idnits 2.17.00 (12 Aug 2021) /tmp/idnits55325/draft-ietf-rtgwg-net2cloud-problem-statement-11.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 : ---------------------------------------------------------------------------- ** There are 3 instances of too long lines in the document, the longest one being 8 characters in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (July 26, 2020) is 664 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: 'ITU-T-X1036' is defined on line 707, but no explicit reference was found in the text == Unused Reference: 'RFC4364' is defined on line 714, but no explicit reference was found in the text == Unused Reference: 'RFC4664' is defined on line 717, but no explicit reference was found in the text Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group L. Dunbar 2 Internet Draft Futurewei 3 Intended status: Informational Andy Malis 4 Expires: January 26, 2021 Malis Consulting 5 C. Jacquenet 6 Orange 7 M. Toy 8 Verizon 9 July 26, 2020 11 Dynamic Networks to Hybrid Cloud DCs Problem Statement 12 draft-ietf-rtgwg-net2cloud-problem-statement-11 14 Abstract 16 This document describes the problems that enterprises face today 17 when interconnecting their branch offices with dynamic workloads in 18 third party data centers (a.k.a. Cloud DCs). There can be many 19 problems associated with network connecting to or among Clouds, many 20 of which probably are out of the IETF scope. The objective of this 21 document is to identify some of the problems that need additional 22 work in IETF Routing area. Other problems are out of the scope of 23 this document. 25 This document focuses on the network problems that many enterprises 26 face when they have workloads & applications & data split among 27 different data centers, especially for those enterprises with 28 multiple sites that are already interconnected by VPNs (e.g., MPLS 29 L2VPN/L3VPN). 31 Current operational problems are examined to determine whether there 32 is a need to improve existing protocols or whether a new protocol is 33 necessary to solve them. 35 Status of this Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF), its areas, and its working groups. Note that 42 other groups may also distribute working documents as Internet- 43 Drafts. 45 Internet-Drafts are draft documents valid for a maximum of six 46 months and may be updated, replaced, or obsoleted by other documents 47 at any time. It is inappropriate to use Internet-Drafts as 48 reference material or to cite them other than as "work in progress." 50 The list of current Internet-Drafts can be accessed at 51 http://www.ietf.org/ietf/1id-abstracts.txt 53 The list of Internet-Draft Shadow Directories can be accessed at 54 http://www.ietf.org/shadow.html 56 This Internet-Draft will expire on January 26, 2009. 58 Copyright Notice 60 Copyright (c) 2020 IETF Trust and the persons identified as the 61 document authors. All rights reserved. 63 This document is subject to BCP 78 and the IETF Trust's Legal 64 Provisions Relating to IETF Documents 65 (http://trustee.ietf.org/license-info) in effect on the date of 66 publication of this document. Please review these documents 67 carefully, as they describe your rights and restrictions with 68 respect to this document. Code Components extracted from this 69 document must include Simplified BSD License text as described in 70 Section 4.e of the Trust Legal Provisions and are provided without 71 warranty as described in the Simplified BSD License. 73 Table of Contents 75 1. Introduction...................................................3 76 1.1. Key Characteristics of Cloud Services:....................3 77 1.2. Connecting to Cloud Services..............................3 78 1.3. Reaching App instances in the optimal Cloud DC locations..4 79 2. Definition of terms............................................5 80 3. High Level Issues of Connecting to Multi-Cloud.................6 81 3.1. Security Issues...........................................6 82 3.2. Authorization and Identity Management.....................6 83 3.3. API abstraction...........................................7 84 3.4. DNS for Cloud Resources...................................8 85 3.5. NAT for Cloud Services....................................9 86 3.6. Cloud Discovery...........................................9 87 4. Interconnecting Enterprise Sites with Cloud DCs...............10 88 4.1. Sites to Cloud DC........................................10 89 4.2. Inter-Cloud Interconnection..............................12 90 5. Problems with MPLS-based VPNs extending to Hybrid Cloud DCs...14 91 6. Problem with using IPsec tunnels to Cloud DCs.................15 92 6.1. Scaling Issues with IPsec Tunnels........................15 93 6.2. Poor performance over long distance......................16 94 7. End-to-End Security Concerns for Data Flows...................16 95 8. Requirements for Dynamic Cloud Data Center VPNs...............17 96 9. Security Considerations.......................................17 97 10. IANA Considerations..........................................18 98 11. References...................................................18 99 11.1. Normative References....................................18 100 11.2. Informative References..................................18 101 12. Acknowledgments..............................................18 103 1. Introduction 105 1.1. Key Characteristics of Cloud Services: 107 Key characteristics of Cloud Services are on-demand, scalable, 108 highly available, and usage-based billing. Cloud Services, such as, 109 compute, storage, network functions (most likely virtual), third 110 party managed applications, etc. are usually hosted and managed by 111 third parties Cloud Operators. Here are some examples of Cloud 112 network functions: Virtual Firewall services, Virtual private 113 network services, Virtual PBX services including voice and video 114 conferencing systems, etc. Cloud Data Center (DC) is shared 115 infrastructure that hosts the Cloud Services to many customers. 117 1.2. Connecting to Cloud Services 119 With the advent of widely available third-party cloud DCs and 120 services in diverse geographic locations and the advancement of 121 tools for monitoring and predicting application behaviors, it is 122 very attractive for enterprises to instantiate applications and 123 workloads in locations that are geographically closest to their end- 124 users. Such proximity can improve end-to-end latency and overall 125 user experience. Conversely, an enterprise can easily shutdown 126 applications and workloads whenever end-users are in motion (thereby 127 modifying the networking connection of subsequently relocated 128 applications and workloads). In addition, enterprises may wish to 129 take advantage of more and more business applications offered by 130 cloud operators. 132 The networks that interconnect hybrid cloud DCs must address the 133 following requirements: 134 - to access all workloads in the desired cloud DCs. 135 Many enterprises include cloud in their disaster recovery 136 strategy, such as enforcing periodic backup policies within the 137 cloud, or running backup applications in the Cloud. 139 - Global reachability from different geographical zones, thereby 140 facilitating the proximity of applications as a function of the 141 end users' location, to improve latency. 142 - Elasticity: prompt connection to newly instantiated 143 applications at Cloud DCs when usages increase and prompt 144 release of connection after applications at locations being 145 removed when demands change. 146 - Scalable security management. 148 1.3. Reaching App instances in the optimal Cloud DC locations 150 Many applications have multiple instances instantiated in different 151 Cloud DCs. The current state of the art solutions are typically 152 based on DNS assisted with load balancer by responding a FQDN (Fully 153 Qualified Domain Name) inquiry with an IP address of the closest or 154 lowest cost DC that can reach the instance. Here are some problems 155 associated with DNS based solutions: 156 - Dependent on client behavior 157 - Client can cache results indefinitely 158 - Client may not receive service even though there are 159 servers available (before cache timeout) in other Cloud 160 DCs. 161 - No inherent leverage of proximity information present in the 162 network (routing) layer, resulting in loss of performance 163 - Client on the west coast can be mapped to a DC on the east 164 coast 165 - Inflexible traffic control: 166 - Local DNS resolver become the unit of traffic management 168 2. Definition of terms 170 Cloud DC: Third party Data Centers that usually host applications 171 and workload owned by different organizations or 172 tenants. 174 Controller: Used interchangeably with SD-WAN controller to manage 175 SD-WAN overlay path creation/deletion and monitoring the 176 path conditions between two or more sites. 178 DSVPN: Dynamic Smart Virtual Private Network. DSVPN is a secure 179 network that exchanges data between sites without 180 needing to pass traffic through an organization's 181 headquarter virtual private network (VPN) server or 182 router. 184 Heterogeneous Cloud: applications and workloads split among Cloud 185 DCs owned or managed by different operators. 187 Hybrid Clouds: Hybrid Clouds refers to an enterprise using its own 188 on-premises DCs in addition to Cloud services provided 189 by one or more cloud operators. (e.g. AWS, Azure, 190 Google, Salesforces, SAP, etc). 192 VPC: Virtual Private Cloud is a virtual network dedicated to 193 one client account. It is logically isolated from other 194 virtual networks in a Cloud DC. Each client can launch 195 his/her desired resources, such as compute, storage, or 196 network functions into his/her VPC. Most Cloud 197 operators' VPCs only support private addresses, some 198 support IPv4 only, others support IPv4/IPv6 dual stack. 200 3. High Level Issues of Connecting to Multi-Cloud 202 There are many problems associated with connecting to hybrid Cloud 203 Services, many of which are out of the IETF scope. This section is 204 to identify some of the high-level problems that can be addressed by 205 IETF, especially by Routing area. Other problems are out of the 206 scope of this document. By no means has this section covered all 207 problems for connecting to Hybrid Cloud Services, e.g. difficulty in 208 managing cloud spending is not discussed here. 210 3.1. Security Issues 212 Cloud Services is built upon shared infrastructure, therefore not 213 secure by nature. Security has been a primary, and valid, concern 214 from the start of cloud computing, e.g. not being able to see the 215 exact location where the data are stored or trace of access. 216 Headlines highlighting data breaches, compromised credentials, and 217 broken authentication, hacked interfaces and APIs, account hijacking 218 haven't helped alleviate concerns. 220 Many Cloud operators offer monitoring services for data stored in 221 Clouds, such as AWS CloudTrail, Azure Monitor, and many third-party 222 monitoring tools to improve visibility to data stored in Clouds. But 223 there is still underline security concerns on illegitimate data and 224 workloads access. 226 Secure user identity management, authentication, and access control 227 mechanisms are important. Developing appropriate security 228 measurements can enhance the confidence needed by enterprises to 229 fully take advantage of Cloud Services. 231 3.2. Authorization and Identity Management 233 One of the more prominent challenges for Cloud Services is Identity 234 Management and Authorization. The Authorization not only includes 235 user authorization, but also the authorization of API calls by 236 applications from different Cloud DCs managed by different Cloud 237 Operators. In addition, there are authorization for Workload 238 Migration, Data Migration, and Workload Management. 240 There are many types of users in cloud environments, e.g. end users 241 for accessing applications hosted in Cloud DCs, Cloud-resource users 242 who are responsible for setting permissions for the resources based 243 on roles, access lists, IP addresses, domains, etc. 245 There are many types of Cloud authorizations: including MAC 246 (Mandatory Access Control) - where each app owns individual access 247 permissions, DAC (Discretionary Access Control) - where each app 248 requests permissions from an external permissions app, RBAC (Role- 249 based Access Control) - where the authorization service owns roles 250 with different privileges on the cloud service, and ABAC (Attribute- 251 based Access Control) - where access is based on request attributes 252 and policies. 254 IETF hasn't yet developed comprehensive specification for Identity 255 management and data models for Cloud Authorizations. 257 3.3. API abstraction 259 Different Cloud Operators have different APIs to access their Cloud 260 resources, security functions, the NAT, etc. 262 It is difficult to move applications built by one Cloud operator's 263 APIs to another. However, it is highly desirable to have a single 264 and consistent way to manage the networks and respective security 265 policies for interconnecting applications hosted in different Cloud 266 DCs. 268 The desired property would be having a single network fabric to 269 which different Cloud DCs and enterprise's multiple sites can be 270 attached or detached, with a common interface for setting desired 271 policies. 273 The difficulty of connecting applications in different Clouds might 274 be stemmed from the fact that they are direct competitors. Usually 275 traffic flow out of Cloud DCs incur charges. Therefore, direct 276 communications between applications in different Cloud DCs can be 277 more expensive than intra Cloud communications. 279 It is desirable to have a common API shim layer or abstraction for 280 different Cloud providers to make it easier to move applications 281 from one Cloud DC to another. 283 3.4. DNS for Cloud Resources 285 DNS name resolution is essential for on-premises and cloud-based 286 resources. For customers with hybrid workloads, which include on- 287 premises and cloud-based resources, extra steps are necessary to 288 configure DNS to work seamlessly across both environments. 290 Cloud operators have their own DNS to resolve resources within their 291 Cloud DCs and to well-known public domains. Cloud's DNS can be 292 configured to forward queries to customer managed authoritative DNS 293 servers hosted on-premises, and to respond to DNS queries forwarded 294 by on-premises DNS servers. 296 For enterprises utilizing Cloud services by different cloud 297 operators, it is necessary to establish policies and rules on 298 how/where to forward DNS queries to. When applications in one Cloud 299 need to communication with applications hosted in another Cloud, 300 there could be DNS queries from one Cloud DC being forwarded to the 301 enterprise's on premise DNS, which in turn be forwarded to the DNS 302 service in another Cloud. Needless to say, configuration can be 303 complex depending on the application communication patterns. 305 However, even with carefully managed policies and configurations, 306 collisions can still occur. If you use an internal name like .cloud 307 and then want your services to be available via or within some other 308 cloud provider which also uses .cloud, then it can't work. 309 Therefore, it is better to use the global domain name even when an 310 organization does not make all its namespace globally resolvable. An 311 organization's globally unique DNS can include subdomains that 312 cannot be resolved at all outside certain restricted paths, zones 313 that resolve differently based on the origin of the query, and zones 314 that resolve the same globally for all queries from any source. 316 Globally unique names do not equate to globally resolvable names or 317 even global names that resolve the same way from every perspective. 318 Globally unique names do prevent any possibility of collision at the 319 present or in the future and they make DNSSEC trust manageable. 320 Consider using a registered and fully qualified domain name (FQDN) 321 from global DNS as the root for enterprise and other internal 322 namespaces. 324 3.5. NAT for Cloud Services 326 Cloud resources, such as VM instances, are usually assigned with 327 private IP addresses. By configuration, some private subnets can 328 have the NAT function to reach out to external network and some 329 private subnets are internal to Cloud only. 331 Different Cloud operators support different levels of NAT functions. 332 For example, AWS NAT Gateway does not currently support connections 333 towards, or from VPC Endpoints, VPN, AWS Direct Connect, or VPC 334 Peering. https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/vpc- 335 nat-gateway.html#nat-gateway-other-services. AWS Direct 336 Connect/VPN/VPC Peering does not currently support any NAT 337 functionality. 339 Google's Cloud NAT allows Google Cloud virtual machine (VM) 340 instances without external IP addresses and private Google 341 Kubernetes Engine (GKE) clusters to connect to the Internet. Cloud 342 NAT implements outbound NAT in conjunction with a default route to 343 allow instances to reach the Internet. It does not implement inbound 344 NAT. Hosts outside of VPC network can only respond to established 345 connections initiated by instances inside the Google Cloud; they 346 cannot initiate their own, new connections to Cloud instances via 347 NAT. 349 For enterprises with applications running in different Cloud DCs, 350 proper configuration of NAT has to be performed in Cloud DC and in 351 their own on-premise DC. 353 3.6. Cloud Discovery 355 One of the concerns of using Cloud services is not aware where the 356 resource is actually located, especially Cloud operators can move 357 application instances from one place to another. When applications 358 in Cloud communicate with on-premise applications, it may not be 359 clear where the Cloud applications are located or to which VPCs they 360 belong. 362 It is highly desirable to have tools to discover cloud services in 363 much the same way as you would discover your on-premises 364 infrastructure. A significant difference is that cloud discovery 365 uses the cloud vendor's API to extract data on your cloud services, 366 rather than the direct access used in scanning your on-premises 367 infrastructure. 369 Standard data models, APIs or tools can alleviate concerns of 370 enterprise utilizing Cloud Resources, e.g. having a Cloud service 371 scan that connects to the API of the cloud provider and collects 372 information directly. 374 4. Interconnecting Enterprise Sites with Cloud DCs 376 Considering that many enterprises already have existing VPNs (e.g. 377 MPLS based L2VPN or L3VPN) interconnecting branch offices & on- 378 premises data centers, connecting to Cloud services will be mixed of 379 different types of networks. When an enterprise's existing VPN 380 service providers do not have direct connections to the 381 corresponding cloud DCs that the enterprise prefers to use, the 382 enterprise has to face additional infrastructure and operational 383 costs to utilize Cloud services. 385 4.1. Sites to Cloud DC 387 Most Cloud operators offer some type of network gateway through 388 which an enterprise can reach their workloads hosted in the Cloud 389 DCs. AWS (Amazon Web Services) offers the following options to reach 390 workloads in AWS Cloud DCs: 392 - AWS Internet gateway allows communication between instances in 393 AWS VPC and the internet. 394 - AWS Virtual gateway (vGW) where IPsec tunnels [RFC6071] are 395 established between an enterprise's own gateway and AWS vGW, so 396 that the communications between those gateways can be secured 397 from the underlay (which might be the public Internet). 398 - AWS Direct Connect, which allows enterprises to purchase direct 399 connect from network service providers to get a private leased 400 line interconnecting the enterprises gateway(s) and the AWS 401 Direct Connect routers. In addition, an AWS Transit Gateway can 402 be used to interconnect multiple VPCs in different Availability 403 Zones. AWS Transit Gateway acts as a hub that controls how 404 traffic is forwarded among all the connected networks which act 405 like spokes. 407 Microsoft's ExpressRoute allows extension of a private network to 408 any of the Microsoft cloud services, including Azure and Office365. 409 ExpressRoute is configured using Layer 3 routing. Customers can opt 410 for redundancy by provisioning dual links from their location to two 411 Microsoft Enterprise edge routers (MSEEs) located within a third- 412 party ExpressRoute peering location. The BGP routing protocol is 413 then setup over WAN links to provide redundancy to the cloud. This 414 redundancy is maintained from the peering data center into 415 Microsoft's cloud network. 417 Google's Cloud Dedicated Interconnect offers similar network 418 connectivity options as AWS and Microsoft. One distinct difference, 419 however, is that Google's service allows customers access to the 420 entire global cloud network by default. It does this by connecting 421 your on-premises network with the Google Cloud using BGP and Google 422 Cloud Routers to provide optimal paths to the different regions of 423 the global cloud infrastructure. 425 Figure below shows an example of some of a tenant's workloads are 426 accessible via a virtual router connected by AWS Internet Gateway; 427 some are accessible via AWS vGW, and others are accessible via AWS 428 Direct Connect. 430 Different types of access require different level of security 431 functions. Sometimes it is not visible to end customers which type 432 of network access is used for a specific application instance. To 433 get better visibility, separate virtual routers (e.g. vR1 & vR2) can 434 be deployed to differentiate traffic to/from different cloud GWs. It 435 is important for some enterprises to be able to observe the specific 436 behaviors when connected by different connections. 438 Customer Gateway can be customer owned router or ports physically 439 connected to AWS Direct Connect GW. 441 +------------------------+ 442 | ,---. ,---. | 443 | (TN-1 ) ( TN-2)| 444 | `-+-' +---+ `-+-' | 445 | +----|vR1|----+ | 446 | ++--+ | 447 | | +-+----+ 448 | | /Internet\ For External 449 | +-------+ Gateway +---------------------- 450 | \ / to reach via Internet 451 | +-+----+ 452 | | 453 | ,---. ,---. | 454 | (TN-1 ) ( TN-2)| 455 | `-+-' +---+ `-+-' | 456 | +----|vR2|----+ | 457 | ++--+ | 458 | | +-+----+ 459 | | / virtual\ For IPsec Tunnel 460 | +-------+ Gateway +---------------------- 461 | | \ / termination 462 | | +-+----+ 463 | | | 464 | | +-+----+ +------+ 465 | | / \ For Direct /customer\ 466 | +-------+ Gateway +----------+ gateway | 467 | \ / Connect \ / 468 | +-+----+ +------+ 469 | | 470 +------------------------+ 472 Figure 1: Examples of Multiple Cloud DC connections. 474 4.2. Inter-Cloud Interconnection 476 The connectivity options to Cloud DCs described in the previous 477 section are for reaching Cloud providers' DCs, but not between cloud 478 DCs. When applications in AWS Cloud need to communicate with 479 applications in Azure, today's practice requires a third-party 480 gateway (physical or virtual) to interconnect the AWS's Layer 2 481 DirectConnect path with Azure's Layer 3 ExpressRoute. 483 Enterprises can also instantiate their own virtual routers in 484 different Cloud DCs and administer IPsec tunnels among them, which 485 by itself is not a trivial task. Or by leveraging open source VPN 486 software such as strongSwan, you create an IPSec connection to the 487 Azure gateway using a shared key. The StrongSwan instance within AWS 488 not only can connect to Azure but can also be used to facilitate 489 traffic to other nodes within the AWS VPC by configuring forwarding 490 and using appropriate routing rules for the VPC. 492 Most Cloud operators, such as AWS VPC or Azure VNET, use non- 493 globally routable CIDR from private IPv4 address ranges as specified 494 by RFC1918. To establish IPsec tunnel between two Cloud DCs, it is 495 necessary to exchange Public routable addresses for applications in 496 different Cloud DCs. 498 In summary, here are some approaches, available now (which might 499 change in the future), to interconnect workloads among different 500 Cloud DCs: 502 a) Utilize Cloud DC provided inter/intra-cloud connectivity 503 services (e.g., AWS Transit Gateway) to connect workloads 504 instantiated in multiple VPCs. Such services are provided with 505 the cloud gateway to connect to external networks (e.g., AWS 506 DirectConnect Gateway). 507 b) Hairpin all traffic through the customer gateway, meaning all 508 workloads are directly connected to the customer gateway, so 509 that communications among workloads within one Cloud DC must 510 traverse through the customer gateway. 511 c) Establish direct tunnels among different VPCs (AWS' Virtual 512 Private Clouds) and VNET (Azure's Virtual Networks) via 513 client's own virtual routers instantiated within Cloud DCs. 514 DMVPN (Dynamic Multipoint Virtual Private Network) or DSVPN 515 (Dynamic Smart VPN) techniques can be used to establish direct 516 Multi-point-to-Point or multi-point-to multi-point tunnels 517 among those client's own virtual routers. 519 Approach a) usually does not work if Cloud DCs are owned and managed 520 by different Cloud providers. 522 Approach b) creates additional transmission delay plus incurring 523 cost when exiting Cloud DCs. 525 For the Approach c), DMVPN or DSVPN use NHRP (Next Hop Resolution 526 Protocol) [RFC2735] so that spoke nodes can register their IP 527 addresses & WAN ports with the hub node. The IETF ION 528 (Internetworking over NBMA (non-broadcast multiple access) WG 529 standardized NHRP for connection-oriented NBMA network (such as ATM) 530 network address resolution more than two decades ago. 532 There are many differences between virtual routers in Public Cloud 533 DCs and the nodes in an NBMA network. NHRP cannot be used for 534 registering virtual routers in Cloud DCs unless an extension of such 535 protocols is developed for that purpose, e.g. taking NAT or dynamic 536 addresses into consideration. Therefore, DMVPN and/or DSVPN cannot 537 be used directly for connecting workloads in hybrid Cloud DCs. 539 5. Problems with MPLS-based VPNs extending to Hybrid Cloud DCs 541 Traditional MPLS-based VPNs have been widely deployed as an 542 effective way to support businesses and organizations that require 543 network performance and reliability. MPLS shifted the burden of 544 managing a VPN service from enterprises to service providers. The 545 CPEs attached to MPLS VPNs are also simpler and less expensive, 546 because they do not need to manage routes to remote sites; they 547 simply pass all outbound traffic to the MPLS VPN PEs to which the 548 CPEs are attached (albeit multi-homing scenarios require more 549 processing logic on CPEs). MPLS has addressed the problems of 550 scale, availability, and fast recovery from network faults, and 551 incorporated traffic-engineering capabilities. 553 However, traditional MPLS-based VPN solutions are sub-optimized for 554 connecting end-users to dynamic workloads/applications in cloud DCs 555 because: 557 - The Provider Edge (PE) nodes of the enterprise's VPNs might not 558 have direct connections to third party cloud DCs that are used 559 for hosting workloads with the goal of providing an easy access 560 to enterprises' end-users. 562 - It takes some time to deploy provider edge (PE) routers at new 563 locations. When enterprise's workloads are changed from one 564 cloud DC to another (i.e., removed from one DC and re- 565 instantiated to another location when demand changes), the 566 enterprise branch offices need to be connected to the new cloud 567 DC, but the network service provider might not have PEs located 568 at the new location. 570 One of the main drivers for moving workloads into the cloud is 571 the widely available cloud DCs at geographically diverse 572 locations, where apps can be instantiated so that they can be 573 as close to their end-users as possible. When the user base 574 changes, the applications may be migrated to a new cloud DC 575 location closest to the new user base. 577 - Most of the cloud DCs do not expose their internal networks. An 578 enterprise with a hybrid cloud deployment can use an MPLS-VPN 579 to connect to a Cloud provider at multiple locations. The 580 connection locations often correspond to gateways of different 581 Cloud DC locations from the Cloud provider. The different 582 Cloud DCs are interconnected by the Cloud provider's own 583 internal network. At each connection location (gateway), the 584 Cloud provider uses BGP to advertise all of the prefixes in the 585 enterprise's VPC, regardless of which Cloud DC a given prefix 586 is actually in. This can result in inefficient routing for the 587 end-to-end data path. 589 Another roadblock is the lack of a standard way to express and 590 enforce consistent security policies for workloads that not only use 591 virtual addresses, but in which are also very likely hosted in 592 different locations within the Cloud DC [RFC8192]. The current VPN 593 path computation and bandwidth allocation schemes may not be 594 flexible enough to address the need for enterprises to rapidly 595 connect to dynamically instantiated (or removed) workloads and 596 applications regardless of their location/nature (i.e., third party 597 cloud DCs). 599 6. Problem with using IPsec tunnels to Cloud DCs 600 As described in the previous section, many Cloud operators expose 601 their gateways for external entities (which can be enterprises 602 themselves) to directly establish IPsec tunnels. Enterprises can 603 also instantiate virtual routers within Cloud DCs to connect to 604 their on-premises devices via IPsec tunnels. 606 6.1. Scaling Issues with IPsec Tunnels 608 If there is only one enterprise location that needs to reach the 609 Cloud DC, an IPsec tunnel is a very convenient solution. 611 However, many medium-to-large enterprises have multiple sites and 612 multiple data centers. For multiple sites to communicate with 613 workloads and apps hosted in cloud DCs, Cloud DC gateways have to 614 maintain many IPsec tunnels to all those locations. In addition, 615 each of those IPsec Tunnels requires pair-wise periodic key 616 refreshment. For a company with hundreds or thousands of locations, 617 there could be hundreds (or even thousands) of IPsec tunnels 618 terminating at the cloud DC gateway, which is very processing 619 intensive. That is why many cloud operators only allow a limited 620 number of (IPsec) tunnels & bandwidth to each customer. 622 Alternatively, you could use a solution like group encryption where 623 a single IPsec SA is necessary at the GW but the drawback is key 624 distribution and maintenance of a key server, etc. 626 6.2. Poor performance over long distance 628 When enterprise CPEs or gateways are far away from cloud DC gateways 629 or across country/continent boundaries, performance of IPsec tunnels 630 over the public Internet can be problematic and unpredictable. Even 631 though there are many monitoring tools available to measure delay 632 and various performance characteristics of the network, the 633 measurement for paths over the Internet is passive and past 634 measurements may not represent future performance. 636 Many cloud providers can replicate workloads in different available 637 zones. An App instantiated in a cloud DC closest to clients may have 638 to cooperate with another App (or its mirror image) in another 639 region or database server(s) in the on-premises DC. This kind of 640 coordination requires predicable networking behavior/performance 641 among those locations. 643 7. End-to-End Security Concerns for Data Flows 645 When IPsec tunnels established from enterprise on-premises CPEs 646 are terminated at the Cloud DC gateway where the workloads or 647 applications are hosted, some enterprises have concerns regarding 648 traffic to/from their workload being exposed to others behind the 649 data center gateway (e.g., exposed to other organizations that 650 have workloads in the same data center). 651 To ensure that traffic to/from workloads is not exposed to 652 unwanted entities, IPsec tunnels may go all the way to the 653 workload (servers, or VMs) within the DC. 655 8. Requirements for Dynamic Cloud Data Center VPNs 657 In order to address the aforementioned issues, any solution for 658 enterprise VPNs that includes connectivity to dynamic workloads or 659 applications in cloud data centers should satisfy a set of 660 requirements: 662 - The solution should allow enterprises to take advantage of the 663 current state-of-the-art in VPN technology, in both traditional 664 MPLS-based VPNs and IPsec-based VPNs (or any combination 665 thereof) that run over the public Internet. 666 - The solution should not require an enterprise to upgrade all 667 their existing CPEs. 668 - The solution should support scalable IPsec key management among 669 all nodes involved in DC interconnect schemes. 670 - The solution needs to support easy and fast, on-the-fly, VPN 671 connections to dynamic workloads and applications in third 672 party data centers, and easily allow these workloads to migrate 673 both within a data center and between data centers. 674 - Allow VPNs to provide bandwidth and other performance 675 guarantees. 676 - Be a cost-effective solution for enterprises to incorporate 677 dynamic cloud-based applications and workloads into their 678 existing VPN environment. 680 9. Security Considerations 682 The draft discusses security requirements as a part of the problem 683 space, particularly in sections 4, 5, and 8. 685 Solution drafts resulting from this work will address security 686 concerns inherent to the solution(s), including both protocol 687 aspects and the importance (for example) of securing workloads in 688 cloud DCs and the use of secure interconnection mechanisms. 690 10. IANA Considerations 692 This document requires no IANA actions. RFC Editor: Please remove 693 this section before publication. 695 11. References 697 11.1. Normative References 699 11.2. Informative References 701 [RFC2735] B. Fox, et al "NHRP Support for Virtual Private 702 networks". Dec. 1999. 704 [RFC8192] S. Hares, et al "Interface to Network Security Functions 705 (I2NSF) Problem Statement and Use Cases", July 2017 707 [ITU-T-X1036] ITU-T Recommendation X.1036, "Framework for creation, 708 storage, distribution and enforcement of policies for 709 network security", Nov 2007. 711 [RFC6071] S. Frankel and S. Krishnan, "IP Security (IPsec) and 712 Internet Key Exchange (IKE) Document Roadmap", Feb 2011. 714 [RFC4364] E. Rosen and Y. Rekhter, "BGP/MPLS IP Virtual Private 715 Networks (VPNs)", Feb 2006 717 [RFC4664] L. Andersson and E. Rosen, "Framework for Layer 2 Virtual 718 Private Networks (L2VPNs)", Sept 2006. 720 12. Acknowledgments 722 Many thanks to Alia Atlas, Chris Bowers, Paul Vixie, Paul Ebersman, 723 Timothy Morizot, Ignas Bagdonas, Michael Huang, Liu Yuan Jiao, 724 Katherine Zhao, and Jim Guichard for the discussion and 725 contributions. 727 Authors' Addresses 729 Linda Dunbar 730 Futurewei 731 Email: Linda.Dunbar@futurewei.com 733 Andrew G. Malis 734 Malis Consulting 735 Email: agmalis@gmail.com 737 Christian Jacquenet 738 Orange 739 Rennes, 35000 740 France 741 Email: Christian.jacquenet@orange.com 743 Mehmet Toy 744 Verizon 745 One Verizon Way 746 Basking Ridge, NJ 07920 747 Email: mehmet.toy@verizon.com