-
Notifications
You must be signed in to change notification settings - Fork 1
/
draft-dhody-pce-pcep-extension-pce-controller-srv6-05.txt
1008 lines (659 loc) · 38.7 KB
/
draft-dhody-pce-pcep-extension-pce-controller-srv6-05.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
PCE Working Group Z. Li
Internet-Draft S. Peng
Intended status: Standards Track X. Geng
Expires: May 5, 2021 Huawei Technologies
M. Negi
RtBrick India
November 1, 2020
PCEP Procedures and Protocol Extensions for Using PCE as a Central
Controller (PCECC) for SRv6
draft-dhody-pce-pcep-extension-pce-controller-srv6-05
Abstract
The Path Computation Element (PCE) is a core component of Software-
Defined Networking (SDN) systems. It can compute optimal paths for
traffic across a network and can also update the paths to reflect
changes in the network or traffic demands.
PCE was developed to derive paths for MPLS Label Switched Paths
(LSPs), which are supplied to the head end of the LSP using the Path
Computation Element Communication Protocol (PCEP). But SDN has a
broader applicability than signaled (G)MPLS traffic-engineered (TE)
networks, and the PCE may be used to determine paths in a range of
use cases. PCEP has been proposed as a control protocol for use in
these environments to allow the PCE to be fully enabled as a central
controller.
A PCE-based Central Controller (PCECC) can simplify the processing of
a distributed control plane by blending it with elements of SDN and
without necessarily completely replacing it. This document specifies
the procedures and PCEP protocol extensions when a PCE-based
controller is also responsible for configuring the forwarding actions
on the routers for Segment Routing (SR) in IPv6 (SRv6), in addition
to computing the SRv6 paths for packet flows and telling the edge
routers what instructions to attach to packets as they enter the
network.
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 https://datatracker.ietf.org/drafts/current/.
Li, et al. Expires May 5, 2021 [Page 1]
Internet-Draft PCECC-SRv6 November 2020
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 May 5, 2021.
Copyright Notice
Copyright (c) 2020 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
(https://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
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
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. PCECC SRv6 . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 6
5. Procedures for Using the PCE as a Central Controller (PCECC)
in SRv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Stateful PCE Model . . . . . . . . . . . . . . . . . . . 6
5.2. New Functions . . . . . . . . . . . . . . . . . . . . . . 6
5.3. PCECC Capability Advertisement . . . . . . . . . . . . . 7
5.4. PCEP session IP address and TED Router ID . . . . . . . . 7
5.5. SRv6 Path Operations . . . . . . . . . . . . . . . . . . 7
5.5.1. PCECC Segment Routing in IPv6 (SRv6) . . . . . . . . 7
5.5.1.1. PCECC SRv6 Node/Prefix SID allocation . . . . . . 8
5.5.1.2. PCECC SRv6 Adjacency SID allocation . . . . . . . 8
5.5.1.3. Redundant PCEs . . . . . . . . . . . . . . . . . 9
5.5.1.4. Re-Delegation and Clean up . . . . . . . . . . . 9
5.5.1.5. Synchronization of SRv6 SID Allocations . . . . . 9
6. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 9
7. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . . 9
7.1.1. PCECC Capability sub-TLV . . . . . . . . . . . . . . 9
7.2. SRv6 Path Setup . . . . . . . . . . . . . . . . . . . . . 10
7.3. CCI Object . . . . . . . . . . . . . . . . . . . . . . . 10
Li, et al. Expires May 5, 2021 [Page 2]
Internet-Draft PCECC-SRv6 November 2020
7.4. FEC Object . . . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. Manageability Considerations . . . . . . . . . . . . . . . . 12
9.1. Control of Function and Policy . . . . . . . . . . . . . 12
9.2. Information and Data Models . . . . . . . . . . . . . . . 12
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 12
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 12
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 12
9.6. Impact On Network Operations . . . . . . . . . . . . . . 13
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
10.1. PCECC-CAPABILITY sub-TLV . . . . . . . . . . . . . . . . 13
10.2. PCEP Object . . . . . . . . . . . . . . . . . . . . . . 13
10.3. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 13
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
12.1. Normative References . . . . . . . . . . . . . . . . . . 14
12.2. Informative References . . . . . . . . . . . . . . . . . 15
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
The Path Computation Element (PCE) [RFC4655] was developed to offload
the path computation function from routers in an MPLS traffic-
engineered network. Since then, the role and function of the PCE has
grown to cover a number of other uses (such as GMPLS [RFC7025]) and
to allow delegated control [RFC8231] and PCE-initiated use of network
resources [RFC8281].
According to [RFC7399], Software-Defined Networking (SDN) refers to a
separation between the control elements and the forwarding components
so that software running in a centralized system, called a
controller, can act to program the devices in the network to behave
in specific ways. A required element in an SDN architecture is a
component that plans how the network resources will be used and how
the devices will be programmed. It is possible to view this
component as performing specific computations to place traffic flows
within the network given knowledge of the availability of network
resources, how other forwarding devices are programmed, and the way
that other flows are routed. This is the function and purpose of a
PCE, and the way that a PCE integrates into a wider network control
system (including an SDN system) is presented in [RFC7491].
In early PCE implementations, where the PCE was used to derive paths
for MPLS Label Switched Paths (LSPs), paths were requested by network
elements (known as Path Computation Clients (PCCs)), and the results
of the path computations were supplied to network elements using the
Path Computation Element Communication Protocol (PCEP) [RFC5440].
Li, et al. Expires May 5, 2021 [Page 3]
Internet-Draft PCECC-SRv6 November 2020
This protocol was later extended to allow a PCE to send unsolicited
requests to the network for LSP establishment [RFC8281].
[RFC8283] introduces the architecture for PCE as a central controller
as an extension of the architecture described in [RFC4655] and
assumes the continued use of PCEP as the protocol used between PCE
and PCC. [RFC8283] further examines the motivations and
applicability for PCEP as a Southbound Interface (SBI), and
introduces the implications for the protocol.
[I-D.ietf-teas-pcecc-use-cases] describes the use cases for the PCE-
based Central Controller (PCECC) architecture.
[I-D.ietf-pce-pcep-extension-for-pce-controller] specify the
procedures and PCEP extensions for using the PCE as the central
controller for static LSPs, where LSPs can be provisioned as explicit
label instructions at each hop on the end-to-end path.
Segment Routing (SR) technology leverages the source routing and
tunneling paradigms. A source node can choose a path without relying
on hop-by-hop signaling protocols such as LDP or RSVP-TE. Each path
is specified as a set of "segments" advertised by link-state routing
protocols (IS-IS or OSPF). [RFC8402] provides an introduction to SR
architecture. The corresponding IS-IS and OSPF extensions are
specified in [RFC8667] and [RFC8665] , respectively. It relies on a
series of forwarding instructions being placed in the header of a
packet. The list of segments forming the path is called the Segment
List and is encoded in the packet header. Segment Routing can be
applied to the IPv6 architecture with the Segment Routing Header
(SRH) [RFC8754]. A segment is encoded as an IPv6 address. An
ordered list of segments is encoded as an ordered list of IPv6
addresses in the routing header. The active segment is indicated by
the Destination Address of the packet. Upon completion of a segment,
a pointer in the new routing header is incremented and indicates the
next segment. The segment routing architecture supports operations
that can be used to steer packet flows in a network, thus providing a
form of traffic engineering. [RFC8664] and
[I-D.ietf-pce-segment-routing-ipv6] specify the SR specific PCEP
extensions.
PCECC may further use PCEP for SR SID (Segment Identifier)
distribution on the SR nodes with some benefits.
[I-D.zhao-pce-pcep-extension-pce-controller-sr] specifies the
procedures and PCEP extensions when a PCE-based controller is also
responsible for configuring the forwarding actions on the routers
(SR-MPLS SID distribution in this case), in addition to computing the
paths for packet flows in a segment routing network and telling the
edge routers what instructions to attach to packets as they enter the
Li, et al. Expires May 5, 2021 [Page 4]
Internet-Draft PCECC-SRv6 November 2020
network. This document extends this to include SRv6 SID distribution
as well.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
Terminologies used in this document is the same as described in the
draft [RFC8283] and [I-D.ietf-teas-pcecc-use-cases].
3. PCECC SRv6
[RFC8664] specifies extensions to PCEP that allow a stateful PCE to
compute, update, or initiate SR-TE paths for MPLS dataplane. An
ingress node of an SR-TE path appends all outgoing packets with a
list of MPLS labels (SIDs). This is encoded in SR-ERO subobject,
capable of carrying a label (SID) as well as the identity of the
node/adjacency label (SID). [I-D.ietf-pce-segment-routing-ipv6]
extends the procedure to include support for SRv6 paths.
As per [RFC8754], an SRv6 Segment is a 128-bit value. "SRv6 SID" or
simply "SID" are often used as a shorter reference for "SRv6
Segment". Further details are in an illustration provided in
[I-D.ietf-spring-srv6-network-programming]. The SR is applied to
IPV6 data plane using SRH. An SR path can be derived from an IGP
Shortest Path Tree (SPT), but SR-TE paths may not follow IGP SPT.
Such paths may be chosen by a suitable network planning tool, or a
PCE and provisioned on the ingress node.
[I-D.ietf-pce-segment-routing-ipv6] specify the SRv6-ERO subobject
capable of carrying an SRv6 SID as well as the identity of the node/
adjacency represented by the SID.
As per [RFC8283], PCECC can allocate and provision the node/prefix/
adjacency label (SID) via PCEP. As per
[I-D.ietf-teas-pcecc-use-cases] this is also applicable to SRv6 SIDs.
The rest of the processing is similar to existing stateful PCE for
SRv6 [I-D.ietf-pce-segment-routing-ipv6].
Li, et al. Expires May 5, 2021 [Page 5]
Internet-Draft PCECC-SRv6 November 2020
4. PCEP Requirements
Following key requirements for PCECC-SRv6 should be considered when
designing the PCECC-based solution:
o A PCEP speaker supporting this draft needs to have the capability
to advertise its PCECC-SRv6 capability to its peers.
o PCEP procedures need to allow for PCC-based SRv6 SID allocations.
o PCEP procedures need means to update (or clean up) the SRv6 SID to
the PCC.
o PCEP procedures need to provide a mean to synchronize the SRv6 SID
allocations between the PCE to the PCC in the PCEP messages.
5. Procedures for Using the PCE as a Central Controller (PCECC) in SRv6
5.1. Stateful PCE Model
Active stateful PCE is described in [RFC8231]. PCE as a Central
Controller (PCECC) reuses the existing active stateful PCE mechanism
as much as possible to control the LSPs.
5.2. New Functions
This document uses the same PCEP messages and its extensions which
are described in [I-D.ietf-pce-pcep-extension-for-pce-controller] and
[I-D.zhao-pce-pcep-extension-pce-controller-sr] for PCECC-SRv6 as
well.
The PCEP messages PCRpt, PCInitiate, PCUpd are used to send LSP
Reports, LSP setup, and LSP update respectively. The extended
PCInitiate message described in
[I-D.ietf-pce-pcep-extension-for-pce-controller] is used to download
or clean up central controller's instructions (CCIs) (SRv6 SID in the
scope of this document). The extended PCRpt message described in
[I-D.ietf-pce-pcep-extension-for-pce-controller] is also used to
report the CCIs (SRv6 SIDs) from PCC to PCE.
[I-D.ietf-pce-pcep-extension-for-pce-controller] specify an object
called CCI for the encoding of the central controller's instructions.
[I-D.zhao-pce-pcep-extension-pce-controller-sr] defined a CCI object-
type for segment routing. This document further defines a new CCI
object-type for SRv6.
Li, et al. Expires May 5, 2021 [Page 6]
Internet-Draft PCECC-SRv6 November 2020
5.3. PCECC Capability Advertisement
During PCEP Initialization Phase, PCEP Speakers (PCE or PCC)
advertise their support of PCECC extensions. A PCEP Speaker includes
the "PCECC Capability" sub-TLV, described in
[I-D.ietf-pce-pcep-extension-for-pce-controller].
A new S-bit is added in the PCECC-CAPABILITY sub-TLV to indicate
support for PCECC-SR in
[I-D.zhao-pce-pcep-extension-pce-controller-sr]. This document adds
another I-bit to indicate support for SR in IPv6. A PCC MUST set the
I-bit in the PCECC-CAPABILITY sub-TLV and include the SRv6-PCE-
CAPABILITY sub-TLV ([I-D.ietf-pce-segment-routing-ipv6]) in the OPEN
Object (inside the PATH-SETUP-TYPE-CAPABILITY TLV) to support the
PCECC SRv6 extensions defined in this document. If I-bit is set in
PCECC-CAPABILITY sub-TLV and the SRv6-PCE-CAPABILITY sub-TLV is not
advertised in the OPEN Object, PCE SHOULD send a PCErr message with
Error-Type=19 (Invalid Operation) and Error-value=TBD4 (SRv6
capability was not advertised) and terminate the session.
The rest of the processing is as per
[I-D.ietf-pce-pcep-extension-for-pce-controller].
5.4. PCEP session IP address and TED Router ID
As described in [I-D.zhao-pce-pcep-extension-pce-controller-sr], it
is important to link the session IP address with the Router ID in TED
for successful PCECC-SRv6 operations.
5.5. SRv6 Path Operations
[RFC8664] specify the PCEP extension to allow a stateful PCE to
compute and initiate SR-TE paths, as well as a PCC to request a path
subject to certain constraint(s) and optimization criteria in SR
networks. [I-D.ietf-pce-segment-routing-ipv6] extends it to support
SRv6.
The Path Setup Type for SRv6 (PST=TBD) is used on the PCEP session
with the Ingress as per [I-D.ietf-pce-segment-routing-ipv6].
5.5.1. PCECC Segment Routing in IPv6 (SRv6)
Segment Routing (SR) as described in [RFC8402] depends on "segments"
that are advertised by Interior Gateway Protocols (IGPs). The SR-
node allocates and advertises the SID (node, adj, etc) and floods
them via the IGP. This document proposes a new mechanism where PCE
allocates the SRv6 SID centrally and uses PCEP to advertise them. In
some deployments, PCE (and PCEP) are better suited than IGP because
Li, et al. Expires May 5, 2021 [Page 7]
Internet-Draft PCECC-SRv6 November 2020
of the centralized nature of PCE and direct TCP based PCEP sessions
to the node.
5.5.1.1. PCECC SRv6 Node/Prefix SID allocation
Each node (PCC) is allocated a node SRv6 SID by the PCECC. The PCECC
sends the PCInitiate message to update the SRv6 SID table of each
node. The TE router ID is determined from the TED or from "IPv4/IPv6
Router-ID" Sub-TLV [I-D.dhodylee-pce-pcep-ls], in the OPEN Object.
On receiving the SRv6 node SID allocation, each node (PCC) uses the
local routing information to determine the next-hop and download the
forwarding instructions accordingly. The PCInitiate message uses the
FEC object [I-D.zhao-pce-pcep-extension-pce-controller-sr].
On receiving the SRv6 node SID allocation:
For the local SID, the node (PCC) needs to update SID with
associated function (END function in this case) in "My Local SID
Table" ([I-D.ietf-spring-srv6-network-programming]).
For the non-local SID, the node (PCC) uses the local routing
information to determine the next-hop and download the forwarding
instructions accordingly.
The forwarding behavior and the end result is similar to IGP based
"Node-SID" in SRv6. Thus, from anywhere in the domain, it enforces
the ECMP-aware shortest-path forwarding of the packet towards the
related node as per [RFC8402].
PCE relies on the Node/Prefix SRv6 SID clean up using the same
PCInitiate message as per [RFC8281].
5.5.1.2. PCECC SRv6 Adjacency SID allocation
For PCECC-SRv6, apart from node-SID, Adj-SID is used where each
adjacency is allocated an Adj-SID by the PCECC. The PCECC sends
PCInitiate message to update the SRv6 SID entry for each adjacency to
the corresponding nodes in the domain. Each node (PCC) download the
SRv6 SID instructions accordingly. Similar to SRv6 Node/Prefix Label
allocation, the PCInitiate message in this case uses the FEC object.
The forwarding behavior and the end result is similar to IGP based
"Adj-SID" in SRv6 as per [RFC8402].
The handling of adjacencies on the LAN subnetworks is specified in
[RFC8402]. PCECC MUST assign Adj-SID for every pair of routers in
the LAN. The rest of the protocol mechanism remains the same.
Li, et al. Expires May 5, 2021 [Page 8]
Internet-Draft PCECC-SRv6 November 2020
PCE relies on the Adj label clean up using the same PCInitiate
message as per [RFC8281].
5.5.1.3. Redundant PCEs
[I-D.litkowski-pce-state-sync] describes the synchronization
mechanism between the stateful PCEs. The SRv6 SIDs allocated by a
PCE MUST also be synchronized among PCEs for PCECC-SRv6 state
synchronization. Note that the SRv6 SIDs are independent of the SRv6
paths, and remains intact till any topology change. The redundant
PCEs MUST have a common view of all SRv6 SIDs allocated in the
domain.
5.5.1.4. Re-Delegation and Clean up
[I-D.ietf-pce-pcep-extension-for-pce-controller] describes the action
needed for CCIs for the static LSPs on a terminated session. Same
holds true for the CCI for SRv6 SID as well.
5.5.1.5. Synchronization of SRv6 SID Allocations
[I-D.ietf-pce-pcep-extension-for-pce-controller] describes the
synchronization of Central Controller's Instructions (CCI) via the
LSP state synchronization as described in [RFC8231] and [RFC8232].
Same procedures are applied for the CCI for the SRv6 SIDs as well.
6. PCEP Messages
The PCEP messages are as per
[I-D.zhao-pce-pcep-extension-pce-controller-sr].
7. PCEP Objects
7.1. OPEN Object
7.1.1. PCECC Capability sub-TLV
[I-D.ietf-pce-pcep-extension-for-pce-controller] defined the PCECC-
CAPABILITY sub-TLV.
A new I-bit is defined in PCECC-CAPABILITY sub-TLV for PCECC-SRv6:
Li, et al. Expires May 5, 2021 [Page 9]
Internet-Draft PCECC-SRv6 November 2020
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |I|S|L|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
[Editor's Note - The above figure is included for ease of the reader
but should be removed before publication.]
I (PCECC-SRv6-CAPABILITY - 1 bit - TBD1): If set to 1 by a PCEP
speaker, it indicates that the PCEP speaker is capable of PCECC-SRv6
capability and the PCE allocates the Node and Adj SRv6 SID on this
session.
7.2. SRv6 Path Setup
The PATH-SETUP-TYPE TLV is defined in [RFC8408]. A PST value of TBD
is used when Path is setup via SRv6 mode as per
[I-D.ietf-pce-segment-routing-ipv6]. The procedure for SRv6 path
setup as specified in [I-D.ietf-pce-segment-routing-ipv6] remians
unchanged.
7.3. CCI Object
The Central Control Instructions (CCI) Object is used by the PCE to
specify the cntroller instructions is defined in
[I-D.ietf-pce-pcep-extension-for-pce-controller]. This document
defines another object-type for SRv6 purpose.
CCI Object-Type is TBD3 for SRv6 as below -
Li, et al. Expires May 5, 2021 [Page 10]
Internet-Draft PCECC-SRv6 November 2020
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CC-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MT-ID | Algorithm | Flags |B|P|G|C|N|E|V|L|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | SRv6 Endpoint Function |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SRv6 Identifier |
| (128-bit) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Optional TLV //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The field CC-ID is as described in
[I-D.ietf-pce-pcep-extension-for-pce-controller]. The field MT-ID,
Algorithm, Flags are defined in
[I-D.zhao-pce-pcep-extension-pce-controller-sr].
Reserved: MUST be set to 0 while sending and ignored on receipt.
SRv6 Endpoint Function: 16-bit field representing supported functions
associated with SRv6 SIDs.
SRv6 Identifier: 128-bit IPv6 addresses representing SRv6 segment.
[Editor's Note - It might be useful to separate the LOC:FUNC part in
the SRv6 SID (future study)]
7.4. FEC Object
The FEC Object is used to specify the FEC information and MAY be
carried within PCInitiate or PCRpt message.
FEC Object (and various Object-Types) are described in
[I-D.zhao-pce-pcep-extension-pce-controller-sr]. SRv6 Node SID MUST
includes the FEC Object-Type 2 for IPv6 Node. SRv6 Adjacency SID
MUST include the FEC Object-Type=4 for IPv6 adjacency. Further FEC
object types could be added in future extensions.
Li, et al. Expires May 5, 2021 [Page 11]
Internet-Draft PCECC-SRv6 November 2020
8. Security Considerations
The security considerations described in
[I-D.ietf-pce-pcep-extension-for-pce-controller] apply to the
extensions described in this document.
As per [RFC8231], it is RECOMMENDED that these PCEP extensions only
be activated on authenticated and encrypted sessions across PCEs and
PCCs belonging to the same administrative authority, using Transport
Layer Security (TLS) [RFC8253] as per the recommendations and best
current practices in [RFC7525] (unless explicitly set aside in
[RFC8253]).
9. Manageability Considerations
9.1. Control of Function and Policy
A PCE or PCC implementation SHOULD allow to configure to enable/
disable PCECC SRv6 capability as a global configuration.
9.2. Information and Data Models
[RFC7420] describes the PCEP MIB, this MIB can be extended to get the
PCECC SRv6 capability status.
The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to
enable/disable PCECC SRv6 capability.
9.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440].
9.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440] and [RFC8231].
9.5. Requirements On Other Protocols
PCEP extensions defined in this document do not put new requirements
on other protocols.
Li, et al. Expires May 5, 2021 [Page 12]
Internet-Draft PCECC-SRv6 November 2020
9.6. Impact On Network Operations
PCEP implementation SHOULD allow a limit to be placed on the rate of
PCInitiate/PCUpd messages (as per [RFC8231]) sent by PCE and
processed by PCC. It SHOULD also allow sending a notification when a
rate threshold is reached.
10. IANA Considerations
10.1. PCECC-CAPABILITY sub-TLV
[I-D.ietf-pce-pcep-extension-for-pce-controller] defines the PCECC-
CAPABILITY sub-TLV and requests that IANA creates a registry to
manage the value of the PCECC-CAPABILITY sub-TLV's Flag field. IANA
is requested to allocate a new bit in the PCECC-CAPABILITY sub-TLV
Flag Field registry, as follows:
Bit Description Reference
TBD1 SRv6 This document
10.2. PCEP Object
IANA is requested to allocate a new code-point for the new CCI
object-type in "PCEP Objects" sub-registry as follows:
Object-Class Value Name Object-Type Reference
TBD CCI
TBD3: SRv6 This document
10.3. PCEP-Error Object
IANA is requested to allocate new error types and error values within
the "PCEP-ERROR Object Error Types and Values" sub-registry of the
PCEP Numbers registry for the following errors:
Error-Type Meaning
---------- -------
19 Invalid operation.
Error-value = TBD4 : SRv6 capability was
not advertised
11. Acknowledgments
Li, et al. Expires May 5, 2021 [Page 13]
Internet-Draft PCECC-SRv6 November 2020
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,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
[I-D.ietf-pce-segment-routing-ipv6]
Li, C., Negi, M., Koldychev, M., Kaladharan, P., and Y.
Zhu, "PCEP Extensions for Segment Routing leveraging the
IPv6 data plane", draft-ietf-pce-segment-routing-ipv6-06
(work in progress), July 2020.
[I-D.ietf-pce-pcep-extension-for-pce-controller]
Li, Z., Peng, S., Negi, M., Zhao, Q., and C. Zhou, "PCEP
Procedures and Protocol Extensions for Using PCE as a
Central Controller (PCECC) of LSPs", draft-ietf-pce-pcep-
extension-for-pce-controller-07 (work in progress),
September 2020.
Li, et al. Expires May 5, 2021 [Page 14]
Internet-Draft PCECC-SRv6 November 2020
[I-D.zhao-pce-pcep-extension-pce-controller-sr]
Li, Z., Peng, S., Negi, M., Zhao, Q., and C. Zhou, "PCEP
Procedures and Protocol Extensions for Using PCE as a
Central Controller (PCECC) of SR-LSPs", draft-zhao-pce-
pcep-extension-pce-controller-sr-07 (work in progress),
July 2020.
12.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC7025] Otani, T., Ogaki, K., Caviglia, D., Zhang, F., and C.
Margaria, "Requirements for GMPLS Applications of PCE",
RFC 7025, DOI 10.17487/RFC7025, September 2013,
<https://www.rfc-editor.org/info/rfc7025>.
[RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path
Computation Element Architecture", RFC 7399,
DOI 10.17487/RFC7399, October 2014,
<https://www.rfc-editor.org/info/rfc7399>.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module",
RFC 7420, DOI 10.17487/RFC7420, December 2014,
<https://www.rfc-editor.org/info/rfc7420>.
[RFC7491] King, D. and A. Farrel, "A PCE-Based Architecture for
Application-Based Network Operations", RFC 7491,
DOI 10.17487/RFC7491, March 2015,
<https://www.rfc-editor.org/info/rfc7491>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X.,
and D. Dhody, "Optimizations of Label Switched Path State
Synchronization Procedures for a Stateful PCE", RFC 8232,
DOI 10.17487/RFC8232, September 2017,
<https://www.rfc-editor.org/info/rfc8232>.
Li, et al. Expires May 5, 2021 [Page 15]
Internet-Draft PCECC-SRv6 November 2020
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An
Architecture for Use of PCE and the PCE Communication
Protocol (PCEP) in a Network with Central Control",
RFC 8283, DOI 10.17487/RFC8283, December 2017,
<https://www.rfc-editor.org/info/rfc8283>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
Hardwick, "Conveying Path Setup Type in PCE Communication
Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408,
July 2018, <https://www.rfc-editor.org/info/rfc8408>.
[RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", RFC 8665,
DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
[I-D.ietf-teas-pcecc-use-cases]
Li, Z., Khasanov, B., Dhody, D., Zhao, Q., Ke, Z., Fang,
L., Zhou, C., Communications, T., Rachitskiy, A., and A.
Gulida, "The Use Cases for Path Computation Element (PCE)
as a Central Controller (PCECC).", draft-ietf-teas-pcecc-
use-cases-06 (work in progress), September 2020.
Li, et al. Expires May 5, 2021 [Page 16]
Internet-Draft PCECC-SRv6 November 2020
[I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep-
yang-15 (work in progress), October 2020.
[I-D.litkowski-pce-state-sync]
Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter
Stateful Path Computation Element (PCE) Communication
Procedures.", draft-litkowski-pce-state-sync-08 (work in
progress), July 2020.
[I-D.dhodylee-pce-pcep-ls]
Dhody, D., Peng, S., Lee, Y., Ceccarelli, D., and A. Wang,
"PCEP extensions for Distribution of Link-State and TE
Information", draft-dhodylee-pce-pcep-ls-17 (work in
progress), July 2020.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-24 (work in
progress), October 2020.
Li, et al. Expires May 5, 2021 [Page 17]
Internet-Draft PCECC-SRv6 November 2020
Appendix A. Contributor Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: [email protected]
Authors' Addresses
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
EMail: [email protected]
Shuping Peng
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
EMail: [email protected]
Xuesong Geng
Huawei Technologies
China
EMail: [email protected]
Mahendra Singh Negi
RtBrick India
N-17L, Floor-1, 18th Cross Rd, HSR Layout Sector-3