| ROLL Working Group | M. Robles |
| Internet-Draft | Ericsson |
| Intended status: Informational | M. Richardson |
| Expires: August 30, 2016 | SSW |
| P. Thubert | |
| Cisco | |
| February 27, 2016 |
When to use RFC 6553, 6554 and IPv6-in-IPv6
draft-ietf-roll-useofrplinfo-01
This document states different cases where RFC 6553, RFC 6554 and IPv6-in-IPv6 encapsulation is required to set the bases to help defining the compression of RPL routing information in LLN environments.
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 on August 30, 2016.
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
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RPL [RFC6550] is a routing protocol for constrained networks. RFC 6553 [RFC6553] defines the "RPL option", carried within the IPv6 Hop-by-Hop header to quickly identify inconsistencies in the routing topology. RFC 6554 [RFC6554] defines the "RPL Source Route Header", an IPv6 Extension Header to deliver datagrams within a RPL routing domain.
Several discussions in the ROLL/6lo/6TiSCH Mailing Lists took place focusing in the definition of how to compress RPL Information in constrained environment. ROLL Virtual Interim Meeting (02-2015) concluded that there is a need to define how to use [RFC6553], [RFC6554] and IPv6-in-IPv6 encapsulation to be able to set the correct environment for compression A Routing Header Dispatch for 6LoWPAN (6LoRH) [I-D.ietf-6lo-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] involving 6loRH: 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.
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]
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 |
+---------+Root +----------+
| |6LBR | |
| +----+--+ |
| | |
| | |
... ... ...
| | |
+-----+-+ +--+---+ +--+---+
|6LR | | | | |
+-----+ | | | | |
| | | | | | +------+
| +-----+-+ +-+----+ +-+----+ |
| | | | |
| | | | |
| | | | |
+-+---+ +-+---+ +--+--+ +- --+ +---+-+
|Leaf | | | | | | | | |
|6LN | | | | | | | | |
+-----+ +-----+ +-----+ +----+ +-----+
Figure 2: A reference RPL Topology.
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
In data plane context a combination of RFC6553, RFC6554 and IPv6-in-IPv6 encapsulation is going to be analyzed for the following traffic flows:
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 means that an intermediate router that needs to add a header must encapsulate the packet in an 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 headers such as a Routing Header or a Hop-by-Hop header may be modified by routers on the path of the packet without the need to add to remove an encapsulating header.
The RPL RH and the RPL option are mutable but recoverable .
RPI should be present in every single RPL data packet. There is an exception in non-storing mode, when a packet is going down from the route: the entire route is written, so there are no loops of confusion about which table to use (purpose of instanceID).
The applicability for storing (RPL-SN) and non-Storing (RPL-NSN) modes for the previous cases is showed as follows:
| Use Case | RPL-SN RPI (RFC 6553) | RPL-SN RH3 (RFC 6554) | RPL-SN IP-in-IP | RPL-NSN RPI | RPL-NSN RH3 | RPL-NSN IP-in-IP |
|---|---|---|---|---|---|---|
| RPL-aware-leaf to root | Yes | No | No | Yes | No | No |
| root to RPL-aware-leaf | Yes | No | No | Yes | Yes | No |
| not-RPL-aware-leaf to root | Yes | No | Yes | Yes | No | Yes |
| root to not-RPL-aware-leaf | Yes | No | Yes | Yes | Yes | Yes |
| RPL-aware-leaf to Internet | Yes | No | Yes | Yes | No | Yes |
| Internet to RPL-aware-leaf | Yes | No | Yes | Yes | Yes | Yes |
| not-RPL-aware-leaf to Internet | Yes | No | Yes | Yes | No | Yes |
| Internet to not-RPL-aware-leaf | Yes | No | Yes | Yes | Yes | Yes |
| RPL-aware-leaf to RPL-aware-leaf | Yes | No | No | Yes | Yes | Yes |
| RPL-aware-leaf to not-RPL-aware-leaf | Yes | No | Yes | Yes | Yes | Yes |
| not-RPL-aware-leaf to RPL-aware-leaf | Yes | No | Yes | Yes | Yes | Yes |
| not-RPL-aware-leaf to not-RPL-aware-leaf | Yes | No | Yes | Yes | Yes | Yes |
As states in Section 16.2 of [RFC6550] a RPL-aware-leaf node does not generally issue DIO messages, a leaf node accepts DIO messages (In inconsistency a leaf node generates DIO with infinite rank, to fix it). It may issue DAO and DIS messages though it generally ignores DAO and DIS messages.
In storing mode is suitable the use of RFC 6553 to send RPL Information through HBH field checking the routing table to find out where to send the message.
In this case the flow comprises:
RPL-aware-leaf (6LN) --> 6LR --> 6LR,... --> root (6LBR) Note: In this document 6LRs, 6LBR are always full-fledge RPL routers
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.
| Header | 6LN | 6LR | 6LBR |
|---|---|---|---|
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- |
| Untouched headers | -- | -- | -- |
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.
| Header | 6LBR | 6LR | 6LN |
|---|---|---|---|
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- |
| Untouched headers | -- | -- | -- |
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.
| Header | 6LBR | 6LR | IPv6 |
|---|---|---|---|
| Inserted headers | IPv6-in-IPv6(RPI) | -- | -- |
| Removed headers | -- | IPv6-in-IPv6(RPI) | -- |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | -- | -- |
| Untouched headers | -- | -- | -- |
In this case the flow comprises:
not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR)
When the packet arrives from IPv6 node to 6LR. This router insert the RPI encapsuladed in a IPv6-in-IPv6 header addressed to the root. The root removes the header and process the packet
| Header | IPv6 | 6LR | 6LBR |
|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RPI) | -- |
| Removed headers | -- | -- | IPv6-in-IPv6(RPI) |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | -- | -- |
| Untouched headers | -- | -- | -- |
RPL information from RFC 6553 should not go out to Internet. The router should take this information out before send the packet to Internet. The HBH Option is going to be analyzed in each node to the root.
In this case the flow comprises:
RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet
6LN insert RPI in a IPv6-in-IPv6 in a outer header, and send the packet to 6LR, which modified the rank in the RPI. When the packet arrives to 6LBR, the RPI is removed.
| Header | 6LN | 6LR | 6LBR | Internet |
|---|---|---|---|---|
| Inserted headers | IPv6-in-IPv6(RPI) | -- | -- | -- |
| Removed headers | -- | -- | IPv6-in-IPv6(RPI) | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | RPI | -- | -- |
| Untouched headers | -- | -- | -- | -- |
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) | -- | -- |
| Removed headers | -- | -- | -- | IPv6-in-IPv6(RPI) |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | RPI | -- |
| Untouched headers | -- | -- | -- | -- |
In this case the flow comprises:
not-RPL-aware-leaf (6LN) = IPv6 node --> 6LR --> root (6LBR) --> Internet
In the IPv6 node the flow label is assumed to be zero, the packet is transmited to 6LR which encapsule the RPI header in an outer IPv6-in-IPv6 header and send to 6LBR, which removes this header and send the packet to Internet and might set the flow label field.
| Header | IPv6 | 6LR | 6LBR | Internet |
|---|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RPI) | -- | -- |
| Removed headers | -- | -- | IPv6-in-IPv6(RPI) | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- |
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN)
6LBR get the packet from Internet and add a RPI header encapsulated in a IPv6-in-IPv6 header addressed to 6LR and send the packet down. The flow label is set to zero on inner IP. The last 6LR removes the RPI header. The IPv6 node might set the flow label since may arrive with zero value. The 6LBR does not know that the is attached to the last 6LR. The non-RPL-aware-leaf drops packet, because RPI has unknown header 0x63, and 0x63 has “01” = discard packet. If RPI had 0x23, it would “skip”.
| Header | Internet | 6LBR | 6LR | IPv6 |
|---|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RPI) | -- | -- |
| Removed headers | -- | -- | IPv6-in-IPv6(RPI) | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- |
In [RFC6550] RPL allows a simple one-hop P2P optimization for both storing and non-storing networks. A node may send a P2P packet 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).
| Header | 6LN src | 6LR | 6LR (common parent) | 6LR | 6LN dst |
|---|---|---|---|---|---|
| Inserted headers | RPI | -- | -- | -- | -- |
| Removed headers | -- | -- | -- | -- | RPI |
| Re-added headers | -- | -- | -- | -- | -- |
| Modified headers | -- | RPI (decreasing rank) | RPI (increasing rank) | -- | -- |
| Untouched headers | -- | -- | -- | -- | -- |
In this case the flow comprises:
6LN --> 6LR --> common parent (6LR) --> 6LR --> not-RPL-aware 6LN
Somehow, the sender has to know that the receiver is not RPL aware, and needs to know 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 can be used on a hop-by-hop basis, 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.
,---.
/ \
( 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 hop
2- If the definition of the Option Type field of RPL Option '01' were changed so that it isn't a "discard if not recognized". This change is an incompatible on-the-wire change. However, this change could perhaps be done with the updated 6LoRH compression work, as that is also an incompatible on-the-wire change for which we presently have no way to signal.
| Header | 6LN | 6LR | 6LR (common parent) | 6LR | IPv6 |
|---|---|---|---|---|---|
| Inserted headers | IPv6-in-IPv6(RPI) | -- | -- | -- | -- |
| Removed headers | -- | -- | -- | IPv6-in-IPv6(RPI) | -- |
| Re-added headers | -- | -- | -- | -- | -- |
| Modified headers | -- | IPv6-in-IPv6(RPI) | IPv6-in-IPv6(RPI) | -- | -- |
| Untouched headers | -- | -- | -- | -- | -- |
In this case the flow comprises:
not-RPL-aware 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN
The 6LR that get the packet from IPv6 node, insert the RPI header encapsulated in IPv6-in-IPv6 header with destination to 6LN, the common parent change the direction of RPI and finally it is removed by 6LN.
| Header | IPv6 | 6LR | common parent (6LR) | 6LR | 6LN |
|---|---|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RPI) | -- | -- | -- |
| Removed headers | -- | -- | -- | -- | IPv6-in-IPv6(RPI) |
| Re-added headers | -- | -- | -- | -- | -- |
| Modified headers | -- | -- | IPv6-in-IPv6(RPI) | IPv6-in-IPv6(RPI) | -- |
| Untouched headers | -- | -- | -- | -- | -- |
In this case the flow comprises:
not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 6LN
The problem to solve is how to indicate where to send the packet when get into LLN. Should attributes be added to the border router indicating this?
| Header | IPv6 src | 6LR | 6LR (common parent) | 6LR | IPv6 dst |
|---|---|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RPI) | -- | -- | -- |
| Removed headers | -- | -- | -- | IPv6-in-IPv6(RPI) | -- |
| Re-added headers | -- | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- | -- |
In non-storing mode the leaf node uses Hop-By-Hop option (RFC 6553) to indicate the routing information to send messages to the DODAG root, this message is going to be analyzed in each node until arrive the DODAG root.
In this case not need to use IPv6-in-IPv6 because no header is not going to be removed, neither RH3, the flow comprises:
RPL-aware-leaf (6LN) --> 6LR --> root (6LBR)
This case is the same case as storing mode.
| Header | 6LN | 6LR | 6LBR |
|---|---|---|---|
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- |
| Untouched headers | -- | -- | -- |
In this case the flow comprises:
root (6LBR)--> 6LR --> RPL-aware-leaf (6LN)
6LBR might instert RPI header, and the rute is indicated in RH3. 6LR updated RH3 and 6LN remove these headers.
| Header | 6LBR | 6LR | 6LN |
|---|---|---|---|
| Inserted headers | (optional: RPI), RH3 | -- | -- |
| Removed headers | -- | -- | RH3,RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RH3 | -- |
| Untouched headers | -- | -- | -- |
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 is fully consumed, but left there. If the RPI is present, the IPv6 node which does not understand it will drop it. To avoid it the RPI should be removed before reach IPv6 node or it is recommended that RPI be omitted. An IPv6-in-IPv6 header should be necessary in this case. The DAO from 6LR about IPv6 could say if that the final IPv6 is not RPL (RPI) capable.
| Header | 6LBR | 6LR | IPv6 |
|---|---|---|---|
| Inserted headers | RH3 | -- | -- |
| Removed headers | -- | -- | -- |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RH3 | -- |
| Untouched headers | -- | -- | -- |
In this case the flow comprises:
IPv6-node --> 6LR1 --> 6LR2 --> root (6LBR)
In this case the RPI is encapsulated in the first 6LR, and is not modified in the followings 6LRs.
| Header | IPv6 | 6LR1 | 6LR2 | 6LBR |
|---|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RPI) | -- | -- |
| Removed headers | -- | -- | -- | IPv6-in-IPv6(RPI) |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | IPv6-in-IPv6(RPI) | -- | -- |
In this case the flow comprises:
RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet
This case requires that the network is awareness of what is external to the LLN. Internet node never sees RPI or IPv6-in-IPv6 header. In the 6LBR the flow label is computed if it is zero. RPI remains unmodified.
| Header | 6LN | 6LR | 6LBR | Internet |
|---|---|---|---|---|
| Inserted headers | IPV6-in-IPv6(RPI) | -- | -- | -- |
| Removed headers | -- | -- | IPV6-in-IPv6(RPI) | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | RPI | -- | -- |
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN)
If the last RH3 entry is the 6LR, then the IPv6-in-IPv6 will be removed there, if the last entry is the 6LN, then the RH3 will go all the way to the leaf. In 6LBR the flow label should be set to zero.
| Header | Internet | 6LBR | 6LR | 6LN |
|---|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RH3,optional:RPI) | -- | -- |
| Removed headers | -- | -- | IPv6-in-IPv6 can be removed if RH3 consumed | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | IPv6-in-IPv6(RH3) | -- |
| Untouched headers | -- | -- | -- | -- |
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. no RPL headers are added in the IPv6 node, since it is ignorant of RPL. Internet node does not see special headers. In 6LBR the flow label is computed if it is zero.
| Header | IPv6 | 6LR | 6LBR | Internet |
|---|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RPI) | -- | -- |
| Removed headers | -- | -- | IPv6-in-IPv6(RPI) | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- |
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN)
In this case the flow label in 6LBR should be set zero in 6LBR, where RH3 is inserted and optionally RHI. RH3 must end at 6LR.
In Non-Storing mode, root knows that the non-RPL-aware-leaf is attached to the parent 6LR, and builds RH3 with IPv6-in-IPv6 with this 6LR as destination.
| Header | Internet | 6LBR | 6LR | IPv6 |
|---|---|---|---|---|
| Inserted headers | -- | IPv6-in-IPv6(RH3,optional:RPI) | -- | -- |
| Removed headers | -- | -- | IPv6-in-IPv6(RH3, RPI) | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- |
In this case the flow comprises:
6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN
This case comprises in the same RPL Domain. In the 6LN the RPI header is inserted. In the 6LBR the RH3 header is inserted in a IPv6-in-IPv6 header and removed at the 6LN destination.
In case of the flow goes from RPL-aware-Leaf to RPL-aware-Leaf, the RPI should be set in a IP-in-IP header, to avoid repetition of RPI header.
| Header | 6LN src | 6LBR | 6LR | 6LN dst |
|---|---|---|---|---|
| Inserted headers | IPv6-in-IPv6(RPI) | IPv6-in-IPv6(RH3 to 6LN,RPI) {IP,payload} | -- | -- |
| Removed headers | -- | -- | -- | IPv6-in-IPv6(RH3,RPI) {IP,RPI,payload} |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- |
In this case the flow comprises:
6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 6LN
The 6LN insert the RPI in a IPv6-in-IPv6 header, which is addressed to 6LBR. The 6LBR remove this RPI header and insert a RH3 header with an optional RPI. These headers are removed by 6LR before send the packet to the IPv6 node.
| Header | 6LN | 6LBR | 6LR | IPv6 |
|---|---|---|---|---|
| Inserted headers | IPv6-in-IPv6(RPI) | IPIP(RH3, opt RPI) | -- | -- |
| Removed headers | -- | IPIP(RPI) | IPIP(RH3, opt RPI) | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- |
In this case the flow comprises:
not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN
RPI is added in 6LR until the root and then removed, then RH3 is added and removed at destination.
| Header | IPv6 | 6LR | 6LBR | 6LN |
|---|---|---|---|---|
| Inserted headers | -- | IPIP(RPI) | IPIP(RH3) | -- |
| Removed headers | -- | IPIP(RPI) | -- | IPIP(RH3) |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- |
In this case the flow comprises:
not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 6LN
RPI is added in 6LR until the root and then might be removed, then RH3 is added. These headers are removed at 6LR before go to destination.
| Header | IPv6 | 6LR | 6LBR | 6LR | IPv6 |
|---|---|---|---|---|---|
| Inserted headers | -- | IPIP(RPI) | IPIP(RH3) | -- | -- |
| Removed headers | -- | -- | IPIP(RPI) | IPIP(RH3, opt RPI) | -- |
| Re-added headers | -- | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- | -- |
| Untouched headers | -- | -- | -- | -- | -- |
There are cases from above that are not clear how to send the information. It requires furhter analysis on how to proceed to send the information from source to destination.
From the above cases, we have in storing mode:
- Flow from RPL-aware-leaf to non-RPL-aware-leaf: Somehow, the sender has to know that the receiver is not RPL aware, and needs to know 6LR, and not even the root knows where the 6LR is located.
- Flow from not-RPL-aware-leaf to not-RPL-aware-leaf: The problem to solve is how to indicate where to send the packet when get into LLN.
There are no IANA considerations related to this document.
TODO.
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 and Robert Cragie.
To be completed with additional Acknowledgments.
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC6550] | Winter, T., Thubert, P., 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. |
| [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. |
| [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. |
| [I-D.ietf-6lo-routing-dispatch] | Thubert, P., Bormann, C., Toutain, L. and R. Cragie, 6LoWPAN Routing Header", Internet-Draft draft-ietf-6lo-routing-dispatch-05, February 2016. |
| [I-D.ietf-6tisch-architecture] | Thubert, P., "An Architecture for IPv6 over the TSCH mode of IEEE 802.15.4", Internet-Draft draft-ietf-6tisch-architecture-09, November 2015. |
| [RFC7102] | Vasseur, JP., "Terms Used in Routing for Low-Power and Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 2014. |
| [Second6TischPlugtest] | 2nd 6Tisch Plugtest" | , "