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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Previdi, Ed. 3 Internet-Draft C. Filsfils, Ed. 4 Intended status: Standards Track Cisco Systems, Inc. 5 Expires: October 20, 2014 B. Decraene 6 S. Litkowski 7 Orange 8 M. Horneffer 9 R. Geib 10 Deutsche Telekom 11 R. Shakir 12 British Telecom 13 R. Raszuk 14 Individual 15 April 18, 2014 17 SPRING Problem Statement and Requirements 18 draft-previdi-spring-problem-statement-03 20 Abstract 22 The ability for a node to specify a forwarding path, other than the 23 normal shortest path, that a particular packet will traverse, 24 benefits a number of network functions. Source-based routing 25 mechanisms have previously been specified for network protocols, but 26 have not seen widespread adoption. In this context, the term 27 'source' means 'the point at which the explicit route is imposed'. 29 This document outlines various use cases, with their requirements, 30 that need to be taken into account by the Source Packet Routing in 31 Networking (SPRING) architecture for unicast traffic. Multicast use- 32 cases and requirements are out of scope of this document. 34 Requirements Language 36 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 37 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 38 document are to be interpreted as described in RFC 2119 [RFC2119]. 40 Status of This Memo 42 This Internet-Draft is submitted in full conformance with the 43 provisions of BCP 78 and BCP 79. 45 Internet-Drafts are working documents of the Internet Engineering 46 Task Force (IETF). Note that other groups may also distribute 47 working documents as Internet-Drafts. The list of current Internet- 48 Drafts is at http://datatracker.ietf.org/drafts/current/. 50 Internet-Drafts are draft documents valid for a maximum of six months 51 and may be updated, replaced, or obsoleted by other documents at any 52 time. It is inappropriate to use Internet-Drafts as reference 53 material or to cite them other than as "work in progress." 55 This Internet-Draft will expire on October 20, 2014. 57 Copyright Notice 59 Copyright (c) 2014 IETF Trust and the persons identified as the 60 document authors. All rights reserved. 62 This document is subject to BCP 78 and the IETF Trust's Legal 63 Provisions Relating to IETF Documents 64 (http://trustee.ietf.org/license-info) in effect on the date of 65 publication of this document. Please review these documents 66 carefully, as they describe your rights and restrictions with respect 67 to this document. Code Components extracted from this document must 68 include Simplified BSD License text as described in Section 4.e of 69 the Trust Legal Provisions and are provided without warranty as 70 described in the Simplified BSD License. 72 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 75 2. Dataplanes . . . . . . . . . . . . . . . . . . . . . . . . . 4 76 3. IGP-based MPLS Tunneling . . . . . . . . . . . . . . . . . . 4 77 3.1. Example of IGP-based MPLS Tunnels . . . . . . . . . . . . 4 78 4. Fast Reroute . . . . . . . . . . . . . . . . . . . . . . . . 5 79 5. Traffic Engineering . . . . . . . . . . . . . . . . . . . . . 5 80 5.1. Examples of Traffic Engineering Use Cases . . . . . . . . 6 81 5.1.1. Traffic Engineering without Bandwidth Admission 82 Control . . . . . . . . . . . . . . . . . . . . . . . 6 83 5.1.2. Traffic Engineering with Bandwidth Admission Control 10 84 6. Interoperability with non-SPRING nodes . . . . . . . . . . . 13 85 7. OAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 86 8. Security . . . . . . . . . . . . . . . . . . . . . . . . . . 14 87 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 88 10. Manageability Considerations . . . . . . . . . . . . . . . . 14 89 11. Security Considerations . . . . . . . . . . . . . . . . . . . 14 90 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 91 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 92 13.1. Normative References . . . . . . . . . . . . . . . . . . 15 93 13.2. Informative References . . . . . . . . . . . . . . . . . 15 94 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 96 1. Introduction 98 The ability for a node to specify a unicast forwarding path, other 99 than the normal shortest path, that a particular packet will 100 traverse, benefits a number of network functions, for example: 102 Some types of network virtualization, including multi-topology 103 networks and the partitioning of network resources for VPNs 105 Network, link, path and node protection such as fast re-route 107 Network programmability 109 OAM techniques 111 Simplification and reduction of network signaling components 113 Load balancing and traffic engineering 115 Source-based routing mechanisms have previously been specified for 116 network protocols, but have not seen widespread adoption other than 117 in MPLS traffic engineering. 119 These network functions may require greater flexibility and per 120 packet source imposed routing than can be achieved through the use of 121 the previously defined methods. In the context of this charter, 122 'source' means 'the point at which the explicit route is imposed'. 124 In this context, Source Packet Routing in Networking (SPRING) 125 architecture is being defined in order to address the use cases and 126 requirements described in this document. 128 SPRING architecture should allow incremental and selective deployment 129 without any requirement of flag day or massive upgrade of all network 130 elements. 132 SPRING architecture should allow optimal virtualization: put policy 133 state in the packet header and not in the intermediate nodes along 134 the path. Hence, the policy is completely virtualized away from 135 midpoints and tail-ends. 137 SPRING architecture objective is not to replace existing source 138 routing and traffic engineering mechanisms but rather complement them 139 and address use cases where removal of signaling and path state in 140 the core is a requirement. 142 2. Dataplanes 144 The SPRING architecture should be general in order to ease its 145 applicability to different dataplanes. 147 MPLS dataplane doesn't require any modification in order to apply a 148 source-based routed model (e.g.: 149 [I-D.filsfils-spring-segment-routing-mpls]). 151 IPv6 specification [RFC2460], amended by [RFC6564] and [RFC7045], 152 defines the Routing Extension Header which provides IPv6 source-based 153 routing capabilities. 155 The SPRING architecture should leverage existing MPLS dataplane 156 without any modification and leverage IPv6 dataplane with a new IPv6 157 Routing Header Type (IPv6 Routing Header is defined in [RFC2460]). 159 3. IGP-based MPLS Tunneling 161 The source-based routing model, applied to the MPLS dataplane, offers 162 the ability to tunnel services (VPN, VPLS, VPWS) from an ingress PE 163 to an egress PE, with or without the expression of an explicit path 164 and without requiring forwarding plane or control plane state in 165 intermediate nodes. 167 The source-based routing model, applied to the MPLS dataplane, offers 168 the ability to tunnel unicast services (VPN, VPLS, VPWS) from an 169 ingress PE to an egress PE, with or without the expression of an 170 explicit path and without requiring forwarding plane or control plane 171 state in intermediate nodes. p2mp and mp2mp tunnels are out of the 172 scope of this document. 174 3.1. Example of IGP-based MPLS Tunnels 176 This section illustrates an example use-case taken from 177 [I-D.filsfils-spring-segment-routing-use-cases]. 179 P1---P2 180 / \ 181 A---CE1---PE1 PE2---CE2---Z 182 \ / 183 P3---P4 185 Figure 1: IGP-based MPLS Tunneling 187 In Figure 1 above, the four nodes A, CE1, CE2 and Z are part of the 188 same VPN. CE2 advertises to PE2 a route to Z. PE2 binds a local 189 label LZ to that route and propagates the route and its label via 190 MPBGP to PE1 with nhop 192.168.0.2. PE1 installs the VPN prefix Z in 191 the appropriate VRF and resolves the next-hop onto the node segment 192 associated with PE2. 194 In order to cope with the reality of current deployments, the SPRING 195 architecture should allow PE to PE forwarding according to the IGP 196 shortest path without the addition of any other signaling protocol. 197 The packet each PE forwards across the network will contain (within 198 their label stack) the necessary information derived from the 199 topology database in order to deliver the packet to the remote PE. 201 4. Fast Reroute 203 FRR technologies have been deployed by network operators in order to 204 cope with link or node failures through pre-computation of backup 205 paths. 207 The SPRING architecture should address following requirements: 209 o support of FRR on any topology 211 o pre-computation and setup of backup path without any additional 212 signaling (other than the regular IGP/BGP protocols) 214 o support of shared risk constraints 216 o support of node and link protection 218 o support of microloop avoidance 220 Further illustrations of the problem statement for FRR are to be 221 found in [I-D.francois-spring-resiliency-use-case]. 223 5. Traffic Engineering 225 Traffic Engineering has been addressed using IGP protocol extensions 226 (for resources information propagation) and RSVP-TE for signaling 227 explicit paths. Different contexts and modes have been defined 228 (single vs. multiple domains, with or without bandwidth admission 229 control, centralized vs. distributed path computation, etc). 231 In all cases, one of the major components of the TE architecture is 232 the soft state based signaling protocol (RSVP-TE) which is used in 233 order to signal and establish the explicit path. Each path, once 234 computed, need to be signaled and state for each path must be present 235 in each node traversed by the path. This incurs a scalability 236 problem especially in the context of SDN where traffic 237 differentiation may be done at a finer granularity (e.g.: application 238 specific). Also the amount of state needed to be maintained and 239 periodically refreshed in all involved nodes contributes 240 significantly to complexity and the number of failures cases, and 241 thus increases operational effort while decreasing overall network 242 reliability. 244 The source-based routing model allows traffic engineering to be 245 implemented without the need of a signaling component. 247 The SPRING architecture should support traffic engineering, 248 including: 250 o loose or strict options 252 o bandwidth admission control 254 o distributed vs. centralized model (PCE, SDN Controller) 256 o disjointness in dual-plane networks 258 o egress peering traffic engineering 260 o load-balancing among non-parallel links 262 o Limiting (scalable, preferably zero) per-service state and 263 signaling on midpoint and tail-end routers. 265 o ECMP-awareness 267 o node resiliency property (i.e.: the traffic-engineering policy is 268 not anchored to a specific core node whose failure could impact 269 the service. 271 5.1. Examples of Traffic Engineering Use Cases 273 As documented in [I-D.filsfils-spring-segment-routing-use-cases] here 274 follows the description of two sets of use cases: 276 o Traffic Engineering without Admission Control 278 o Traffic Engineering with Admission Control 280 5.1.1. Traffic Engineering without Bandwidth Admission Control 282 In this section, we describe Traffic Engineering use-cases without 283 bandwidth admission control. 285 5.1.1.1. Disjointness in dual-plane networks 287 Many networks are built according to the dual-plane design, as 288 illustrated in Figure 2: 290 Each access region k is connected to the core by two C routers 291 (C(1,k) and C(2,k)). 293 C(1,k) is part of plane 1 and aggregation region K 295 C(2,k) is part of plane 2 and aggregation region K 297 C(1,k) has a link to C(2, j) iff k = j. 299 The core nodes of a given region are directly connected. 300 Inter-region links only connect core nodes of the same plane. 302 {C(1,k) has a link to C(1, j)} iff {C(2,k) has a link to C(2, j)}. 304 The distribution of these links depends on the topological 305 properties of the core of the AS. The design rule presented 306 above specifies that these links appear in both core planes. 308 We assume a common design rule found in such deployments: the inter- 309 plane link costs (Cik-Cjk where i<>j) are set such that the route to 310 an edge destination from a given plane stays within the plane unless 311 the plane is partitioned. 313 Edge Router A 314 / \ 315 / \ 316 / \ Agg Region A 317 / \ 318 / \ 319 C1A----------C2A 320 | \ | \ 321 | \ | \ 322 | C1B----------C2B 323 Plane1 | | | | Plane2 324 | | | | 325 C1C--|-----C2C | 326 \ | \ | 327 \ | \ | 328 C1Z----------C2Z 329 \ / 330 \ / Agg Region Z 331 \ / 332 \ / 333 Edge Router Z 335 Figure 2: Dual-Plane Network and Disjointness 337 In this scenario, the operator requires the ability to deploy 338 different strategies. For example, A should be able to use the three 339 following options: 341 o the traffic is load-balanced across any ECMP path through the 342 network 344 o the traffic is load-balanced across any ECMP path within the 345 Plane1 of the network 347 o the traffic is load-balanced across any ECMP path within the 348 Plane2 of the network 350 Most of the data traffic from A to Z would use the first option, such 351 as to exploit the capacity efficiently. The operator would use the 352 two other choices for specific premium traffic that has requested 353 disjoint transport. 355 The SPRING architecture should support this use case with the 356 following requirements: 358 o Zero per-service state and signaling on midpoint and tail-end 359 routers. 361 o ECMP-awareness. 363 o Node resiliency property: the traffic-engineering policy is not 364 anchored to a specific core node whose failure could impact the 365 service. 367 5.1.1.2. Egress Peering Traffic Engineering 369 +------+ 370 | | 371 +---D F 372 +---------+ / | AS 2 |\ +------+ 373 | X |/ +------+ \ | Z |---L/8 374 A C---+ \| | 375 | |\\ \ +------+ /| AS 4 |---M/8 376 | AS1 | \\ +-H |/ +------+ 377 | | \\ | G 378 +----P----+ +===E AS 3 | 379 | +--Q---+ 380 | | 381 +----------------+ 383 Figure 3: Reference Diagram 385 Assuming the topology illustrated in the diagram above, a solution is 386 required to allow a centralized controller to force an ingress PE or 387 a content source to use a specific egress PE and a specific egress 388 interface of that egress PE to reach some destination. We call this 389 solution "EPE" for "Egress Peer Engineering". 391 For example, the solution MUST provide a mechanism in order to 392 instruct node A to prefer C-H link for destination L/8 and prefer the 393 parallel links between C and E for destination M/8. 395 The solution MUST apply to the Internet use-case where the Internet 396 routes are assumed to use IPv4 unlabeled. The solution MUST NOT 397 require to place the internet routes in a VRF and allocate labels on 398 a per route, per-path basis. 400 The solution MUST NOT make assumption in the way iBGP scheme is 401 deployed (RRs, Confederations or iBGP full mesh). 403 5.1.1.3. Load-balancing among non-parallel links 405 The SPRING architecture should allow a given node should be able to 406 load share traffic across multiple non parallel links even if these 407 ones lead to different neighbors. This may be useful to support 408 traffic engineering policies. 410 +---C---D---+ 411 | | 412 PE1---A---B-----F-----E---PE2 414 Figure 4: Multiple (non-parallel) Adjacencies 416 In the above example, the operator requires PE1 to load-balance its 417 PE2-destined traffic between the ABCDE and ABFE paths. 419 5.1.2. Traffic Engineering with Bandwidth Admission Control 421 The implementation of bandwidth admission control within a network 422 (and its possible routing consequence which consists in routing along 423 explicit paths where the bandwidth is available) requires a capacity 424 planning process. 426 The spreading of load among ECMP paths is a key attribute of the 427 capacity planning processes applied to packet-based networks. 429 5.1.2.1. Capacity Planning Process 431 Capacity Planning anticipates the routing of the traffic matrix onto 432 the network topology, for a set of expected traffic and topology 433 variations. The heart of the process consists in simulating the 434 placement of the traffic along ECMP-aware shortest-paths and 435 accounting for the resulting bandwidth usage. 437 The bandwidth accounting of a demand along its shortest-path is a 438 basic capability of any planning tool or PCE server. 440 For example, in the network topology described below, and assuming a 441 default IGP metric of 1 and IGP metric of 2 for link GF, a 1600Mbps 442 A-to-Z flow is accounted as consuming 1600Mbps on links AB and FZ, 443 800Mbps on links BC, BG and GF, and 400Mbps on links CD, DF, CE and 444 EF. 446 C-----D 447 / \ \ 448 A---B +--E--F--Z 449 \ / 450 G------+ 452 Figure 5: Capacity Planning an ECMP-based demand 454 ECMP is extremely frequent in SP, Enterprise and DC architectures and 455 it is not rare to see as much as 128 different ECMP paths between a 456 source and a destination within a single network domain. It is a key 457 efficiency objective to spread the traffic among as many ECMP paths 458 as possible. 460 This is illustrated in the below network diagram which consists of a 461 subset of a network where already 5 ECMP paths are observed from A to 462 M. 464 C 465 / \ 466 B-D-L-- 467 / \ / \ 468 A E \ 469 \ M 470 \ G / 471 \ / \ / 472 F K 473 \ / 474 I 476 Figure 6: ECMP Topology Example 478 When the capacity planning process detects that a traffic growth 479 scenario and topology variation would lead to congestion, a capacity 480 increase is triggered and if it cannot be deployed in due time, a 481 traffic engineering solution is activated within the network. 483 A basic traffic engineering objective consists of finding the 484 smallest set of demands that need to be routed off their shortest 485 path to eliminate the congestion, then to compute an explicit path 486 for each of them and instantiating these traffic-engineered policies 487 in the network. 489 SPRING architecture should offer a simple support for ECMP-based 490 shortest path placement as well as for explicit path policy without 491 incurring additional signaling in the domain. This includes: 493 o the ability to steer a packet across a set of ECMP paths 495 o the ability to diverge from a set of ECMP shortest paths to one or 496 more paths not in the set of shortest paths 498 5.1.2.2. SDN/SR use-case 500 The SDN use-case lies in the SDN controller, (e.g.: Stateful PCE as 501 described in [I-D.ietf-pce-stateful-pce]. 503 The SDN controller is responsible to control the evolution of the 504 traffic matrix and topology. It accepts or denies the addition of 505 new traffic into the network. It decides how to route the accepted 506 traffic. It monitors the topology and upon topological change, 507 determines the minimum traffic that should be rerouted on an 508 alternate path to alleviate a bandwidth congestion issue. 510 The algorithms supporting this behavior are a local matter of the SDN 511 controller and are outside the scope of this document. 513 The means of collecting traffic and topology information are the same 514 as what would be used with other SDN-based traffic-engineering 515 solutions (e.g. [RFC7011] and [I-D.ietf-idr-ls-distribution]. 517 The means of instantiating policy information at a traffic- 518 engineering head-end are the same as what would be used with other 519 SDN-based traffic-engineering solutions (e.g.: 520 [I-D.ietf-i2rs-architecture], [I-D.crabbe-pce-pce-initiated-lsp] and 521 [I-D.sivabalan-pce-segment-routing]). 523 In the context of Centralized-Based Optimization and the SDN use- 524 case, here are the benefits that the SPRING architecture should 525 deliver: 527 Explicit routing capability with or without ECMP-awareness. 529 No signaling hop-by-hop through the network. 531 State is only maintained at the policy head-end. No state is 532 maintained at mid-points and tail-ends. 534 Automated guaranteed FRR for any topology. 536 Optimum virtualization: the policy state is in the packet header 537 and not in the intermediate nodes along the path. The policy is 538 completely virtualized away from midpoints and tail-ends. 540 Highly responsive to change: the SDN Controller only needs to 541 apply a policy change at the head-end. No delay is introduced due 542 to programming the midpoints and tail-end along the path. 544 5.1.2.2.1. SDN Example 546 The data-set consists in a full-mesh of 12000 explicitly-routed 547 tunnels observed on a real network. These tunnels resulted from 548 distributed headend-based CSPF computation. 550 We measured that only 65% of the traffic is forwarded over its 551 shortest path. 553 Three well-known defects are illustrated in this data set: 555 The lack of ECMP support in explicitly routed tunnels: ATM-alike 556 traffic-steering mechanisms steer the traffic along a non-ECMP 557 path. 559 The increase of the number of explicitly-routed non-ECMP tunnels 560 to enumerate all the ECMP options. 562 The inefficiency of distributed optimization: too much traffic is 563 forwarded off its shortest path. 565 We applied the SDN use-case to this dataset implying a source route 566 model where the path of the packet is encoded within the packet 567 itself. This means that: 569 The distributed CSPF computation is replaced by centralized 570 optimization and BW admission control, supported by the SDN 571 Controller. 573 As part of the optimization, we also optimized the IGP-metrics 574 such as to get a maximum of traffic load-spread among ECMP 575 paths by default. 577 The traffic-engineering policies are supported by a source route 578 model (e.g.: [I-D.filsfils-rtgwg-segment-routing]). 580 As a result, we measured that 98% of the traffic would be kept on its 581 normal policy (over the shortest-path) and only 2% of the traffic 582 requires a path away from the shortest-path. 584 Let us highlight a few benefits: 586 98% of the traffic-engineering head-end policies are eliminated. 588 Indeed, by default, an ingress edge node capable of injecting 589 source routed packets steers the traffic to the egress edge 590 node. No configuration or policy needs to be maintained at the 591 ingress edge node to realize this. 593 100% of the states at mid/tail nodes are eliminated. 595 6. Interoperability with non-SPRING nodes 597 SPRING must inter-operate with non-SPRING nodes. 599 An illustration of interoperability between SPRING and other MPLS 600 Signalling Protocols (LDP) is described here in 601 [I-D.filsfils-spring-segment-routing-ldp-interop]. 603 Interoperability with IPv6 non-SPRING nodes will be described in a 604 future document. 606 7. OAM 608 The SPRING WG should provide OAM and the management needed to manage 609 SPRING enabled networks. The SPRING procedures may also be used as a 610 tool for OAM in SPRING enabled networks. 612 OAM use cases and requirements are described in 613 [I-D.geib-spring-oam-usecase] and 614 [I-D.kumar-spring-sr-oam-requirement]. 616 8. Security 618 There is an assumed trust model such that any node imposing an 619 explicit route on a packet is assumed to be allowed to do so. In 620 such context trust boundaries should strip explicit routes from a 621 packet. 623 For each data plane technology that SPRING specifies, a security 624 analysis must be provided showing how protection is provided against 625 an attacker disrupting the network by for example, maliciously 626 injecting SPRING packets. 628 9. IANA Considerations 630 TBD 632 10. Manageability Considerations 634 TBD 636 11. Security Considerations 638 TBD 640 12. Acknowledgements 642 The authors would like to thank Yakov Rekhter for his contribution to 643 this document. 645 13. References 647 13.1. Normative References 649 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 650 Requirement Levels", BCP 14, RFC 2119, March 1997. 652 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 653 (IPv6) Specification", RFC 2460, December 1998. 655 [RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and 656 M. Bhatia, "A Uniform Format for IPv6 Extension Headers", 657 RFC 6564, April 2012. 659 [RFC7011] Claise, B., Trammell, B., and P. Aitken, "Specification of 660 the IP Flow Information Export (IPFIX) Protocol for the 661 Exchange of Flow Information", STD 77, RFC 7011, September 662 2013. 664 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 665 of IPv6 Extension Headers", RFC 7045, December 2013. 667 13.2. Informative References 669 [I-D.crabbe-pce-pce-initiated-lsp] 670 Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP 671 Extensions for PCE-initiated LSP Setup in a Stateful PCE 672 Model", draft-crabbe-pce-pce-initiated-lsp-03 (work in 673 progress), October 2013. 675 [I-D.filsfils-rtgwg-segment-routing] 676 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 677 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 678 Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, 679 "Segment Routing Architecture", draft-filsfils-rtgwg- 680 segment-routing-01 (work in progress), October 2013. 682 [I-D.filsfils-spring-segment-routing-ldp-interop] 683 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 684 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 685 Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, 686 "Segment Routing interoperability with LDP", draft- 687 filsfils-spring-segment-routing-ldp-interop-00 (work in 688 progress), October 2013. 690 [I-D.filsfils-spring-segment-routing-mpls] 691 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 692 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 693 Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, 694 "Segment Routing with MPLS data plane", draft-filsfils- 695 spring-segment-routing-mpls-00 (work in progress), October 696 2013. 698 [I-D.filsfils-spring-segment-routing-use-cases] 699 Filsfils, C., Francois, P., Previdi, S., Decraene, B., 700 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 701 Ytti, S., Henderickx, W., Tantsura, J., Kini, S., and E. 702 Crabbe, "Segment Routing Use Cases", draft-filsfils- 703 spring-segment-routing-use-cases-00 (work in progress), 704 March 2014. 706 [I-D.francois-spring-resiliency-use-case] 707 Francois, P., Filsfils, C., Decraene, B., and R. Shakir, 708 "Use-cases for Resiliency in SPRING", draft-francois- 709 spring-resiliency-use-case-02 (work in progress), April 710 2014. 712 [I-D.geib-spring-oam-usecase] 713 Geib, R. and C. Filsfils, "Use case for a scalable and 714 topology aware MPLS data plane monitoring system", draft- 715 geib-spring-oam-usecase-01 (work in progress), February 716 2014. 718 [I-D.ietf-i2rs-architecture] 719 Atlas, A., Halpern, J., Hares, S., Ward, D., and T. 720 Nadeau, "An Architecture for the Interface to the Routing 721 System", draft-ietf-i2rs-architecture-02 (work in 722 progress), February 2014. 724 [I-D.ietf-idr-ls-distribution] 725 Gredler, H., Medved, J., Previdi, S., Farrel, A., and S. 726 Ray, "North-Bound Distribution of Link-State and TE 727 Information using BGP", draft-ietf-idr-ls-distribution-04 728 (work in progress), November 2013. 730 [I-D.ietf-pce-stateful-pce] 731 Crabbe, E., Medved, J., Minei, I., and R. Varga, "PCEP 732 Extensions for Stateful PCE", draft-ietf-pce-stateful- 733 pce-08 (work in progress), February 2014. 735 [I-D.kumar-spring-sr-oam-requirement] 736 Kumar, N., Pignataro, C., Akiya, N., Geib, R., and G. 737 Mirsky, "OAM Requirements for Segment Routing Network", 738 draft-kumar-spring-sr-oam-requirement-00 (work in 739 progress), February 2014. 741 [I-D.sivabalan-pce-segment-routing] 742 Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E., and 743 R. Raszuk, "PCEP Extensions for Segment Routing", draft- 744 sivabalan-pce-segment-routing-02 (work in progress), 745 October 2013. 747 Authors' Addresses 749 Stefano Previdi (editor) 750 Cisco Systems, Inc. 751 Via Del Serafico, 200 752 Rome 00142 753 Italy 755 Email: sprevidi@cisco.com 757 Clarence Filsfils (editor) 758 Cisco Systems, Inc. 759 Brussels 760 BE 762 Email: cfilsfil@cisco.com 764 Bruno Decraene 765 Orange 766 FR 768 Email: bruno.decraene@orange.com 770 Stephane Litkowski 771 Orange 772 FR 774 Email: stephane.litkowski@orange.com 775 Martin Horneffer 776 Deutsche Telekom 777 Hammer Str. 216-226 778 Muenster 48153 779 DE 781 Email: Martin.Horneffer@telekom.de 783 Ruediger Geib 784 Deutsche Telekom 785 Heinrich Hertz Str. 3-7 786 Darmstadt 64295 787 DE 789 Email: Ruediger.Geib@telekom.de 791 Rob Shakir 792 British Telecom 793 London 794 UK 796 Email: rob.shakir@bt.com 798 Robert Raszuk 799 Individual 801 Email: robert@raszuk.net