ROLL Working Group M. Robles Internet-Draft Ericsson Intended status: Informational M. Richardson Expires:September 22,October 6, 2016 SSW P. Thubert CiscoMarch 21,April 4, 2016 When to use RFC 6553, 6554 and IPv6-in-IPv6draft-ietf-roll-useofrplinfo-02draft-ietf-roll-useofrplinfo-03 Abstract This documentstateslooks at different data flows through LLN networks where RPL is used to establish routing. The document enumerates the cases where RFC 6553, RFC 6554 and IPv6-in-IPv6 encapsulation isrequired to setrequired. This analysis provides thebasesbasis on which tohelp defining thedesign efficient compression ofRPL routing information in LLN environments.these headers. 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 http://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 onSeptember 22,October 6, 2016. Copyright Notice Copyright (c) 2016 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 (http://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 Simplified BSD License text 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology and Requirements Language . . . . . . . . . . . . 3 3. Sample/reference topology . . . . . . . . . . . . . . . . . . 3 4. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Example of Flow from RPL-aware-leaf to root . . . . . . .89 5.2. Example of Flow from root to RPL-aware-leaf . . . . . . .910 5.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 10 5.4. Example of Flow from not-RPL-aware-leaf to root . . . . .1011 5.5. Example of Flow from RPL-aware-leaf to Internet . . . . .1112 5.6. Example of Flow from Internet to RPL-aware-leaf . . . . .1112 5.7. Example of Flow from not-RPL-aware-leaf to Internet . . .1213 5.8. Example of Flow from Internet to non-RPL-aware-leaf . . .1314 5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 14 5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 15 5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 17 5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware- leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 19 6.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 19 6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 20 6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 20 6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 21 6.5. Example of Flow from RPL-aware-leaf to Internet . . . . .2122 6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 22 6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 23 6.8. Example of Flow from Internet to non-RPL-aware-leaf . . .2423 6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . .2524 6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf2625 6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf2726 6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware- leaf . . . . . . . . . . . . . . . . . . . . . . . . . .2726 7.Problem statementObservations about the problem . . . . . . . . . . . . . . . 27 7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 27 7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 28 8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . .2928 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 10. Security Considerations . . . . . . . . . . . . . . . . . . . 29 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 29 12.1. Normative References . . . . . . . . . . . . . . . . . . 29 12.2. Informative References . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 1. Introduction RPL [RFC6550] is a routing protocol for constrained networks. RFC 6553 [RFC6553] defines the "RPLoption",option" (RPI), carried within the IPv6Hop- by-HopHop-by-Hop header to quickly identify inconsistencies (loops) in the routing topology. RFC 6554 [RFC6554] defines the "RPL Source RouteHeader",Header" (RH3), an IPv6 Extension Header to deliver datagrams within a RPL routingdomain. Several discussionsdomain, particularly in non-storing mode. These various items are referred to as RPL artifacts, and they are seen on all of theROLL/6lo/6TiSCH Mailing Lists took place focusingdata-plane traffic that occurs inthe definition of how to compressRPLInformationrouted networks; they do not inconstrained environment. ROLL Virtual Interim Meeting (02-2015) concluded that theregeneral appear on the RPL control plane traffic at all which isa need to define howmostly hop-by-hop traffic (one exception being DAO messages in non-storing mode). It has become clear from attempts touse [RFC6553], [RFC6554]do multi-vendor interoperability, andIPv6-in-IPv6 encapsulationfrom a desire to compress as many of the above artifacts as possible that not all implementors agree when artifacts are necessary, or when they can beablesafely omitted, or removed. An interim meeting went through the 24 cases defined here tosetdiscover if there were any shortcuts, and this document is the result of that discussion. This document should not be defining anything new, but it may clarify what is correctenvironment for compressionand incorrect behaviour. The related document A Routing Header Dispatch for 6LoWPAN (6LoRH)[I-D.ietf-6lo-routing-dispatch][I-D.ietf-roll-routing-dispatch] defines a method to compress RPL Option information and Routing Header type 3 (RFC6554) and an efficient IP-in-IP technique. Uses cases proposed for the [Second6TischPlugtest] involving6loRH: When the packet travel inside the RPL domain, the IP in IP 6LoRH is not be presented in the packet and when the packet travel outside a RPL domain, Ip in IP 6LoRH is present in the packet. This document is going to be focused in data plane messages and how can be transmitted within the above mentioned RFCs.6loRH. 2. Terminology and Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Terminology defined in [RFC7102] 3. Sample/reference topology A RPL network is composed of a 6LBR (6LoWPAN Border Router), Backbone Router (6BBR), 6LR (6LoWPAN Router) and 6LN (6LoWPAN Node) as leaf logically organized in a DODAG structure (Destination Oriented Directed Acyclic Graph). RPL defines the RPL Control messages (control plane ), a new ICMPv6 message with Type 155. DIS, DIO and DAO messages are all RPL Control messages but with different Code values. RPL supports two modes of Downward traffic: in storing mode, it is fully stateful or an in non-storing, it is fully source routed. A RPL Instance is either fully storing or fully non-storing, i.e. a RPL Instance with a combination of storing and non-storing nodes is not supported with the current specifications. +--------------+ | Upper Layers | | | +--------------+ | RPL | | | +--------------+ | ICMPv6 | | | +--------------+ | IPv6 | | | +--------------+ | 6LoWPAN | | | +--------------+ | PHY-MAC | | | +--------------+ Figure 1: RPL Stack. +---------+ +---+Internet | | +---------+ | +----+--+ |DODAG | node:01 +---------+Root +----------+ | |6LBR | | | +----+--+ | | | | | | | ... ... ... | | | +-----+-+ +--+---+ +--+---+ |6LR | | | | | +-----+ | | | | | | | 11 | | 12 | | 13 +------+ | +-----+-+ +-+----+ +-+----+ | | | | | | | | | | | | 21 | 22 | 23 | 24 | 25 +-+---+ +-+---+ +--+--+ +- --+ +---+-+ |Leaf | | | | | |Leaf| |Leaf | || | |6LN |6LR | | | | | | 6LN| | 6LR | +-----+ +-----+ +-----+ +----+ +-----+ Figure 2: A reference RPL Topology. The numbers in or above the nodes are there so that they may be referenced in subsequent sections. The leaf marked 6LN (24) is a device which does not speak RPL at all, but uses Router- Advertisements, 6LowPAN DAR/DAC and efficient-ND only to participate in the network. This document is in part motivated by the work that is ongoing at the 6TiSCH working group. The 6TiSCH architecture [I-D.ietf-6tisch-architecture] draft explains the network architecture of a 6TiSCH network. This architecture is used for the remainder of this document. The scope of the 6TiSCH Architecture is a Backbone Link that federates multiple LLNs (mesh) as a single IPv6 Multi-Link Subnet. Each LLN in the subnet is anchored at a Backbone Router (6BBR). The Backbone Routers interconnect the LLNs over the Backbone Link and emulate that the LLN nodes are present on the Backbone thus creating a so-called: Multi-Link Subnet. An LLN node can move freely from an LLN anchored at a Backbone Router to another LLN anchored at the same or a different Backbone Router inside the Multi-Link Subnet and conserve its addresses. | +-----+ | | Border Router to the RPL domain | | (may be a RPL virtual root) +-----+ | | Backbone +-------------------+-------------------+ | | | +-----+ +-----+ +-----+ | | Backbone | | Backbone | | Backbone | | router | | router | | router +|---|+ +-|||-+ +-[_]-+ | | PCI-exp / | \ USB | Ethernet ( ) ( ) ( )( )( ) (6LBR == RPL DODAG root) o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 6LR == RPL router) o o o o o o o o o z o o o o o o (6LoWPAN Host) <----------------------- RPL Instance ------------------------> Figure 3: RPL domain architecture 4. Use cases In data plane context a combination of RFC6553, RFC6554 and IPv6-in- IPv6 encapsulation is going to be analyzed for the following traffic flows:-Flow fromRPL-aware-leaf to root-Flow fromroot to RPL-aware-leaf-Flow fromnot-RPL-aware-leaf to root-Flow fromroot to not-RPL-aware-leaf-Flow fromRPL-aware-leaf to Internet-Flow fromInternet to RPL-aware-leaf-Flow fromnot-RPL-aware-leaf to Internet-Flow fromInternet to not-RPL-aware-leaf-Flow fromRPL-aware-leaf to RPL-aware-leaf-Flow fromRPL-aware-leaf to not-RPL-aware-leaf-Flow fromnot-RPL-aware-leaf to RPL-aware-leaf-Flow fromnot-RPL-aware-leaf to not-RPL-aware-leaf This document assumes a rule that a Header cannot be inserted or removed on the fly inside an IPv6 packet that is being routed.-This is a fundamental precept of the IPv6 architecture as outlined in [RFC2460] is that Extensions may not be added or removed except by the sender or the receiver. A second important thing is that packets with a Hop-by-Hop option which are marked with option type 01 ([RFC2460] section 4.2) must be discarded if received by a host or router which does not understand that option. This means that in general, any packet that leaves the RPL domain of an LLN (or leaves the LLN entirely) is likely to be discarded if it still contains an [RFC6553] RPL Option Header known as the RPI. The combination of these two rules means that the arrangement of headers must be done so that traffic intended to exit the RPL domain can have the RPI option removed prior to leaving the RPL domain. An intermediate router that needs to add a header must encapsulate the packet in an (additional) outer IP header where the new header can be placed.-This also means that a Header can only be removed by an intermediate router if it is placed in an encapsulating IPv6 Header, and in that case, the whole encapsulating header must be removed - a replacement may be added.This document recognizes that some headersFurther, an intermediate router can only remove suchas a Routing Header or a Hop-by-Hopan outer header if that outer header has the router as the destination! Both RPI and RH3 headers may be modified by routers on the path of the packet without the need to add to remove an encapsulating header.TheBoth headers were designed with this modification in mind, and both the RPL RH and the RPL option are marked mutable butrecoverable .recoverable, so an IPsec AH security header can be applied across these headers, but it may not secure all the values in those headers. RPI should be present in every single RPL data packet. There isanone exception in non-storingmode,mode: when a packet is going down from theroute:route. In a downward non-storing mode, the entire route is written, so therearecan be no loopsofby construction, nor any confusion about which forwarding table touse (purpose of instanceID).use. There may be cases (such as in 6tisch) where the instanceID may still be needed to pick an appropriate priority or channel at each hop. The applicability for storing (RPL-SN) and non-Storing (RPL-NSN) modes for the previous cases is showed as follows:+---------------+------+------+---------+--------+--------+---------+In tables, the term "RPL aware leaf" is has been shortened to "Raf", and "not-RPL aware leaf" has been shortened to "~Raf" to make the table fit in available space. The earlier examples are more complete to make sure that the process is clear, while later examples are more consise. 5. Storing mode This table summarizes what headers are needed in the following scenarios, and indicates the IPIP header must be inserted on a hop- by-hop basis, and when it can target the destination node directly. There are three possible situations: hop-by-hop necessary (indicated by "hop"), or destination address possible (indicated by "dst"). In all cases hop by hop can be used. In cases where no IPIP header is needed, the column is left blank. +---------------+--------------+--------------+----------+----------+ | Use Case |RPL- | RPL- | RPL-SN | RPL- | RPL- | RPL-NSN | | | SN | SN | IP-in- | NSN | NSN | IP-in- | | |RPI| RH3 | IP | RPI | RH3 | IP | | |(RFC | RH3 (RFC | IP-in-IP | IPIP dst | | | 6553) | 6554) |6553 | 6554 | | | | | | | ) | ) | | | | | +---------------+------+------+---------+--------+--------+---------+|RPL-aware-|Yes+---------------+--------------+--------------+----------+----------+ |No | NoRaf to root | Yes | No | No || leaf to root | | | | | |-- | | root toRPL-Raf | Yes | No | No |Yes | Yes | No | | aware-leaf | | | | | |-- | |not-RPL-root to ~Raf | Yes | No | Yes |Yes | No | Yeshop | |aware-leaf~Raf to| | | | | | | | root | | | | | | | |rootto not-| Yes | No | Yes |Yes | Yes | Yes | | RPL-aware- | | | | | | | | leaf | | | | | | | | RPL-aware- | Yesroot |No|YesRaf to | Yes | No | Yes || leaf to | | | | | |root | | Internet | | | | | || |Internet to | Yes | No | Yes |Yes | Yes | Yes | | RPL-aware- | | | | | | | | leaf | | |raf | | Raf | | |not-RPL-|Yes|No|Yes~Raf to | Yes | No | Yes || aware-leaf to | | | | | |root | | Internet | | | | | || |Internet to | Yes | No | Yes |Yes | Yes | Yes | | not-RPL- | | | | | | | | aware-leafhop | | ~Raf | | | | | |RPL-aware-Raf to Raf | Yes | No | No |Yes | Yes | Yes-- | |leafRaf toRPL- | | | | | | | | aware-leaf | | | | | | | | RPL-aware-~Raf | Yes | No | Yes |Yes | Yes | Yeshop | |leaf~Raf tonot- | | | | | | | | RPL-aware- | | | | | | | | leaf | | | | | | | | not-RPL-Raf | Yes | No | Yes |Yes | Yes | Yesdst | |aware-leaf~Raf to| | | | | | | | RPL-aware- | | | | | | | | leaf | | | | | | | | not-RPL-~Raf | Yes | No | Yes |Yes | Yes | Yes | | aware-leaf to | | | | | | | | not-RPL- | | | | | | | | aware-leaf | | | | | |hop |+---------------+------+------+---------+--------+--------+---------++---------------+--------------+--------------+----------+----------+ Table 1:Posibility to transmitHeaders needed in Storingor Non-Storingmode: RPI, RH3, IP-in-IP encapsulation5. Storing mode5.1. Example of Flow from RPL-aware-leaf to root As states in Section 16.2 of [RFC6550] a RPL-aware-leaf node does not generally issue DIOmessages,messages; a leaf node accepts DIO messages(Infrom upstream. (When the inconsistency in routing occurs, a leaf nodegenerateswill generate a DIO with an infinite rank, to fix it). It may issue DAO and DIS messages though it generally ignores DAO and DIS messages. In storingmodemode, it is suitabletheto useofRFC 6553 (RPI) to send RPL Informationthrough HBH field checking the routing table to find out where to send the message.instanceID and rank information. In this case the flow comprises: RPL-aware-leaf (6LN) --> 6LR --> 6LR,... --> root (6LBR) Note: In this document 6LRs, 6LBR are always full-fledge RPLroutersrouters, and are the RPL root node. The 6LN inserts the RPI header, and send the packet to 6LR which decrement the rank in RPI and send the packet up. When the packet arrives to 6LBR, the RPI is removed and the packet is processed. The RPI header can be removed by the 6LBR because the packet is addressed to the 6LBR. The 6LN must know that it is communicating with the 6LBR in order to be able to make use of this scenario. The 6LN can know the address of the 6LBR because it knows the address of the root via the DODAGID in the DIO messages. +-------------------+-----+------+------+ | Header | 6LN | 6LR | 6LBR | +-------------------+-----+------+------+ | Inserted headers | RPI | -- | -- | | Removed headers | -- | -- | RPI | | Re-added headers | -- | -- | -- | | Modified headers | -- | RPI | -- | | Untouched headers | -- | -- | -- | +-------------------+-----+------+------+ Storing: Summary of the use of headers from RPL-aware-leaf to root 5.2. Example of Flow from root to RPL-aware-leaf In this case the flow comprises: root (6LBR)--> 6LR --> RPL-aware-leaf (6LN) In this case the 6LBR insert RPI header and send the packet down, the 6LR is going to increment the rank in RPI (examines instanceID for multiple tables), the packet is processed in 6LN and RPI removed. No IPIP header is required. +-------------------+------+-------+------+ | Header | 6LBR | 6LR | 6LN | +-------------------+------+-------+------+ | Inserted headers | RPI | -- | -- | | Removed headers | -- | -- | RPI | | Re-added headers | -- | -- | -- | | Modified headers | -- | RPI | -- | | Untouched headers | -- | -- | -- | +-------------------+------+-------+------+ Storing: Summary of the use of headers from root to RPL-aware-leaf 5.3. Example of Flow from root to not-RPL-aware-leaf In this case the flow comprises: root (6LBR)--> 6LR --> not-RPL-aware-leaf (6LN) It includes IPv6-in-IPv6 encapsulation to transmit information not related with the RPL domain. In the 6LBR the RPI header is inserted into an IPv6-in-IPv6 header addressed to the last 6LR, which removes the header before pass the packet to the IPv6 node.+-------------------+-------------------+-------------------+------+The question in this scenario is how the root knows how to address the IPv6-in-IPv6 header. It can not know that the destination isn't RPL aware, so it must insert an IPv6 that can be removed on the last RPL aware node. Since the root can not know in a storing network where the last RPL aware node is, the IPv6-in-IPv6 header must added hop-by-hop along the path from root to leaf. An alternative option is to add an attribute in the RPL Target Option to indicate that the target is not RPL aware: future work may explore this possibility. +-------------------+-----------+-----------+------+ | Header | 6LBR | 6LR | IPv6 |+-------------------+-------------------+-------------------+------++-------------------+-----------+-----------+------+ | Inserted headers |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | -- | | Removed headers | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | | Re-added headers | -- | -- | -- | | Modified headers | -- | -- | -- | | Untouched headers | -- | -- | -- |+-------------------+-------------------+-------------------+------++-------------------+-----------+-----------+------+ Storing: Summary of the use of headers from root to not-RPL-aware- leaf 5.4. Example of Flow from not-RPL-aware-leaf to root In this case the flow comprises: not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) When the packet arrives from IPv6 node to6LR. This router insert6LR, the 6LR will insert an RPI header, encapsuladed in a IPv6-in-IPv6 header. The IPv6-in-IPv6 header can be addressed to the next hop, or to the root. The root removes the header and process thepacket +-------------------+------+--------------------+-------------------+packet. +-------------------+------+------------+-----------+ | Header | IPv6 | 6LR | 6LBR |+-------------------+------+--------------------+-------------------++-------------------+------+------------+-----------+ | Inserted headers | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | | Removed headers | -- | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | | Re-added headers | -- | -- | -- | | Modified headers | -- | -- | -- | | Untouched headers | -- | -- | -- |+-------------------+------+--------------------+-------------------++-------------------+------+------------+-----------+ Storing: Summary of the use of headers from not-RPL-aware-leaf to root 5.5. Example of Flow from RPL-aware-leaf to Internet RPL information from RFC 6553 should not go out toInternet.Internet as it will cause the packet to be discarded at the first non-RPI aware router. Therouter should6LBR must be able to take this information out beforesendsending the packet upwards to the Internet.The HBH Option is going toThis requires the RPI header beanalyzedplaced ineach node toan IPIP header that theroot.root can remove. In this case the flow comprises: RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet The 6LN will insert the RPI in a IPv6-in-IPv6 in a outer header,and send the packet to 6LR,whichmodified the rank in the RPI. When the packet arrivesmay be addressed to6LBR,theRPI is removed. +----------+-------------------+-----+-------------------+----------+6LBR (root), or alternatively, it could be addressed hop-by-hop. +-------------------+-----------+------+-----------+----------+ | Header | 6LN | 6LR | 6LBR | Internet |+----------+-------------------+-----+-------------------+----------++-------------------+-----------+------+-----------+----------+ | Inserted headers |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | -- | -- | |headers | | | | | |Removed headers | -- | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | |headers | | | | | |Re-added headers | -- | -- | -- | -- | |headers | | | | | |Modified headers | -- | RPI | -- | -- | | Untouched headers || | | | | Untouche |-- | -- | -- | -- || d | | | | | | headers | | | | | +----------+-------------------+-----+-------------------+----------++-------------------+-----------+------+-----------+----------+ Storing: Summary of the use of headers from RPL-aware-leaf to Internet 5.6. Example of Flow from Internet to RPL-aware-leaf In this case the flow comprises: Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN) When the packet arrives from Internet to 6LBR the RPI header is added in a outer IPv6-in-IPv6 header and send to 6LR, which modifies the rank in the RPI. When the packet arrives 6LN the RPI header is removed and the packet processed.+----------+----------+-------------------+-----+-------------------++-------------------+----------+------------+------+------------+ | Header | Internet | 6LBR | 6LR | 6LN |+----------+----------+-------------------+-----+-------------------++-------------------+----------+------------+------+------------+ | Inserted headers | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | -- | |headers | | | | | |Removed headers | -- | -- | -- |IPv6-in-IPv6(RPI) | | headers | | | |IPIP(RPI) | | Re-added headers | -- | -- | -- | -- | |headers | | | | | |Modified headers | -- | -- | RPI | -- | | Untouched headers || | | | | Untouche |-- | -- | -- | -- || d | | | | | | headers | | | | | +----------+----------+-------------------+-----+-------------------++-------------------+----------+------------+------+------------+ Storing: Summary of the use of headers from Internet to RPL-aware- leaf 5.7. Example of Flow from not-RPL-aware-leaf to Internet In this case the flow comprises: not-RPL-aware-leaf (6LN)= IPv6 node--> 6LR --> root (6LBR) --> InternetIn the IPv6The 6LR nodethe flow label is assumedwill add an IPIP(RPI) header addressed either tobe zero,thepacket is transmited to 6LR which encapsuleroot, or hop-by-hop such that the root can remove the RPI headerin an outer IPv6-in-before passing upwards. The originating node will ideally leave the IPv6header and send to 6LBR, which removes this header and sendflow label as zero so that it can be better compressed through thepacket to InternetLLN, andmightthe 6LBR will set the flow labelfield. +----------+-----+-------------------+-------------------+----------+to a non-zero value when sending to the Internet. +-------------------+------+------------+------------+----------+ | Header |IPv6LN | 6LR | 6LBR | Internet || | 6 | | | | +----------+-----+-------------------+-------------------+----------++-------------------+------+------------+------------+----------+ | Inserted headers | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | -- | |headers | | | | | |Removed headers | -- | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | |headers | | | | | |Re-added headers | -- | -- | -- | -- | |headers | | | | | |Modified headers | -- | -- | -- | -- | | Untouched headers || | | | | Untouche |-- | -- | -- | -- || d | | | | | | headers | | | | | +----------+-----+-------------------+-------------------+----------++-------------------+------+------------+------------+----------+ Storing: Summary of the use of headers from not-RPL-aware-leaf to Internet 5.8. Example of Flow from Internet to non-RPL-aware-leaf In this case the flow comprises: Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN) The 6LBRget the packet from Internet andwill have to addaan RPI headerencapsulated in a IPv6-in-IPv6 header addressedwithin an IPIP header. The IPIP will need to6LR and sendbe addressed hop-by-hop along thepacket down. The flow labelpath as in storing mode, the 6LBR has no idea if the 6LN isset to zero on inner IP. The last 6LR removesRPL aware or not, nor what theRPI header. The IPv6closest attached 6LR nodemightis. The 6LBR MAY set the flow labelsince may arrive withon the inner IPIP header to zerovalue. The RPI should beinIP-in-IP header. +----------+---------+-------------------+-------------------+------+order to aid in compression, as the packet will not emerge again from the LLN. +-------------------+----------+------------+------------+------+ | Header |InterneInternet | 6LBR | 6LR | IPv6 || | t | | | | +----------+---------+-------------------+-------------------+------++-------------------+----------+------------+------------+------+ | Inserted headers | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | -- | |headers | | | | | |Removed headers | -- | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | |headers | | | | | |Re-added headers | -- | -- | -- | -- | |headers | | | | | |Modified headers | -- | -- | -- | -- | | Untouched headers || | | | | Untouche |-- | -- | -- | -- || d | | | | | | headers | | | | | +----------+---------+-------------------+-------------------+------++-------------------+----------+------------+------------+------+ Storing: Summary of the use of headers from Internet to non-RPL- aware-leaf 5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf In [RFC6550] RPL allows a simple one-hopP2Poptimization for both storing and non-storing networks. A node may send aP2Ppacket destined to a one-hop neighbor directly to that node. Section 9 in [RFC6550]. In this case the flow comprises: 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN This case is assumed in the same RPL Domain. In the common parent, the direction of RPI is changed (from increasing to decreasing the rank). While the 6LR nodes will update the RPI, no node needs to add or remove the RPI, so no IPIP headers are necessary. The ability to do this depends upon the sending know that the destination is: a) inside the LLN, and b) RPL capable. The sender can determine if the destination is inside the LLN by looking if the destination address is matched by the DIO's PIO option. This check may be modified by the use of backbone routers, but in this case it is assumed that the backbone routers are RPL capable and so can process the RPI header correctly. The other check, that the destination is RPL capable is not currently discernible by the sender. This information is necessary to distinguish this test case from Section 5.10. +-------------+-------+---------------+---------------+-----+-------+ | Header | 6LN | 6LR | 6LR (common | 6LR | 6LN | | | src | | parent) | | dst | +-------------+-------+---------------+---------------+-----+-------+ | Inserted | RPI | -- | -- | -- | -- | | headers | | | | | | | Removed | -- | -- | -- | -- | RPI | | headers | | | | | | | Re-added | -- | -- | -- | -- | -- | | headers | | | | | | | Modified | -- | RPI | RPI | -- | -- | | headers | | (decreasing | (increasing | | | | | | rank) | rank) | | | | Untouched | -- | -- | -- | -- | -- | | headers | | | | | | +-------------+-------+---------------+---------------+-----+-------+ Storing: Summary of the use of headers for RPL-aware-leaf to RPL- aware-leaf 5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf In this case the flow comprises: 6LN --> 6LR --> common parent (6LR) --> 6LR --> not-RPL-aware 6LNSomehow, the sender has to knowThe sender, being aware out of band, that the receiver is not RPL aware,andsends adds an RPI header inside an IPIP header. The IPIP header needs toknow 6LR, and not even the root knows where the 6LR is (in storing mode). This case FAILS. Possible solutions, which are not mutually exclusive: 1 - An IPv6-in-IPv6 header canbeusedaddressed on a hop-by-hopbasis, using either link-local addresses, or even IPv6 Global Unicast Addresses, but each IPv6-in-IPv6 header needs to be added/removed at each hop.basis so that the last 6LR can remove the RPI header. ,---. / \ ( 6LR2 ) IP3,RPI,IP,ULP ,-" . ,-" `---' `. ,' `. ,---. ,-" `,---. / +" / \ ( 6LR1 ) Remove the IP3,RPI( 6LR3 ) \ / \ / /---' `---'| / IP2,RPI,IP,ULP \ / | / \ ,---+-. | / \ +--+----+ ( 6LN ) | | \ / | IPv6 | IP,ULP `-----' | | IP1,RPI,IP,ULP +-------+ Figure 4: Solution IPv6-in-IPv6 in each hop2- IfAlternatively, if the definition of the Option Type field of RPL Option '01' were changed so that it isn't a "discard if notrecognized".recognized", then no IPIP header would be necessary. This change is an incompatible on-the-wirechange. However, thischangecould perhaps beand would require some kind of flag day, possibly a change that is done simultaenously withthean updated 6LoRHcompression work, as that is also an incompatible on-the-wire change for which we presently have no way to signal. +-------+------------+------------+-------------+-------------+-----+compress. +-----------+-----------+-----------+------------+-----------+------+ |HeadeHeader | 6LN | 6LR | 6LR(common| 6LR |IPv | | r | | | parent) |IPv6 |6|+-------+------------+------------+-------------+-------------+-----+|Inser|IPv6-in-|--(common |--|--|--| |ted h | IPv6(RPI)| | parent) | | | +-----------+-----------+-----------+------------+-----------+------+ |eaderInserted | IPIP(RPI) | -- | -- | -- | -- | |sheaders | | | | | | |RemovRemoved | -- | -- | -- |IPv6-in-IPIP(RPI) | -- | |ed he | | | | IPv6(RPI) | | | adersheaders | | | | | | |Re-Re-added | -- | -- | -- | -- | -- | |added | | | | | | | heade | | | | | | | rsheaders | | | | | | |ModifModified | -- |IPv6-in-IPIP(RPI) |IPv6-in-IPIP(RPI) | -- | -- | |ied h | | IPv6(RPI) | IPv6(RPI) | | | | eader | | | | | | | sheaders | | | | | | |UntouUntouched | -- | -- | -- | -- | -- | |ched | | | | | | | heade | | | | | | | rsheaders | | | | | |+-------+------------+------------+-------------+-------------+-----++-----------+-----------+-----------+------------+-----------+------+ Storing: Summary of the use of headers from RPL-aware-leaf to not- RPL-aware-leaf 5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf In this case the flow comprises: not-RPL-aware 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN The 6LRthat getreceives the packet from the the IPv6node, insertnode and inserts and the RPI header encapsulated in IPv6-in-IPv6 header. The IPIP headerwith destinationcould be addresses to6LN,thecommon parent change6LN if thedirection of RPI and finally itdestination isremoved by 6LN. +-------+----+------------+-------------+-------------+-------------+known to the RPL aware, otherwise must send the packet using a hop-by-hop IPIP header. Similar considerations apply from section Section 5.10. +-----------+------+-----------+------------+-----------+-----------+ |HeadeHeader |IPIPv6 | 6LR | common | 6LR | 6LN | |r|v6| | parent | | | | | | | (6LR) | | |+-------+----+------------+-------------+-------------+-------------++-----------+------+-----------+------------+-----------+-----------+ |InserInserted | -- |IPv6-in-IPIP(RPI) | -- | -- | -- | |ted h | | IPv6(RPI) | | | | | eader | | | | | | | sheaders | | | | | | |RemovRemoved | -- | -- | -- | -- |IPv6-in- | | ed he | | | | | IPv6(RPI)IPIP(RPI) | |adersheaders | | | | | | |Re-Re-added | -- | -- | -- | -- | -- | |added | | | | | | | heade | | | | | | | rsheaders | | | | | | |ModifModified | -- | -- |IPv6-in-IPIP(RPI) |IPv6-in-IPIP(RPI) | -- | |ied h | | | IPv6(RPI) | IPv6(RPI) | | | eader | | | | | | | sheaders | | | | | | |UntouUntouched | -- | -- | -- | -- | -- | |ched | | | | | | | heade | | | | | | | rsheaders | | | | | |+-------+----+------------+-------------+-------------+-------------++-----------+------+-----------+------------+-----------+-----------+ Storing: Summary of the use of headers from not-RPL-aware-leaf to RPL-aware-leaf 5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf In this case the flow comprises: not-RPL-aware 6LN (IPv6 node)--> 6LR --> root (6LBR) --> 6LR --> not- RPL-aware 6LN (IPv6 node)The problem to solve is how to indicate where to send the packet when get into LLN. One approach is thatThis flow combines the6LBR should know in which 6LRproblems of theIPv6 node is attached. The RPI informationtwo previous sections. There isencapsulated in a IPv6-in-IPv6 header, each IPv6-in-IPv6 header needsno choice at the first 6LR: it must insert an RPI, and to do that it must add an IPIP header. That IPIP header must beadded/ removed at each hop.. +---------+-----+----------------+---------+-----------------+------+addressed on a hop-by-hop basis. +-------------+--------+-----------+-----------+-----------+--------+ | Header |IPvIPv6 | 6LR | 6LR | 6LR | IPv6 | | |6src | | (common | | dst | | |src| | parent) | | |+---------+-----+----------------+---------+-----------------+------++-------------+--------+-----------+-----------+-----------+--------+ |InserteInserted | -- |IPv6-in-IPIP(RPI) | -- | -- | -- | |dheaders | | | | | |IPv6(RPI)| Removed | -- | -- | -- | IPIP(RPI) | -- | | headers | | | | | | |RemovedRe-added | -- | -- | -- |IPv6-in--- | -- | | headers | | | |IPv6(RPI)| | |Re-Modified | -- | -- | -- | -- | -- | |addedheaders | | | | | | | Untouched | -- | -- | -- | -- | -- | | headers | | | | | | +-------------+--------+-----------+-----------+-----------+--------+ Storing: Summary of the use of headers from not-RPL-aware-leaf to not-RPL-aware-leaf 6. Non Storing mode +------------------+------+------+-------+-----------+ |ModifieUse Case |--RPI |--RH3 | IPIP | IPIP dst | +------------------+------+------+-------+-----------+ | Raf to root | Yes | No | No | -- | | root to Raf | Yes | Yes | No | -- | | root to ~Raf | No | Yes | Yes | -- | |d~Raf to root | Yes | No | Yes | root | | Raf to Internet |headersYes | No | Yes | root | | Internet to Raf | opt |UntouchYes |--Yes |--dst |--|--~Raf to Internet |--Yes | No |edYes | root | | Internet to ~Raf | opt | Yes | Yes |headers6LR | | Raf to Raf | Yes | Yes | Yes |+---------+-----+----------------+---------+-----------------+------+ Storing: Summary of the use of headers from not-RPL-aware-leafroot/dst | | Raf tonot-RPL-aware-leaf 6. Non Storing mode~Raf | Yes | Yes | Yes | root/6LN | | ~Raf to Raf | Yes | Yes | Yes | root/6LN | | ~Raf to ~Raf | Yes | Yes | Yes | root/6LN | +------------------+------+------+-------+-----------+ Table 2: Headers needed in Non-Storing mode: RPI, RH3, IP-in-IP encapsulation 6.1. Example of Flow from RPL-aware-leaf to root In non-storing mode the leaf node usesHop-By-Hop option (RFC 6553) to indicate thedefault routinginformationto sendmessages to the DODAG root, this message is goingtraffic tobe analyzed in each node until arrivetheDODAGroot.In this case not need to use IPv6-in-IPv6 because noThe RPI headeris not going tomust beremoved, neither RH3, the flow comprises:included to avoid/detect loops. RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) Thiscasesituation is the same case as storing mode.+-------------------+-----+------+------++-------------------+-----+-----+------+ | Header | 6LN | 6LR | 6LBR |+-------------------+-----+------+------++-------------------+-----+-----+------+ | Inserted headers | RPI | -- | -- | | Removed headers | -- | -- | RPI | | Re-added headers | -- | -- |--RPI | | Modified headers | -- |RPI-- | -- | | Untouched headers | -- | -- | -- |+-------------------+-----+------+------++-------------------+-----+-----+------+ Non Storing: Summary of the use of headers from RPL-aware-leaf to root 6.2. Example of Flow from root to RPL-aware-leaf In this case the flow comprises: root (6LBR)--> 6LR --> RPL-aware-leaf (6LN) The 6LBRmight instert RPI header,will insert an RH3, andthe rutemay optionally insert an RPI header. No IPIP header isindicated in RH3. 6LR updated RH3 and 6LN remove these headers. +-------------------+----------------------+------+----------+necessary as the traffic originates with an RPL aware node. +-------------------+-----------------+------+----------+ | Header | 6LBR | 6LR | 6LN |+-------------------+----------------------+------+----------++-------------------+-----------------+------+----------+ | Inserted headers |(optional:(opt: RPI), RH3 | -- | -- | | Removed headers | -- | -- | RH3,RPI | | Re-added headers | -- | -- | -- | | Modified headers | -- | RH3 | -- | | Untouched headers | -- | -- | -- |+-------------------+----------------------+------+----------++-------------------+-----------------+------+----------+ Non Storing: Summary of the use of headers from root to RPL-aware- leaf 6.3. Example of Flow from root to not-RPL-aware-leaf In this case the flow comprises: root (6LBR)--> 6LR --> not-RPL-aware-leaf (IPv6 node) In 6LBR the RH3 is added, and modified in 6LR where it is fully consumed, but left there. If the RPI is left present, the IPv6 node which does not understand it will dropit. To avoid itit, therefore the RPI should be removed beforereach IPv6 nodereaching the IPv6-only node. To permit removal, an IPIP header (hop-by-hop) oritaddressed to the last 6LR isrecommended that RPI be omitted. An IPv6-in-IPv6necessary. Due the complete knowledge of the topology at the root, the 6LBR is able to address the IPIP headershould be necessary in this case. The DAO from 6LR about IPv6 could say if thatto thefinal IPv6last 6LR. Omitting the RPI entirely isnot RPL (RPI) capable.therefore a better solution, as no IPIP header is necessary. +-------------------+------+-----+------+ | Header | 6LBR | 6LR | IPv6 | +-------------------+------+-----+------+ | Inserted headers | RH3 | -- | -- | | Removed headers | -- | -- | -- | | Re-added headers | -- | -- | -- | | Modified headers | -- | RH3 | -- | | Untouched headers | -- | -- | -- | +-------------------+------+-----+------+ Non Storing: Summary of the use of headers from root to not-RPL- aware-leaf 6.4. Example of Flow from not-RPL-aware-leaf to root In this case the flow comprises: IPv6-node --> 6LR1 --> 6LR2 --> root (6LBR) In this case the RPI isencapsulated inadded by the first 6LR, encapsulated in an IPIP header, and is not modified in the followings 6LRs.+-------------+------+-------------------+------+-------------------+The RPI and entire packet is consumed by the root. +-------------------+------+------------+------+------------+ | Header | IPv6 | 6LR1 | 6LR2 | 6LBR |+-------------+------+-------------------+------+-------------------++-------------------+------+------------+------+------------+ | Inserted headers | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | -- | |headers | | | | | |Removed headers | -- | -- | -- |IPv6-in-IPv6(RPI) | | headers | | | |IPIP(RPI) | | Re-added headers | -- | -- | -- | -- | |headers | | | | | |Modified headers | -- | -- | -- | -- | |headers | | | | | |Untouched headers | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | -- || headers | | | | | +-------------+------+-------------------+------+-------------------++-------------------+------+------------+------+------------+ Non Storing: Summary of the use of headers from not-RPL-aware-leaf to root 6.5. Example of Flow from RPL-aware-leaf to Internet In this case the flow comprises: RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet This case requires that thenetwork is awareness of what is external to the LLN. Internet node never seesRPIor IPv6-in-IPv6 header. Inbe added, but remoted by the6LBR6LBR. The 6LN must therefore add the RPI inside an IPIP header, addressed to the root. This case is identical to storing-mode case. The IPv6 flow labelis computed ifshould be set to zero to aid in compression, and the 6LBR will set itis zero. RPI remains unmodified. +----------+-------------------+-----+-------------------+----------+to a non-zero value when sending towards the Internet. +-------------------+-----------+------+------------+----------+ | Header | 6LN | 6LR | 6LBR | Internet |+----------+-------------------+-----+-------------------+----------++-------------------+-----------+------+------------+----------+ | Inserted headers |IPV6-in-IPv6(RPI)IPIP(RPI) | -- | -- | -- | |headers | | | | | |Removed headers | -- | -- |IPV6-in-IPv6(RPI)IPIP(RPI) | -- | |headers | | | | | |Re-added headers | -- | -- | -- | -- | |headers | | | | | |Modified headers | -- | -- | -- | -- | | Untouched headers || | | | | Untouche |-- | RPI | -- | -- || d | | | | | | headers | | | | | +----------+-------------------+-----+-------------------+----------++-------------------+-----------+------+------------+----------+ Non Storing: Summary of the use of headers from RPL-aware-leaf to Internet 6.6. Example of Flow from Internet to RPL-aware-leaf In this case the flow comprises: Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN)If the lastThe 6LBR must add an RH3entry is the 6LR, thenheader. As theIPv6-in-IPv66LBR willbe removed there, if the last entry isknow the6LN, thenpath and address of theRH3 will go alltarget not, it can address thewayIPIP header tothe leaf. Inthat node. The 6LBR will zero the flow labelshould be setupon entry in order tozero. +---------+--------+-------------------------+----------------+-----+aid compression. The RPI may be added or not. +----------------+----------+--------------------+------------+-----+ | Header |InternInternet | 6LBR | 6LR | 6LN | +----------------+----------+--------------------+------------+-----+ || et | | | | +---------+--------+-------------------------+----------------+-----+ | InserteInserted | -- |IPv6-in-IPIP(RH3,opt:RPI) | -- | -- | |d | | IPv6(RH3,optional:RPI) | | | |headers | | | | | | Removed | -- | -- |IPv6-in-IPv6IPIP(RH3) | -- | | headers | | |can be removed | | || | |if RH3 | | | | | | consumed | | | Re-Re-added | -- | -- | -- | -- | |added | | | | | |headers | | | | | |ModifieModified | -- | -- |IPv6-in-IPIP(RH3) | -- | |d | | | IPv6(RH3) | | |headers | | | | | |UntouchUntouched | -- | -- | -- | -- | |ed | | | | | |headers | | | | |+---------+--------+-------------------------+----------------+-----++----------------+----------+--------------------+------------+-----+ Non Storing: Summary of the use of headers from Internet to RPL- aware-leaf 6.7. Example of Flow from not-RPL-aware-leaf to Internet In this case the flow comprises: not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet In this case the flow label is recommended to be zero in the IPv6 node.noAs RPL headers are added in the IPv6 node,since it is ignorant of RPL. Internet node does not see special headers. In 6LBRtheflow label is computed if itfirst 6LN will add an RPI header inside a new IPIP header. The IPIP header will be addressed to the root. This case iszero. +----------+-----+-------------------+-------------------+----------+identical to the storing-mode case. +-------------------+------+-----------+------------+----------+ | Header |IPvIPv6 | 6LR | 6LBR | Internet || | 6 | | | | +----------+-----+-------------------+-------------------+----------++-------------------+------+-----------+------------+----------+ | Inserted headers | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | -- | |headers | | | | | |Removed headers | -- | -- |IPv6-in-IPv6(RPI)IPIP(RPI) | -- | |headers | | | | | |Re-added headers | -- | -- | -- | -- | |headers | | | | | |Modified headers | -- | -- | -- | -- | | Untouched headers || | | | | Untouche |-- | -- | -- | -- || d | | | | | | headers | | | | | +----------+-----+-------------------+-------------------+----------++-------------------+------+-----------+------------+----------+ Non Storing: Summary of the use of headers from not-RPL-aware-leaf to Internet 6.8. Example of Flow from Internet to non-RPL-aware-leaf In this case the flow comprises: Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN)In this case the flow label inThe 6LBRshould be set zero in 6LBR, wheremust add an RH3is insertedheader inside an IPIP header. The 6LBR will know the path, andoptionally RHI. RH3 must end at 6LR. In Non-Storing mode, root knowswill recognize that thenon-RPL-aware-leaffinal node isattached to the parent 6LR, and builds RH3 with IPv6-in-IPv6 with this 6LRnot an RPL capable node asdestination. +---------+--------+-------------------------+---------------+------+it will have received the connectivity DAO from the nearest 6LR. The 6LBR can therefore make the IPIP header destination be the last 6LR. The 6LBR will zero the flow label upon entry in order to aid compression. +--------------+----------+-------------------+--------------+------+ | Header |InternInternet | 6LBR | 6LR | IPv6 | +--------------+----------+-------------------+--------------+------+ || et | | | | +---------+--------+-------------------------+---------------+------+ | InserteInserted | -- |IPv6-in-IPIP(RH3,opt:RPI) | -- | -- | |d | | IPv6(RH3,optional:RPI) | | | |headers | | | | | | Removed | -- | -- |IPv6-in-IPIP(RH3, | -- | | headers | | |IPv6(RH3, | | | | | |RPI) | | |Re-Re-added | -- | -- | -- | -- | |added | | | | | |headers | | | | | |ModifieModified | -- | -- | -- | -- | |d | | | | | |headers | | | | | |UntouchUntouched | -- | -- | -- | -- | |ed | | | | | |headers | | | | |+---------+--------+-------------------------+---------------+------++--------------+----------+-------------------+--------------+------+ NonStoring: Summary of the use of headers from Internet to non-RPL- aware-leaf 6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf In this case the flow comprises: 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN This casecomprisesinvolves only nodes inthesame RPL Domain.In the 6LN theThe originating node will add an RPI headeris inserted. Into the6LBRoriginal packet, and send theRH3 header is inserted in a IPv6-in-IPv6packet upwards. The originating node could put the RPI into an IPIP headerand removed ataddressed to the6LN destination. In case ofroot, so that theflow goes from RPL-aware-Leaf6LBR can remove that header. The 6LBR will need to insert an RH3 header, which requires that it add an IPIP header. It may be able toRPL-aware-Leaf,remove the RPIshould be setif it was contained ina IP-in-IP header,an IPIP header addressed toavoid repetition ofit. Otherwise, there may be an RPIheader. +---------+---------------+---------------+-----+-------------------+header buried inside the inner IP header, which should get ignored. Networks that use the RPL P2P extension [RFC6997] are essentially non-storing DODAGs and fall into this scenario. +----------------+-----------+----------------+-----+---------------+ | Header | 6LN src | 6LBR | 6LR | 6LN dst |+---------+---------------+---------------+-----+-------------------++----------------+-----------+----------------+-----+---------------+ |InserteInserted |IPv6-in-IPIP(RPI) |IPv6-in-IPIP(RH3 to | -- | -- | |d | IPv6(RPI) | IPv6(RH3 to | | | |headers | | 6LN,RPI) | | | || | {IP,payload} | | | |Removed | -- | -- | -- |IPv6-in-IPIP(RH3,RPI) | | headers | | | |IPv6(RH3,RPI) | | || || {IP,RPI,payload} | | Re-Re-added | -- | -- | -- | -- | |added | | | | | |headers | | | | | |ModifieModified | -- | -- | -- | -- | |d | | | | | |headers | | | | | |UntouchUntouched | -- | -- | -- | -- | |ed | | | | | |headers | | | | |+---------+---------------+---------------+-----+-------------------++----------------+-----------+----------------+-----+---------------+ Non Storing: Summary of the use of headers for RPL-aware-leaf to RPL- aware-leaf 6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf In this case the flow comprises: 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 6LNTheAs in the previous case, the 6LN will insertthean RPIin a IPv6-in-IPv6 header,header whichisMUST be in an IPIP header addressed to6LBR. Thethe root so that the 6LBR can remove thisRPI header andRPI. The 6LBR will then insertaan RH3 inside a new IPIP headerwith an optional RPI. These headers are removed by 6LR before send the packetaddressed to theIPv66LN above the destination node.+------------+-------------------+-------------+-------------+------++---------------+-----------+---------------+----------------+------+ | Header | 6LN | 6LBR | 6LR | IPv6 |+------------+-------------------+-------------+-------------+------++---------------+-----------+---------------+----------------+------+ | Inserted |IPv6-in-IPv6(RPI)IPIP(RPI) | IPIP(RH3, opt | -- | -- | | headers | |optRPI) | | | | Removed | -- | IPIP(RPI) | IPIP(RH3, opt | -- | | headers | | |optRPI) | | | Re-added | -- | -- | -- | -- | | headers | | | | | | Modified | -- | -- | -- | -- | | headers | | | | | | Untouched | -- | -- | -- | -- | | headers | | | | |+------------+-------------------+-------------+-------------+------++---------------+-----------+---------------+----------------+------+ Non Storing: Summary of the use of headers from RPL-aware-leaf to not-RPL-aware-leaf 6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf In this case the flow comprises: not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN This scenario is mostly identical to the previous one. The RPI is addedinby the first 6LRuntilinside an IPIP header addressed to therootroot. The 6LBR will remove this RPI, andthen removed, thenadd it's own IPIP header containing an RH3is added and removed at destination.header. +-------------------+------+------------+-----------+------------+ | Header | IPv6 | 6LR | 6LBR | 6LN | +-------------------+------+------------+-----------+------------+ | Inserted headers | -- | IPIP(RPI) | IPIP(RH3) | -- | | Removed headers | -- | IPIP(RPI) | -- | IPIP(RH3) | | Re-added headers | -- | -- | -- | -- | | Modified headers | -- | -- | -- | -- | | Untouched headers | -- | -- | -- | -- | +-------------------+------+------------+-----------+------------+ Non Storing: Summary of the use of headers from not-RPL-aware-leaf to RPL-aware-leaf 6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf In this case the flow comprises: not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 6LNRPIThis scenario isadded in 6LR untiltheroot and then might be removed, then RH3 is added. These headers are removed at 6LR before go to destination.combination of the previous two cases. +--------------+------+-----------+-----------+--------------+------+ | Header | IPv6 | 6LR | 6LBR | 6LR | IPv6 | +--------------+------+-----------+-----------+--------------+------+ | Inserted | -- | IPIP(RPI) | IPIP(RH3) | -- | -- | | headers | | | | | | | Removed | -- | -- | IPIP(RPI) | IPIP(RH3, | -- | | headers | | | | opt RPI) | | | Re-added | -- | -- | -- | -- | -- | | headers | | | | | | | Modified | -- | -- | -- | -- | -- | | headers | | | | | | | Untouched | -- | -- | -- | -- | -- | | headers | | | | | | +--------------+------+-----------+-----------+--------------+------+ Non Storing: Summary of the use of headers from not-RPL-aware-leaf to not-RPL-aware-leaf 7.Problem statement There are cases from above that are not clear how to send the information. It requires furhter analysis on how to proceed to sendObservations about theinformation from source to destination. Fromproblem 7.1. Storing mode In theabove cases, we have incompletely general storingmode: - Flow from RPL-aware-leaf to non-RPL-aware-leaf: Somehow, the sender hascase, which includes not-RPL aware leaf nodes, it is not possible for a sending node to knowthatif thereceiverdestination isnotRPL aware, andneeds to know 6LR,therefore it must always use hop-by-hop IPIP encapsulation, andnot evenit can never omit theroot knowsIPIP encapsulation. See table Table 1 The simplest fully general stiaution for storing mode is to always put in hop-by-hop IPIP headers. [I-D.ietf-roll-routing-dispatch] shows that this hop-by-hop IPIP header can be compressed down to {TBD} bytes. There are potential significant advantages to having a single code path that always processes IPIP headers with no options. If all RPL aware nodes can be told/configured that there are no non- RPL aware leaf nodes, then the only case where an IPIP header is needed is when communicating outside the6LRLLN. The 6LBR knows well when the communication islocated. - Flowfromnot-RPL-aware-leaf to not-RPL-aware-leaf: The problemthe outside, and the 6LN can tell by comparing the destination address tosolvethe prefix provided in the PIO. If it ishowknown that there are no communications outside the RPL domain (noting that the RPL domain may well extend toindicate whereoutside the LLN), then RPI headers can be included in all packets, and IPIP headers are *never* needed. This may be significantly advantageous in relatively closed systems such as in building or industrial automation. Again, there are advantages tosendhaving a single code path. In order to support thepacket when get into LLN. One approach isabove two cases with full generality, the6LBRdifferent situations (always do IPIP vs never use IPIP) should beawaresignaled inwhich 6LRthe RPL protocol itself. 7.2. Non-Storing mode This the non-storing case, dealing with non-RPL aware leaf nodes is much easier as theIPv66LBR (DODAG root) has complete knowledge about the connectivity of all nodes, and all traffic flows through the root node. The 6LBR can recognize non-RPL aware leaf nodes because it will receive a DAO about that nodeattached. As was mentionedfrom the 6LN immediately above that node. This means that the non-storing mode case can avoid ever using hop-by-hop IPIP headers. It is unclear what it would mean for an RH3 header to be present in a hop-by-hop IPIP header. The receiving node ought to consume thedocument,IPIP header, and therefore consume the RH3 as well, and then attempt to send the packet again. But intermediate 6LN nodes would not know how to forward the packet, so the RH3 would need to be retained. This is apossible solution couldnew kind of IPv6 packet processing. Therefore it may beadapted to all cases: An IPv6-in-IPv6that on the outbound leg of non-storing RPL networks, that hop-by-hop IPIP header can NOT beused on a hop-by- hop basis, using either link-local addresses, or even IPv6 Global Unicast Addresses, but each IPv6-in-IPv6used. [I-D.ietf-roll-routing-dispatch] shows how the destination=root, and destination=6LN IPIP header can be compressed down to {TBD} bytes. Unlike in the storing mode case, there are no need for all nodes to know about the existence of non-RPL aware nodes. Only the 6LBR needs tobe added/ removed at each hop.change when there are non-RPL aware nodes. Further, in the non- storing case, the 6LBR is informed by the DAOs when there are non-RPL aware nodes. 8. 6LoRH Compression cases The[I-D.ietf-6lo-routing-dispatch][I-D.ietf-roll-routing-dispatch] proposes a compression method for RPI, RH3 and IPv6-in-IPv6.The uses cases mentioned in this draft MUST use 6LoRH. Examples ofIn Storing Mode, for theuseexamples of6LoRH are found in Apendix AFlow from RPL-aware-leaf to non- RPL-aware-leaf and non-RPL-aware-leaf to non-RPL-aware-leaf comprise an IP-in-IP and RPI compression headers. The type of[I-D.ietf-6lo-routing-dispatch].this case is critical since IP-in-IP is encapsulating a RPI header. +--+-----+---+--------------+-----------+-------------+-------------+ |1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI - 6LoRH | LOWPAN IPHC | +--+-----+---+--------------+-----------+-------------+-------------+ Figure 5: Critical IP-in-IP (RPI). 9. IANA Considerations There are no IANA considerations related to this document. 10. Security Considerations The security considerations covering of [RFC6553] and [RFC6554] apply when the packets get into RPL Domain. 11. Acknowledgments This work is partially funded by the FP7 Marie Curie Initial Training Network (ITN) METRICS project (grant agreement No. 607728). The authors would like to acknowledge the review, feedback, and comments of Thomas Watteyne, Xavier Vilajosana, Robert Cragie and Simon Duquennoy. 12. References 12.1. 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, <http://www.rfc-editor.org/info/rfc2119>. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. Alexander, "RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks", RFC 6550, DOI 10.17487/RFC6550, March 2012, <http://www.rfc-editor.org/info/rfc6550>. [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, <http://www.rfc-editor.org/info/rfc6553>. [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 Routing Header for Source Routes with the Routing Protocol for Low-Power and Lossy Networks (RPL)", RFC 6554, DOI 10.17487/RFC6554, March 2012, <http://www.rfc-editor.org/info/rfc6554>. 12.2. Informative References[I-D.ietf-6lo-routing-dispatch] Thubert, P., Bormann, C., Toutain, L., and R. Cragie, "6LoWPAN Routing Header", draft-ietf-6lo-routing- dispatch-05 (work in progress), February 2016.[I-D.ietf-6tisch-architecture] Thubert, P., "An Architecture for IPv6 over the TSCH mode of IEEE 802.15.4", draft-ietf-6tisch-architecture-09 (work in progress), November 2015. [I-D.ietf-roll-routing-dispatch] Thubert, P., Bormann, C., Toutain, L., and R. Cragie, "6LoWPAN Routing Header", draft-ietf-roll-routing- dispatch-00 (work in progress), March 2016. [RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and J. Martocci, "Reactive Discovery of Point-to-Point Routes in Low-Power and Lossy Networks", RFC 6997, DOI 10.17487/RFC6997, August 2013, <http://www.rfc-editor.org/info/rfc6997>. [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 2014, <http://www.rfc-editor.org/info/rfc7102>. [Second6TischPlugtest] "2nd 6Tisch Plugtest", <http://www.ietf.org/mail- archive/web/6tisch/current/pdfgDMQcdCkRz.pdf>. Authors' Addresses Maria Ines Robles Ericsson Hirsalantie 11 Jorvas 02420 Finland Email: maria.ines.robles@ericsson.com Michael C. Richardson Sandelman Software Works 470 Dawson Avenue Ottawa, ON K1Z 5V7 CA Email: mcr+ietf@sandelman.ca URI: http://www.sandelman.ca/ Pascal Thubert Cisco Systems, Inc Village d'Entreprises Green Side 400, Avenue de Roumanille Batiment T3, Biot - Sophia Antipolis 06410 France Email: pthubert@cisco.com