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roll-useofrplinfo-13.txt
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ROLL Working Group M. Robles
Internet-Draft Ericsson
Updates: 6550 (if approved) M. Richardson
Intended status: Standards Track SSW
Expires: October 5, 2017 P. Thubert
Cisco
April 3, 2017
When to use RFC 6553, 6554 and IPv6-in-IPv6
draft-ietf-roll-useofrplinfo-13
Abstract
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.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 5, 2017.
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
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
Robles, et al. Expires October 5, 2017 [Page 1]
Internet-Draft Useof6553 April 2017
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Requirements Language . . . . . . . . . . . . 3
2.1. hop-by-hop IPv6-in-IPv6 headers . . . . . . . . . . . . . 4
3. Sample/reference topology . . . . . . . . . . . . . . . . . . 4
4. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 10
5.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 11
5.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 12
5.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 12
5.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 13
5.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 14
5.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 14
5.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 15
5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 16
5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 17
5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 18
5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 20
6.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 21
6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 22
6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 22
6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 23
6.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 24
6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 25
6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 25
6.8. Example of Flow from Internet to not-RPL-aware-leaf . . . 26
6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 27
6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 28
6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 29
6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 30
7. Observations about the cases . . . . . . . . . . . . . . . . 31
7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 31
7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 32
8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . . 32
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
10. Security Considerations . . . . . . . . . . . . . . . . . . . 32
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 35
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 35
Robles, et al. Expires October 5, 2017 [Page 2]
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12.1. Normative References . . . . . . . . . . . . . . . . . . 35
12.2. Informative References . . . . . . . . . . . . . . . . . 36
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38
1. Introduction
RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks)
[RFC6550] is a routing protocol for constrained networks. RFC 6553
[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 [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.
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).
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.
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.
The related document A Routing Header Dispatch for 6LoWPAN (6LoRH)
[I-D.ietf-roll-routing-dispatch] defines a method to compress RPL
Option information and Routing Header type 3 [RFC6554], an efficient
IP-in-IP technique, and use cases proposed for the
[Second6TischPlugtest] involving 6loRH.
The related document updates [RFC6550]. 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 [RFC6553] RPL Option Header known as
the RPI or [RFC6554] SRH3 Extension Header (S)RH3. Due to changes to
[I-D.ietf-6man-rfc2460bis] the RPI Hop-by-Hop option MAY be left in
place even if the end host does not understand it.
2. Terminology and Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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Terminology defined in [RFC7102] applies to this document: LBR, LLN,
RPL, RPL Domain and ROLL.
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 of a DODAG is called RPL-aware-leaf.
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 of a DODAG is called not-RPL-aware-leaf.
2.1. hop-by-hop IPv6-in-IPv6 headers
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.
3. Sample/reference topology
A RPL network is composed of a 6LBR (6LoWPAN Border Router), Backbone
Router (6BBR), 6LR (6LoWPAN Router) and 6LN (6LoWPAN Node) as leaf
logically organized in a DODAG structure (Destination Oriented
Directed Acyclic Graph).
RPL defines the RPL Control messages (control plane), a new ICMPv6
[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.
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.
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+--------------+
| Upper Layers |
| |
+--------------+
| RPL |
| |
+--------------+
| ICMPv6 |
| |
+--------------+
| IPv6 |
| |
+--------------+
| 6LoWPAN |
| |
+--------------+
| PHY-MAC |
| |
+--------------+
Figure 1: RPL Stack.
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+---------+
+---+Internet |
| +---------+
|
+----+--+
| DODAG | node:01
+---------+ Root +----------+
| | 6LBR | |
| +----+--+ |
| | |
| | |
... ... ...
| | |
+-----+-+ +--+---+ +--+---+
|6LR | | | | |
+-----+ | | | | |
| | 11 | | 12 | | 13 +------+
| +-----+-+ +-+----+ +-+----+ |
| | | | |
| | | | |
| 21 | 22 | 23 | 24 | 25
+-+---+ +-+---+ +--+--+ +- --+ +---+-+
|Leaf | | | | | |Leaf| |Leaf |
| 6LN | | | | | | 6LN| | 6LN |
+-----+ +-----+ +-----+ +----+ +-----+
Figure 2: A reference RPL Topology.
Figure 2 shows 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 [RFC6775]. In the
document this leaf (24) is often named IPv6 node. The 6LBR in the
figure is the root of the Global DODAG.
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.
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4. Use cases
In data plane context a combination of RFC6553, RFC6554 and IPv6-in-
IPv6 encapsulation is going to be analyzed for the following traffic
flows.
This version of the document assumes the changes in
[I-D.ietf-6man-rfc2460bis] are passed (at the time to write this
specification, the draft is on version 05).
The uses cases describe the communication between RPL-aware-nodes,
with the root (6LBR), and with Internet. This document also describe
the communication between nodes acting as leaf that does not
understand RPL and they are part of hte LLN. We name these nodes as
not-RPL-aware-leaf.(e.g. section 5.4- Flow from not-RPL-aware-leaf to
root) We describe also how is the communication inside of the LLN
when it has the final destination addressed outside of the LLN e.g.
with destination to Internet. (e.g. section 5.7- Flow from not-RPL-
aware-leaf to Internet)
The uses cases comprise as follow:
RPL-aware-leaf to root
root to RPL-aware-leaf
not-RPL-aware-leaf to root
root to not-RPL-aware-leaf
RPL-aware-leaf to Internet
Internet to RPL-aware-leaf
not-RPL-aware-leaf to Internet
Internet to not-RPL-aware-leaf
RPL-aware-leaf to RPL-aware-leaf (storing and non-storing)
RPL-aware-leaf to not-RPL-aware-leaf (non-storing)
not-RPL-aware-leaf to RPL-aware-leaf (storing and non-storing)
not-RPL-aware-leaf to not-RPL-aware-leaf (non-storing)
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
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is a fundamental precept of the IPv6 architecture as outlined in
[RFC2460]. Extensions may not be added or removed except by the
sender or the receiver.
But, options in the Hop-by-Hop option which are marked with option
type 01 ([RFC2460] section 4.2 and [I-D.ietf-6man-rfc2460bis]) SHOULD
be ignored when received by a host or router which does not
understand that option.
This means that in general, any packet that leaves the RPL domain of
an LLN (or leaves the LLN entirely) will NOT be discarded, when it
has the [RFC6553] RPL Option Header known as the RPI or [RFC6554]
SRH3 Extension Header (S)RH3.
The recent change to the second of these rules means that the RPI
Hop-by-Hop option MAY be left in place even if the end host does not
understand it.
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.
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.
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.
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.
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
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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.
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.
The earlier examples are more extensive to make sure that the process
is clear, while later examples are more concise.
5. Storing mode
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.
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 these 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.
In all cases the RPI headers are needed, since it identifies
inconsistencies (loops) in the routing topology. In all cases the
RH3 is not need because we do not indicate the route in stroing mode.
The leaf can be a router 6LR or a host, both indicated as 6LN
(Figure 2).
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+--------------+-----------+---------------+
| Use Case | IP-in-IP | IP-in-IP dst |
+--------------+-----------+---------------+
| Raf to root | No | -- |
| root to Raf | No | -- |
| root to ~Raf | No | -- |
| ~Raf to root | Yes | root |
| Raf to Int | No | -- |
| Int to Raf | Yes | raf |
| ~Raf to Int | root | raf |
| ~Raf to Int | Yes | root |
| Int to ~Raf | Yes | hop |
| Raf to Raf | No | -- |
| Raf to ~Raf | No | -- |
| ~Raf to Raf | Yes | dst |
| ~Raf to ~Raf | Yes | hop |
+--------------+-----------+---------------+
Table 1: IP-in-IP encapsulation in Storing mode
5.1. Example of Flow from RPL-aware-leaf to root
In storing mode, RFC 6553 (RPI) is used to send RPL Information
instanceID and rank information.
As stated in Section 16.2 of [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.
In this case the flow comprises:
RPL-aware-leaf (6LN) --> 6LR_i --> root(6LBR)
6LR_i are the intermediate routers from source to destination. In
this case, "1 <= i >= n", n is the number of routers (6LR) that the
packet go through from source (6LN) to destination (6LBR).
As it was mentioned In this document 6LRs, 6LBR are always full-
fledge RPL routers.
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.
No IP-in-IP header is required.
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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.
+-------------------+-----+-------+------+
| Header | 6LN | 6LR_i | 6LBR |
+-------------------+-----+-------+------+
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- |
| Untouched headers | -- | -- | -- |
+-------------------+-----+-------+------+
Storing: Summary of the use of headers from RPL-aware-leaf to root
5.2. Example of Flow from root to RPL-aware-leaf
In this case the flow comprises:
root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)
6LR_i are the intermediate routers from source to destination. In
this case, "1 <= i >= n", n is the number of routers (6LR) that the
packet go through from source (6LBR) to destination (6LN).
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.
No IP-in-IP header is required.
+-------------------+------+-------+------+
| Header | 6LBR | 6LR_i | 6LN |
+-------------------+------+-------+------+
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- |
| Untouched headers | -- | -- | -- |
+-------------------+------+-------+------+
Storing: Summary of the use of headers from root to RPL-aware-leaf
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5.3. Example of Flow from root to not-RPL-aware-leaf
In this case the flow comprises:
root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)
6LR_i are the intermediate routers from source to destination. In
this case, "1 <= i >= n", n is the number of routers (6LR) that the
packet go through from source (6LBR) to destination (IPv6).
As the RPI extension can be ignored by the not-RPL-aware leaf, this
situation is identical to the previous scenario.
+-------------------+------+-------+----------------+
| Header | 6LBR | 6LR_i | IPv6 |
+-------------------+------+-------+----------------+
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | -- |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- |
| Untouched headers | -- | -- | RPI (Ignored) |
+-------------------+------+-------+----------------+
Storing: Summary of the use of headers from root to not-RPL-aware-
leaf
5.4. Example of Flow from not-RPL-aware-leaf to root
In this case the flow comprises:
not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)
6LR_i are the intermediate routers from source to destination. In
this case, "1 < i >= n", n is the number of routers (6LR) that the
packet go through from source (IPv6) to destination (6LBR). For
example, 6LR_1 (i=1) is the router that receives the packets from the
IPv6 node.
When the packet arrives from IPv6 node to 6LR_1, the 6LR_1 will
insert a 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.
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+------------+------+---------------+---------------+---------------+
| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR |
+------------+------+---------------+---------------+---------------+
| Inserted | -- | IP-in-IP(RPI) | -- | -- |
| headers | | | | |
| Removed | -- | -- | -- | IP-in-IP(RPI) |
| headers | | | | |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | IP-in-IP(RPI) | -- |
| headers | | | | |
| Untouched | -- | -- | -- | -- |
| headers | | | | |
+------------+------+---------------+---------------+---------------+
Storing: Summary of the use of headers from not-RPL-aware-leaf to
root
5.5. Example of Flow from RPL-aware-leaf to Internet
RPL information from RFC 6553 MAY go out to Internet as it will be
ignored by nodes which have not been configured to be RPI aware.
In this case the flow comprises:
RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet
6LR_i are the intermediate routers from source to destination. In
this case, "1 <= i >= n", n is the number of routers (6LR) that the
packet go through from source (6LN) to 6LBR.
No IP-in-IP header is required.
Note: In this use case we use a node as leaf, but this use case can
be also applicable to any RPL-node type (e.g. 6LR)
+-------------------+------+-------+------+----------------+
| Header | 6LN | 6LR_i | 6LBR | Internet |
+-------------------+------+-------+------+----------------+
| Inserted headers | RPI | -- | -- | -- |
| Removed headers | -- | -- | -- | -- |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | RPI | -- | -- |
| Untouched headers | -- | -- | RPI | RPI (Ignored) |
+-------------------+------+-------+------+----------------+
Storing: Summary of the use of headers from RPL-aware-leaf to
Internet
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5.6. Example of Flow from Internet to RPL-aware-leaf
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)
6LR_i are the intermediate routers from source to destination. In
this case, "1 <= i >= n", n is the number of routers (6LR) that the
packet go through from 6LBR to destination(6LN).
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.
+----------+---------+--------------+---------------+---------------+
| Header | Interne | 6LBR | 6LR_i | 6LN |
| | t | | | |
+----------+---------+--------------+---------------+---------------+
| Inserted | -- | IP-in- | -- | -- |
| headers | | IP(RPI) | | |
| Removed | -- | -- | -- | IP-in-IP(RPI) |
| headers | | | | |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | IP-in-IP(RPI) | -- |
| headers | | | | |
| Untouche | -- | -- | -- | -- |
| d | | | | |
| headers | | | | |
+----------+---------+--------------+---------------+---------------+
Storing: Summary of the use of headers from Internet to RPL-aware-
leaf
5.7. Example of Flow from not-RPL-aware-leaf to Internet
In this case the flow comprises:
not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->
Internet
6LR_i are the intermediate routers from source to destination. In
this case, "1 < i >= n", n is the number of routers (6LR) that the
packet go through from source(IPv6) to 6LBR.
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The 6LR_1 (i=1) 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.
The originating node will ideally leave the IPv6 flow label as zero
so that the packet can be better compressed through the LLN. The
6LBR will set the flow label of the packet to a non-zero value when
sending to the Internet.
+---------+-----+-------------+-------------+-------------+---------+
| Header | IPv | 6LR_1 | 6LR_i | 6LBR | Interne |
| | 6 | | [i=2,..,n]_ | | t |
+---------+-----+-------------+-------------+-------------+---------+
| Inserte | -- | IP-in- | -- | -- | -- |
| d | | IP(RPI) | | | |
| headers | | | | | |
| Removed | -- | -- | -- | IP-in- | -- |
| headers | | | | IP(RPI) | |
| Re- | -- | -- | -- | -- | -- |
| added | | | | | |
| headers | | | | | |
| Modifie | -- | -- | IP-in- | -- | -- |
| d | | | IP(RPI) | | |
| headers | | | | | |
| Untouch | -- | -- | -- | -- | -- |
| ed | | | | | |
| headers | | | | | |
+---------+-----+-------------+-------------+-------------+---------+
Storing: Summary of the use of headers from not-RPL-aware-leaf to
Internet
5.8. Example of Flow from Internet to non-RPL-aware-leaf
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)
6LR_i are the intermediate routers from source to destination. In
this case, "1 < i >= n", n is the number of routers (6LR) that the
packet go through from 6LBR to not-RPL-aware-leaf (IPv6). 6LR_i
updates the rank in the RPI.
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.
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The 6LBR MAY set the flow label on the inner IP-in-IP header to zero
in order to aid in compression.
+-----------+----------+---------------+---------------+------------+
| Header | Internet | 6LBR | 6LR_i | IPv6 |
+-----------+----------+---------------+---------------+------------+
| Inserted | -- | IP-in-IP(RPI) | -- | -- |
| headers | | | | |
| Removed | -- | -- | -- | -- |
| headers | | | | |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | IP-in-IP(RPI) | -- |
| headers | | | | |
| Untouched | -- | -- | -- | RPI |
| headers | | | | (Ignored) |
+-----------+----------+---------------+---------------+------------+
Storing: Summary of the use of headers from Internet to non-RPL-
aware-leaf
5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf
In [RFC6550] RPL allows a simple one-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 [RFC6550].
In this case the flow comprises:
6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> 6LN
6LR_ia are the intermediate routers from source to the common parent
(6LR_x) In this case, "1 <= ia >= n", n is the number of routers
(6LR) that the packet go through from 6LN to the common parent
(6LR_x).
6LR_id are the intermediate routers from the common parent (6LR_x) to
destination 6LN. In this case, "1 <= id >= m", m is the number of
routers (6LR) that the packet go through from the common parent
(6LR_x) to destination 6LN.
This case is assumed in the same RPL Domain. In the common parent,
the direction of RPI is changed (from increasing to decreasing the
rank).
While the 6LR nodes will update the RPI, no node needs to add or
remove the RPI, so no IP-in-IP headers are necessary. This may be
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done regardless of where the destination is, as the included RPI will
be ignored by the receiver.
+---------------+--------+--------+---------------+--------+--------+
| Header | 6LN | 6LR_ia | 6LR_x (common | 6LR_id | 6LN |
| | src | | parent) | | dst |
+---------------+--------+--------+---------------+--------+--------+
| Inserted | RPI | -- | -- | -- | -- |
| headers | | | | | |
| Removed | -- | -- | -- | -- | RPI |
| headers | | | | | |
| Re-added | -- | -- | -- | -- | -- |
| headers | | | | | |
| Modified | -- | RPI | RPI | RPI | -- |
| headers | | | | | |
| Untouched | -- | -- | -- | -- | -- |
| headers | | | | | |
+---------------+--------+--------+---------------+--------+--------+
Storing: Summary of the use of headers for RPL-aware-leaf to RPL-
aware-leaf
5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf
In this case the flow comprises:
6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> not-RPL-aware
6LN (IPv6)
6LR_ia are the intermediate routers from source (6LN) to the common
parent (6LR_x) In this case, "1 <= ia >= n", n is the number of
routers (6LR) that the packet go through from 6LN to the common
parent (6LR_x).
6LR_id are the intermediate routers from the common parent (6LR_x) to
destination not-RPL-aware 6LN (IPv6). In this case, "1 <= id >= m",
m is the number of routers (6LR) that the packet go through from the
common parent (6LR_x) to destination 6LN.
This situation is identical to the previous situation Section 5.9
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+-----------+------+--------+---------------+--------+--------------+
| Header | 6LN | 6LR_ia | 6LR_x(common | 6LR_id | IPv6 |
| | src | | parent) | | |
+-----------+------+--------+---------------+--------+--------------+
| Inserted | RPI | -- | -- | -- | -- |
| headers | | | | | |
| Removed | -- | -- | -- | -- | RPI |
| headers | | | | | |
| Re-added | -- | -- | -- | -- | -- |
| headers | | | | | |
| Modified | -- | RPI | RPI | RPI | -- |
| headers | | | | | |
| Untouched | -- | -- | -- | -- | RPI(Ignored) |
| headers | | | | | |
+-----------+------+--------+---------------+--------+--------------+
Storing: Summary of the use of headers for RPL-aware-leaf to RPL-
aware-leaf
5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf
In this case the flow comprises:
not-RPL-aware 6LN (IPv6) --> 6LR_ia --> common parent (6LR_x) -->
6LR_id --> 6LN
6LR_ia are the intermediate routers from source (not-RPL-aware 6LN
(IPv6)) to the common parent (6LR_x) In this case, "1 <= ia >= n", n
is the number of routers (6LR) that the packet go through from source
to the common parent.
6LR_id are the intermediate routers from the common parent (6LR_x) to
destination 6LN. In this case, "1 <= id >= m", m is the number of
routers (6LR) that the packet go through from the common parent
(6LR_x) to destination 6LN.
The 6LR_ia (ia=1) 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.