--- 1/draft-ietf-roll-turnon-rfc8138-09.txt 2020-08-05 10:13:12.412745239 -0700 +++ 2/draft-ietf-roll-turnon-rfc8138-10.txt 2020-08-05 10:13:12.440745950 -0700 @@ -1,19 +1,19 @@ ROLL P. Thubert, Ed. Internet-Draft L. Zhao Updates: 8138 (if approved) Cisco Systems -Intended status: Standards Track 27 July 2020 -Expires: 28 January 2021 +Intended status: Standards Track 5 August 2020 +Expires: 6 February 2021 A RPL DODAG Configuration Option for the 6LoWPAN Routing Header - draft-ietf-roll-turnon-rfc8138-09 + draft-ietf-roll-turnon-rfc8138-10 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. Status of This Memo @@ -23,21 +23,21 @@ 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 28 January 2021. + This Internet-Draft will expire on 6 February 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 @@ -54,23 +54,23 @@ 2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 3 2.3. Requirements Language . . . . . . . . . . . . . . . . . . 4 3. The RPL DODAG Configuration Option . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . . . . . . 7 - 9. Normative References . . . . . . . . . . . . . . . . . . . . 7 - 10. Informative References . . . . . . . . . . . . . . . . . . . 8 + 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 + 9. Normative References . . . . . . . . . . . . . . . . . . . . 8 + 10. Informative References . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction The packet compression technique defined in [RFC8138] can only be activated in a RPL [RFC6550] network when all the nodes support it. Otherwise, a non-capable node acting as leaf-only would fail to communicate, and acting as a router it would drop the compressed packets and black-hole a portion of the network. @@ -90,36 +90,36 @@ The idea is to use the flag 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 - The Terminology used in this document is consistent with and + The terminology used in this document is consistent with and incorporates that described in "Terms Used in Routing for Low-Power and Lossy Networks (LLNs)" [RFC7102]. Other terms in use in LLNs are found in "Terminology for Constrained-Node Networks" [RFC7228]. - "RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by - a RPLInstanceID) are defined in "RPL: IPv6 Routing Protocol for - Low-Power and Lossy Networks" [RFC6550]. The RPI is the abstract - information that RPL defines to be placed in data packets, e.g., as - the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By - extension the term "RPI" is often used to refer to the RPL Option + "RPL", the "RPL Packet Information" (RPI), and "RPL Instance" + (indexed by a RPLInstanceID) are defined in "RPL: IPv6 Routing + Protocol for Low-Power and Lossy Networks" [RFC6550]. The RPI is the + abstract information that RPL defines to be placed in data packets, + e.g., as the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. + By extension the term "RPI" is often used to refer to the RPL Option itself. The DODAG Information Solicitation (DIS), Destination Advertisement Object (DAO) and DODAG Information Object (DIO) messages are also specified in [RFC6550]. - This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware + This document uses the terms RPL-Unaware Leaf (RUL) and RPL-Aware Leaf (RAL) consistently with "Using RPI Option Type, Routing Header for Source Routes and IPv6-in-IPv6 encapsulation in the RPL Data Plane" [USEofRPLinfo]. The term RPL-Aware Node (RAN) refers to a node that is either a RAL or a RPL Router. A RAN manages the reachability of its addresses and prefixes by injecting them in RPL by itself. In contrast, a RUL leverages "Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery" [RFC8505] to obtain reachability services from its parent router(s) as specified in "Routing for RPL Leaves" [UNAWARE-LEAVES]. @@ -179,64 +179,65 @@ The suggested bit position of the "T" flag is indicated in Section 6. [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. Section 6.3.1 of [RFC6550] defines a 3-bit Mode of Operation (MOP) in - the DIO Base Object. For MOP values 0 to 6, the use of compression - depends on the "T" flag as specified in this document. A MOP value - of 7 and above MUST use compression by default and ignore the setting - of the "T" flag. + 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. 4. Updating RFC 8138 A node SHOULD source packets in the compressed form using [RFC8138] if and only if the "T" flag is set. This behaviour can be overridden by e.g., configuration or network management. Overriding may be - needed e.g., to cope with a legacy implementations of the Root that + needed e.g., to cope with a legacy implementation of the Root that supports [RFC8138] but not this specification and cannot set the "T" flag. The decision of using [RFC8138] is made by the originator of the packet depending on its capabilities and its knowledge of the state of the "T" flag. A router that encapsulates a packet is the originator of the resulting packet and is responsible to compress the outer headers with [RFC8138], but it MUST leave the encapsulated packet as is. An external target [USEofRPLinfo] is not expected to support - [RFC8138]. In most cases, packets from/to an external target are - tunneled back and forth between the RPL border router and the Root - regardless of the MOP used in the RPL DODAG. The inner packet is - typically not compressed with [RFC8138] so the 6LR just needs to - decapsulate the (compressed) outer header and forward the - (uncompressed) inner packet towards the external target. + [RFC8138]. In most cases, packets from and to an external target are + tunneled back and forth between the border router (referred to as + 6LR) that serves the external target and the Root, regardless of the + MOP used in the RPL DODAG. The inner packet is typically not + compressed with [RFC8138], so for outgoing packets, the border router + just needs to decapsulate the (compressed) outer header and forward + the (uncompressed) inner packet towards the external target. A router MUST uncompress a packet that is to be forwarded to an external target. Otherwise, the router MUST forward the packet in 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 - requires a "flag day"; all nodes must be upgraded, and then the - network can be rebooted with the [RFC8138] compression turned on. + without a turn-on signaling requires a "flag day"; all nodes must be + upgraded, and then 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), adding nodes that do not support [RFC8138] after a roll back may be problematic if the roll back did not fully complete. 5.1. Coexistence @@ -318,24 +319,35 @@ Setting and resetting 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 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 Alvaro Retana, Dominique Barthel and Rahul - Jadhav for their in-depth reviews and constructive suggestions. + The authors wish to thank Carles Gomez, 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, .