DODAG Configuration + option". Therefore, a legacy parent propagates the "T" flag as set + by the Root whether it supports this specification or not. So when + the "T" flag is set, it is transparently flooded to all the nodes in + the DODAG. 4. Updating RFC 8138 A node SHOULD generate packets in the compressed form using [RFC8138] if and only if the "T" flag is set. This behavior can be overridden by configuration or network management. Overriding may be needed e.g., to turn on the compression in a network where all nodes support [RFC8138] but the Root does not support this specification and cannot set the "T" flag, or to disable it locally in case of a problem. @@ -221,31 +222,31 @@ the form that the source used, either compressed or uncompressed. A RUL [UNAWARE-LEAVES] is both a leaf and an external target. A RUL does not participate in RPL and depends on the parent router to obtain connectivity. In the case of a RUL, forwarding towards an external target actually means delivering the packet. 5. Transition Scenarios A node that supports [RFC8138] but not this specification can only be - used in an homogeneous network. Enabling the [RFC8138] compression + used in a homogeneous network. Enabling the [RFC8138] compression without a turn-on signaling method requires a "flag day"; by which time all nodes must be upgraded, and at which point the network can be rebooted with the [RFC8138] compression turned on. The intent for this specification is to perform a migration once and for all without the need for a flag day. In particular it is not the intention to undo the setting of the "T" flag. Though it is possible - to roll back (see Section 5.3, the network operator SHOULD ensure - that the roll back operation is completed before adding nodes that do - not support [RFC8138]. + to roll back (see Section 5.3), the roll back operation SHOULD be + complete before the network operator adds nodes that do not support + [RFC8138]. 5.1. Coexistence A node that supports this specification can operate in a network with the [RFC8138] compression turned on or off with the "T" flag set accordingly and in a network in transition from off to on or on to off (see Section 5.2). A node that does not support [RFC8138] can interoperate with nodes that do in a network with [RFC8138] compression turned off. If the @@ -267,28 +268,28 @@ To ensure that a packet is forwarded across the RPL DODAG in the form in which it was generated, it is required that all the RPL nodes support [RFC8138] at the time of the switch. Setting the "T" flag is ultimately the responsibility of the Network Administrator. The expectation is that the network management or upgrading tools in place enable the Network Administrator to know when all the nodes that may join a DODAG were migrated. In the case of a RPL instance with multiple Roots, all nodes that participate to the RPL Instance may potentially join any DODAG. The network MUST be - operated with the "T" flag reset until all nodes in the RPL Instance + operated with the "T" flag unset until all nodes in the RPL Instance are upgraded to support this specification. 5.3. Rolling Back When turning [RFC8138] compression off in the network, the Network Administrator MUST wait until all nodes have converged to the "T" - flag reset before allowing nodes that do not support the compression + flag unset before allowing nodes that do not support the compression in the network. To that effect, whether the compression is active in a node SHOULD be exposed the node's management interface. Nodes that do not support [RFC8138] SHOULD NOT be deployed in a network where the compression is turned on. If that is done, the node can only operate as a RUL. 6. IANA Considerations IANA is requested to assign a new option flag from the Registry for @@ -310,47 +311,46 @@ based attack in the network, more in [RFC7416]. This document applies typically to an existing deployment and does not change its security requirements and operations. It is assumed that the security mechanisms as defined for RPL are followed. Setting the "T" flag before all routers are upgraded may cause a loss of packets. The new bit is protected as the rest of the configuration so this is just one of the many attacks that can happen if an attacker manages to inject a corrupted configuration. - Setting and resetting the "T" flag may create inconsistencies in the + Setting and unsetting the "T" flag may create inconsistencies in the network but as long as all nodes are upgraded to [RFC8138] support they will be able to forward both forms. The source is responsible for selecting whether the packet is compressed or not, and all routers must use the format that the source selected. So the result of an inconsistency is merely that both forms will be present in the network, at an additional cost of bandwidth for packets in the uncompressed form. - An attacker in the middle of the network may reset the "T" flag to - cause extra energy spending in the subset of the DODAG formed by its - descendants (its subDAG). Conversely it may set the "T" flag, so - that nodes located downstream would compress when that it is not - desired, potentially resulting in the loss of packets. In a tree - structure, the attacker would be in position to drop the packets from - and to the attacked nodes. So the attacks above would be more - complex and more visible than simply dropping selected packets. The - downstream node may have other parents and see both settings, which - could raise attention. + An attacker may unset the "T" flag to force additional energy + consumption of child or descendant nodes in its subDAG. Conversely + it may set the "T" flag, so that nodes located downstream would + compress when that it is not desired, potentially resulting in the + loss of packets. In a tree structure, the attacker would be in + position to drop the packets from and to the attacked nodes. So the + attacks above would be more complex and more visible than simply + dropping selected packets. The downstream node may have other + parents and see both settings, which could raise attention. 8. Acknowledgments The authors wish to thank Murray Kucherawy, Meral Shirazipour, Barry Leiba, Tirumaleswar Reddy, Nagendra Kumar Nainar, Stewart Bryant, - Carles Gomez, Eric Vyncke, and especially Alvaro Retana, Dominique - Barthel and Rahul Jadhav for their in-depth reviews and constructive - suggestions. + Carles Gomez, Eric Vyncke, Roman Danyliw, and especially Benjamin + Kaduk, Alvaro Retana, Dominique Barthel and Rahul Jadhav for their + in-depth reviews and constructive suggestions. Also many thanks to Michael Richardson for being always helpful and responsive when need comes. 9. 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, . @@ -377,21 +377,21 @@ [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. Perkins, "Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, . [UNAWARE-LEAVES] Thubert, P. and M. Richardson, "Routing for RPL Leaves", Work in Progress, Internet-Draft, draft-ietf-roll-unaware- - leaves-18, June 12, 2020, . 10. Informative References [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- Power and Lossy Networks (RPL) Option for Carrying RPL Information in Data-Plane Datagrams", RFC 6553, DOI 10.17487/RFC6553, March 2012, . @@ -404,21 +404,21 @@ and M. Richardson, Ed., "A Security Threat Analysis for the Routing Protocol for Low-Power and Lossy Networks (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015, . [USEofRPLinfo] Robles, I., Richardson, M., and P. Thubert, "Using RPI Option Type, Routing Header for Source Routes and IPv6-in- IPv6 encapsulation in the RPL Data Plane", Work in Progress, Internet-Draft, draft-ietf-roll-useofrplinfo-40, - June 25, 2020, . Authors' Addresses Pascal Thubert (editor) Cisco Systems, Inc Building D 45 Allee des Ormes - BP1200 06254 MOUGINS - Sophia Antipolis France