idnits 2.17.1 draft-nsdt-teas-transport-slice-definition-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack a Security Considerations section. ** The document seems to lack an IANA Considerations section. (See Section 2.2 of https://www.ietf.org/id-info/checklist for how to handle the case when there are no actions for IANA.) Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 421 has weird spacing: '...| 10 ms or b...' -- The document date (November 2, 2019) is 1636 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Informational ---------------------------------------------------------------------------- -- Missing reference section? 'EU-x' on line 137 looks like a reference -- Missing reference section? 'EU-y' on line 137 looks like a reference -- Missing reference section? 'EP11' on line 199 looks like a reference -- Missing reference section? 'EP21' on line 199 looks like a reference -- Missing reference section? 'EP12' on line 201 looks like a reference -- Missing reference section? 'EP22' on line 201 looks like a reference -- Missing reference section? 'EP1m' on line 203 looks like a reference -- Missing reference section? 'EP2n' on line 203 looks like a reference -- Missing reference section? 'UPF1' on line 272 looks like a reference -- Missing reference section? 'UPF2' on line 274 looks like a reference -- Missing reference section? 'UPF3' on line 276 looks like a reference -- Missing reference section? 'Mbps' on line 445 looks like a reference -- Missing reference section? 'FW1' on line 292 looks like a reference -- Missing reference section? 'ER1' on line 293 looks like a reference -- Missing reference section? 'FW2' on line 294 looks like a reference Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 17 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 teas R. Rokui 3 Internet-Draft Nokia 4 Intended status: Informational S. Homma 5 Expires: May 5, 2020 NTT 6 K. Makhijani 7 Futurewei 8 November 2, 2019 10 IETF Definition of Transport Slice 11 draft-nsdt-teas-transport-slice-definition-00 13 Abstract 15 This document describes the definition of transport slice in IETF and 16 considerations on implementation (realization) of transport slice. 17 This work is part of work on TEAS WG network slicing Design Team. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at https://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on May 5, 2020. 36 Copyright Notice 38 Copyright (c) 2019 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (https://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. High level architecture of end-to-end network slicing . . . . 3 55 3. IETF Definition of Transport slice . . . . . . . . . . . . . 5 56 3.1. Scenario-1 . . . . . . . . . . . . . . . . . . . . . . . 6 57 3.2. Scenario-2 . . . . . . . . . . . . . . . . . . . . . . . 7 58 3.3. Scenario-3 . . . . . . . . . . . . . . . . . . . . . . . 7 59 4. Implementation (aka Realization) of Transport slice . . . . . 9 60 4.1. Implementation of Scenario-1 . . . . . . . . . . . . . . 9 61 4.2. Implementation of Scenario-2 . . . . . . . . . . . . . . 11 62 4.3. Implementation of Scenario-3 . . . . . . . . . . . . . . 12 63 5. Definition of SLA and Isolation levels . . . . . . . . . . . 15 64 6. Informative References . . . . . . . . . . . . . . . . . . . 15 65 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 67 1. Introduction 69 Network slicing is an approach to provide separate virtual networks 70 depending on requirements of each service. Network slicing receives 71 attention due to factors such as diversity of services and devices, 72 and it is also a fundamental concept of the 5G for applying networks 73 to such various types of requirements (Ref [TS.23.501-3GPP]). 74 However there are other applications which might benefit from network 75 slicing. Following is a list of other applicaitons: 77 o 5G network slicig 79 o Wholesale business VPN 81 o Network sharing among operators 83 o NVVI connectivity (DCI) 85 A network slice is composed of several parts such as endpoints and 86 transport connecctivity between them. However, there is no concrete 87 definition of network slices established on transport and how to 88 realize them. 90 This document describes the definition of transport slice from IETF 91 aspect and considerations on their realization as well. 93 2. High level architecture of end-to-end network slicing 95 To demonstrate IETF definition of both E2E network slice and 96 transport slice, consider a typical network shown in Figure 1 where 97 the network operator-Y has various networks of various technologies 98 (e.g. IP, MPLS, Optics, PON, Microwave, 5G RAN, 5G Core etc.). Each 99 network contains one or more nodes of (aka physical or virtual 100 network functions, PNFs or VNFs), which have various capabilities and 101 technologies such as: 103 o Routers 105 o Switches 107 o Application servers 109 o Firewalls 111 o 4G/5G RAN nodes 113 o 4G/5G Core nodes 115 o etc. 117 Each node (aka endpoint) in the network might support various 118 technologies such as IP, MPLS, Microwave, 5G RAN, 5G Core etc. For 119 example, 121 o Network-1 might contains multiple 5G gNBs connected to a few 122 routers as Cell Site Gateways (CSG). 124 o Network-3 might have one or more L2/L3 routers and switches which 125 are running on top on Optical network. 127 o Network-2 might have a few nodes of 5G RAN which are connected by 128 PON. 130 <========================= E2E NS =====================> 132 <-OS1-> <-TS1-> <-TS2-> <-OS2-> ... <-TSn-> <-OSm-> 134 .--. .--. .--. 135 ( )--. ( )--. ( )--. 136 .' ' .' ' .' ' 137 [EU-x] ( Network-1 ) ( Network-2 ) ... ( Network-p ) [EU-y] 138 `-----------' `-----------' `----------' 140 Legends 141 E2E NS: End-2-end network slice 142 TSy: Transport Slice y 143 OSx: Other Slice x 144 EU-x: End User-x 146 Figure 1: E2E network slice 148 To further clarify the concept of the E2E network slice, consider the 149 network operator-Y has various customers (tenants). One of its 150 customers, needs to have a separate independent E2E logical network 151 for specific service (e.g. CCTV, autonomous driving, HD map etc) for 152 specific SLA requirement (e.g. high secure connection with Latency 153 less than 5ms) from End User-x (EU-x) from one side of the network to 154 End User-y (EU-y) to the other side. This E2E logical network is 155 call an "E2E network slice". A typical example of EU-x in 5G is the 156 User equipment such as infotainment unit in the car, CCTV, Car for 157 autonomous driving etc. and a typical example of EU-y in 5G is 5G 158 application server, IMS etc. 160 As shown in Figure 1 we use the term "E2E network slice" to show this 161 logical i ndependent network from EU-X to EU-Y. It is important to 162 consider that an "E2E network slice" is associated to a customer 163 (tenant) and a service type (e.g. CCTV, autonomous driving etc.). 164 Also there is only one E2E context between EU-x and EU-y. Anything 165 else is not E2E. 167 For example, customer "City of NY" would like to connect all its CCTV 168 cameras for entire city together. To do so, it asks Operator-Y who 169 has coverage in NY to create a new separate independent logical 170 network with SLA requirement of B/W greater than 10Mbps. In this 171 case, a single E2E network slice (with NS ID 10) will be created by 172 Operator-Y for Customer "City of NY", service type of CCT and SLA of 173 10Mbps. 175 It is also possible that customer and service type associate to an 176 E2E network slice to be a wild card. For instance, in above example, 177 the E2E network slice 10, can be associated not only to service type 178 CCTV but another service "Public Safety", i.e. NS ID 10 is used for 179 two services for City of NY. 181 3. IETF Definition of Transport slice 183 The IETF definition of a transport slice is as follows: 185 A Transport Slice is an abstract network topology connecting 186 different endpoints with appropriate isolation and specific Service 187 Level Agreement (SLA) described in terms of shared or dedicated 188 network resources, level of isolation etc. 190 In other words, a transport slice is a group of connections which 191 connecting various endpointss in the network to achieve specific SLA 192 for a customer as shown in Figure 2. Examples of the endpoints are 193 any physical or virtual network functions (PNF/VNF) or any network 194 services. 196 <------- Transport slice --------> 198 .--. .--. 199 [EP11] ( )- . ( )- . [EP21] 200 .' ' .' ' 201 [EP12] ( Network-1 ) ... ( Network-p ) [EP22] 202 : `-----------' `-----------' : 203 [EP1m] [EP2n] 205 Legend 206 EP: Endpoint 208 Figure 2: Transport slice 210 Referring to Figure 1, when operator-Y would like to create a 211 specific E2E network slice, it should create one or more of two types 212 of artefacts: 214 o Transport slice (aka Transport sub-slices or Transport sub-nets) 216 o Other slice (aka Other sub-slices or other sub-nets) 218 As shown in Figure 1, an E2E network slice might have one or more of 219 "Transport Slices" and one or more of "Other Slices" of any 220 combinations. One of the critical parts of an E2E network slice is 221 "Transport Slices" which provides various connections with certain 222 SLA between various nodes (aka endpoints). 224 "The Other Slices" is out-of-scope of current work but in summary 225 they contain various context or personality in the network to support 226 a specific e2e network slice, i.e. The "Other Slices" are referred to 227 as slices created by networks or components where IETF protocols do 228 not strictly apply and operator can choose any method for defining 229 them. For instance, in 5G, the prime example of these slices are: 231 o 5G RAN slice (aka RAN sub-slice, RAN sub-net or RAN-NNSI): 232 Contains the context or personality on various 5G RAN network 233 functions (e.g. gNB, eNB, CU, DU etc) in support of specific e2e 234 network slice with certain SLA 236 o 5G Core slice (aka Core sub-slice, Core sub-net or Core-NNSI): 237 Contains the context or personality on various 5G Core network 238 functions (e.g UPF, SMF, AMF, etc) in support of specific e2e 239 network slice with certain SLA 241 Figure 2 demonstrates the definition of a Transport Slice where a 242 single Transport slice provides connectivity between "m" endpoints on 243 left hand side to "n" endpoints on right hand side with specific 244 characteristic for Service Level Agreement (SLA). 246 Each transport slice has main characteristics: 248 o Transport slice definition: Technology agnostic to address a set 249 of connections between various endpoints with certain SLA 251 o Transport slice Implementation (aka realization): In addition to 252 its definition, a Transport Slice has an implementation (aka 253 realization) in the operator's network. Unlike transport slice 254 definition, its implementation (aka realization) might be 255 technology specific. 257 A few examples below demonstrate the idea of transport slice in 258 various scenarios. 260 3.1. Scenario-1 262 Figure 3 depicts an example of transport slice connecting two 5G RAN 263 nodes (gNB) to three 5G Core user plan function nodes (UPF). In this 264 case a transport slice 20 is created with SLA of latency 10 [msec] or 265 better between 5G endpoints gNBs and UPFs. 267 <--- Transport slice(TS ID:20) ---> 268 with SLA of latency, less 269 than 10[msec] 271 .--. .--. 272 [gNB1] ( )--. ( )--. [UPF1] 273 .'Network ' .' Network ' 274 ( Midhaul ) ( Backhaul ) [UPF2] 275 [gNB2] `----------' `-----------' 276 [UPF3] 278 Figure 3: Example of Transport Slice 20 connecting gNBs to 5G Core 279 UPF 281 3.2. Scenario-2 283 Figure 4 depicts another example where transport slice 30 is created 284 to connect router ER1 to two firewall endpoints with SLA of 10 [Mbps] 285 or higher bandwidth. 287 <--- Transport slice(TS ID:30) ---> 288 with SLA B/W 5Mbps 290 .----. 291 ( )----. 292 .---' '----. [FW1] 293 [ER1] ( Network ) 294 `-----------------------' [FW2] 296 Legends 297 ER: Edge Router 298 FW: Firewall 300 Figure 4: Example of Transport Slice connecting Router to two 301 firewalls 303 3.3. Scenario-3 305 Another example of transport slice is SFC case as shown in Figure 5 306 and Figure 6 which depict an example with SF1 and SF2 (e.g. DPI, 307 Firewall, WAF, video optimizer, content cache server, NAT/CGN, Load 308 balancer) and the transport slice between ER1 and ER2 traverses these 309 SFs. There are two approaches: 311 o Approach-1 shown in Figure 5 where Transport slice 40 chains 312 router ER1, SF1, SF2, and router ER2. Transport slice 40 needs 313 lower than 30 ms delay. However, endpoints SF1 and SF2 are 314 implicitly identified during the transport slice implementation. 315 In this case, a single transport slice is created between ER1 and 316 ER2. 318 o Approach-2 shown in Figure 6 where the transport slice 40 can be 319 broken into transport slices 41, 42, 43. In this case SF1 and SF2 320 are explicityly identified and as a results three transport slides 321 between following endpoints will be realized: 323 * Between endpoints ER1 and SF1 325 * Between endpoints SF1 and SF2 327 * Between endpoints SF2 and ER2 329 <--- Transport slice(TS ID:40) ---> 330 with SLA of latency 30ms 332 +-----+ 333 | SF1 | 334 + *** + .----. 335 * * ( )--. 336 * * ( ) 337 * * --' Network '--. 338 [ER1]******** *********** *************[ER2] 339 `-------------*-*--------' 340 * * 341 + *** + 342 | SF2 | 343 +-----+ 345 Figure 5: Approach-1: Example of Transport Slice connecting Edge 346 Routers ER1 and ER2 with SFC 348 <-- Transport slice (TS ID:40) --> 349 with SLA latency 30ms 350 <- TS41 -> <- TS42 -> <- TS43 --> 351 SLA SLA SLA 352 5[ms] 20[ms] 5[ms] 354 +-----+ 355 | SF1 | 356 + *** + .----. 357 * * ( )--. 358 * * ( ) 359 * * --' Network '--. 360 [ER1]******** *********** *************[ER2] 361 `-------------*-*--------' 362 * * 363 + *** + 364 | SF2 | 365 +-----+ 367 Figure 6: Approach-2: Example of Transport Slice connecting Edge 368 Routers ER1 and ER2 with SFC 370 4. Implementation (aka Realization) of Transport slice 372 In addition to its definition, a Transport Slice has another 373 characteristic which is its implementation (aka realization) in the 374 operator's network. Unlike transport slice definition, which is 375 technology agnostics, its implementation (aka realization) is 376 technology specific. To clarify the concept of transport slice 377 implementation, in following section the implementation of scenarios 378 described above will be described. 380 4.1. Implementation of Scenario-1 382 Figure 7 depicts the implementation (realization) of the transport 383 slice 20 of Figure 3. Operator's transport slice controller receives 384 an abstract API to create a transport slice between 5G endpoints gNB1 385 and gNB2 to 5G Core endpoints UPF1, UPF2 and UPF3 with SLA of 10 386 [ms]. 388 Since in most cases neither 5G RAN endpoints nor the 5G Core 389 endpoints can support any IP/MPLS/Optics services, the endpoints to 390 implement the transport slice 20 will not be the endpoints passed in. 391 This is one of the most important aspects to consider when 392 implementing the transport slices. 394 As shown in Figure 7, the implementation of transport slice 20 395 required the transport slice controller to find out the "best" 396 endpoints which support the realization of transport slice 20 in the 397 network, i.e. endpoints ER1, ER2 and ER3. After that, the 398 implementation of the transport slice 20 will be initiated by 399 creation of various services/tunnels/paths between edge routers ER1, 400 ER2 and ER3. The type of Services/Tunnels/Paths depends on the 401 supported technologies of endpoints ER1, ER2 and ER3. 403 In this scenario, the end points of transport slice implementation 404 are not those endpoints passed in, i.e. 406 o Definition of transport slice is between gNB1 and gNB2 to UPF1, 407 UPF2, and UPF3 409 o Implementation of transport slice is between edge routers ER1, ER2 410 and ER3 412 | Create Transport slice 20 between gNB1 & gNB2 413 | to UPF1 & UPF2 & UPF3 with SLA latency 414 | 10 ms or better 415 v 416 +-------------------------------------+ 417 |Operator-Y Transport Slice Controller| 418 +-------------------------------------+ 419 | Implement (aka Realize) transport slice 20 420 | between ER1, ER2 and ER3 with SLA latency 421 | 10 ms or better 422 v +----+ 423 .----. +UPF1| 424 [gNB1] +----+ ( )---. /+--=-+ 425 \ | |===========================[ER2]+ 426 \| ER1| ( Network ) +----+ 427 /| |===========================[ER3]+-|UPF2| 428 / +----+ `----------------' + +----+ 429 [gNB2] \ 430 \+----+ 431 +UPF3| 432 +----+ 433 Legends 434 === : Tunnels & Services 435 ER: Edge Router 437 Figure 7: Implementation (aka Realization) of Transport slice 20 of 438 Figure-3 440 4.2. Implementation of Scenario-2 442 Figure 8 depicts the realization of transport slice 30 of Figure-4. 443 Operator's Transport Slice Controller receives a request to create a 444 transport slice between network functions R1 and firewalls FW1 and 445 FW2 with SLA of 5 [Mbps]. Depends on the underlying network 446 topology, Operator's transport slice controller will implement (aka 447 realize) the transport slice. For example, if both network functions 448 (i.e. R1, FW1, FW2) and network supports segment routing, two 449 Tunnels/Services of type SR can be created (or used) in the network 450 between R1, FW1 and FW2 to realise the transport slice 30. However, 451 if the network just supports RSVP, two tunnels/services of type RSVP 452 can be used to realize this transport slice. 454 Note that since the network functions ER1, FW1 and FW2 support 455 segment routing, the endpoints of the tunnels in this example are 456 those endpointss passed in, i.e. the endpoints of the both transport 457 slice definiton and its implementation are R1, FW1 and FW2: 459 o Definition of transport slice is between network functions R1 to 460 FW1 and FW2 462 o Implementation of transport slice is between network functions R1 463 to FW1 and FW2 465 We will see in next example that in some scenarios this is not the 466 case and the endpoints of Transport Slice definition might be 467 different from endpoints of its implementation (aka realization of 468 transport slices). 470 It is very clear that regardless of how transport slice is realized 471 in the network (i.e. using tunnels of type RSVP or SR), the 472 definition of transport slice 30 does not change at all but rather 473 its implementation. 475 | Create Transport slice 30 between 476 | ER1 and FW1 and FW2 with SLA 5 Mbps 477 v 478 +---------------------------------------+ 479 | Operator-Y Transport Slice Controller | 480 +---------------------------------------+ 481 | Implement (aka Realize) transport 482 | slice 30 between R1 and FW1 & FW2 483 | with SLA 5 Mbps 484 v 485 .----. 486 +----+ .----( )----. 487 | |=============================[FW1] 488 | ER | ( Network ) 489 | |=============================[FW2] 490 +----+ `----------------' 492 Legends 493 === : Tunnels & Services of type SR 494 or RSVP with SLA 5 Mbps 496 Figure 8: Implementation (aka Realization) of Transport slice 30 of 497 Figure-4 499 4.3. Implementation of Scenario-3 501 Figure 9 depicts the implementation (realization) of the transport 502 slice 40 of Figure 5 where a transport slice needed between network 503 functions R1 and R2 across SF1 and SF2. However, the location of SF1 504 and SF2 are decided internally with a logic in Transport Slice 505 Controller. For example, when SLA requires the high secure transport 506 slice between ER1 and ER2 which in turn results on adding SF2 and SF2 507 to the implementation of transport slice 40 implicitly by transport 508 slice controller. 510 Figure 10 shows the implementation (realization) of the transport 511 slice 40 of Figure 6. In this case the location of SF1 and SF2 has 512 been explicitly decided by higher level logic. In this case three 513 transport slices 41, 42 and 43 will be created separately and 514 eventually bind together to form a single transport slice 40 to meet 515 the SLA that delay is lower than 30 ms. 517 | Create transport slice between ER1 518 | and ER2 with latency 30 [msec] 519 v 520 +------------------+ +-----------+ 521 | Transport slice |<------------>| SF | 522 | controller | | Manager | 523 +------------------+ +-----------+ 524 | Implementation transport slice 40 525 | between ER1 & ER2 traversing SF1 and SF2 526 | with SLA of latency 30 [msec] 527 V 528 <----------------- TS 40 -------------------> 529 +-----+ 530 | SF1 | 531 + === + .----. 532 # # ( )--. 533 # # ( ) 534 # # --' Network '--. 535 [ER1]========= ========= ===================[ER2] 536 `-------------- # # --------' 537 # # 538 + == + 539 | SF2 | 540 +-----+ 542 Legends 543 ===== : Tunnels & Services 545 Figure 9: Implementation (aka Realization) of Transport slice 40 of 546 Figure-5 548 | Requirements on communication 549 | between ER1 and ER2 550 v 551 +-----------------+ +-----------+ 552 | Orchestrator | <--------> | SF Manager| 553 +-----------------+ +-----------+ 554 | Create transport slice between ER1 and SF1, 555 | with latency 5 [msec] 556 | Create transport slice between SF1 and SF2, 557 | with latency 20 [msec] 558 | Create transport slice between SF2 and ER2, 559 | with latency 5 [msec] 560 v 561 +-------------------+ 562 | Transport slice | 563 | manager/controller| 564 +-------------------+ 565 | | | Realize TS 41 between ER and 566 | | | SF1 with latency 5 msec 567 +------+ | +-------+ Realize TS 42 between SF1 and 568 | | | SF2 with latency 20 msec 569 | | | Realize TS 43 between SF2 and 570 | | | ER2 with latency 5 msec 571 v v v 572 <--TS 41--> <--TS 42--> <--TS 43 --> 573 <---------------- TS 40 ----------------> 574 +-----+ 575 #=| SF1 | 576 # +-----+ .----. 577 # # ( )--. 578 # .---#' Network '--. 579 [ER1]=====#( #==========# )#=====[ER2] 580 `--------------#------' # 581 # # 582 +-----+ # 583 | SF2 |====# 584 +-----+ 586 Legend 587 === : Tunnels & Services 589 Figure 10: Implementation (aka Realization) of Transport slice 40 of 590 Figure-6 592 5. Definition of SLA and Isolation levels 594 TBD 596 6. Informative References 598 [TS.23.501-3GPP] 599 3rd Generation Partnership Project (3GPP), "3GPP TS 23.501 600 (V16.2.0): System Architecture for the 5G System (5GS); 601 Stage 2 (Release 16)", September 2019, 602 . 605 Authors' Addresses 607 Reza Rokui 608 Nokia 609 Canada 611 Email: reza.rokui@nokia.com 613 Shunsuke Homma 614 NTT 615 Japan 617 Email: shunsuke.homma.fp@hco.ntt.co.jp 619 Kiran Makhijani 620 Futurewei 621 USA 623 Email: kiranm@futurewei.com