-
Notifications
You must be signed in to change notification settings - Fork 8
/
Copy pathdraft-ietf-softwire-map-dhcp-03.txt
1120 lines (722 loc) · 40.2 KB
/
draft-ietf-softwire-map-dhcp-03.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
Softwire WG T. Mrugalski
Internet-Draft ISC
Intended status: Standards Track O. Troan
Expires: August 24, 2013 W. Dec
Cisco
C. Bao
Tsinghua University
L. Yeh
Freelancer Technologies
X. Deng
February 20, 2013
DHCPv6 Options for Mapping of Address and Port
draft-ietf-softwire-map-dhcp-03
Abstract
This document specifies DHCPv6 options for the provisioning of
Mapping of Address and Port (MAP) Customer Edge (CE) devices, based
on the MAP paramaters defined in [I-D.ietf-softwire-map].
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 August 24, 2013.
Copyright Notice
Copyright (c) 2013 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
Mrugalski, et al. Expires August 24, 2013 [Page 1]
Internet-Draft MAP DHCPv6 Options February 2013
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. MAP Information . . . . . . . . . . . . . . . . . . . . . . . 4
4. DHCPv6 MAP Options . . . . . . . . . . . . . . . . . . . . . . 4
4.1. MAP Options Cardinality . . . . . . . . . . . . . . . . . 5
4.2. MAP Container Option . . . . . . . . . . . . . . . . . . . 5
4.3. MAP Rule Option . . . . . . . . . . . . . . . . . . . . . 6
4.4. MAP DMR Option . . . . . . . . . . . . . . . . . . . . . . 8
4.5. MAP Port Parameters Option . . . . . . . . . . . . . . . . 9
5. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . . 10
6. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . . 11
7. Usage of flags and paramaters . . . . . . . . . . . . . . . . 11
8. Deployment considerations . . . . . . . . . . . . . . . . . . 12
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
10. Security Considerations . . . . . . . . . . . . . . . . . . . 13
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
12.1. Normative References . . . . . . . . . . . . . . . . . . . 14
12.2. Informative References . . . . . . . . . . . . . . . . . . 14
Appendix A. MAP Options Examples . . . . . . . . . . . . . . . . 15
A.1. Example 1: BMR Option . . . . . . . . . . . . . . . . . . 15
A.2. Example 2: DMR Option . . . . . . . . . . . . . . . . . . 16
A.3. Example 3: 1:1 Rule with No Address Sharing . . . . . . . 17
A.4. Example 4: 1:1 Rule with Address Sharing . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Mrugalski, et al. Expires August 24, 2013 [Page 2]
Internet-Draft MAP DHCPv6 Options February 2013
1. Introduction
Mapping of Address and Port (MAP) defined in [I-D.ietf-softwire-map]
is a mechanism for providing IPv4 connectivity service to end users
over a service provider's IPv6 network, allowing for shared or
dedicated IPv4 addressing. It consists of a set of one or more MAP
Border Relay (BR) routers, responsible for stateless forwarding, and
one or more MAP Customer Edge (CE) routers, that collectively form a
MAP Domain when configured with common MAP rule-sets. In a
residential broadband deployment the CE is sometimes referred to as a
Residential Gateway (RG) or Customer Premises Equipment (CPE).
A typical MAP CE will serve its end-user with one WAN side interface
connected to an operator domain providing a MAP service. To function
in the MAP domain, the CE requires to be provisioned with the
appropriate MAP service paramaters for that domain. Particularly in
larger networks it is not feasible to configure such parameters
manually, which forms the requirement for a dynamic MAP provisioning
mechanism that is defined in this document based on the existing
DHCPv6 [RFC3315] protocol. The configuration of the MAP BR is
outside of scope of this document.
This document specifies the DHCPv6 options that allow MAP CE
provisioning, based on the definitions of parameters provided in
[I-D.ietf-softwire-map], and is applicable to both MAP-E and MAP-T
transport variants. The definition of DHCPv6 options for MAP CE
provisioning does not preclude the definition of other dynamic
methods for configuring MAP devices, or supplementing such
configuration, nor is the use of DHCPv6 provisioning mandatory for
MAP operation.
Since specification of MAP architecture is still expected to evolve,
DHCPv6 options may have to evolve too to fit the revised MAP
specification.
Defined proposal is not a dynamic port allocation mechanism.
Readers interested in deployment considerations are encouraged to
read [I-D.mdt-softwire-map-deployment].
2. Conventions
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].
Mrugalski, et al. Expires August 24, 2013 [Page 3]
Internet-Draft MAP DHCPv6 Options February 2013
3. MAP Information
The following presents the information parameters that are used to
configure a MAP CE:
o A Default Mapping Rule (DMR). This rule governs the default
forwarding/mapping behaviour of the MAP CE, ie it informs the CE
of the BR router's address or prefix that is typically used as a
default. The DMR is a mandatory parameter for a MAP CE.
o A Basic Mapping Rule (BMR). This rule governs the MAP
configuration of the CE, including that of completing the CE's MAP
IPv6 address, as well as deriving the CEs IPv4 parameters. Key
parameters of a BMR include: i) The IPv4 Prefix - Used to derive
the CE's IPv4 address; ii) The Embedded Address bit length - Used
to derive how many, if any, of the CE's IPv6 address is mapped to
the IPv4 address. iii) The IPv6 prefix - used to determine the
CE's IPv6 MAP domain prefix that is to form the base for the CE's
MAP address. The BMR is an optional rule for a MAP CE.
o A Forward Mapping Rule (FMR). This rule governs the MAP CE-CE
forwarding behaviour for IPv4 destinations covered by the rule.
The FMR is effectively a special type of an BMR, given that it
shares exactly the same configuration parameters, except that
these parameters are only applied for setting up forwarding. Its
presence enables a given CE to communicate directly in "mesh mode"
with other CEs. The FMR is an optional rule, and the absence of
such a rule indicates that the CE is to simply use its default
mapping rule for all destinations.
o Transport mode; encapsulation (MAP-E, [I-D.ietf-softwire-map]) or
translation (MAP-T, [I-D.ietf-softwire-map-t]) modes to be used
for the MAP CE Domain.
o Additional parameters. The MAP specification allows great
flexibility in the level of automation a CE uses to derive its
IPv4 address and port-sharing (PSID), ranging from full derivation
of these parameters from the CE's IPv6 prefix, to full
parametrization of MAP configuration independent of the CE's IPv6
prefix. Optional parameters such as the PSID allow this
flexibility.
4. DHCPv6 MAP Options
The DHCPv6 protocol is used for MAP CE provisioning following regular
DHCPv6 notions, with the MAP CE assuming a DHCPv6 client role, and
the MAP parameters provided by the DHCPv6 server following typical
DHCPv6 server side policies. The format and usage of the MAP options
is defined in the following sections.
Discussion: As the exact parameters required to configure MAP rules
Mrugalski, et al. Expires August 24, 2013 [Page 4]
Internet-Draft MAP DHCPv6 Options February 2013
and MAP in general are expected to change, this section is expected
to be updated and follow changes in the [I-D.ietf-softwire-map].
Discussion: It should be noted that initial concept of 4rd/MAP
provisioning was presented in DHC working group meeting. It used one
complex option to convey all required parameters. Strong suggestion
from DHC WG was to use several simpler options. Options (possibly
nested) are preferred over conditional option formatting. See DHCP
option guidelines document [I-D.ietf-dhc-option-guidelines]).
Server that supports MAP configuration and is configured to provision
requesting CE MUST include exactly one OPTION_MAP option in a REPLY
message for each MAP domain. It is envisaged that in typical
network, there will be only one MAP domain deployed.
4.1. MAP Options Cardinality
Server configured to provision MAP configuration SHOULD return one
MAP Container Option for each MAP domain, when requested by clients.
As there will typically be only one MAP Domain configured, server
will typically return a single instance of MAP Container Option.
Returned MAP Container Option MUST include exactly one MAP DMR Rule
option. It also MAY include zero or more MAP Rule Options. It also
MAY include MAP Port Parameters option. It MAY include additional
options that may be defined in the future.
4.2. MAP Container Option
This MAP Container Option specifies the container used to group all
rules and optional port parameters for a specified MAP domain.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_MAP | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| flags | .
+-+-+-+-+-+-+-+-+ encapsulated-options (variable length) .
. .
+---------------------------------------------------------------+
Figure 1: MAP Container Option
o option-code: OPTION_MAP (TBD1)
Mrugalski, et al. Expires August 24, 2013 [Page 5]
Internet-Draft MAP DHCPv6 Options February 2013
o option-length: 1 + Length of encapsulated options
o flags: This 8-bits long conveys the MAP Flags that apply to all
encapsulated options. The meaning of specific bits is explained
in Figure 2.
o encapsulated-options: options associatied with this MAP domain.
The encapsulated options field encapsulates those options that are
specific to this MAP Option. Currently there are three options that
MAY appear here: OPTION_MAP_RULE, OPTION_MAP_DMR and
OPTION_MAP_PORTPARAMS. Other options suitable for a MAP domain may
be defined in the future. A DHCP message MAY include multiple MAP
Container Options (representing multiple MAP domains), but typically
it will have only one.
The Format of the MAP flags field is:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|Reserved |T|
+-+-+-+-+-+-+-+-+
Figure 2: MAP Option Flags
o Reserved: 7-bits reserved for future use.
o T: 1 bit field that specifies transport mode to use: translation
(0) or encapsulation (1).
Discussion: It was suggested to also provision information whether
MAP network is working in hub and spoke or mesh mode. That is not
necessary, as mesh mode is assumed when there is at least one FMR
present.
4.3. MAP Rule Option
Figure Figure 3 shows the format of the MAP Rule option used for
conveying the BMR and FMR.
Server includes zero or more MAP Rule Options in MAP Container
Option.
Server MAY send more than one MAP Rule Option, if it is configured to
do so. Clients MUST NOT send MAP Rule Option.
Mrugalski, et al. Expires August 24, 2013 [Page 6]
Internet-Draft MAP DHCPv6 Options February 2013
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_MAP_RULE | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix4-len | rule-ipv4-prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (continued) | ea-len | rule-flags | prefix6-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rule-ipv6-prefix |
| (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. encapsulated-options (variable length) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: MAP Rule Option
o option-code: OPTION_MAP_RULE (TBD2)
o option-length: length of the option, excluding option-code and
option-length fields, including length of all encapsulated
options, expressed in bytes.
o prefix4-len: 8 bits long field expressing the bit mask length of
the IPv4 prefix specified in the rule-ipv4-prefix field.
o rule-ipv4-prefix: a fixed length 32 bit field that specifies the
IPv4 prefix for the MAP rule.
o ea-len: 8 bits long field that specifies the Embedded-Address (EA)
bit length. Values allowed range from 0 to 48.
o rule-flags: 8 bits long field carrying flags applicable to the
rule. The meaning of specific bits is explained in Figure 4.
o prefix6-len: 8 bits long field expressing the bit mask length of
the IPv6 prefix specified in the rule-ipv6-prefix field.
o rule-ipv6-prefix: a variable length field that specifies the IPv6
domain prefix for the MAP rule. The field is padded with follow
up zero bits up to the nearest octet boundary when prefix6-len is
not divisible by 8.
o encapsulated options: a variable field that may contain zero or
more options that specify additional parameters for this MAP BMR/
FMR rule. Currently there are no such options defined, but they
may be defined in the future.
The value of the EA-len and prefix4-len SHOULD be equal to or greater
than 32.
The Format of the MAP Rule Flags field is:
Mrugalski, et al. Expires August 24, 2013 [Page 7]
Internet-Draft MAP DHCPv6 Options February 2013
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|Reserved |F|
+-+-+-+-+-+-+-+-+
Figure 4: MAP Rule Flags
o Reserved: 7-bits reserved for future use as flags.
o F-Flag: 1 bit field that specifies whether the rule is to be used
for forwarding (FMR). 0x0 = This rule is NOT used as a FMR. 0x1 =
This rule is also a FMR.
o Note: BMR rules can be also FMR rules by setting the F flag. BMR
rules are determined by a match of the Rule-IPv6-prefix against
the CPE's prefix(es).
It is expected that in a typical MAP deployment scenarios, there will
be a single DMR and a single BMR, which could also be designated as
an FMR using the F-Flag.
Discussion: This option format attempts to use option formats
recommended by [I-D.ietf-dhc-option-guidelines], namely variable
length prefix formats. It should be noted that this format follows
prefix length + prefix notation. Reasons for using variable IPv6
prefix field, but fixed IPv4 prefix are given in
[I-D.ietf-dhc-option-guidelines], Section 5.9.
4.4. MAP DMR Option
MAP DMR Option is used to convey values for Default Mapping Rule.
MAP DMR Option MUST appear in each MAP Container Option exactly once.
It MUST NOT appear in the DHCP message directly. Figure Figure 5
shows the format of the MAP Rule option used for conveying a DMR.
Mrugalski, et al. Expires August 24, 2013 [Page 8]
Internet-Draft MAP DHCPv6 Options February 2013
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_MAP_DMR | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|dmr-prefix6-len| dmr-ipv6-prefix |
+-+-+-+-+-+-+-+-+ (variable length) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. encapsulated-options (variable length) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: MAP DMR Option
o option-code: OPTION_MAP_DMR (TBD3)
o option-length: 1 + length of dmr-ipv6-prefix + encapsulated
options, specified in bytes.
o dmr-prefix6-len: 8 bits long field expressing the bit mask length
of the IPv6 prefix specified in the dmr-ipv6-prefix field.
o dmr-ipv6-prefix: a variable length field that specifies the IPv6
prefix or address for the MAP BR. This field is padded with
follow up zeros to the nearest octet boundary when dmr-prefix6-len
is not divisible by 8.
o encapsulated options: nested options associatied to this MAP DMR
option. Currently there are no such options defined, but they may
be defined in the future.
4.5. MAP Port Parameters Option
Port Parameters Option specifies optional Rule Port Parameters that
MAY be provided as part of the Mapping Rule. It MAY appear as
encapsulated option in OPTION_MAP option. It MUST NOT appear
directly in a message. It MUST NOT appear in OPTION_MAP_RULE nor
OPTION_MAP_DMR options.
See [I-D.ietf-softwire-map], Section 5.1 for detailed description of
MAP algorithm that explains meaning of all parameters.
Mrugalski, et al. Expires August 24, 2013 [Page 9]
Internet-Draft MAP DHCPv6 Options February 2013
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_MAP_PORTPARAMS | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| offset | PSID-len | PSID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: MAP Port Parameters Option
o option-code: OPTION_MAP_PORTPARAMS (TBD4)
o option-length: 4
o offset: (PSID offset) 8 bits long field that specifies the numeric
value for the MAP algorithm's excluded port range/offset bits
(A-bits), as per section 5.1.1 in [I-D.ietf-softwire-map].
Allowed values are between 0 and 16, with the default value being
4.
o PSID-len: Bit length value of the number of significant bits in
the PSID field. (also known as 'k'). When set to 0, the PSID
field is to be ignored. After the first 'a' bits, there are k
bits in the port number representing valid of PSID. Subsequently,
the address sharing ratio would be 2^k.
o PSID: Explicit 16-bit (unsigned word) PSID value. The PSID value
algorithmically identifies a set of ports assigned to a CE. The
first k-bits on the left of this 2-octets field is the PSID value.
The remaining (16-k) bits on the right are padding zeros.
When receiveing the Port Parameters option with an explicit PSID, the
client MUST use this explicit PSID in configuring its MAP interface.
5. DHCPv6 Server Behavior
RFC 3315 Section 17.2.2 [RFC3315] describes how a DHCPv6 client and
server negotiate configuration values using the ORO. As a
convenience to the reader, we mention here that a server will by
default not reply with a MAP Rule Option if the client has not
explicitly enumerated it on its Option Request Option.
A Server following this specification MUST allow the configuration of
one or more MAP Rule Options, exactly one DMR Option and optional
Port Parameters Option and SHOULD send such options grouped under a
single MAP Container Option.
Server MUST include a MAP Container Option (which encapsulates all
MAP Rule, MAP DMR, and MAP Port parameters Options) in its responses
if client requested it using OPTION_MAP in client's Option Request
Option (ORO).
Mrugalski, et al. Expires August 24, 2013 [Page 10]
Internet-Draft MAP DHCPv6 Options February 2013
Server MAY include more than one MAP Container Options only in the
unlikely case of having more than one MAP Domain configured.
The server SHOULD be capable of following per client assignment rules
when assigning MAP options.
6. DHCPv6 Client Behavior
A MAP CE acting as DHCPv6 client will request MAP configuration to be
assigned by the DHCPv6 server located in the ISP network. A client
supporting MAP functionality SHOULD request OPTION_MAP option in its
ORO in SOLICIT, REQUEST, RENEW, REBIND and INFORMATION-REQUEST
messages.
When processing received MAP options the following behaviour is
expected:
o A client MUST support processing multiple received OPTION_MAP_RULE
options in a OPTION_MAP option
o A client receiving an unsupported MAP option, or an unrecognized
parameter value SHOULD discard the entire OPTION_MAP.
o Exactly one OPTION_MAP_DMR is allowed per OPTION_MAP option.
Client MUST ignore entire OPTION_MAP if there is zero or more than
one MAP DMR Option.
The client MUST be capable of applying the received MAP option
parameters for the configuration of the local MAP instance.
Note that system implementing MAP CE functionality may have multiple
network interfaces, and these interfaces may be configured
differently; some may be connected to networks that call for MAP, and
some may be connected to networks that are using normal dual stack or
other means. The MAP CE system should approach this specification on
an interface-by-interface basis. For example, if the CE system is
attached to multiple networks that provide the MAP Mapping Rule
Option, then the CE system MUST configure a MAP connection (i.e. a
translation or encapsulation) for each interface separately as each
MAP provides IPv4 connectivity for each distinct interface. Means to
bind a MAP configuration to a given interface in a multiple
interfaces device are out of scope of this document.
7. Usage of flags and paramaters
The defined MAP options contain a number of flags and parameters that
are intended to provide full flexibility in the configuration of a
MAP CE. Some usage examples are:
Mrugalski, et al. Expires August 24, 2013 [Page 11]
Internet-Draft MAP DHCPv6 Options February 2013
o A MAP CE receiving an OPTION_MAP option with the T flag set to 1
will assume a MAP-E (encapsulation) mode of operation for the
domain and all associated rules. Conversely, when the received
option has the T flag set to 0, the CE will assume a MAP-T
(stateless NAT46 translation) mode of operation.
o The presence of a OPTION_MAP_RULE option, along with IPv4 prefix
parameters, indicates to the MAP CE that NAPT44 mode of operation
is expected, following the address mapping rules defined in
[I-D.ietf-softwire-map]. Conversely, the absence of an
OPTION_MAP_RULE option indicates that NAT44 mode is not required,
and that the MAP CE is to plainly encapsulate (MAP-E mode) or
statelessly translate using NAT64 (MAP-T mode) any IPv4 traffic
sent following the DMR.
o The MAP domain ipv6-prefix in the BMR should correspond to a
service prefix assigned to the CPE by the operator, with the
latter being assigned using regular IPv6 means, e.g. DHCP PD
[RFC3633] or SLAAC. This parameter allows the CPE to select the
prefix for MAP operation.
o The EA_LEN parameter, along with the length of the IPv4 prefix in
the BMR option, allows the MAP CE to determine whether address
sharing is in effect, and what is the address sharing ratio. Eg:
A prefix4-len of 16 bits, and EA-len of 18 combines to a 32 bit
IPv4 address with a sharing ratio of 4.
o The use of the F(orward) flag in the BMR allows a CE to apply a
received BMR as an FMR, thereby enabling mesh-mode for the domain
covered by the BMR rule.
o In the absence of a BMR, the presence of the mandatory DMR
indicates to the CPE the address or prefix of a BR, and makes the
MAP CE fully compatible with DS-Lite and stateful or stateless
NAT64 core nodes. Eg a MAP CE configured in MAP-E mode, with just
a DMR and a BR IPv6 address equivalent to that of the AFTR,
effectively acts as a DS-Lite B4 element. For more discussion
about MAP deployment considerations, see
[I-D.mdt-softwire-map-deployment].
8. Deployment considerations
Usage of PSID Option should be avoided if possible and PSID embedded
in the delegated prefix should be used instead. This allows MAP
deployment to not introduce any additional state in DHCP server.
Port Parameters Option must be assigned on a per CE basis, thus
requiring more complicated server configuration.
In a typical environment, there will be only one MAP domain, so
server will provide only a single instance of MAP Container Option
that acts a container for MAP Rules and other options that are
specific to that MAP domain.
Mrugalski, et al. Expires August 24, 2013 [Page 12]
Internet-Draft MAP DHCPv6 Options February 2013
In case of multiple provisioning domains, as defined in
[I-D.ietf-homenet-arch], one server may be required to provide
information about more than one MAP domain. In such case it is
envisaged that the server will provide two or more instances of MAP
Container Options, each with its own set of encapsulated options that
define MAP rules for each specific MAP domain. Details of mulitple
provisioning domains are discussed in Section 4.1 of
[I-D.mdt-softwire-map-deployment]. Such a deployment is outside of
scope for this document.
9. IANA Considerations
IANA is kindly requested to allocate the following DHCPv6 option
codes: TBD1 for OPTION_MAP, TBD2 for OPTION_MAP_RULE, TBD3 for
OPTION_MAP_DMR, and TBD4 for OPTION_MAP_PORTPARAMS. All values
should be added to the DHCPv6 option code space defined in Section
24.3 of [RFC3315].
10. Security Considerations
Implementation of this document does not present any new security
issues, but as with all DHCPv6-derived configuration state, it is
completely possible that the configuration is being delivered by a
third party (Man In The Middle). As such, there is no basis to trust
that the access over the MAP can be trusted, and it should not
therefore bypass any security mechanisms such as IP firewalls.
Readers concerned with security of MAP provisioning over DHCPv6 are
encouraged to read [I-D.ietf-dhc-secure-dhcpv6].
Section XX of [I-D.ietf-softwire-map] discusses security issues of
the MAP mechanism.
Section 23 of [RFC3315] discusses DHCPv6-related security issues.
11. Acknowledgements
This document was created as a product of a MAP design team.
Following people were members of that team: Congxiao Bao, Mohamed
Boucadair, Gang Chen, Maoke Chen, Wojciech Dec, Xiaohong Deng, Jouni
Korhonen, Xing Li, Satoru Matsushima, Tomasz Mrugalski, Tetsuya
Murakami, Jacni Qin, Necj Scoberne, Qiong Sun, Tina Tsou, Dan Wing,
Leaf Yeh and Jan Zorz.
Former MAP design team members are: Remi Despres.
Mrugalski, et al. Expires August 24, 2013 [Page 13]
Internet-Draft MAP DHCPv6 Options February 2013
Authors would like to thank Bernie Volz for his insightful comments
and suggestions.
This work draws ideas from previous drafts:
[I-D.boucadair-dhcpv6-shared-address-option],
[I-D.mrugalski-dhc-dhcpv6-4rd], [I-D.murakami-softwire-4rd] and
others.
12. References
12.1. Normative References
[I-D.ietf-softwire-map]
Troan, O., Dec, W., Li, X., Bao, C., Matsushima, S., and
T. Murakami, "Mapping of Address and Port with
Encapsulation (MAP)", draft-ietf-softwire-map-04 (work in
progress), February 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
12.2. Informative References
[I-D.boucadair-dhcpv6-shared-address-option]
Boucadair, M., Levis, P., Grimault, J., Savolainen, T.,
and G. Bajko, "Dynamic Host Configuration Protocol
(DHCPv6) Options for Shared IP Addresses Solutions",
draft-boucadair-dhcpv6-shared-address-option-01 (work in
progress), December 2009.
[I-D.ietf-dhc-option-guidelines]
Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and
S. Krishnan, "Guidelines for Creating New DHCPv6 Options",
draft-ietf-dhc-option-guidelines-09 (work in progress),
December 2012.
[I-D.ietf-dhc-secure-dhcpv6]
Jiang, S. and S. Shen, "Secure DHCPv6 Using CGAs",
draft-ietf-dhc-secure-dhcpv6-07 (work in progress),
Mrugalski, et al. Expires August 24, 2013 [Page 14]
Internet-Draft MAP DHCPv6 Options February 2013
September 2012.
[I-D.ietf-homenet-arch]
Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
"Home Networking Architecture for IPv6",
draft-ietf-homenet-arch-07 (work in progress),
February 2013.
[I-D.ietf-softwire-map-t]
Li, X., Bao, C., Dec, W., Troan, O., Matsushima, S., and
T. Murakami, "Mapping of Address and Port using
Translation (MAP-T)", draft-ietf-softwire-map-t-01 (work
in progress), February 2013.
[I-D.mdt-softwire-map-deployment]
Sun, Q., Chen, M., Chen, G., Sun, C., Tsou, T., and S.
Perreault, "Mapping of Address and Port (MAP) - Deployment
Considerations", draft-mdt-softwire-map-deployment-02
(work in progress), June 2012.
[I-D.mrugalski-dhc-dhcpv6-4rd]
Mrugalski, T., "DHCPv6 Options for IPv4 Residual
Deployment (4rd)", draft-mrugalski-dhc-dhcpv6-4rd-00 (work
in progress), July 2011.
[I-D.murakami-softwire-4rd]
Murakami, T., Troan, O., and S. Matsushima, "IPv4 Residual
Deployment on IPv6 infrastructure - protocol
specification", draft-murakami-softwire-4rd-01 (work in
progress), September 2011.
Appendix A. MAP Options Examples
DHCPv6 server provisioning a single MAP Rule to a CE (DHCPv6 client)
will convey the following MAP options in its messages:
A.1. Example 1: BMR Option
Given the MAP domain information and an IPv6 address of an endpoint:
o IPv6 prefix assigned to the end user: 2001:db8:0012:3400::/56
o Basic Mapping Rule: {2001:db8:0000::/40 (Rule IPv6 prefix),
192.0.2.0/24 (Rule IPv4 prefix), 16 (Rule EA-bits length)}
o PSID offset: 4
This configuration example includes one MAP Container Option
(OPTION_MAP) that has two nested options: one MAP Rule Option
Mrugalski, et al. Expires August 24, 2013 [Page 15]
Internet-Draft MAP DHCPv6 Options February 2013
(OPTION_MAP_RULE) and one MAP Port Parameters Option
(OPTION_MAP_PORTPARAMS).
OPTION_MAP=TBD1
option-length=26 # (i.e. 1(OPTION_MAP) + suboptions: 17
# (OPTION_MAP_RULE) and 8 (OPTION_MAP_PORT_PARAMS)
flags=0x01 # encapsulation
encapsulated-options: 2 options specified below
OPTION_MAP_RULE=TBD2
option-length=17
prefix4-len=24
rule-ipv4-prefix=192.0.2.0 # rules-ipv4-prefix length is always
# 4 bytes
ea-len=16
rule-flags=0x01 # BMR and FMR
prefix6-length=40 # prefix-length implies rule-ipv6-
# prefix is a 5 bytes(40bits)
rule-ipv6-prefix=2001:db8:0000:: # long field.
encapsulated-options: none # no nested options in MAP_RULE
OPTION_MAP_PORTPARAMS=TBD4
option-length=4
offset=4
PSID-len=8
PSID=52
Figure 7: BMR Option Example
A.2. Example 2: DMR Option
An IPv4 host behind the MAP CE (addressed as per the previous
examples) corresponding with IPv4 host 203.0.113.1 will have its
packets converted into IPv6 using the DMR configured on the MAP CE as
follows:
o Default Mapping Rule: {2001:db8:ffff::1/128 (Rule IPv6 prefix),
0.0.0.0/0 (Rule IPv4 prefix), null (BR IPv4 address)}
This configuration example uses one MAP Container Option (OPTION_MAP)
with a single MAP DMR Option (OPTION_MAP_DMR) in it.
Mrugalski, et al. Expires August 24, 2013 [Page 16]
Internet-Draft MAP DHCPv6 Options February 2013
OPTION_MAP=TBD1
option-length=22 # 1 + nested option (MAP_DMR, 21 bytes)
flags=0x01 # encapsulation
encapsulated-options=one MAP_DMR option specified below
OPTION_MAP_DMR=TDB3
option-length=17
dmr-prefix6-len=128 #dmr-ipv6-prefix is 16bytes(128 bits) long
dmr-ipv6-prefix=2001:db8:ffff::1
encapsulated-options: none
Figure 8: DMR Option Examples
A.3. Example 3: 1:1 Rule with No Address Sharing
Given the MAP domain information and an IPv6 address of an endpoint:
o IPv6 prefix assigned to the end user: 2001:db8:0012:3400::/56
o Basic Mapping Rule: {2001:db8:0012:3400::/56 (Rule IPv6 prefix),
192.0.2.1/32 (Rule IPv4 prefix), 0 (Rule EA-bits length)}
o PSID offset: n/a
This configuration uses one MAP Container Option (OPTION_MAP) that
includes one nested MAP Rule Option (OPTION_MAP_RULE).
OPTION_MAP=TBD1
option-length=20 # 1 for OPTION_MAP and 19 for (OPTION_MAP_RULE)
flags=0x00 # just for BMR, not for FMR
encapsulated-options: one MAP Rule option, specified below
OPTION_MAP_RULE=TBD2
option-length=15
prefix4-len=32
rule-ipv4-prefix=192.0.2.1
ea-len=0
rule-flags=0x00 # for BMR only
prefix6-length=56 # length of the rule-ipv6-prefix
# is 7 bytes (56bits)
rule-ipv6-prefix=2001:db8:0012:3400::
encapsulated-options: none
Figure 9: 1:1 Rule with No Address Sharing Examples
Mrugalski, et al. Expires August 24, 2013 [Page 17]
Internet-Draft MAP DHCPv6 Options February 2013
A.4. Example 4: 1:1 Rule with Address Sharing
Given the MAP domain information and an IPv6 address of an endpoint:
o IPv6 prefix assigned to the end user: 2001:db8:0012:3400::/56
o Basic Mapping Rule: {2001:db8:0012:3400::/56 (Rule IPv6 prefix),
192.0.2.1/32 (Rule IPv4 prefix), 0 (Rule EA-bits length) PSID-len
8, PSID 11 }
o PSID offset: 4
This configuration example features one MAP Container Option
(OPTION_MAP) that includes two nested options: one MAP Rule Option
(OPTION_MAP_RULE) and one MAP Port Parameters Option
(OPTION_MAP_PORTPARAMS).
OPTION_MAP=TBD1
option-length=28
flags=0x01
encapsulated-options: includes two options specified below
OPTION_MAP_RULE=TBD2
option-length=15
rule-ipv4-prefix=192.0.2.1
rule-flags=0x00 # for BMR only
ea-len=0
prefix4-len=32
prefix6-length=56 # rule-ipv6-prefix length is 7 bytes(56 bits)
rule-ipv6-prefix=2001:db8:0012:3400::
encapsulated-options: none
OPTION_MAP_PORTPARAMS=TDB4
option-length=4
offset=4
PSID-len=8
PSID=11
Figure 10: 1:1 Rule with no Address Sharing Examples