[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]
Versions: (draft-robles-roll-useofrplinfo) 00
01 02 03 04 05 06 07 08 09 10 11 12
13 14 15 16 17 18 19 20 21 22 23 24
25
ROLL Working Group M. Robles
Internet-Draft Ericsson
Intended status: Informational M. Richardson
Expires: January 19, 2017 SSW
P. Thubert
Cisco
July 18, 2016
When to use RFC 6553, 6554 and IPv6-in-IPv6
draft-ietf-roll-useofrplinfo-06
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 January 19, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
Robles, et al. Expires January 19, 2017 [Page 1]
Internet-Draft Useof6553 July 2016
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 . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 9
5.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 10
5.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 11
5.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 12
5.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 12
5.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 13
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 . . . 14
5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 15
5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 16
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 . . . . . . . 20
6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 21
6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 21
6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 22
6.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 23
6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 23
6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 24
6.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 25
6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 25
6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 26
6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 27
6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 28
7. Observations about the problem . . . . . . . . . . . . . . . 28
7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 28
7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 29
8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . . 30
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
10. Security Considerations . . . . . . . . . . . . . . . . . . . 30
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
Robles, et al. Expires January 19, 2017 [Page 2]
Internet-Draft Useof6553 July 2016
12.1. Normative References . . . . . . . . . . . . . . . . . . 30
12.2. Informative References . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
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.
2. Terminology and Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Terminology defined in [RFC7102] applies to this document: LBR, LLN,
RPL, RPL Domain and ROLL.
Robles, et al. Expires January 19, 2017 [Page 3]
Internet-Draft Useof6553 July 2016
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.
Robles, et al. Expires January 19, 2017 [Page 4]
Internet-Draft Useof6553 July 2016
+--------------+
| Upper Layers |
| |
+--------------+
| RPL |
| |
+--------------+
| ICMPv6 |
| |
+--------------+
| IPv6 |
| |
+--------------+
| 6LoWPAN |
| |
+--------------+
| PHY-MAC |
| |
+--------------+
Figure 1: RPL Stack.
Robles, et al. Expires January 19, 2017 [Page 5]
Internet-Draft Useof6553 July 2016
+---------+
+---+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.
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) and (25) are routers.
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.
Robles, et al. Expires January 19, 2017 [Page 6]
Internet-Draft Useof6553 July 2016
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:
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
RPL-aware-leaf to not-RPL-aware-leaf
not-RPL-aware-leaf to RPL-aware-leaf
not-RPL-aware-leaf to not-RPL-aware-leaf
This document assumes a rule that a Header cannot be inserted or
removed on the fly inside an IPv6 packet that is being routed. A
fundamental precept of the IPv6 architecture as outlined in [RFC2460]
is that Extensions may not be added or removed except by the sender
or the receiver.
Note: current discussions on [I-D.ietf-6man-rfc2460bis] related to
extensions headers may affect some cases in this document (Ticket
nro. 9) in 6man. [TO DO].
A second important thing is that packets with a Hop-by-Hop option
which are marked with option type 01 ([RFC2460] section 4.2) must be
discarded if received by a host or router which does not understand
that option. This means that in general, any packet that leaves the
RPL domain of an LLN (or leaves the LLN entirely) is likely to be
discarded if it still contains an [RFC6553] RPL Option Header known
as the RPI.
Robles, et al. Expires January 19, 2017 [Page 7]
Internet-Draft Useof6553 July 2016
The combination of these two rules means that the arrangement of
headers must be done so that traffic intended to exit the RPL domain
can have the RPI option removed prior to leaving the RPL domain.
An intermediate router that needs to add a header must encapsulate
the packet in an (additional) outer IP header where the new header
can be placed.
This also means that a Header can only be removed by an intermediate
router if it is placed in an encapsulating IPv6 Header, and in that
case, the whole encapsulating header must be removed - a replacement
may be added. Further, an intermediate router can only remove such
an outer header if that outer header has the router as the
destination!
Both RPI and RH3 headers may be modified by routers on the path of
the packet without the need to add or 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 may not secure all the values in those headers.
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. There may be cases (such as in
6tisch) where the instanceID may still be needed to pick an
appropriate priority or channel at each hop.
The applicability for storing (RPL-SM) and non-Storing (RPL-NSM)
modes for the previous cases is showed as follows:
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 consise.
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
Robles, et al. Expires January 19, 2017 [Page 8]
Internet-Draft Useof6553 July 2016
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 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.
The leaf can be a router 6LR or a host, both indicated as 6LN.
+--------------+-------+-------+-----------+---------------+
| Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst |
+--------------+-------+-------+-----------+---------------+
| Raf to root | Yes | No | No | -- |
| root to Raf | Yes | No | No | -- |
| root to ~Raf | Yes | No | Yes | hop |
| ~Raf to root | Yes | No | Yes | root |
| Raf to Int | Yes | No | Yes | root |
| Int to Raf | Yes | No | Yes | raf |
| ~Raf to Int | Yes | No | Yes | root |
| Int to ~Raf | Yes | No | Yes | hop |
| Raf to Raf | Yes | No | No | -- |
| Raf to ~Raf | Yes | No | Yes | hop |
| ~Raf to Raf | Yes | No | Yes | dst |
| ~Raf to ~Raf | Yes | No | Yes | hop |
+--------------+-------+-------+-----------+---------------+
Table 1: Headers needed in Storing mode: RPI, RH3, IP-in-IP
encapsulation
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 storing mode, RFC 6553 (RPI) is used to send RPL Information
instanceID and rank information.
Robles, et al. Expires January 19, 2017 [Page 9]
Internet-Draft Useof6553 July 2016
In this case the flow comprises:
RPL-aware-leaf (6LN) --> 6LR --> 6LR,... --> root (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.
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 | 6LBR |
+-------------------+-----+------+------+
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- |
| Untouched headers | -- | -- | -- |
+-------------------+-----+------+------+
Storing: Summary of the use of headers from RPL-aware-leaf to root
5.2. Example of Flow from root to RPL-aware-leaf
In this case the flow comprises:
root (6LBR)--> 6LR --> RPL-aware-leaf (6LN)
In this case the 6LBR 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.
Robles, et al. Expires January 19, 2017 [Page 10]
Internet-Draft Useof6553 July 2016
+-------------------+------+-------+------+
| Header | 6LBR | 6LR | 6LN |
+-------------------+------+-------+------+
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RPI | -- |
| Untouched headers | -- | -- | -- |
+-------------------+------+-------+------+
Storing: Summary of the use of headers from root to RPL-aware-leaf
5.3. Example of Flow from root to not-RPL-aware-leaf
In this case the flow comprises:
root (6LBR)--> 6LR --> not-RPL-aware-leaf (6LN)
The question in this scenario is how the root knows how to address
the IPv6-in-IPv6 header. It can not know that the destination isn't
RPL aware, so it must insert an IPv6 header that can be removed on
the last RPL aware node. Since the root can not know in a storing
network where the last RPL aware node is, the IPv6-in-IPv6 header
must be added hop-by-hop along the path from root to leaf.
The root (6LBR) uses 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 it passes the packet to the IPv6
node (6LN).
An alternative option is to add an attribute in the RPL Target Option
to indicate that the target is not RPL aware: future work may explore
this possibility.
+-------------------+---------------+---------------+------+
| Header | 6LBR | 6LR | IPv6 |
+-------------------+---------------+---------------+------+
| Inserted headers | IP-in-IP(RPI) | -- | -- |
| Removed headers | -- | IP-in-IP(RPI) | -- |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | -- | -- |
| Untouched headers | -- | -- | -- |
+-------------------+---------------+---------------+------+
Storing: Summary of the use of headers from root to not-RPL-aware-
leaf
Robles, et al. Expires January 19, 2017 [Page 11]
Internet-Draft Useof6553 July 2016
5.4. Example of Flow from not-RPL-aware-leaf to root
In this case the flow comprises:
not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR)
When the packet arrives from IPv6 node to 6LR, the 6LR will insert an
RPI header, encapsuladed in a IPv6-in-IPv6 header. The IPv6-in-IPv6
header can be addressed to the next hop, or to the root. The root
removes the header and processes the packet.
+-------------------+------+----------------+---------------+
| Header | IPv6 | 6LR | 6LBR |
+-------------------+------+----------------+---------------+
| Inserted headers | -- | IP-in-IP(RPI) | -- |
| Removed headers | -- | -- | IP-in-IP(RPI) |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | -- | -- |
| Untouched headers | -- | -- | -- |
+-------------------+------+----------------+---------------+
Storing: Summary of the use of headers from not-RPL-aware-leaf to
root
5.5. Example of Flow from RPL-aware-leaf to Internet
RPL information from RFC 6553 should not go out to Internet as it
will cause the packet to be discarded at the first non-RPI aware
router. The 6LBR must be able to take this information out before
sending the packet upwards to the Internet. This requires the RPI
header be placed in an IP-in-IP header that the root can remove.
In this case the flow comprises:
RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet
The 6LN will insert the RPI in a IPv6-in-IPv6 in a outer header,
which may be addressed to the 6LBR (root), or alternatively, it could
be addressed hop-by-hop.
Robles, et al. Expires January 19, 2017 [Page 12]
Internet-Draft Useof6553 July 2016
+-----------------+---------------+------+---------------+----------+
| Header | 6LN | 6LR | 6LBR | Internet |
+-----------------+---------------+------+---------------+----------+
| Inserted | IP-in-IP(RPI) | -- | -- | -- |
| headers | | | | |
| Removed headers | -- | -- | IP-in-IP(RPI) | -- |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | RPI | -- | -- |
| headers | | | | |
| Untouched | -- | -- | -- | -- |
| headers | | | | |
+-----------------+---------------+------+---------------+----------+
Storing: Summary of the use of headers from RPL-aware-leaf to
Internet
5.6. Example of Flow from Internet to RPL-aware-leaf
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN)
When the packet arrives from Internet to 6LBR the RPI header is added
in a outer IPv6-in-IPv6 header and 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 | Internet | 6LBR | 6LR | 6LN |
+-----------------+----------+---------------+------+---------------+
| Inserted | -- | IP-in-IP(RPI) | -- | -- |
| headers | | | | |
| Removed headers | -- | -- | -- | IP-in-IP(RPI) |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | RPI | -- |
| headers | | | | |
| Untouched | -- | -- | -- | -- |
| headers | | | | |
+-----------------+----------+---------------+------+---------------+
Storing: Summary of the use of headers from Internet to RPL-aware-
leaf
Robles, et al. Expires January 19, 2017 [Page 13]
Internet-Draft Useof6553 July 2016
5.7. Example of Flow from not-RPL-aware-leaf to Internet
In this case the flow comprises:
not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet
The 6LR 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 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.
+-----------------+------+---------------+---------------+----------+
| Header | 6LN | 6LR | 6LBR | Internet |
+-----------------+------+---------------+---------------+----------+
| Inserted | -- | IP-in-IP(RPI) | -- | -- |
| headers | | | | |
| Removed headers | -- | -- | IP-in-IP(RPI) | -- |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | -- | -- |
| headers | | | | |
| Untouched | -- | -- | -- | -- |
| headers | | | | |
+-----------------+------+---------------+---------------+----------+
Storing: Summary of the use of headers from not-RPL-aware-leaf to
Internet
5.8. Example of Flow from Internet to non-RPL-aware-leaf
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN)
The 6LBR will have to add an RPI header within an IP-in-IP header.
The IP-in-IP will need to be addressed hop-by-hop along the path as
in storing mode, the 6LBR has no idea if the 6LN is RPL aware or not,
nor what the closest attached 6LR node is.
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.
Robles, et al. Expires January 19, 2017 [Page 14]
Internet-Draft Useof6553 July 2016
+-----------------+----------+---------------+---------------+------+
| Header | Internet | 6LBR | 6LR | IPv6 |
+-----------------+----------+---------------+---------------+------+
| Inserted | -- | IP-in-IP(RPI) | -- | -- |
| headers | | | | |
| Removed headers | -- | -- | IP-in-IP(RPI) | -- |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | -- | -- |
| headers | | | | |
| Untouched | -- | -- | -- | -- |
| headers | | | | |
+-----------------+----------+---------------+---------------+------+
Storing: Summary of the use of headers from Internet to non-RPL-
aware-leaf
5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf
In [RFC6550] RPL allows a simple one-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 --> common parent (6LR) --> 6LR --> 6LN
This case is assumed in the same RPL Domain. In the common parent,
the direction of RPI is changed (from increasing to decreasing the
rank).
While the 6LR nodes will update the RPI, no node needs to add or
remove the RPI, so no IP-in-IP headers are necessary. The ability to
do this depends upon the sending the 6LN to know that the destination
is: a) inside the LLN, and b) RPL capable.
The sender can determine if the destination is inside the LLN by
looking if the destination address is matched by the DIO's PIO
option. This check may be modified by the use of backbone routers,
but in this case it is assumed that the backbone routers are RPL
capable and so can process the RPI header correctly.
The other check, that the destination is RPL capable is not currently
discernible by the sender. This information is necessary to
distinguish this test case from Section 5.10.
Robles, et al. Expires January 19, 2017 [Page 15]
Internet-Draft Useof6553 July 2016
+-------------+-------+---------------+---------------+-----+-------+
| Header | 6LN | 6LR | 6LR (common | 6LR | 6LN |
| | src | | parent) | | dst |
+-------------+-------+---------------+---------------+-----+-------+
| Inserted | RPI | -- | -- | -- | -- |
| headers | | | | | |
| Removed | -- | -- | -- | -- | RPI |
| headers | | | | | |
| Re-added | -- | -- | -- | -- | -- |
| headers | | | | | |
| Modified | -- | RPI | RPI | -- | -- |
| headers | | (decreasing | (increasing | | |
| | | rank) | rank) | | |
| Untouched | -- | -- | -- | -- | -- |
| headers | | | | | |
+-------------+-------+---------------+---------------+-----+-------+
Storing: Summary of the use of headers for RPL-aware-leaf to RPL-
aware-leaf
5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf
In this case the flow comprises:
6LN --> 6LR --> common parent (6LR) --> 6LR --> not-RPL-aware 6LN
The sender, being aware out of band, that the receiver is not RPL
aware, adds an RPI header inside 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.
Robles, et al. Expires January 19, 2017 [Page 16]
Internet-Draft Useof6553 July 2016
,---.
/ \
( 6LR2 ) IP3,RPI,IP,ULP
,-" .
,-" `---' `.
,' `.
,---. ,-" `,---.
/ +" / \
( 6LR1 ) Remove the IP3,RPI( 6LR3 )
\ / \ /
/---' `---'|
/ IP2,RPI,IP,ULP \
/ |
/ \
,---+-. |
/ \ +--+----+
( 6LN ) | |
\ / | IPv6 | IP,ULP
`-----' | |
IP1,RPI,IP,ULP +-------+
Figure 3: Solution IPv6-in-IPv6 in each hop
As we mentioned previously, packets with a Hop-by-Hop option which
are marked with option type 01 ([RFC2460] section 4.2) must be
discarded if received by a host or router which does not understand
that option. This means that in general, any packet that leaves the
RPL domain of an LLN (or leaves the LLN entirely) is likely to be
discarded if it still contains an [RFC6553] RPL Option Header known
as the RPI. For this case, if the definition of the Option Type
field of RPL Option '01' were changed so that it isn't a "discard if
not recognized", then no IP-in-IP header would be necessary. This
change is an incompatible on-the-wire change and would require some
kind of flag day, possibly a change that is done simultaenously with
an updated 6LoRH compress.
Robles, et al. Expires January 19, 2017 [Page 17]
Internet-Draft Useof6553 July 2016
+--------+------------+------------+------------+------------+------+
| Header | 6LN | 6LR | 6LR | 6LR | IPv6 |
| | | | (common | | |
| | | | parent) | | |
+--------+------------+------------+------------+------------+------+
| Insert | IP-in- | -- | -- | -- | -- |
| ed hea | IP(RPI) | | | | |
| ders | | | | | |
| Remove | -- | -- | -- | IP-in- | -- |
| d head | | | | IP(RPI) | |
| ers | | | | | |
| Re- | -- | -- | -- | -- | -- |
| added | | | | | |
| header | | | | | |
| s | | | | | |
| Modifi | -- | IP-in- | IP-in- | -- | -- |
| ed hea | | IP(RPI) | IP(RPI) | | |
| ders | | | | | |
| Untouc | -- | -- | -- | -- | -- |
| hed he | | | | | |
| aders | | | | | |
+--------+------------+------------+------------+------------+------+
Storing: Summary of the use of headers from RPL-aware-leaf to not-
RPL-aware-leaf
5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf
In this case the flow comprises:
not-RPL-aware 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN
The 6LR 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 could be addressed to the 6LN if the destination is known to
the RPL aware, otherwise it must send the packet using a hop-by-hop
IP-in-IP header. Similar considerations apply from section
Section 5.10.
Robles, et al. Expires January 19, 2017 [Page 18]
Internet-Draft Useof6553 July 2016
+--------+------+------------+------------+------------+------------+
| Header | IPv6 | 6LR | common | 6LR | 6LN |
| | | | parent | | |
| | | | (6LR) | | |
+--------+------+------------+------------+------------+------------+
| Insert | -- | IP-in- | -- | -- | -- |
| ed hea | | IP(RPI) | | | |
| ders | | | | | |
| Remove | -- | -- | -- | -- | IP-in- |
| d head | | | | | IP(RPI) |
| ers | | | | | |
| Re- | -- | -- | -- | -- | -- |
| added | | | | | |
| header | | | | | |
| s | | | | | |
| Modifi | -- | -- | IP-in- | IP-in- | -- |
| ed hea | | | IP(RPI) | IP(RPI) | |
| ders | | | | | |
| Untouc | -- | -- | -- | -- | -- |
| hed he | | | | | |
| aders | | | | | |
+--------+------+------------+------------+------------+------------+
Storing: Summary of the use of headers from not-RPL-aware-leaf to
RPL-aware-leaf
5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf
In this case the flow comprises:
not-RPL-aware 6LN (IPv6 node)--> 6LR --> root (6LBR) --> 6LR --> not-
RPL-aware 6LN (IPv6 node)
This flow combines the problems of the two previous sections. There
is no choice at the first 6LR: it must insert an RPI, and to do that
it must add an IP-in-IP header. That IP-in-IP header must be
addressed on a hop-by-hop basis.
Robles, et al. Expires January 19, 2017 [Page 19]
Internet-Draft Useof6553 July 2016
+----------+-----+-------------+--------------+--------------+------+
| Header | IPv | 6LR | 6LR (common | 6LR | IPv6 |
| | 6 | | parent) | | dst |
| | src | | | | |
+----------+-----+-------------+--------------+--------------+------+
| Inserted | -- | IP-in- | -- | -- | -- |
| headers | | IP(RPI) | | | |
| Removed | -- | -- | -- | IP-in- | -- |
| headers | | | | IP(RPI) | |
| Re-added | -- | IP-in- | IP-in- | IP-in- | -- |
| headers | | IP(RPI) | IP(RPI) | IP(RPI) | |
| Modified | -- | -- | -- | -- | -- |
| headers | | | | | |
| Untouche | -- | -- | -- | -- | -- |
| d | | | | | |
| headers | | | | | |
+----------+-----+-------------+--------------+--------------+------+
Storing: Summary of the use of headers from not-RPL-aware-leaf to
not-RPL-aware-leaf
6. Non Storing mode
+--------------+------+------+-----------+---------------+
| Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst |
+--------------+------+------+-----------+---------------+
| Raf to root | Yes | No | No | -- |
| root to Raf | Yes | Yes | No | -- |
| root to ~Raf | No | Yes | Yes | 6LR |
| ~Raf to root | Yes | No | Yes | root |
| Raf to Int | Yes | No | Yes | root |
| Int to Raf | opt | Yes | Yes | dst |
| ~Raf to Int | Yes | No | Yes | root |
| Int to ~Raf | opt | Yes | Yes | 6LR |
| Raf to Raf | Yes | Yes | Yes | root/dst |
| Raf to ~Raf | Yes | Yes | Yes | root/6LR |
| ~Raf to Raf | Yes | Yes | Yes | root/6LN |
| ~Raf to ~Raf | Yes | Yes | Yes | root/6LR |
+--------------+------+------+-----------+---------------+
Table 2: Headers needed in Non-Storing mode: RPI, RH3, IP-in-IP
encapsulation
6.1. Example of Flow from RPL-aware-leaf to root
In non-storing mode the leaf node uses default routing to send
traffic to the root. The RPI header must be included to avoid/detect
loops.
Robles, et al. Expires January 19, 2017 [Page 20]
Internet-Draft Useof6553 July 2016
RPL-aware-leaf (6LN) --> 6LR --> root (6LBR)
This situation is the same case as storing mode.
+-------------------+-----+------+------+
| Header | 6LN | 6LR | 6LBR |
+-------------------+-----+------+------+
| Inserted headers | RPI | -- | -- |
| Removed headers | -- | -- | RPI |
| Re-added headers | -- | RPI | -- |
| Modified headers | -- | -- | -- |
| Untouched headers | -- | -- | -- |
+-------------------+-----+------+------+
Non Storing: Summary of the use of headers from RPL-aware-leaf to
root
6.2. Example of Flow from root to RPL-aware-leaf
In this case the flow comprises:
root (6LBR)--> 6LR --> RPL-aware-leaf (6LN)
The 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 6LBR because, the
root knows the whole topology in non-storing mode.
+-------------------+-----------------+------+----------+
| Header | 6LBR | 6LR | 6LN |
+-------------------+-----------------+------+----------+
| Inserted headers | (opt: RPI), RH3 | -- | -- |
| Removed headers | -- | -- | RH3,RPI |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RH3 | -- |
| Untouched headers | -- | -- | -- |
+-------------------+-----------------+------+----------+
Non Storing: Summary of the use of headers from root to RPL-aware-
leaf
6.3. Example of Flow from root to not-RPL-aware-leaf
In this case the flow comprises:
root (6LBR)--> 6LR --> not-RPL-aware-leaf (IPv6 node)
Robles, et al. Expires January 19, 2017 [Page 21]
Internet-Draft Useof6553 July 2016
In 6LBR the RH3 is added, modified in each intermediate 6LR and it is
fully consumed in the last 6LR, but left there. If the RPI is left
present, the IPv6 node which does not understand it will drop it,
therefore the RPI should be removed before reaching the IPv6-only
node. To permit removal, an IP-in-IP header (hop-by-hop) or
addressed to the last 6LR is necessary. 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.
Omitting the RPI entirely is therefore a better solution, as no IP-
in-IP header is necessary.
+-------------------+------+-----+------+
| Header | 6LBR | 6LR | IPv6 |
+-------------------+------+-----+------+
| Inserted headers | RH3 | -- | -- |
| Removed headers | -- | -- | -- |
| Re-added headers | -- | -- | -- |
| Modified headers | -- | RH3 | -- |
| Untouched headers | -- | -- | -- |
+-------------------+------+-----+------+
Non Storing: Summary of the use of headers from root to not-RPL-
aware-leaf
6.4. Example of Flow from not-RPL-aware-leaf to root
In this case the flow comprises:
IPv6-node --> 6LR1 --> 6LR2 --> root (6LBR)
In this case the RPI is added by the first 6LR, encapsulated in an
IP-in-IP header, and is not modified in the followings 6LRs. The RPI
and entire packet is consumed by the root.
+-------------------+------+----------------+------+----------------+
| Header | IPv6 | 6LR1 | 6LR2 | 6LBR |
+-------------------+------+----------------+------+----------------+
| Inserted headers | -- | IP-in-IP(RPI) | -- | -- |
| Removed headers | -- | -- | -- | IP-in-IP(RPI) |
| Re-added headers | -- | -- | -- | -- |
| Modified headers | -- | -- | -- | -- |
| Untouched headers | -- | IP-in-IP(RPI) | -- | -- |
+-------------------+------+----------------+------+----------------+
Non Storing: Summary of the use of headers from not-RPL-aware-leaf to
root
Robles, et al. Expires January 19, 2017 [Page 22]
Internet-Draft Useof6553 July 2016
6.5. Example of Flow from RPL-aware-leaf to Internet
In this case the flow comprises:
RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet
This case requires that the RPI be added, but removed by the 6LBR.
The 6LN must therefore add the RPI inside an IP-in-IP header,
addressed to the root. This case is identical to storing-mode case.
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.
+-----------------+---------------+------+---------------+----------+
| Header | 6LN | 6LR | 6LBR | Internet |
+-----------------+---------------+------+---------------+----------+
| Inserted | IP-in-IP(RPI) | -- | -- | -- |
| headers | | | | |
| Removed headers | -- | -- | IP-in-IP(RPI) | -- |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | -- | -- |
| headers | | | | |
| Untouched | -- | RPI | -- | -- |
| headers | | | | |
+-----------------+---------------+------+---------------+----------+
Non Storing: Summary of the use of headers from RPL-aware-leaf to
Internet
6.6. Example of Flow from Internet to RPL-aware-leaf
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN)
The 6LBR must add an RH3 header. As the 6LBR will know the path and
address of the target not, 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.
The RPI may be added or not.
Robles, et al. Expires January 19, 2017 [Page 23]
Internet-Draft Useof6553 July 2016
+----------+----------+-----------------------+---------------+-----+
| Header | Internet | 6LBR | 6LR | 6LN |
+----------+----------+-----------------------+---------------+-----+
| Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- |
| headers | | | | |
| Removed | -- | -- | IP-in-IP(RH3) | -- |
| headers | | | | |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | IP-in-IP(RH3) | -- |
| headers | | | | |
| Untouche | -- | -- | -- | -- |
| d | | | | |
| headers | | | | |
+----------+----------+-----------------------+---------------+-----+
Non Storing: Summary of the use of headers from Internet to RPL-
aware-leaf
6.7. Example of Flow from not-RPL-aware-leaf to Internet
In this case the flow comprises:
not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet
In this case the flow label is recommended to be zero in the IPv6
node. 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).
+-----------------+------+---------------+---------------+----------+
| Header | IPv6 | 6LR | 6LBR | Internet |
+-----------------+------+---------------+---------------+----------+
| Inserted | -- | IP-in-IP(RPI) | -- | -- |
| headers | | | | |
| Removed headers | -- | -- | IP-in-IP(RPI) | -- |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | -- | -- |
| headers | | | | |
| Untouched | -- | -- | -- | -- |
| headers | | | | |
+-----------------+------+---------------+---------------+----------+
Non Storing: Summary of the use of headers from not-RPL-aware-leaf to
Internet
Robles, et al. Expires January 19, 2017 [Page 24]
Internet-Draft Useof6553 July 2016
6.8. Example of Flow from Internet to non-RPL-aware-leaf
In this case the flow comprises:
Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (IPv6 node)
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.
+----------+---------+-----------------------+---------------+------+
| Header | Interne | 6LBR | 6LR | IPv6 |
| | t | | | |
+----------+---------+-----------------------+---------------+------+
| Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- |
| headers | | | | |
| Removed | -- | -- | IP-in-IP(RH3, | -- |
| headers | | | RPI) | |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | -- | -- |
| headers | | | | |
| Untouche | -- | -- | -- | -- |
| d | | | | |
| headers | | | | |
+----------+---------+-----------------------+---------------+------+
NonStoring: Summary of the use of headers from Internet to non-RPL-
aware-leaf
6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf
In this case the flow comprises:
6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN
This 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.
The originating node could put the RPI into an IP-in-IP header
addressed to the root, so that the 6LBR can remove that header.
The 6LBR will need to insert an RH3 header, which requires that it
add an IP-in-IP header. It may be able to remove the RPI if it was
Robles, et al. Expires January 19, 2017 [Page 25]
Internet-Draft Useof6553 July 2016
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.
Networks that use the RPL P2P extension [RFC6997] are essentially
non-storing DODAGs and fall into this scenario.
+----------+---------------+--------------+-----+-------------------+
| Header | 6LN src | 6LBR | 6LR | 6LN dst |
+----------+---------------+--------------+-----+-------------------+
| Inserted | IP-in-IP(RPI) | IP-in-IP(RH3 | -- | -- |
| headers | | to 6LN,RPI) | | |
| Removed | -- | -- | -- | IP-in-IP(RH3,RPI) |
| headers | | | | |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | -- | -- |
| headers | | | | |
| Untouche | -- | -- | -- | -- |
| d | | | | |
| headers | | | | |
+----------+---------------+--------------+-----+-------------------+
Non Storing: Summary of the use of headers for RPL-aware-leaf to RPL-
aware-leaf
6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf
In this case the flow comprises:
6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware (IPv6 node)
As in the previous case, the 6LN will insert an RPI 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 above the destination node.
Robles, et al. Expires January 19, 2017 [Page 26]
Internet-Draft Useof6553 July 2016
+-----------+---------------+---------------+----------------+------+
| Header | 6LN | 6LBR | 6LR | IPv6 |
+-----------+---------------+---------------+----------------+------+
| Inserted | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | -- |
| headers | | opt RPI) | | |
| Removed | -- | IP-in-IP(RPI) | IP-in-IP(RH3, | -- |
| headers | | | opt RPI) | |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | -- | -- |
| headers | | | | |
| Untouched | -- | -- | -- | -- |
| headers | | | | |
+-----------+---------------+---------------+----------------+------+
Non Storing: Summary of the use of headers from RPL-aware-leaf to
not-RPL-aware-leaf
6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf
In this case the flow comprises:
not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN
This scenario is mostly identical to the previous one. The RPI is
added by the first 6LR 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.
+------------+------+---------------+---------------+---------------+
| Header | IPv6 | 6LR | 6LBR | 6LN |
+------------+------+---------------+---------------+---------------+
| Inserted | -- | IP-in-IP(RPI) | IP-in-IP(RH3) | -- |
| headers | | | | |
| Removed | -- | IP-in-IP(RPI) | -- | IP-in-IP(RH3) |
| headers | | | | |
| Re-added | -- | -- | -- | -- |
| headers | | | | |
| Modified | -- | -- | -- | -- |
| headers | | | | |
| Untouched | -- | -- | -- | -- |
| headers | | | | |
+------------+------+---------------+---------------+---------------+
Non Storing: Summary of the use of headers from not-RPL-aware-leaf to
RPL-aware-leaf
Robles, et al. Expires January 19, 2017 [Page 27]
Internet-Draft Useof6553 July 2016
6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf
In this case the flow comprises:
not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware
(IPv6 node)
This scenario is the combination of the previous two cases.
+----------+-----+-------------+--------------+--------------+------+
| Header | IPv | 6LR | 6LBR | 6LR | IPv6 |
| | 6 | | | | |
+----------+-----+-------------+--------------+--------------+------+
| Inserted | -- | IP-in- | IP-in- | -- | -- |
| headers | | IP(RPI) | IP(RH3) | | |
| Removed | -- | -- | IP-in- | IP-in- | -- |
| headers | | | IP(RPI) | IP(RH3, opt | |
| | | | | RPI) | |
| Re-added | -- | -- | -- | -- | -- |
| headers | | | | | |
| Modified | -- | -- | -- | -- | -- |
| headers | | | | | |
| Untouche | -- | -- | -- | -- | -- |
| d | | | | | |
| headers | | | | | |
+----------+-----+-------------+--------------+--------------+------+
Non Storing: Summary of the use of headers from not-RPL-aware-leaf to
not-RPL-aware-leaf
7. Observations about the problem
7.1. Storing mode
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 Table 1
The simplest fully general approach for storing mode is to always put
in hop-by-hop IP-in-IP headers. [I-D.ietf-roll-routing-dispatch]
shows that this hop-by-hop IP-in-IP header can be compressed down to
{TBD} bytes.
There are potential significant advantages to having a single code
path that always processes IP-in-IP headers with no options.
Robles, et al. Expires January 19, 2017 [Page 28]
Internet-Draft Useof6553 July 2016
If all RPL aware nodes can be told/configured that there are no non-
RPL aware leaf nodes, then the only case where an IP-in-IP header is
needed is when communicating outside the LLN. The 6LBR knows well
when the communication is from the outside, and the 6LN can tell by
comparing the destination address to the prefix provided in the PIO.
If it is known that there are no communications outside the RPL
domain (noting that the RPL domain may well extend to outside the
LLN), then RPI headers can be included in all packets, and IP-in-IP
headers are *never* needed. This may be significantly advantageous
in relatively closed systems such as in building or industrial
automation. Again, there are advantages to having a single code
path.
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.
7.2. Non-Storing mode
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.
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.
It is unclear what it would mean for an RH3 header to be present in a
hop-by-hop IP-in-IP header. The receiving node ought to consume the
IP-in-IP header, and therefore consume the RH3 as well, and then
attempt to send the packet again. But intermediate 6LN nodes would
not know how to forward the packet (because they do not save the
sate), so the RH3 would need to be retained. This is a new kind of
IPv6 packet processing. Therefore it may be that on the outbound leg
of non-storing RPL networks, that hop-by-hop IP-in-IP header can NOT
be used.
[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.
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.
Robles, et al. Expires January 19, 2017 [Page 29]
Internet-Draft Useof6553 July 2016
8. 6LoRH Compression cases
The [I-D.ietf-roll-routing-dispatch] proposes a compression method
for RPI, RH3 and IPv6-in-IPv6.
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.
+--+-----+---+--------------+-----------+-------------+-------------+
|1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI - 6LoRH | LOWPAN IPHC |
+--+-----+---+--------------+-----------+-------------+-------------+
Figure 4: Critical IP-in-IP (RPI).
9. IANA Considerations
There are no IANA considerations related to this document.
10. Security Considerations
The security considerations covering of [RFC6553] and [RFC6554] apply
when the packets get into RPL Domain.
11. Acknowledgments
This work is partially funded by the FP7 Marie Curie Initial Training
Network (ITN) METRICS project (grant agreement No. 607728).
The authors would like to acknowledge the review, feedback, and
comments of Robert Cragie, Simon Duquennoy, Cenk Guendogan, Peter van
der Stok, Xavier Vilajosana and Thomas Watteyne.
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
Robles, et al. Expires January 19, 2017 [Page 30]
Internet-Draft Useof6553 July 2016
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012,
<http://www.rfc-editor.org/info/rfc6550>.
[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
Power and Lossy Networks (RPL) Option for Carrying RPL
Information in Data-Plane Datagrams", RFC 6553,
DOI 10.17487/RFC6553, March 2012,
<http://www.rfc-editor.org/info/rfc6553>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554,
DOI 10.17487/RFC6554, March 2012,
<http://www.rfc-editor.org/info/rfc6554>.
12.2. Informative References
[I-D.ietf-6man-rfc2460bis]
Deering, D. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", draft-ietf-6man-rfc2460bis-05 (work
in progress), June 2016.
[I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-10 (work
in progress), June 2016.
[I-D.ietf-roll-routing-dispatch]
Thubert, P., Bormann, C., Toutain, L., and R. Cragie,
"6LoWPAN Routing Header", draft-ietf-roll-routing-
dispatch-00 (work in progress), March 2016.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", RFC 4443,
DOI 10.17487/RFC4443, March 2006,
<http://www.rfc-editor.org/info/rfc4443>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<http://www.rfc-editor.org/info/rfc6775>.
Robles, et al. Expires January 19, 2017 [Page 31]
Internet-Draft Useof6553 July 2016
[RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and
J. Martocci, "Reactive Discovery of Point-to-Point Routes
in Low-Power and Lossy Networks", RFC 6997,
DOI 10.17487/RFC6997, August 2013,
<http://www.rfc-editor.org/info/rfc6997>.
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
2014, <http://www.rfc-editor.org/info/rfc7102>.
[Second6TischPlugtest]
"2nd 6Tisch Plugtest", <http://www.ietf.org/mail-
archive/web/6tisch/current/pdfgDMQcdCkRz.pdf>.
Authors' Addresses
Maria Ines Robles
Ericsson
Hirsalantie 11
Jorvas 02420
Finland
Email: maria.ines.robles@ericsson.com
Michael C. Richardson
Sandelman Software Works
470 Dawson Avenue
Ottawa, ON K1Z 5V7
CA
Email: mcr+ietf@sandelman.ca
URI: http://www.sandelman.ca/
Pascal Thubert
Cisco Systems, Inc
Village d'Entreprises Green Side 400, Avenue de Roumanille
Batiment T3, Biot - Sophia Antipolis 06410
France
Email: pthubert@cisco.com
Robles, et al. Expires January 19, 2017 [Page 32]
Html markup produced by rfcmarkup 1.129b, available from
https://tools.ietf.org/tools/rfcmarkup/