One document matched: draft-ietf-roll-useofrplinfo-08.xml
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]>
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<rfc category="info" docName="draft-ietf-roll-useofrplinfo-08" ipr="trust200902">
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<!-- ***** FRONT MATTER ***** -->
<front>
<!-- The abbreviated title is used in the page header - it is only necessary if the
full title is longer than 39 characters -->
<title abbrev="Useof6553">When to use RFC 6553, 6554 and IPv6-in-IPv6</title>
<author initials="M.I." surname="Robles" fullname="Maria Ines Robles">
<organization abbrev="Ericsson">Ericsson</organization>
<address>
<postal>
<street>Hirsalantie 11</street>
<city>Jorvas</city>
<code>02420</code>
<country>Finland</country>
</postal>
<email>maria.ines.robles@ericsson.com</email>
</address>
</author>
<author initials="M." surname="Richardson" fullname="Michael C. Richardson">
<organization abbrev="SSW">Sandelman Software Works</organization>
<address>
<postal>
<street>470 Dawson Avenue</street>
<city>Ottawa</city>
<region>ON</region>
<code>K1Z 5V7</code>
<country>CA</country>
</postal>
<email>mcr+ietf@sandelman.ca</email>
<uri>http://www.sandelman.ca/mcr/</uri>
</address>
</author>
<author initials="P." surname="Thubert" fullname="Pascal Thubert">
<organization abbrev="Cisco">Cisco Systems, Inc</organization>
<address>
<postal>
<street> Village d'Entreprises Green Side 400, Avenue de Roumanille</street>
<city>Batiment T3</city>
<region>Biot - Sophia Antipolis </region>
<code>06410</code>
<country>France</country>
</postal>
<email>pthubert@cisco.com </email>
<uri></uri>
</address>
</author>
<date year="2016" />
<area>Internet</area>
<workgroup>ROLL Working Group</workgroup>
<keyword>RPL Option</keyword>
<keyword>6LoWPAN</keyword>
<keyword>RFC 6553</keyword>
<abstract>
<t>
This document looks at different data flows through LLN (Low-Power and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) is used to establish routing.
The document enumerates the cases where RFC 6553, RFC 6554 and IPv6-in-IPv6 encapsulation is required. This analysis
provides the basis on which to design efficient compression of these headers.
</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>
RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) <xref target="RFC6550"/> is a routing protocol for
constrained networks. RFC 6553 <xref target="RFC6553"/>
defines the "RPL option" (RPI), carried within the IPv6 Hop-by-Hop
header to quickly identify
inconsistencies (loops) in the routing topology. RFC 6554 <xref
target="RFC6554"/> defines the "RPL Source Route Header" (RH3), an
IPv6 Extension Header to deliver datagrams within a RPL
routing domain, particularly in non-storing mode.
</t>
<t>
These various items are referred to as RPL artifacts, and
they are seen on all of the data-plane traffic that occurs in
RPL routed networks; they do not in general appear on the RPL
control plane traffic at all which is mostly hop-by-hop
traffic (one exception being DAO messages in non-storing mode).
</t>
<t>
It has become clear from attempts to do multi-vendor
interoperability, and from 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 be safely
omitted, or removed.
</t>
<t>
An interim meeting went through the 24 cases defined here to
discover 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 correct and
incorrect behaviour.
</t>
<t>
The related document <xref
target="I-D.ietf-roll-routing-dispatch"> A Routing Header
Dispatch for 6LoWPAN (6LoRH) </xref> defines a method to
compress RPL Option information and Routing Header type 3
<xref
target="RFC6554"/>, an efficient IP-in-IP technique, and use cases
proposed for the <xref target="Second6TischPlugtest"/>
involving 6loRH.
</t>
</section>
<section title="Terminology and Requirements Language">
<t>
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 <xref target="RFC2119">RFC 2119</xref>.
</t>
<t>
Terminology defined in <xref target="RFC7102"/> applies to this document: LBR, LLN, RPL, RPL Domain and ROLL.
</t>
<t>
RPL-node: It is device which implements RPL, thus we can say that the device is RPL-capable or RPL-aware.
Please note that the device can be found inside the LLN or outside LLN.
In this document a RPL-node which is a leaf is called RPL-aware-leaf.
</t>
<t>
RPL-not-capable: It is device which do not implement RPL, thus we can say that the device is not-RPL-aware.
Please note that the device can be found inside the LLN.
In this document a not-RPL-node which is a leaf is called not-RPL-aware-leaf.
</t>
<section title="hop-by-hop IPv6-in-IPv6 headers">
<t>
The term "hop-by-hop IPv6-in-IPv6" header refers to: adding a header
that originates from a node to an adjacent node, using the
addresses (usually the GUA or ULA, but could use the link-local addresses)
of each node. If the packet must traverse multiple hops, then it
must be decapsulated at each hop, and then re-encapsulated again
in a similar fashion.
</t>
</section>
</section>
<section title="Sample/reference topology">
<t>
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).
</t>
<t>
RPL defines the RPL Control messages (control plane), a new
ICMPv6 <xref target="RFC4443"/> message with Type 155. DIS (DODAG Information Solicitation), DIO (DODAG Information Object) and DAO (Destination Advertisement Object) messages are
all RPL Control messages but with different Code values. A RPL Stack is showed in Figure 1.
</t>
<t>
RPL supports two modes of Downward traffic: in storing mode (RPL-SM),
it is fully stateful or an in non-storing (RPL-NSM), 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 at the time of writing this document.
</t>
<t>
<figure title="RPL Stack."
anchor="fig_RPLStack" align="center">
<artwork><![CDATA[
+--------------+
| Upper Layers |
| |
+--------------+
| RPL |
| |
+--------------+
| ICMPv6 |
| |
+--------------+
| IPv6 |
| |
+--------------+
| 6LoWPAN |
| |
+--------------+
| PHY-MAC |
| |
+--------------+
]]></artwork></figure>
</t>
<t>
<figure title="A reference RPL Topology." anchor="fig_CommonTopology" align="center">
<artwork><![CDATA[
+---------+
+---+Internet |
| +---------+
|
+----+--+
| DODAG | node:01
+---------+ Root +----------+
| | 6LBR | |
| +----+--+ |
| | |
| | |
... ... ...
| | |
+-----+-+ +--+---+ +--+---+
|6LR | | | | |
+-----+ | | | | |
| | 11 | | 12 | | 13 +------+
| +-----+-+ +-+----+ +-+----+ |
| | | | |
| | | | |
| 21 | 22 | 23 | 24 | 25
+-+---+ +-+---+ +--+--+ +- --+ +---+-+
|Leaf | | | | | |Leaf| |Leaf |
| 6LN | | | | | | 6LN| | 6LN |
+-----+ +-----+ +-----+ +----+ +-----+
]]></artwork></figure>
</t>
<t> In Figure 2 is showed the reference RPL Topology for this document. The numbers in or above the nodes are there so that
they may be referenced in subsequent sections. In the figure, a 6LN can be a router or a host.
The 6LN leafs marked as (21) is a RPL host that does not have forwarding capability and (25) is a RPL router.
The leaf marked 6LN (24) is a device which does not speak RPL at all (not-RPL-aware),
but uses Router-Advertisements, 6LowPAN DAR/DAC and efficient-ND only to participate in the network <xref target="RFC6775"/>.
In the document this leaf (24) is often named IPv6 node. The 6LBR in the figure is the root of the Global DODAG.
</t>
<t>
This document is in part motivated by the work that is ongoing at the
6TiSCH working group.
The <xref target="I-D.ietf-6tisch-architecture">6TiSCH architecture
</xref> draft explains the network architecture of a 6TiSCH network.
</t>
</section>
<section title="Use cases">
<t>
In data plane context a combination of RFC6553, RFC6554 and
IPv6-in-IPv6 encapsulation is going to be analyzed for the
following traffic flows.
</t>
<t>This version of the document assumes the changes in <xref
target="I-D.ietf-6man-rfc2460bis"/> are passed (at the time to write this specification, the draft is on version 05).
</t>
<t>
<list>
<t>
RPL-aware-leaf to root
</t>
<t>
root to RPL-aware-leaf
</t>
<t>
not-RPL-aware-leaf to root
</t>
<t>
root to not-RPL-aware-leaf
</t>
<t>
RPL-aware-leaf to Internet
</t>
<t>
Internet to RPL-aware-leaf
</t>
<t>
not-RPL-aware-leaf to Internet
</t>
<t>
Internet to not-RPL-aware-leaf
</t>
<t>
RPL-aware-leaf to RPL-aware-leaf (storing and non-storing)
</t>
<t>
RPL-aware-leaf to not-RPL-aware-leaf (non-storing)
</t>
<t>
not-RPL-aware-leaf to RPL-aware-leaf (storing and non-storing)
</t>
<t>
not-RPL-aware-leaf to not-RPL-aware-leaf (non-storing)
</t>
</list>
</t>
<t>
This document assumes the 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 <xref target="RFC2460" />. Extensions may not
be added or removed except by the sender or the receiver.
</t>
<t>
But, options in the Hop-by-Hop option which are marked with
option type 01 (<xref target="RFC2460" /> section 4.2 and
<xref target="I-D.ietf-6man-rfc2460bis" />) SHOULD be ignored
when received by a host or router which does not understand that
option.
</t>
<t>
This means that in general, any packet that leaves the RPL domain
of an LLN (or leaves the LLN entirely) will NOT be discarded,
when it has the <xref target="RFC6553" /> RPL Option
Header known as the RPI or <xref target="RFC6554" /> SRH3
Extension Header (S)RH3.
</t>
<t>
The recent change to the second of these rules it means that the RPI
Hop-by-Hop option MAY be left in place even if the end host does not
understand it.
</t>
<t>
NOTE: There is some possible security risk when the RPI
information is released to the Internet. At this point this is
a theoretical situation. It is clear that the RPI option would
waste some network bandwidth when it escapes.
</t>
<t>
An intermediate router that needs to add an extension header
(SHR3 or RPI Option) must encapsulate the packet in an
(additional) outer IP header. The new header can be placed is
placed after this new outer IP header.
</t>
<t>
A corollory is that an SHR3 or RPI Option can only be removed by an
intermediate router if it is placed in an encapsulating IPv6
Header, which is addressed to the intermediate router.
When it does so, the whole encapsulating header must be
removed. (A replacement may be added). This sometimes can
result in outer IP headers being addressed to the next hop
router using link-local addresses.
</t>
<t>
Both RPI and RH3 headers may be modified in very specific ways
by routers on the path of the packet without the need to add to
remove an encapsulating header. Both headers were designed with
this modification in
mind, and both the RPL RH and the RPL option are marked mutable
but recoverable: so an IPsec AH security header can be applied
across these headers, but it can not secure the values which mutate.
</t>
<t>
RPI should be present in every single RPL data packet. There is one
exception in non-storing mode: when a packet is going down from the
root. In a downward non-storing mode, the entire route is
written, so there can be no loops by construction, nor any
confusion about which forwarding table to use (as the root has
already made all routing decisions). There still may be
cases (such as in 6tisch) where the instanceID portion of the RPI
header may still be needed to pick an appropriate priority or
channel at each hop.
</t>
<t>
In the tables present in this document, 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.
</t>
<t>
The earlier examples are more extensive to make sure that the
process is clear, while later examples are more consise.
</t>
</section>
<section title=" Storing mode">
<t>
In storing mode (fully stateful), the sender cannot determine whether the destination is RPL-capable and
thus would need an IP-in-IP header. The IP-in-IP
header needs to be addressed on a hop-by-hop basis so that the last 6LR can remove
the RPI header. Additionally, 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.
</t>
<t>
The following table summarizes what headers are needed in the following
scenarios, and indicates when the IP-in-IP 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 IP-in-IP header is needed, the column is left blank.
</t>
<t>
The leaf can be a router 6LR or a host, both indicated as 6LN.
</t>
<texttable anchor="table_storing" title="Headers needed in Storing mode: RPI, RH3, IP-in-IP encapsulation" >
<ttcol> Use Case </ttcol>
<ttcol> RPI </ttcol>
<ttcol> RH3 </ttcol>
<ttcol> IP-in-IP </ttcol>
<ttcol> IP-in-IP dst </ttcol>
<c> Raf to root</c>
<c> Yes</c>
<c> No</c>
<c> No</c>
<c> -- </c>
<c> root to Raf</c>
<c> Yes</c>
<c> No</c>
<c> No</c>
<c> -- </c>
<c> root to ~Raf</c>
<c> Yes</c>
<c> No</c>
<c> No</c>
<c> -- </c>
<c> ~Raf to root</c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> root </c>
<c> Raf to Int</c>
<c> Yes</c>
<c> No</c>
<c> No</c>
<c> -- </c>
<c> Int to Raf</c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> raf </c>
<c> ~Raf to Int</c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> root </c>
<c> Int to ~Raf</c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> hop </c>
<c> Raf to Raf</c>
<c> Yes</c>
<c> No</c>
<c> No</c>
<c> -- </c>
<c> Raf to ~Raf</c>
<c> Yes</c>
<c> No</c>
<c> No</c>
<c> -- </c>
<c> ~Raf to Raf </c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> dst </c>
<c> ~Raf to ~Raf</c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> hop </c>
</texttable>
<section title="Example of Flow from RPL-aware-leaf to root">
<t>
In storing mode, RFC 6553 (RPI) is used
to send RPL Information instanceID and rank
information.
</t>
<t>
As stated in Section 16.2 of <xref
target="RFC6550"/> a RPL-aware-leaf node does not
generally issue DIO messages; a leaf node accepts
DIO messages from upstream.
(When the inconsistency in routing occurs, a leaf
node will 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.
</t>
<t>
In this case the flow comprises:
</t>
<t>
RPL-aware-leaf (6LN) --> 6LR1,... --> 6LRN --> root
(6LBR)
</t>
<t> As it was mentioned In this document 6LRs, 6LBR are always
full-fledge RPL routers.
</t>
<t>
The 6LN inserts the RPI header, and sends the
packet to 6LR which decrements the rank in RPI and
sends the packet up. When the packet arrives at
6LBR, the RPI is removed and the packet is
processed.
</t>
<t>
No IP-in-IP header is required.
</t>
<t> 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
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.
</t>
<texttable title="Storing: Summary of the use of headers from RPL-aware-leaf to root">
<ttcol> Header</ttcol>
<ttcol> 6LN</ttcol>
<ttcol> 6LR</ttcol>
<ttcol> 6LBR</ttcol>
<c> Inserted headers</c>
<c> RPI</c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> RPI </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> RPI </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> --</c>
<c> --</c>
</texttable>
</section>
<section title="Example of Flow from root to RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
root (6LBR) --> 6LR1,... --> 6LRN --> RPL-aware-leaf (6LN)
</t>
<t>
In this case the 6LBR inserts RPI header and
sends 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.
</t>
<t>
No IP-in-IP header is required.
</t>
<texttable title="Storing: Summary of the use of headers from root to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LR</ttcol>
<ttcol> 6LN</ttcol>
<c> Inserted headers</c>
<c> RPI </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> RPI </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> RPI </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title="Example of Flow from root to not-RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
root (6LBR) --> 6LR1,... --> 6LRN --> not-RPL-aware-leaf (IPv6)
</t>
<t>
As the RPI extension can be ignored by the
not-RPL-aware leaf, this situation is identical to
the previous scenario.
</t>
<texttable title="Storing: Summary of the use of headers from root to not-RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LR(1..N)</ttcol>
<ttcol> 6LN</ttcol>
<c> Inserted headers</c>
<c> RPI </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> RPI </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> RPI (Ignored) </c>
</texttable>
</section>
<section title="Example of Flow from not-RPL-aware-leaf to root">
<t>
In this case the flow comprises:
</t>
<t>
not-RPL-aware-leaf (IPv6) --> 6LR1,... --> 6LRN --> root (6LBR)
</t>
<t>
When the packet arrives from IPv6 node to
6LR, the 6LR1 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 processes
the packet.
</t>
<texttable title="Storing: Summary of the use of headers from not-RPL-aware-leaf to root">
<ttcol> Header</ttcol>
<ttcol> IPv6</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LRN</ttcol>
<ttcol> 6LBR</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI)</c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title="Example of Flow from RPL-aware-leaf to Internet">
<t>
RPL information from RFC 6553 MAY go out to
Internet as it will be ignored by nodes which have
not been configured to be RPI aware.
</t>
<t>
In this case the flow comprises:
</t>
<t>
RPL-aware-leaf (6LN) --> 6LR1,... --> 6LRN --> root (6LBR) --> Internet
</t>
<t>
No IP-in-IP header is required.
</t>
<texttable title="Storing: Summary of the use of headers from RPL-aware-leaf to Internet">
<ttcol> Header</ttcol>
<ttcol> 6LN</ttcol>
<ttcol> 6LR(1..N)</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> Internet</ttcol>
<c> Inserted headers</c>
<c> RPI </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> RPI </c>
<c> -- </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> RPI (Ignored) </c>
</texttable>
</section>
<!-- section 5.6 -->
<section title="Example of Flow from Internet to RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
Internet --> root (6LBR) --> 6LR1,... --> 6LRN --> RPL-aware-leaf (6LN)
</t>
<t>
When the packet arrives from Internet to 6LBR
the RPI header is added in a outer
IPv6-in-IPv6 header and sent to 6LR, which
modifies the rank in the RPI. When the packet
arrives at 6LN the RPI header is removed and the
packet processed.
</t>
<texttable title="Storing: Summary of the use of headers from Internet to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> Internet</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LR(1...N)</ttcol>
<ttcol> 6LN</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<!-- section 5.6 -->
<section title="Example of Flow from not-RPL-aware-leaf to Internet">
<t>
In this case the flow comprises:
</t>
<t>
not-RPL-aware-leaf (IPv6) --> 6LR1,... --> 6LRN --> root (6LBR) --> Internet
</t>
<t>
The 6LR1 node will add an IP-in-IP(RPI) header addressed either
to the root, or hop-by-hop such that the root can remove
the RPI header before passing upwards.
</t>
<t>
The originating node will ideally leave the IPv6 flow
label as zero so that it can be better compressed through
the LLN, and the 6LBR will set the flow label to a
non-zero value when sending to the Internet.
</t>
<texttable title="Storing: Summary of the use of headers from not-RPL-aware-leaf to Internet">
<ttcol> Header</ttcol>
<ttcol> IPv6 </ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LBN</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> Internet</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c>IP-in-IP(RPI) </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> --</c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title=" Example of Flow from Internet to non-RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
Internet --> root (6LBR) --> 6LR1,... --> 6LRN --> not-RPL-aware-leaf (IPv6)
</t>
<t>
The 6LBR will have to add an RPI header within an
IP-in-IP header. The IP-in-IP can be addressed to
the not-RPL-aware-leaf, leaving the RPI inside.
</t>
<t>
The 6LBR MAY set the flow label on the inner IP-in-IP
header to zero in order to aid in compression, as
the packet will not emerge again from the LLN.
</t>
<texttable title="Storing: Summary of the use of headers from Internet to non-RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> Internet</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LR(1...N)</ttcol>
<ttcol> IPv6</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c>IP-in-IP(RPI) </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c>-- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> RPI (Ignored) </c>
</texttable>
</section>
<!-- section 5.9 -->
<section anchor="storingraftoraf" title="Example of Flow from RPL-aware-leaf to RPL-aware-leaf">
<t>
In <xref target="RFC6550"/> RPL allows a simple one-hop
optimization for both storing and non-storing
networks.
A node may send a packet destined to a one-hop
neighbor directly to that node. Section 9 in <xref
target="RFC6550"/>.
</t>
<t>
In this case the flow comprises:
</t>
<t>
6LN --> 6LR1 --> common parent (6LRx) --> 6LRN --> 6LN
</t>
<t>
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).
</t>
<t>
While the 6LR nodes will update the RPI, no node needs to
add or remove the RPI, so no IP-in-IP headers are
necessary.
This may be done regardless of where the destination is,
as the included RPI will be ignored by the receiver.
</t>
<texttable title="Storing: Summary of the use of headers for RPL-aware-leaf to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> 6LN src</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LRx (common parent)</ttcol>
<ttcol> 6LRN</ttcol>
<ttcol> 6LN dst</ttcol>
<c> Inserted headers</c>
<c> RPI </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> RPI</c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> RPI (decreasing rank) </c>
<c> RPI (increasing rank)</c>
<c> -- </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<!-- section 5.10 -->
<section anchor="storingraftononraf" title="Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
6LN --> 6LR1 --> common parent (6LRx) --> 6LRN --> not-RPL-aware 6LN (IPv6)
</t>
<t>
This situation is identical to the previous situation
<xref target="storingraftoraf" />
</t>
<texttable title="Storing: Summary of the use of headers for RPL-aware-leaf to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> 6LN src</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LRx (common parent)</ttcol>
<ttcol> 6LRN</ttcol>
<ttcol> IPv6</ttcol>
<c> Inserted headers</c>
<c> RPI </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> RPI</c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> RPI (decreasing rank) </c>
<c> RPI (increasing rank)</c>
<c> -- </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> RPI(Ignored) </c>
</texttable>
</section>
<section anchor="storingnotraftoraf" title="Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
not-RPL-aware 6LN (IPv6) --> 6LR1 --> common parent (6LRx) --> 6LRN --> 6LN
</t>
<t>
The 6LR1 receives the packet from the the IPv6 node and
inserts
and the RPI header encapsulated in IPv6-in-IPv6 header.
The IP-in-IP header is addressed to the destination 6LN.
</t>
<texttable title="Storing: Summary of the use of headers from not-RPL-aware-leaf to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> IPv6</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> common parent (6LRx)</ttcol>
<ttcol> 6LRn</ttcol>
<ttcol> 6LN</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> --</c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title="Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
not-RPL-aware 6LN (IPv6 src)--> 6LR1 --> 6LR2 --> root (6LBR) --> 6LRn --> not-RPL-aware 6LN (IPv6 dst)
</t>
<t>
This flow is identical to
<xref target="storingnotraftoraf" />
</t>
<t>
The 6LR receives the packet from the the IPv6 node and inserts
the RPI header (RPIa) encapsulated in IPv6-in-IPv6 header.
The IPv6-in-IPv6 header is addressed to the 6LBR. The 6LBR remove the IPv6-in-IPv6 header and
insert another one (RPIb) with destination to 6LRn node.
</t>
<texttable title="Storing: Summary of the use of headers from not-RPL-aware-leaf to non-RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> IPv6 src</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LR2</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LRn</ttcol>
<ttcol> IPv6 dst</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPIa) </c>
<c> --</c>
<c> IP-in-IP(RPIb) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> --</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> --</c>
<c> -- </c>
<c> IP-in-IP(RPIb) </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPIa)</c>
<c> -- </c>
<c> IP-in-IP(RPIb) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> --</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
</section>
<section title="Non Storing mode">
<texttable anchor="table_nonstoring" title="Headers needed in Non-Storing mode: RPI, RH3, IP-in-IP encapsulation" >
<ttcol> Use Case </ttcol>
<ttcol> RPI </ttcol>
<ttcol> RH3 </ttcol>
<ttcol> IP-in-IP </ttcol>
<ttcol> IP-in-IP dst </ttcol>
<c> Raf to root</c>
<c> Yes</c>
<c> No</c>
<c> No</c>
<c> --</c>
<c> root to Raf</c>
<c> Opt</c>
<c> Yes</c>
<c> No</c>
<c> --</c>
<c> root to ~Raf</c>
<c> No</c>
<c> Yes</c>
<c> Yes</c>
<c> 6LR </c>
<c> ~Raf to root</c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> root </c>
<c> Raf to Int</c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> root </c>
<c> Int to Raf</c>
<c> Opt</c>
<c> Yes</c>
<c> Yes</c>
<c> dst </c>
<c> ~Raf to Int</c>
<c> Yes</c>
<c> No</c>
<c> Yes</c>
<c> root </c>
<c> Int to ~Raf</c>
<c> Opt</c>
<c> Yes</c>
<c> Yes</c>
<c> 6LR </c>
<c> Raf to Raf</c>
<c> Yes</c>
<c> Yes</c>
<c> Yes</c>
<c> root/dst</c>
<c> Raf to ~Raf</c>
<c> Yes</c>
<c> Yes</c>
<c> Yes</c>
<c> root/6LR</c>
<c> ~Raf to Raf </c>
<c> Yes</c>
<c> Yes</c>
<c> Yes</c>
<c> root/6LN</c>
<c> ~Raf to ~Raf</c>
<c> Yes</c>
<c> Yes</c>
<c> Yes</c>
<c> root/6LR</c>
</texttable>
<section title=" Example of Flow from RPL-aware-leaf to root">
<t>
In non-storing mode the leaf node uses default
routing to send traffic to the root. The RPI header
must be included to avoid/detect loops.
</t>
<t>
RPL-aware-leaf (6LN) --> 6LR --> root (6LBR)
</t>
<t>
This situation is the same case as storing mode.
</t>
<texttable title="Non Storing: Summary of the use of headers from RPL-aware-leaf to root">
<ttcol> Header</ttcol>
<ttcol> 6LN</ttcol>
<ttcol> 6LR</ttcol>
<ttcol> 6LBR</ttcol>
<c> Inserted headers</c>
<c> RPI</c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> RPI </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> RPI </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> --</c>
<c> --</c>
</texttable>
</section>
<section anchor="nsroottoraf" title=" Example of Flow from root to RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
root (6LBR)--> 6LR --> RPL-aware-leaf (6LN)
</t>
<t>
The 6LBR will insert an RH3, and may optionally insert an
RPI header. No IP-in-IP header is necessary as the traffic
originates with an RPL aware node, the 6LBR.
The destination is known to RPL-aware because, the root knows the whole topology in non-storing mode.
</t>
<texttable title="Non Storing: Summary of the use of headers from root to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LR</ttcol>
<ttcol> 6LN</ttcol>
<c> Inserted headers</c>
<c> (opt: RPI), RH3</c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> RH3,RPI </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c>RH3 </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title=" Example of Flow from root to not-RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
root (6LBR)--> 6LR1...-->6LRn --> not-RPL-aware-leaf (IPv6)
</t>
<t>
In 6LBR the RH3 is added, modified in each intermediate 6LR (6LR1 and so on) and
it is fully consumed in the last 6LR (6LRn), but left there.
If RPI is left present, the IPv6 node which
does not understand it will ignore it (following 2460bis), thus encapsulation is not necesary.
Due the complete knowledge of the
topology at the root, the 6LBR is able to address
the IP-in-IP header to the last 6LR.
</t>
<texttable title=" Non Storing: Summary of the use of headers from root to not-RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LRn</ttcol>
<ttcol> IPv6</ttcol>
<c> Inserted headers</c>
<c> (opt: RPI), RH3 </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> RH3 </c>
<c> -- </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> (opt: RPI), RH3 </c>
<c>(opt: RPI), RH3</c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> RPI </c>
</texttable>
</section>
<section title=" Example of Flow from not-RPL-aware-leaf to root">
<t>
In this case the flow comprises:
</t>
<t>
IPv6-node --> 6LR1 ...--> 6LRn --> root (6LBR)
</t>
<t>
In this case the RPI is added by the first
6LR (6LR1), encapsulated in an IP-in-IP header, and is
modified in the followings 6LRs. The RPI and
entire packet is consumed by the root.
</t>
<texttable title="Non Storing: Summary of the use of headers from not-RPL-aware-leaf to root">
<ttcol> Header</ttcol>
<ttcol> IPv6</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LR2</ttcol>
<ttcol> 6LBR</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title=" Example of Flow from RPL-aware-leaf to Internet">
<t>
In this case the flow comprises:
</t>
<t>
RPL-aware-leaf (6LN) --> 6LR1 ...--> 6LRn --> root (6LBR) --> Internet
</t>
<t>
This case is identical to storing-mode case.
</t>
<t>
The IPv6 flow label should be set to zero to aid
in compression, and the 6LBR will set it to a
non-zero value when sending towards the Internet.
</t>
<texttable title="Non Storing: Summary of the use of headers from RPL-aware-leaf to Internet">
<ttcol> Header</ttcol>
<ttcol> 6LN</ttcol>
<ttcol> 6LR(1..N)</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> Internet</ttcol>
<c> Inserted headers</c>
<c> RPI </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> RPI </c>
<c> -- </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> RPI (Ignored) </c>
</texttable>
</section>
<section title=" Example of Flow from Internet to RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
Internet --> root (6LBR) --> 6LR1...--> 6LRn --> RPL-aware-leaf (6LN)
</t>
<t>
The 6LBR must add an RH3 header. As the 6LBR will
know the path and address of the target node, it can
address the IP-in-IP header to that node.
The 6LBR will zero the flow label upon entry in
order to aid compression.
</t>
<t>
The RPI may be added or not, it is optional.
</t>
<texttable title="Non Storing: Summary of the use of headers from Internet to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> Internet</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LR</ttcol>
<ttcol> 6LN</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RH3,opt:RPI) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RH3,opt:RPI) </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RH3,opt:RPI) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title=" Example of Flow from not-RPL-aware-leaf to Internet">
<t>
In this case the flow comprises:
</t>
<t>
not-RPL-aware-leaf (IPv6) --> 6LR1..--> 6LRn --> root (6LBR) --> Internet
</t>
<t>
In this case the flow label is recommended to
be zero in the IPv6 node. As RPL headers are
added in the IPv6 node, the first 6LN will
add an RPI header inside a new IP-in-IP header.
The IP-in-IP header will be addressed to the
root. This case is identical to the
storing-mode case (Section 5.7).
</t>
<texttable title="Non Storing: Summary of the use of headers from not-RPL-aware-leaf to Internet">
<ttcol> Header</ttcol>
<ttcol> IPv6</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LRn</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> Internet</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI)</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI) </c>
<c> -- </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title=" Example of Flow from Internet to non-RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
Internet --> root (6LBR) --> 6LR1...--> 6LRn --> not-RPL-aware-leaf (IPv6)
</t>
<t>
The 6LBR must add an RH3 header inside an IP-in-IP
header.
The 6LBR will know the path, and will recognize
that the final node is not an RPL capable node as
it will have received the connectivity DAO from the
nearest 6LR. The 6LBR can therefore make the IP-in-IP
header destination be the last 6LR.
The 6LBR will set to zero the flow label upon entry in
order to aid compression.
</t>
<texttable title=" NonStoring: Summary of the use of headers from Internet to non-RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> Internet</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LRn</ttcol>
<ttcol> IPv6</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RH3,opt:RPI) </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RH3, RPI) </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RH3, RPI) </c>
<c> IP-in-IP(RH3, RPI) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> RPI </c>
</texttable>
</section>
<section title=" Example of Flow from RPL-aware-leaf to RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
6LN --> 6LR1 --> root (6LBR) --> 6LRN --> 6LN
</t>
<t>
This case involves only nodes in same RPL Domain.
The originating node will add an RPI header to the
original packet, and send the packet upwards.
</t>
<t>
The originating node SHOULD put the RPI into an IP-in-IP
header addressed to the root, so that the 6LBR can
remove that header. If it does not, then
additional resources are wasted on the way down to
carry the useless RPI option.
</t>
<t>
The 6LBR will need to insert an RH3 header, which
requires that it add an IP-in-IP header. It SHOULD be
able to remove the RPI, as it was contained in an
IP-in-IP header addressed to it. Otherwise, there MAY
be an RPI header buried inside the inner IP header,
which should get ignored.
</t>
<t>
Networks that use the RPL P2P extension <xref target="RFC6997" />
are essentially non-storing DODAGs and fall into this
scenario or scenario <xref target="nsroottoraf"/>, with
the originating node acting as 6LBR.
</t>
<texttable title="Non Storing: Summary of the use of headers for RPL-aware-leaf to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> 6LN src</ttcol>
<ttcol> 6LR1 </ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LRN</ttcol>
<ttcol> 6LN dst</ttcol>
<c> Inserted headers</c>
<c> IP-in-IP(RPI1) </c>
<c> -- </c>
<c> IP-in-IP(RH3 to 6LN, opt RPI2) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI1) </c>
<c> -- </c>
<c> IP-in-IP(RH3, opt RPI2)</c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title=" Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
6LN --> 6LR1 --> root (6LBR) --> 6LRn --> not-RPL-aware (IPv6)
</t>
<t>
As in the previous case, the 6LN will insert an RPI (RPI1)
header which MUST be in an IP-in-IP header addressed to
the root so that the 6LBR can remove this RPI.
The 6LBR will then insert an RH3 inside a new IP-in-IP
header addressed to the 6LN destination node. The RPI is optional from 6LBR to 6LRn (RPI2).
</t>
<texttable title="Non Storing: Summary of the use of headers from RPL-aware-leaf to not-RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> 6LN</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LRn</ttcol>
<ttcol> IPv6</ttcol>
<c> Inserted headers</c>
<c> IP-in-IP(RPI1) </c>
<c> -- </c>
<c> IP-in-IP(RH3, opt RPI2) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI1) </c>
<c> IP-in-IP(RH3, opt RPI2) </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> IP-in-IP(RPI1) </c>
<c> -- </c>
<c> IP-in-IP(RH3, opt RPI2) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> opt RPI2 </c>
</texttable>
</section>
<section title=" Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
not-RPL-aware 6LN (IPv6) --> 6LR1 --> root (6LBR) --> 6LRn --> 6LN
</t>
<t>
This scenario is mostly identical to the previous
one. The RPI is added by the first 6LR (6LR1) inside an
IP-in-IP header addressed to the root. The 6LBR will
remove this RPI, and add it's own IP-in-IP header
containing an RH3 header and optional RPI (RPI2).
</t>
<texttable title="Non Storing: Summary of the use of headers from not-RPL-aware-leaf to RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> IPv6</ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LRn</ttcol>
<ttcol> 6LN</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI1) </c>
<c> IP-in-IP(RH3, opt RPI2)</c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI1) </c>
<c> -- </c>
<c> IP-in-IP(RH3, opt RPI2) </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RH3, opt RPI2) </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
<section title=" Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf">
<t>
In this case the flow comprises:
</t>
<t>
not-RPL-aware 6LN (IPv6 src)--> 6LR1 --> root (6LBR) --> 6LRn --> not-RPL-aware (IPv6 dst)
</t>
<t>
This scenario is the combination of the previous two cases.
</t>
<texttable title="Non Storing: Summary of the use of headers from not-RPL-aware-leaf to not-RPL-aware-leaf">
<ttcol> Header</ttcol>
<ttcol> IPv6 src </ttcol>
<ttcol> 6LR1</ttcol>
<ttcol> 6LBR</ttcol>
<ttcol> 6LRn</ttcol>
<ttcol> IPv6 dst</ttcol>
<c> Inserted headers</c>
<c> -- </c>
<c> IP-in-IP(RPI1) </c>
<c> IP-in-IP(RH3) </c>
<c> -- </c>
<c> -- </c>
<c> Removed headers</c>
<c> -- </c>
<c> -- </c>
<c> IP-in-IP(RPI1) </c>
<c> IP-in-IP(RH3, opt RPI2) </c>
<c> -- </c>
<c> Re-added headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Modified headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> Untouched headers</c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
<c> -- </c>
</texttable>
</section>
</section>
<section title="Observations about the cases">
<section title="Storing mode">
<!-- <t>
Without the modifications in 2460 bis, we would have in the completely general storing case, which includes not-RPL
aware leaf nodes, it is not possible for a sending node to know
if the destination is RPL aware, and therefore it must always use
hop-by-hop IP-in-IP encapsulation, and it can never omit the IP-in-IP
encapsulation. See table <xref target="table_storing" />
</t>
-->
<t>
<xref target="I-D.ietf-roll-routing-dispatch" /> shows that this
hop-by-hop IP-in-IP header can be compressed down to {TBD} bytes.
</t>
<t>
There are potential significant advantages to having a single
code path that always processes IP-in-IP headers with no options.
</t>
<t>
Thanks to the relaxation of the RFC2406 rule about discarding
unknown Hop-by-Hop options, there is no longer any uncertainty
about when to use an IPIP header in the storing mode case.
The RPI header SHOULD always be added when 6LRs originate
packets (without IPIP headers), and IPIP headers should always
be added (addressed to the root when on the way up, to the
end-host when on the way down) when a 6LR finds it needs to
insert an RPI header.
(XXX - this is a problem for storing mode optimization)
</t>
<t>
In order to support the above two cases with full generality, the
different situations (always do IP-in-IP vs never use IP-in-IP) should be
signaled in the RPL protocol itself.
</t>
</section>
<section title="Non-Storing mode">
<t>
In the non-storing case, dealing with non-RPL aware leaf nodes
is much easier as the 6LBR (DODAG root) has complete knowledge
about the connectivity of all DODAG nodes, and all traffic flows
through the root node.
</t>
<t>
The 6LBR can recognize non-RPL aware leaf nodes because it will
receive a DAO about that node from the 6LN immediately above that
node. This means that the non-storing mode case can avoid ever
using hop-by-hop IP-in-IP headers.
</t>
<t>
<xref target="I-D.ietf-roll-routing-dispatch" /> shows how the
destination=root, and destination=6LN IP-in-IP header can be
compressed down to {TBD} bytes.
</t>
<t>
Unlike in the storing mode case, there is no need for all nodes
to know about the existence of non-RPL aware nodes. Only the
6LBR needs to 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.
</t>
</section>
</section>
<section title="6LoRH Compression cases">
<t>
The <xref target="I-D.ietf-roll-routing-dispatch"/> proposes a compression method for RPI, RH3 and IPv6-in-IPv6.
</t>
<t>
In Storing Mode, for the examples of Flow 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
this case is critical since IP-in-IP is encapsulating a RPI
header.
</t>
<t>
<figure title="Critical IP-in-IP (RPI)." anchor="rtghc"><artwork><![CDATA[
+--+-----+---+--------------+-----------+-------------+-------------+
|1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI - 6LoRH | LOWPAN IPHC |
+--+-----+---+--------------+-----------+-------------+-------------+
]]></artwork></figure>
</t>
</section>
<section title="IANA Considerations">
<t>
There are no IANA considerations related to this document.
</t>
</section>
<section anchor="Security" title="Security Considerations">
<t>
The security considerations covering of <xref target="RFC6553"/> and
<xref target="RFC6554"/> apply when the packets get into RPL
Domain.
</t>
</section>
<section anchor="Acknowledgments" title="Acknowledgments">
<t>
This work is partially funded by the FP7 Marie Curie Initial Training
Network (ITN) METRICS project (grant agreement No. 607728).
</t>
<t>
The authors would like to acknowledge the review, feedback, and
comments of Robert Cragie, Simon Duquennoy, Cenk Gündogan, Peter
van der Stok, Xavier Vilajosana and Thomas Watteyne.
</t>
</section>
</middle>
<back>
<references title="Normative References">
<!--?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml"?-->
&RFC6553;
&RFC6554;
&RFC2119;
<?rfc include="reference.RFC.2460" ?>
<?ref include="reference.I-D.ietf-6man-rfc2460bis" ?>
&RFC6550;
</references>
<references title="Informative References">
<!--?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml"?-->
&RFC6775;
&RFC4443;
&RFC7102;
&I-D.ietf-6tisch-architecture;
<?rfc include="reference.I-D.ietf-roll-routing-dispatch" ?>
<?rfc include="reference.RFC.6997" ?>
<reference anchor="Second6TischPlugtest" target="http://www.ietf.org/mail-archive/web/6tisch/current/pdfgDMQcdCkRz.pdf">
<front>
<title>2nd 6Tisch Plugtest </title>
<author/>
<date/>
</front>
</reference>
</references>
<!-- Change Log
v00 2011-03-07 BPa Initial version
-->
</back>
</rfc>
<!--
Local Variables:
mode: xml
End:
-->
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