forked from roll-wg/useofrplinfo
-
Notifications
You must be signed in to change notification settings - Fork 0
/
roll-useofrplinfo-05.txt
1736 lines (1169 loc) · 71.1 KB
/
roll-useofrplinfo-05.txt
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
ROLL Working Group M. Robles
Internet-Draft Ericsson
Intended status: Informational M. Richardson
Expires: December 2, 2016 SSW
P. Thubert
Cisco
May 31, 2016
When to use RFC 6553, 6554 and IPv6-in-IPv6
draft-ietf-roll-useofrplinfo-05
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 December 2, 2016.
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 December 2, 2016 [Page 1]
Internet-Draft Useof6553 May 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
3. Sample/reference topology . . . . . . . . . . . . . . . . . . 4
4. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6
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 . . . . . 10
5.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 11
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 . . . 13
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 17
5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 19
6.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 19
6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 20
6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 20
6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 21
6.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 22
6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 22
6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 23
6.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 24
6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 24
6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 25
6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 26
6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7. Observations about the problem . . . . . . . . . . . . . . . 27
7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 27
7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 28
8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . . 29
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
10. Security Considerations . . . . . . . . . . . . . . . . . . . 29
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 29
12.1. Normative References . . . . . . . . . . . . . . . . . . 29
Robles, et al. Expires December 2, 2016 [Page 2]
Internet-Draft Useof6553 May 2016
12.2. Informative References . . . . . . . . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
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) and an
efficient IP-in-IP technique. Uses 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 December 2, 2016 [Page 3]
Internet-Draft Useof6553 May 2016
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.
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.
+--------------+
| Upper Layers |
| |
+--------------+
| RPL |
| |
+--------------+
| ICMPv6 |
| |
+--------------+
| IPv6 |
| |
+--------------+
| 6LoWPAN |
| |
+--------------+
| PHY-MAC |
| |
+--------------+
Figure 1: RPL Stack.
Robles, et al. Expires December 2, 2016 [Page 4]
Internet-Draft Useof6553 May 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.
The numbers in or above the nodes are there so that they may be
referenced in subsequent sections. In the figure 2, 6LN can be a
router or a host. The 6LN leaf 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 mentioned as well as 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. This architecture is used for the
remainder of this document.
The scope of the 6TiSCH (IPv6 over the TSCH mode of IEEE 802.15.4e)
Architecture is a Backbone Link that federates multiple LLNs (mesh)
as a single IPv6 Multi-Link Subnet. Each LLN in the subnet is
anchored at a Backbone Router (6BBR). The Backbone Routers
Robles, et al. Expires December 2, 2016 [Page 5]
Internet-Draft Useof6553 May 2016
interconnect the LLNs over the Backbone Link and emulate that the LLN
nodes are present on the Backbone thus creating a so-called: Multi-
Link Subnet. An LLN node can move freely from an LLN anchored at a
Backbone Router to another LLN anchored at the same or a different
Backbone Router inside the Multi-Link Subnet and conserve its
addresses.
+---------+
+---+Internet |
| +---------+
|
|
+-----+
| | Border Router to the RPL domain
| | (may be a RPL virtual root)
+-----+
|
| Backbone
+-------------------+-------------------+
| | |
+-----+ +-----+ +-----+
| | Backbone | | Backbone | | Backbone
| | router | | router | | router
+|---|+ +-|||-+ +-[_]-+
| | PCI-exp / | \ USB | Ethernet
( ) ( ) ( )( )( ) (6LBR == RPL DODAG root)
o o o o o o o o o o o o
o o o o o o o o o o o o o o o o
o o o o o o o o o o 6LR == RPL router) o o
o o o o o o o z
o o o o o o (6LoWPAN Host)
<----------------------- RPL Instances ------------------------>
Figure 3: RPL domain architecture
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
Robles, et al. Expires December 2, 2016 [Page 6]
Internet-Draft Useof6553 May 2016
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. This
is 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.
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.
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!
Robles, et al. Expires December 2, 2016 [Page 7]
Internet-Draft Useof6553 May 2016
Both RPI and RH3 headers may be modified 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 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 tables, 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 complete to make sure that the process
is clear, while later examples are more consise.
5. Storing mode
This table summarizes what headers are needed in the following
scenarios, and indicates 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 indicated as 6LN.
Robles, et al. Expires December 2, 2016 [Page 8]
Internet-Draft Useof6553 May 2016
+--------------+-------+-------+-----------+---------------+
| 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.
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, and are the RPL root node.
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
Robles, et al. Expires December 2, 2016 [Page 9]
Internet-Draft Useof6553 May 2016
with the 6LBR in order to be able 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 insert RPI header and send the packet down, the
6LR is going to increment the rank in RPI (examines instanceID for
multiple tables), the packet is processed in 6LN and RPI removed.
No IP-in-IP header is required.
+-------------------+------+-------+------+
| 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
Robles, et al. Expires December 2, 2016 [Page 10]
Internet-Draft Useof6553 May 2016
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
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.
Robles, et al. Expires December 2, 2016 [Page 11]
Internet-Draft Useof6553 May 2016
+-------------------+------+----------------+---------------+
| 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.
+-----------------+---------------+------+---------------+----------+
| 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
Robles, et al. Expires December 2, 2016 [Page 12]
Internet-Draft Useof6553 May 2016
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
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.
Robles, et al. Expires December 2, 2016 [Page 13]
Internet-Draft Useof6553 May 2016
+-----------------+------+---------------+---------------+----------+
| 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.
+-----------------+----------+---------------+---------------+------+
| 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
Robles, et al. Expires December 2, 2016 [Page 14]
Internet-Draft Useof6553 May 2016
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 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.
+-------------+-------+---------------+---------------+-----+-------+
| 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
Robles, et al. Expires December 2, 2016 [Page 15]
Internet-Draft Useof6553 May 2016
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, sends 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.
,---.
/ \
( 6LR2 ) IP3,RPI,IP,ULP
,-" .
,-" `---' `.
,' `.
,---. ,-" `,---.
/ +" / \
( 6LR1 ) Remove the IP3,RPI( 6LR3 )
\ / \ /
/---' `---'|
/ IP2,RPI,IP,ULP \
/ |
/ \
,---+-. |
/ \ +--+----+
( 6LN ) | |
\ / | IPv6 | IP,ULP
`-----' | |
IP1,RPI,IP,ULP +-------+
Figure 4: Solution IPv6-in-IPv6 in each hop
Alternatively, 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 December 2, 2016 [Page 16]
Internet-Draft Useof6553 May 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 addresses to the 6LN if the destination is known to
the RPL aware, otherwise 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 December 2, 2016 [Page 17]
Internet-Draft Useof6553 May 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.