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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-12) exists of draft-irtf-nwcrg-coding-and-congestion-02 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NetWork Communications Research Group (NWCRG) N. Kuhn, Ed. 3 Internet-Draft CNES 4 Intended status: Informational E. Lochin, Ed. 5 Expires: October 29, 2020 ENAC 6 April 27, 2020 8 Network coding for satellite systems 9 draft-irtf-nwcrg-network-coding-satellites-13 11 Abstract 13 This document is the product of the Coding for Efficient Network 14 Communications Research Group (NWCRG). It conforms to the directions 15 found in the NWCRG taxonomy. 17 The objective is to contribute to a larger deployment of network 18 coding techniques in and above the network layer in satellite 19 communication systems. The document also identifies open research 20 issues related to the deployment of network coding in satellite 21 communication systems. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on October 29, 2020. 40 Copyright Notice 42 Copyright (c) 2020 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. A Note on Satellite Networks Topology . . . . . . . . . . . . 3 59 3. Use-cases for Improving SATCOM System Performance Using 60 Network Coding . . . . . . . . . . . . . . . . . . . . . . . 5 61 3.1. Two-way Relay Channel Mode . . . . . . . . . . . . . . . 5 62 3.2. Reliable Multicast . . . . . . . . . . . . . . . . . . . 5 63 3.3. Hybrid Access . . . . . . . . . . . . . . . . . . . . . . 6 64 3.4. LAN Packet Losses . . . . . . . . . . . . . . . . . . . . 7 65 3.5. Varying Channel Conditions . . . . . . . . . . . . . . . 8 66 3.6. Improving Gateway Handover . . . . . . . . . . . . . . . 8 67 4. Research Challenges . . . . . . . . . . . . . . . . . . . . . 9 68 4.1. Joint-use of Network Coding and Congestion Control in 69 SATCOM Systems . . . . . . . . . . . . . . . . . . . . . 9 70 4.2. Efficient Use of Satellite Resources . . . . . . . . . . 10 71 4.3. Interaction with Virtualized Satellite Gateways and 72 Terminals . . . . . . . . . . . . . . . . . . . . . . . . 10 73 4.4. Delay/Disruption Tolerant Networking (DTN) . . . . . . . 10 74 5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 11 75 6. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . 11 76 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 77 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 78 9. Security Considerations . . . . . . . . . . . . . . . . . . . 13 79 10. Informative References . . . . . . . . . . . . . . . . . . . 13 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 82 1. Introduction 84 This document is the product of and represents the collaborative work 85 and consensus of the Coding for Efficient Network Communications 86 Research Group (NWCRG); while it is not an IETF product and not a 87 standard it intends to inform the SATellite COMmunication (SATCOM) 88 and Internet research communities about recent developments in 89 Network Coding. A glossary is proposed in Section 6 to clarify the 90 terminology use throughout the document. 92 As will be shown in this document, the implementation of network 93 coding techniques above the network layer of the ISO model, at 94 application or transport layers, offers an opportunity for improving 95 the end-to-end performance of SATCOM systems. While physical- and 96 link-layer coding error protection is usually enough to provide 97 Quasi-Error Free transmission thus minimizing packet loss, when 98 residual errors at those layers cause packet losses, retransmissions 99 add significant delays (in particular in geostationary system with 100 over 0.7 second round-trip delays). Hence the use of network coding 101 at the upper layers can improve the quality of service in SATCOM 102 subnetworks and eventually favorably impact the experience of end 103 users. 105 While there is an active research Community working on network coding 106 techniques above the network layer in general and in SATCOM in 107 particular, not much of this work made it to commercial systems in 108 the satellite industry. In this context, this document aims at 109 identifying opportunities for further usage of network coding in 110 commercial SATCOM networks. 112 The notation used in this document is based on the NWCRG taxonomy 113 [RFC8406]: 115 o Channel and link error correcting codes are considered part of the 116 PHYsical (PHY) layer error protection and are out of the scope of 117 this document. 119 o Forward Erasure Correction (FEC) (also called Application-Level 120 FEC) operates in and above the network layer and targets packet 121 loss recovery. 123 o This document considers only coding (or coding techniques or 124 coding schemes) that use a linear combination of packets and 125 excludes for example content coding (e.g., to compress a video 126 flow) or other non-linear operation. 128 2. A Note on Satellite Networks Topology 130 There are multiple SATCOM systems, for example broadcast TV, point to 131 point communication or IoT and monitoring. Therefore, depending on 132 the purpose of the system, the associated ground segments 133 architecture will be different. This section focuses on a satellite 134 system that follows the European Telecommunications Standards 135 Institute (ETSI) Digital Video Broadcasting (DVB) standards to 136 provide broadband Internet access via ground-based gateways 137 [ETSIEN2014]. One must note that the overall data capacity of one 138 satellite may be higher than the capacity that one single gateway 139 supports. Hence, there are usually multiple gateways for one unique 140 satellite platform. 142 In this context, Figure 1 shows an example of a multi-gateway 143 satellite system, where BBFRAME stands for Base-Band FRAME, PLFRAME 144 for Physical Layer FRAME and PEP for Performance Enhancing Proxy. 146 More information on a generic SATCOM ground segment architecture for 147 bidirectional Internet access can be found in [SAT2017]. 149 +--------------------------+ 150 | application servers | 151 | (data, coding, multicast)| 152 +--------------------------+ 153 | ... | 154 ----------------------------------- 155 | | | | | | 156 +--------------------+ +--------------------+ 157 | network function | | network function | 158 |(firewall, PEP, etc)| |(firewall, PEP, etc)| 159 +--------------------+ +--------------------+ 160 | ... | IP packets | ... | 161 --- 162 +------------------+ +------------------+ | 163 | access gateway | | access gateway | | 164 +------------------+ +------------------+ | 165 | BBFRAME | | gateway 166 +------------------+ +------------------+ | 167 | physical gateway | | physical gateway | | 168 +------------------+ +------------------+ | 169 --- 170 | PLFRAME | 171 +------------------+ +------------------+ 172 | outdoor unit | | outdoor unit | 173 +------------------+ +------------------+ 174 | satellite link | 175 +------------------+ +------------------+ 176 | outdoor unit | | outdoor unit | 177 +------------------+ +------------------+ 178 | | 179 +------------------+ +------------------+ 180 | sat terminals | | sat terminals | 181 +------------------+ +------------------+ 182 | | | | 183 +----------+ | +----------+ | 184 |end user 1| | |end user 3| | 185 +----------+ | +----------+ | 186 +----------+ +----------+ 187 |end user 2| |end user 4| 188 +----------+ +----------+ 190 Figure 1: Data plane functions in a generic satellite multi-gateway 191 system. More details can be found in DVB standard documents. 193 3. Use-cases for Improving SATCOM System Performance Using Network 194 Coding 196 This section details use-cases where network coding techniques could 197 improve SATCOM system performance. 199 3.1. Two-way Relay Channel Mode 201 This use-case considers two-way communication between end-users, 202 through a satellite link as seen in Figure 2. 204 Satellite terminal A sends a packet flow A and satellite terminal B 205 sends a packet flow B to a coding server. The coding server then 206 sends a combination of both flows instead of each individual flows. 207 This results in non-negligible capacity savings that has been 208 demonstrated in the past [ASMS2010]. In the example, a dedicated 209 coding server is introduced (note that its location could be 210 different based on deployment use-case). The network coding 211 operations could also be done at the satellite level, although this 212 would require a lot of computational resource on-board and may not be 213 supported by today's satellites. 215 -X}- : traffic from satellite terminal X to the server 216 ={X+Y= : traffic from X and Y combined sent from 217 the server to terminals X and Y 219 +-----------+ +-----+ 220 |Sat term A |--A}-+ | | 221 +-----------+ | | | +---------+ +------+ 222 ^^ +--| |--A}--| |--A}--|Coding| 223 || | SAT |--B}--| Gateway |--B}--|Server| 224 ===={A+B=========| |={A+B=| |={A+B=| | 225 || | | +---------+ +------+ 226 vv +--| | 227 +-----------+ | | | 228 |Sat term B |--B}-+ | | 229 +-----------+ +-----+ 231 Figure 2: Network Architecture for Two-way Relay Channel using NC 233 3.2. Reliable Multicast 235 The use of multicast servers is one way to better utilize satellite 236 broadcast capabilities. Multicast is proposed in the SHINE ESA 237 project [I-D.vazquez-nfvrg-netcod-function-virtualization] [SHINE]. 238 This use-case considers adding redundancy to a multicast flow 239 depending on what has been received by different end-users, resulting 240 in non-negligible savings of the scarce SATCOM resources. This 241 scenario is shown in Figure 3. 243 -Li}- : packet indicating the loss of packet i of a multicast flow M 244 ={M== : multicast flow including the missing packets 246 +-----------+ +-----+ 247 |Terminal A |-Li}-+ | | 248 +-----------+ | | | +---------+ +------+ 249 ^^ +-| |-Li}--| | |Multi | 250 || | SAT |-Lj}--| Gateway |--|Cast | 251 ===={M==========| |={M===| | |Server| 252 || | | +---------+ +------+ 253 vv +-| | 254 +-----------+ | | | 255 |Terminal B |-Lj}-+ | | 256 +-----------+ +-----+ 258 Figure 3: Network Architecture for a Reliable Multicast using NC 260 A multicast flow (M) is forwarded to both satellite terminals A and 261 B. However packet Ni (respectively Nj) gets lost at terminal A 262 (respectively B), and terminal A (respectively B) returns a negative 263 acknowledgment Li (respectively Lj), indicating that the packet is 264 missing. Using coding, either the access gateway or the multicast 265 server can include a repair packet (rather than the individual Ni and 266 Nj packets) in the multicast flow to let both terminals recover from 267 losses. 269 This could also be achieved by using other multicast or broadcast 270 systems, such as NACK-Oriented Reliable Multicast (NORM) [RFC5740] or 271 File Delivery over Unidirectional Transport (FLUTE) [RFC6726]. Both 272 NORM and FLUTE are limited to block coding, none of them supporting 273 more flexible sliding window encoding schemes that allow decoding 274 before receiving the whole block an added delay benefit 275 [RFC8406][RFC8681]. 277 3.3. Hybrid Access 279 This use-case considers improving multiple path communications with 280 network coding at the transport layer (see Figure 4, where DSL stands 281 for Digital Subscriber Line, LTE for Long Term Evolution and SAT for 282 SATellite). This use-case is inspired by the Broadband Access via 283 Integrated Terrestrial Satellite Systems (BATS) project and has been 284 published as an ETSI Technical Report [ETSITR2017]. 286 To cope with packet loss (due to either end-user mobility or 287 physical-layer residual errors), network coding can be introduced 288 both at the Customer Premises Equipment (CPE) and at the 289 concentrator. Apart from packet losses, other gains from this 290 approach include a better tolerance to out-of-order packet delivery 291 which occur when exploited links exhibit high asymmetry in terms of 292 Round-Trip Time (RTT). Depending on the ground architecture 293 [I-D.chin-nfvrg-cloud-5g-core-structure-yang] [SAT2017], some ground 294 equipment might be hosting both SATCOM and cellular network 295 functionality. 297 -{}- : bidirectional link 299 +---+ +--------------+ 300 +-{}-|SAT|-{}-|BACKBONE | 301 +----+ +---+ | +---+ |+------------+| 302 |End |-{}-|CPE|-{}-| ||CONCENTRATOR|| 303 |User| +---+ | +---+ |+------------+| +-----------+ 304 +----+ |-{}-|DSL|-{}-| |-{}-|Application| 305 | +---+ | | |Server | 306 | | | +-----------+ 307 | +---+ | | 308 +-{}-|LTE|-{}-+--------------+ 309 +---+ 311 Figure 4: Network Architecture for a Hybrid Access Using Network 312 Coding 314 3.4. LAN Packet Losses 316 This use-case considers using network coding in the scenario where a 317 lossy WIFI link is used to connect to the SATCOM network. When 318 encrypted end-to-end applications based on UDP are used, a 319 Performance Enhancing Proxy (PEP) cannot operate hence other 320 mechanism need to be used. The WIFI packet losses will result in an 321 end-to-end retransmission that will harm the end-user quality of 322 experience and poorly utilize SATCOM bottleneck resource for non- 323 revenue generating traffic. In this use-case, adding network coding 324 techniques will prevent the end-to-end retransmission from occurring 325 since the packet losses would probably recovered. 327 The architecture is shown in Figure 5. 329 -{}- : bidirectional link 330 -''- : Wi-Fi link 331 C : where network coding techniques could be introduced 333 +----+ +--------+ +---+ +-------+ +-------+ +--------+ 334 |End | |Sat. | |SAT| |Phy | |Access | |Network | 335 |user|-''-|Terminal|-{}-| |-{}-|Gateway|-{}-|Gateway|-{}-|Function| 336 +----+ +--------+ +---+ +-------+ +-------+ +--------+ 337 C C C C 339 Figure 5: Network Architecture for dealing with LAN Losses 341 3.5. Varying Channel Conditions 343 This use-case considers the usage of network coding to cope with sub 344 second physical channel condition changes where the physical-layer 345 mechanisms (Adaptive Coding and Modulation (ACM)) may not adapt the 346 modulation and error-correction coding in time: the residual errors 347 lead to higher layer packet losses that can be recovered with network 348 coding. This use-case is mostly relevant when mobile users are 349 considered or when the satellite frequency band introduces quick 350 changes in channel condition (Q/V bands, Ka band, etc.). Depending 351 on the use-case (e.g., very high frequency bands, mobile users) or 352 depending on the deployment use-cases (e.g., performance of the 353 network between each individual data block), the relevance of adding 354 network coding is different. 356 The system architecture is shown in Figure 6. 358 -{}- : bidirectional link 359 C : where network coding techniques could be introduced 361 +---------+ +---+ +--------+ +-------+ +--------+ 362 |Satellite| |SAT| |Physical| |Access | |Network | 363 |Terminal |-{}-| |-{}-|Gateway |-{}-|Gateway|-{}-|Function| 364 +---------+ +---+ +--------+ +-------+ +--------+ 365 C C C C 367 Figure 6: Network Architecture for dealing with Varying Link 368 Characteristics 370 3.6. Improving Gateway Handover 372 This use-case considers the recovery of packets that may be lost 373 during gateway handover. Whether for off-loading a given equipment 374 or because the transmission quality differs from gateway to gateway, 375 switching the transmission gateway may be beneficial. However, 376 packet losses can occur if the gateways are not properly synchronized 377 or if the algorithm used to trigger gateway handover is not properly 378 tuned. During these critical phases, network coding can be added to 379 improve the reliability of the transmission and allow a seamless 380 gateway handover. 382 Figure 7 illustrates this use-case. 384 -{}- : bidirectional link 385 ! : management interface 386 C : where network coding techniques could be introduced 387 C C 388 +--------+ +-------+ +--------+ 389 |Physical| |Access | |Network | 390 +-{}-|gateway |-{}-|gateway|-{}-|function| 391 | +--------+ +-------+ +--------+ 392 | ! ! 393 +---------+ +---+ +---------------+ 394 |Satellite| |SAT| | Control plane | 395 |Terminal |-{}-| | | manager | 396 +---------+ +---+ +---------------+ 397 | ! ! 398 | +--------+ +-------+ +--------+ 399 +-{}-|Physical|-{}-|Access |-{}-|Network | 400 |gateway | |gateway| |function| 401 +--------+ +-------+ +--------+ 402 C C 404 Figure 7: Network Architecture for dealing with Gateway Handover 406 4. Research Challenges 408 This section proposes a few potential approaches to introduce and use 409 network coding in SATCOM systems. 411 4.1. Joint-use of Network Coding and Congestion Control in SATCOM 412 Systems 414 Many SATCOM systems typically use Performance Enhancing Proxy (PEP) 415 RFC 3135 [RFC3135]. PEPs usually split end-to-end connections and 416 forward transport or application layer packets to the satellite 417 baseband gateway that deals with layer-2 and layer-1 encapsulation. 418 PEPs contribute to mitigate congestion in a SATCOM systems by 419 limiting the impact of long delays on Internet protocols. A PEP 420 mechanism could also include network coding operation and thus 421 support the use-cases that have been discussed in the Section 3 of 422 this document. 424 Deploying network coding in the PEP could be relevant and be 425 independent from the specifics of a SATCOM link. This however leads 426 to research questions dealing with the potential interaction between 427 network coding and congestion control. This is discussed in 428 [I-D.irtf-nwcrg-coding-and-congestion] 430 4.2. Efficient Use of Satellite Resources 432 There is a recurrent trade-off in SATCOM systems: how much overhead 433 from redundant reliability packets can be introduced to guarantee a 434 better end-user QoE while optimizing capacity usage ? At which layer 435 this supplementary redundancy should be added ? 437 This problem has been tackled in the past by the deployment of 438 physical-layer error-correction codes, but there remains questions on 439 adapting the coding overhead and added delay for, e.g., the quickly 440 varying channel conditions use-case where ACM may not be reacting 441 quickly enough as was discussed in Section 3.5. 443 4.3. Interaction with Virtualized Satellite Gateways and Terminals 445 In the emerging virtualized network infrastructure, network coding 446 could be easily deployed as a Virtual Network Functions (VNF). The 447 next generation of SATCOM ground segments will rely on a virtualized 448 environment to integrate to terrestrial networks. This trend towards 449 Network Function Virtualization (NFV) is also central to 5G and next 450 generation cellular networks, making this research applicable to 451 other deployment scenarios 452 [I-D.chin-nfvrg-cloud-5g-core-structure-yang]. As one example, the 453 network coding VNF deployment in a virtualized environment has been 454 presented in [I-D.vazquez-nfvrg-netcod-function-virtualization]. 456 A research challenge would be the optimization of the NFV service 457 function chaining, considering a virtualized infrastructure and other 458 SATCOM specific functions, in order to guarantee efficient radio-link 459 usage and provide easy-to-deploy SATCOM services. Moreover, another 460 challenge related to a virtualized SATCOM equipment is the management 461 of limited buffered capacities in large gateways. 463 4.4. Delay/Disruption Tolerant Networking (DTN) 465 Communications among deep-space platforms and terrestrial gateways 466 can be a challenge. Reliable end-to-end (E2E) communications over 467 such paths must cope with very long delays and frequent link 468 disruptions; indeed, E2E connectivity may be available only 469 intermittently. Delay/Disruption Tolerant Networking (DTN) [RFC4838] 470 is a solution to enable reliable internetworking space communications 471 where both standard ad-hoc routing and E2E Internet protocols cannot 472 be used. Moreover, DTN can also be seen as an alternative solution 473 to transfer data between a central PEP and a remote PEP. 475 Network Coding enables E2E reliable communications over a DTN with 476 potential adaptive re-encoding, as proposed in [THAI15]. Here, the 477 use-cases proposed in Section 3.5 would legitimize the usage of 478 network coding within the DTN stack to improve the physical channel 479 utilization and minimize the effects of the E2E transmission delays. 480 In this context, the use of packet erasure coding techniques inside a 481 Consultative Committee for Space Data Systems (CCSDS) architecture 482 has been specified in [CCSDS-131.5-O-1]. One research challenge 483 remains on how such network coding can be integrated in the IETF DTN 484 stack. 486 5. Conclusion 488 This document introduces some wide-scale network coding techniques 489 opportunities in satellite telecommunications systems. 491 Even though this document focuses on satellite systems, it is worth 492 pointing out that some scenarios proposed here may be relevant to 493 other wireless telecommunication systems. As one example, the 494 generic architecture proposed in Figure 1 may be mapped onto cellular 495 networks as follows: the 'network function' block gathers some of the 496 functions of the Evolved Packet Core subsystem, while the 'access 497 gateway' and 'physical gateway' blocks gather the same type of 498 functions as the Universal Mobile Terrestrial Radio Access Network. 499 This mapping extends the opportunities identified in this document 500 since they may also be relevant for cellular networks. 502 6. Glossary 504 The glossary of this memo extends the glossary of the taxonomy 505 document [RFC8406] as follows: 507 o ACM : Adaptive Coding and Modulation; 509 o BBFRAME: Base-Band FRAME - satellite communication layer 2 510 encapsulation work as follows: (1) each layer 3 packet is 511 encapsulated with a Generic Stream Encapsulation (GSE) mechanism, 512 (2) GSE packets are gathered to create BBFRAMEs, (3) BBFRAMEs 513 contain information related to how they have to be modulated (4) 514 BBFRAMEs are forwarded to the physical-layer; 516 o CPE: Customer Premises Equipment; 518 o COM: COMmunication; 519 o DSL: Digital Subscriber Line; 521 o DTN: Delay/Disruption Tolerant Networking; 523 o DVB: Digital Video Broadcasting; 525 o E2E: End-to-end; 527 o ETSI: European Telecommunications Standards Institute; 529 o FEC: Forward Erasure Correction; 531 o FLUTE: File Delivery over Unidirectional Transport; 533 o IntraF: Intra-Flow Coding; 535 o InterF: Inter-Flow Coding; 537 o IoT: Internet of Things; 539 o LTE: Long Term Evolution; 541 o MPC: Multi-Path Coding; 543 o NC: Network Coding; 545 o NFV: Network Function Virtualization - concept of running 546 software-defined network functions; 548 o NORM: NACK-Oriented Reliable Multicast; 550 o PEP: Performance Enhancing Proxy [RFC3135] - a typical PEP for 551 satellite communications include compression, caching and TCP 552 acceleration; 554 o PLFRAME: Physical Layer FRAME - modulated version of a BBFRAME 555 with additional information (e.g., related to synchronization); 557 o QEF: Quasi-Error-Free; 559 o QoE: Quality-of-Experience; 561 o QoS: Quality-of-Service; 563 o RTT: Round-Trip Time; 565 o SAT: SATellite; 566 o SATCOM: generic term related to all kinds of SATellite 567 COMmunication systems; 569 o SPC: Single-Path Coding; 571 o VNF: Virtual Network Function - implementation of a network 572 function using software. 574 7. Acknowledgements 576 Many thanks to John Border, Stuart Card, Tomaso de Cola, Vincent 577 Roca, Lloyd Wood and Marie-Jose Montpetit for their help in writing 578 this document. 580 8. IANA Considerations 582 This memo includes no request to IANA. 584 9. Security Considerations 586 Security considerations are inherent to any access network, and in 587 particular SATCOM systems. The use of FEC or Network Coding in 588 SATCOM also comes with risks (e.g., a single corrupted redundant 589 packet may propagate to several flows when they are protected 590 together in an Inter-Flow coding approach, see section Section 3). 591 While this document does not further elaborate on this, the security 592 considerations discussed in [RFC6363] apply. 594 10. Informative References 596 [ASMS2010] 597 De Cola, T. and et. al., "Demonstration at opening session 598 of ASMS 2010", Advanced Satellite Multimedia Systems 599 (ASMS) Conference , 2010. 601 [CCSDS-131.5-O-1] 602 "Erasure correcting codes for use in near-earth and deep- 603 space communications", CCSDS Experimental 604 specification 131.5-0-1, 2014. 606 [ETSIEN2014] 607 "Digital Video Broadcasting (DVB); Second Generation DVB 608 Interactive Satellite System (DVB-RCS2); Part 2: Lower 609 Layers for Satellite standard", ETSI EN 301 545-2, 2014. 611 [ETSITR2017] 612 "Satellite Earth Stations and Systems (SES); Multi-link 613 routing scheme in hybrid access network with heterogeneous 614 links", ETSI TR 103 351, 2017. 616 [I-D.chin-nfvrg-cloud-5g-core-structure-yang] 617 Chen, C. and Z. Pan, "Yang Data Model for Cloud Native 5G 618 Core structure", draft-chin-nfvrg-cloud-5g-core-structure- 619 yang-00 (work in progress), December 2017. 621 [I-D.irtf-nwcrg-coding-and-congestion] 622 Kuhn, N., Lochin, E., Michel, F., and M. Welzl, "Coding 623 and congestion control in transport", draft-irtf-nwcrg- 624 coding-and-congestion-02 (work in progress), March 2020. 626 [I-D.vazquez-nfvrg-netcod-function-virtualization] 627 Vazquez-Castro, M., Do-Duy, T., Romano, S., and A. Tulino, 628 "Network Coding Function Virtualization", draft-vazquez- 629 nfvrg-netcod-function-virtualization-02 (work in 630 progress), November 2017. 632 [RFC3135] Border, J., Kojo, M., Griner, J., Montenegro, G., and Z. 633 Shelby, "Performance Enhancing Proxies Intended to 634 Mitigate Link-Related Degradations", RFC 3135, 635 DOI 10.17487/RFC3135, June 2001, 636 . 638 [RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst, 639 R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant 640 Networking Architecture", RFC 4838, DOI 10.17487/RFC4838, 641 April 2007, . 643 [RFC5740] Adamson, B., Bormann, C., Handley, M., and J. Macker, 644 "NACK-Oriented Reliable Multicast (NORM) Transport 645 Protocol", RFC 5740, DOI 10.17487/RFC5740, November 2009, 646 . 648 [RFC6363] Watson, M., Begen, A., and V. Roca, "Forward Error 649 Correction (FEC) Framework", RFC 6363, 650 DOI 10.17487/RFC6363, October 2011, 651 . 653 [RFC6726] Paila, T., Walsh, R., Luby, M., Roca, V., and R. Lehtonen, 654 "FLUTE - File Delivery over Unidirectional Transport", 655 RFC 6726, DOI 10.17487/RFC6726, November 2012, 656 . 658 [RFC8406] Adamson, B., Adjih, C., Bilbao, J., Firoiu, V., Fitzek, 659 F., Ghanem, S., Lochin, E., Masucci, A., Montpetit, M-J., 660 Pedersen, M., Peralta, G., Roca, V., Ed., Saxena, P., and 661 S. Sivakumar, "Taxonomy of Coding Techniques for Efficient 662 Network Communications", RFC 8406, DOI 10.17487/RFC8406, 663 June 2018, . 665 [RFC8681] Roca, V. and B. Teibi, "Sliding Window Random Linear Code 666 (RLC) Forward Erasure Correction (FEC) Schemes for 667 FECFRAME", RFC 8681, DOI 10.17487/RFC8681, January 2020, 668 . 670 [SAT2017] Ahmed, T., Dubois, E., Dupe, JB., Ferrus, R., Gelard, P., 671 and N. Kuhn, "Software-defined satellite cloud RAN", 672 International Journal on Satellite Communnications and 673 Networking vol. 36 - https://doi.org/10.1002/sat.1206, 674 2017. 676 [SHINE] Pietro Romano, S. and et. al., "Secure Hybrid In Network 677 caching Environment (SHINE) ESA project", ESA project , 678 2017 on-going. 680 [THAI15] Thai, T., Chaganti, V., Lochin, E., Lacan, J., Dubois, E., 681 and P. Gelard, "Enabling E2E reliable communications with 682 adaptive re-encoding over delay tolerant networks", 683 Proceedings of the IEEE International Conference on 684 Communications http://dx.doi.org/10.1109/ICC.2015.7248441, 685 June 2015. 687 Authors' Addresses 689 Nicolas Kuhn (editor) 690 CNES 691 18 Avenue Edouard Belin 692 Toulouse 31400 693 France 695 Email: nicolas.kuhn@cnes.fr 697 Emmanuel Lochin (editor) 698 ENAC 699 10 Avenue Edouard Belin 700 Toulouse 31400 701 France 703 Email: emmanuel.lochin@enac.fr