--- 1/draft-ietf-roll-aodv-rpl-01.txt 2017-09-09 05:13:22.987714313 -0700 +++ 2/draft-ietf-roll-aodv-rpl-02.txt 2017-09-09 05:13:23.031715364 -0700 @@ -1,87 +1,88 @@ ROLL S. Anamalamudi Internet-Draft Huaiyin Institute of Technology Intended status: Standards Track M. Zhang -Expires: September 13, 2017 AR. Sangi +Expires: March 13, 2018 AR. Sangi Huawei Technologies C. Perkins Futurewei S.V.R.Anand Indian Institute of Science - March 12, 2017 + September 9, 2017 Asymmetric AODV-P2P-RPL in Low-Power and Lossy Networks (LLNs) - draft-ietf-roll-aodv-rpl-01 + draft-ietf-roll-aodv-rpl-02 Abstract Route discovery for symmetric and asymmetric Point-to-Point (P2P) traffic flows is a desirable feature in Low power and Lossy Networks (LLNs). For that purpose, this document specifies a reactive P2P route discovery mechanism for hop-by-hop routing (storing mode) based on Ad Hoc On-demand Distance Vector Routing (AODV) based RPL protocol. Two separate Instances are used to construct directional paths in case some of the links between source and target node are asymmetric. 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/. + 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 September 13, 2017. + This Internet-Draft will expire on March 13, 2018. Copyright Notice Copyright (c) 2017 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 + (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 - 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 + 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Overview of AODV-RPL . . . . . . . . . . . . . . . . . . . . 5 4. AODV-RPL Mode of Operation (MoP) . . . . . . . . . . . . . . 5 - 5. RREQ Message . . . . . . . . . . . . . . . . . . . . . . . . 8 - 6. RREP Message . . . . . . . . . . . . . . . . . . . . . . . . 9 - 7. Gratuitous RREP . . . . . . . . . . . . . . . . . . . . . . . 11 - 8. Operation of Trickle Timer . . . . . . . . . . . . . . . . . 12 - 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 - 9.1. New Mode of Operation: AODV-RPL . . . . . . . . . . . . . 12 - 9.2. AODV-RPL Options: RREQ and RREP . . . . . . . . . . . . . 12 - 10. Security Considerations . . . . . . . . . . . . . . . . . . . 12 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 11.1. Normative References . . . . . . . . . . . . . . . . . . 13 - 11.2. Informative References . . . . . . . . . . . . . . . . . 14 - Appendix A. ETX/RSSI Values to select S bit . . . . . . . . . . 14 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 + 5. RREQ Message . . . . . . . . . . . . . . . . . . . . . . . . 9 + 6. RREP Message . . . . . . . . . . . . . . . . . . . . . . . . 10 + 7. Gratuitous RREP . . . . . . . . . . . . . . . . . . . . . . . 12 + 8. Operation of Trickle Timer . . . . . . . . . . . . . . . . . 13 + 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 + 9.1. New Mode of Operation: AODV-RPL . . . . . . . . . . . . . 13 + 9.2. AODV-RPL Options: RREQ and RREP . . . . . . . . . . . . . 13 + 10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 + 11. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 13 + 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 + 12.1. Normative References . . . . . . . . . . . . . . . . . . 14 + 12.2. Informative References . . . . . . . . . . . . . . . . . 15 + Appendix A. ETX/RSSI Values to select S bit . . . . . . . . . . 15 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 1. Introduction RPL[RFC6550], the IPv6 distance vector routing protocol for Low-power and Lossy Networks (LLNs), is designed to support multiple traffic flows through a root-based Destination-Oriented Directed Acyclic Graph (DODAG). For traffic flows between routers within the DODAG (i.e., Point-to-Point (P2P) traffic), this means that data packets either have to traverse the root in non-storing mode (source routing), or traverse a common ancestor in storing mode (hop-by-hop @@ -121,20 +122,33 @@ node due to temporary DODAG formation. For networks composed of bidirectional asymmetric links (see Section 4), AODV-RPL specifies P2P route discovery, utilizing RPL with a new MoP. AODV-RPL makes use of two multicast messages to discover possibly asymmetric routes. AODV-RPL eliminates the need for address vector control overhead, significantly reducing the control packet size which is important for Constrained LLN networks. Both discovered routes meet the application specific metrics and constraints that are defined in the Objective Function for each Instance [RFC6552]. + The route discovery process in AODV-RPL is modeled on the analogous + process that has been specified in AODV [RFC6550]. The on-demand + nature of AODV route discovery is natural for the needs of peer-to- + peer routing as envisioned for RPL-based LLNs. Similar terminology + has been adopted for use with the discovery messages, namely RREQ for + Route Request, and RREP for Route Reply. AODV-RPL is, at heart, a + simpler protocol than AODV, since there are no analogous operations + for flagging Route Errors, blacklisting unidirectional links, + multihoming, or handling unnumbered interfaces. Some of the simpler + features of AODV, on the other hand, have been imported into AODV-RPL + -- for instance, prefix advertisement is allowed on RREP and RREQ + message where appropriate. + 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Additionally, this document uses the following terms: AODV Ad Hoc On-demand Distance Vector Routing[RFC3561]. @@ -168,27 +182,27 @@ Paired DODAGs Two DODAGs for a single application. P2P Point-to-Point -- in other words, not constrained to traverse a common ancestor. RREQ message An AODV-RPL MoP DIO message containing the RREQ option. The - InstanceID in DIO object of RREQ option MUST be always an odd - number. + InstanceID in the DIO object of the RREQ option MUST be always an + odd number. RREP message An AODV-RPL MoP DIO message containing the RREP option. The - InstanceID in DIO object of RREP option MUST be always an even - number (InstanceID of RREQ-Instance+1). + InstanceID in the DIO object of the RREP option MUST be always an + even number (usually, InstanceID of RREQ-Instance+1). source routing The mechanism by which the source supplies the complete route towards the target node along with each data packet. [RFC6997]. TargNode The IPv6 router (Target Node) for which OrigNode requires a route and initiates Route Discovery within the LLN network. upstream @@ -215,25 +229,25 @@ In AODV-RPL, route discovery is initiated by forming a temporary DAG rooted at the OrigNode. Paired DODAGs (Instances) are constructed according to a new AODV-RPL Mode of Operation (MoP) during route formation between the OrigNode and TargNode. The RREQ-Instance is formed by route control messages from OrigNode to TargNode whereas the RREP-Instance is formed by route control messages from TargNode to OrigNode (as shown in Figure 2). Intermediate routers join the Paired DODAGs based on the rank as calculated from the DIO message. Henceforth in this document, the RREQ-Instance message means the AODV-RPL DIO message from OrigNode to TargNode, containing the RREQ - option. Similarly, the RREP-Instance means the AODV-RPL DIO message - from TargNode to OrigNode, containing the RREP option. Subsequently, - the RREQ-Instance is used for data transmission from TargNode to - OrigNode and RREP-Instance is used for Data transmission from - OrigNode to TargNode. + option. Similarly, the RREP-Instance message means the AODV-RPL DIO + message from TargNode to OrigNode, containing the RREP option. + Subsequently, the RREQ-Instance is used for data transmission from + TargNode to OrigNode and RREP-Instance is used for Data transmission + from OrigNode to TargNode. The AODV-RPL Mode of Operation defines a new bit, the Symmetric bit ('S'), which is added to the base DIO message as illustrated in Figure 1. OrigNode sets the the 'S' bit to 1 in the RREQ-Instance message when initiating route discovery. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RPLInstanceID |Version Number | Rank | @@ -288,66 +302,75 @@ (RREQ-Instance). Metric Container Options AODV-Instance(RREQ-Instance) messages MAY carry one or more Metric Container options to indicate the relevant routing metrics. The 'S' bit is set to mean that the route is symmetric. If the RREQ- Instance arrives over an interface that is known to be symmetric, and the 'S' bit is set to 1, then it remains set at 1, as illustrated in - Figure 2. - - In this figure: - S := OrigNode; R := Intermediate nodes; D := TargNode + Figure 2. In Figure 2 and Figure 3, BR is the BorderRouter, S is the + OrigNode, R is an intermediate node, and D is the TargNode. - R---------R---------R---------R - |<--S=1-->|<--S=1-->|<--S=1-->| - | | | | - <--S=1--> | | <--S=1--> - | | | | - | | | | - S---------R---------R---------R---------R---------R---------D - <--S=1-->| | | |<--S=1-->|<--S=1-->| - | | | | | | - | | | | | | - R---------R---------R---------R---------R---------R + BR + / | \ + / | \ + / | \ + R R R + / \ | / \ + / \ | / \ + / \ | / \ + R -------- R --- R ----- R -------- R + / \ <--s=1--> / \ <--s=1--> / \ + <--s=1--> \ / \ / <--s=1--> + / \ / \ / \ + S ---------- R ------ R------ R ----- R ----------- D + / \ / \ / \ / \ + / \ / \ / \ / \ + / \ / \ / \ / \ + R ----- R ----------- R ----- R ----- R ----- R ---- R----- R >---- RREQ-Instance (Control: S-->D; Data: D-->S) -------> <---- RREP-Instance (Control: D-->S; Data: S-->D) -------< Figure 2: AODV-RPL with Symmetric Paired Instances If the RREQ-Instance arrives over an interface that is not known to be symmetric, or is known to be asymmetric, the 'S' bit is set to be 0. Moreover, if the 'S' bit arrives already set to be '0', it is set to be '0' on retransmission (Figure 3). Based on the 'S' bit received in RREQ-Instance, the TargNode decides whether or not the route is symmetric before transmitting the RREP-Instance message upstream towards the OrigNode. The metric used to determine symmetry (i.e., set the "S" bit to be "1" (Symmetric) or "0" (asymmetric)) is implementation specific. We used ETX/RSSI to verify the feasibility of the protocol operations in this draft, as discussed in Appendix A. - R---------R--------R--------R - | --S=1-->|--S=1-->|--S=0-->| - | | | | - --S=1--> | | --S=0--> - | | | | - --S=1-->| | | | - S--------R---------R--------R--------R--------R---------D - <--S=0--| | | |--S=0-->| --S=0-->| - | | | | | | - <--S=0-- | | | | <--S=0-- - | | | | | | - | <--S=0--|<--S=0--|<--S=0--|<--S=0--|<--S=0-- | - R---------R--------R--------R--------R---------R + BR + / | \ + / | \ + / | \ + R R R + / \ | / \ + / \ | / \ + / \ | / \ + R --------- R --- R ---- R --------- R + / \ --s=1--> / \ --s=0--> / \ + --s=1--> \ / \ / --s=0--> + / \ / \ / \ + S ---------- R ------ R------ R ----- R ----------- D + / \ / \ / \ / \ + / <--s=0-- / \ / \ / <--s=0-- + / \ / \ / \ / \ + R ----- R ----------- R ----- R ----- R ----- R ---- R----- R + <--s=0-- <--s=0-- <--s=0-- <--s=0-- <--s=0-- >---- RREQ-Instance (Control: S-->D; Data: D-->S) -------> <---- RREP-Instance (Control: D-->S; Data: S-->D) -------< Figure 3: AODV-RPL with Asymmetric Paired Instances 5. RREQ Message 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 @@ -363,32 +386,30 @@ Figure 4: DIO RREQ option format for AODV-RPL MoP OrigNode supplies the following information in the RREQ option of the RREQ-Instance message: Type The type of the RREQ option(see Section 9.2). Orig SeqNo - Sequence Number of OrigNode. Dest SeqNo + If nonzero, the last known Sequence Number for TargNode for which a route is desired. TargNode IPv6 Address IPv6 address of the TargNode that receives RREQ-Instance message. - This address MUST be in the RREQ option (see Figure 4) of AODV- - RPL. In order to establish the upstream route from TargNode to OrigNode, OrigNode multicasts the RREQ-Instance message (see Figure 4) to its one-hop neighbours. In order to enable intermediate nodes R_i to associate a future RREP message to an incoming RREQ message, the InstanceID of RREQ-Instance MUST assign an odd number. Each intermediate node R_i computes the rank for RREQ-Instance and creates a routing table entry for the upstream route towards the source if the routing metrics/constraints are satisfied. For this @@ -470,33 +491,34 @@ earlier Route Discovery operation), then the 'T' bit is set and an alternative even number is chosen for the InstanceID of RREP from TargNode. The OrigNode IP address for RREQ-Instance is available as the DODAGID in the DIO base message (see Figure 1). When TargNode receives a RREQ message with the 'S' bit set to 1 (as illustrated in Figure 2), it unicasts the RREP message with the 'S' bit set to 1. In this case, route control messages and application data between OrigNode and TargNode for both RREQ-Instance and RREP-Instance are transmitted - along symmetric links. When 'T' bit set is to "1" in the RREP- - Instance, then TargNode IPv6 Address is transmitted in RREP option. - Otherwise, the TargNode IPv6 Address is elided in RREP option. + along symmetric links. When the 'T' bit is set to "1" in the RREP- + Instance, then the TargNode IPv6 Address is transmitted in the RREP + option. Otherwise, the TargNode IPv6 Address is elided in the RREP + option. When (as illustrated in Figure 3) the TargNode receives RREQ message with the 'S' bit set to 0, it also multicasts the RREP message with the 'S' bit set to 0. Intermediate nodes create a routing table entry for the path towards the TargNode while processing the RREP message to OrigNode. Once OrigNode receives the RREP message, it starts transmitting the application data to TargNode along the path - as discovered through RREP messages. Similarly, application data - from TargNode to OrigNode is transmitted through the path that is - discovered from RREQ message. + as discovered through RREP messages. On the other hand, application + data from TargNode to OrigNode is transmitted through the path that + is discovered from RREQ message. 7. Gratuitous RREP Under some circumstances, an Intermediate Node that receives a RREQ message MAY transmit a "Gratuitous" RREP message back to OrigNode instead of continuing to multicast the RREQ message towards TargNode. For these circumstances, the 'G' bit of the RREP option is provided to distinguish the Gratuitous RREP sent by the Intermediate node from the RREP sent by TargNode. @@ -547,78 +569,105 @@ | TBD3 (0x0B) | RREP Option | This document | +-------------+---------------------+---------------+ Figure 7: AODV-RPL Options 10. Security Considerations This document does not introduce additional security issues compared to base RPL. For general RPL security considerations, see [RFC6550]. -11. References -11.1. Normative References +11. Future Work + + It may become feasible in the future to design a non-storing version + of AODV-RPL's route discovery protocol. Under the current assumption + of route asymmetry across bidirectional links, the specification is + expected to be straightforward. It should be possible to re-use the + same methods of incremental construction for source routes within + analogous fields within AODV-RPL's RREQ and RREP messages as is + currently done for DAO messages -- in other words the RPL messages + for DODAG construction. + + There has been some discussion about how to determine the initial + state of a link after an AODV-RPL-based network has begun operation. + The current draft operates as if the links are symmetric until + additional metric information is collected. The means for making + link metric information is considered out of scope for AODV-RPL. In + the future, RREQ and RREP messages could be equipped with new fields + for use in verifying link metrics. In particular, it is possible to + identify unidirectional links; an RREQ received across a + unidirectional link has to be dropped, since the destination node + cannot make use of the received DODAG to route packets back to the + source node that originated the route discovery operation. This is + roughly the same as considering a unidirectional link to present an + infinite cost metric that automatically disqualifies it for use in + the reverse direction. + +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, - . + . [RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On- Demand Distance Vector (AODV) Routing", RFC 3561, DOI 10.17487/RFC3561, July 2003, - . + . [RFC5548] Dohler, M., Ed., Watteyne, T., Ed., Winter, T., Ed., and D. Barthel, Ed., "Routing Requirements for Urban Low-Power and Lossy Networks", RFC 5548, DOI 10.17487/RFC5548, May - 2009, . + 2009, . [RFC5673] Pister, K., Ed., Thubert, P., Ed., Dwars, S., and T. Phinney, "Industrial Routing Requirements in Low-Power and Lossy Networks", RFC 5673, DOI 10.17487/RFC5673, October - 2009, . + 2009, . [RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation Routing Requirements in Low-Power and Lossy Networks", RFC 5826, DOI 10.17487/RFC5826, April 2010, - . + . [RFC5867] Martocci, J., Ed., De Mil, P., Riou, N., and W. Vermeylen, "Building Automation Routing Requirements in Low-Power and Lossy Networks", RFC 5867, DOI 10.17487/RFC5867, June - 2010, . + 2010, . [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, - . + . [RFC6552] Thubert, P., Ed., "Objective Function Zero for the Routing Protocol for Low-Power and Lossy Networks (RPL)", RFC 6552, DOI 10.17487/RFC6552, March 2012, - . + . [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, - . + . [RFC6998] Goyal, M., Ed., Baccelli, E., Brandt, A., and J. Martocci, "A Mechanism to Measure the Routing Metrics along a Point- to-Point Route in a Low-Power and Lossy Network", RFC 6998, DOI 10.17487/RFC6998, August 2013, - . + . -11.2. Informative References +12.2. Informative References [I-D.thubert-roll-asymlink] Thubert, P., "RPL adaptation for asymmetrical links", draft-thubert-roll-asymlink-02 (work in progress), December 2011. Appendix A. ETX/RSSI Values to select S bit We have tested the combination of "RSSI(downstream)" and "ETX (upstream)" to decide whether the link is symmetric or asymmetric at @@ -644,26 +693,26 @@ We tested the operations in this specification by making the following experiment, using the above parameters. In our experiment, a communication link is considered as symmetric if the ETX value of NodeA->NodeB and NodeB->NodeA (See Figure.8) are, say, within 1:3 ratio. This ratio should be taken as a notional metric for deciding link symmetric/asymmetric nature, and precise definition of the ratio is beyond the scope of the draft. In general, NodeA can only know the ETX value in the direction of NodeA -> NodeB but it has no direct way of knowing the value of ETX from NodeB->NodeA. Using physical testbed experiments and realistic wireless channel propagation - models, one can come up with a relationship between RSSI and ETX that - can be represented as an expression or a mapping table. Such a + models, one can determine a relationship between RSSI and ETX + representable as an expression or a mapping table. Such a relationship in turn can be used to estimate ETX value at nodeA for link NodeB--->NodeA from the received RSSI from NodeB. Whenever nodeA determines that the link towards the nodeB is bi-directional - asymmetric then the "S" bit is set to "S=0". Later on, link from + asymmetric then the "S" bit is set to "S=0". Later on, the link from NodeA to Destination is asymmetric with "S" bit remains to "0". Authors' Addresses Satish Anamalamudi Huaiyin Institute of Technology No.89 North Beijing Road, Qinghe District Huaian 223001 China