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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group K. Chittimaneni 3 Internet-Draft Google Inc. 4 Intended status: Informational T. Chown 5 Expires: January 15, 2014 University of Southampton 6 L. Howard 7 Time Warner Cable 8 V. Kuarsingh 9 Rogers Communications 10 Y. Pouffary 11 Hewlett Packard 12 E. Vyncke 13 Cisco Systems 14 July 14, 2013 16 Enterprise IPv6 Deployment Guidelines 17 draft-ietf-v6ops-enterprise-incremental-ipv6-03 19 Abstract 21 Enterprise network administrators worldwide are in various stages of 22 preparing for or deploying IPv6 into their networks. The 23 administrators face different challenges than operators of Internet 24 access providers, and have reasons for different priorities. The 25 overall problem for many administrators will be to offer Internet- 26 facing services over IPv6, while continuing to support IPv4, and 27 while introducing IPv6 access within the enterprise IT network. The 28 overall transition will take most networks from an IPv4-only 29 environment to a dual stack network environment and potentially an 30 IPv6-only operating mode. This document helps provide a framework 31 for enterprise network architects or administrators who may be faced 32 with many of these challenges as they consider their IPv6 support 33 strategies. 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). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at http://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on January 15, 2014. 51 Copyright Notice 53 Copyright (c) 2013 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (http://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 69 1.1. Enterprise Assumptions . . . . . . . . . . . . . . . . . 4 70 1.2. IPv4-only Considerations . . . . . . . . . . . . . . . . 4 71 1.3. Reasons for a Phased Approach . . . . . . . . . . . . . . 4 72 2. Preparation and Assessment Phase . . . . . . . . . . . . . . 6 73 2.1. Program Planning . . . . . . . . . . . . . . . . . . . . 6 74 2.2. Inventory Phase . . . . . . . . . . . . . . . . . . . . . 8 75 2.2.1. Network infrastructure readiness assessment . . . . . 8 76 2.2.2. Applications readiness assessment . . . . . . . . . . 8 77 2.2.3. Importance of readiness validation and testing . . . 9 78 2.3. Training . . . . . . . . . . . . . . . . . . . . . . . . 9 79 2.4. Security Policy . . . . . . . . . . . . . . . . . . . . . 9 80 2.4.1. IPv6 is no more secure than IPv4 . . . . . . . . . . 9 81 2.4.2. Similarities between IPv6 and IPv4 security . . . . . 10 82 2.4.3. Specific Security Issues for IPv6 . . . . . . . . . . 11 83 2.5. Routing . . . . . . . . . . . . . . . . . . . . . . . . . 13 84 2.6. Address Plan . . . . . . . . . . . . . . . . . . . . . . 13 85 2.7. Tools Assessment . . . . . . . . . . . . . . . . . . . . 15 86 3. External Phase . . . . . . . . . . . . . . . . . . . . . . . 17 87 3.1. Connectivity . . . . . . . . . . . . . . . . . . . . . . 17 88 3.2. Security . . . . . . . . . . . . . . . . . . . . . . . . 18 89 3.3. Monitoring . . . . . . . . . . . . . . . . . . . . . . . 19 90 3.4. Servers and Applications . . . . . . . . . . . . . . . . 19 91 3.5. Network Prefix Translation for IPv6 . . . . . . . . . . . 20 92 4. Internal Phase . . . . . . . . . . . . . . . . . . . . . . . 20 93 4.1. Security . . . . . . . . . . . . . . . . . . . . . . . . 21 94 4.2. Network Infrastructure . . . . . . . . . . . . . . . . . 21 95 4.3. End user devices . . . . . . . . . . . . . . . . . . . . 23 96 4.4. Corporate Systems . . . . . . . . . . . . . . . . . . . . 24 98 5. IPv6-only . . . . . . . . . . . . . . . . . . . . . . . . . . 24 99 6. Considerations For Specific Enterprises . . . . . . . . . . . 25 100 6.1. Content Delivery Networks . . . . . . . . . . . . . . . . 25 101 6.2. Data Center Virtualization . . . . . . . . . . . . . . . 26 102 6.3. University Campus Networks . . . . . . . . . . . . . . . 26 103 7. Security Considerations . . . . . . . . . . . . . . . . . . . 27 104 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 27 105 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 106 10. Informative References . . . . . . . . . . . . . . . . . . . 27 107 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 109 1. Introduction 111 An Enterprise Network is defined in [RFC4057] as a network that has 112 multiple internal links, one or more router connections to one or 113 more Providers, and is actively managed by a network operations 114 entity (the "administrator", whether a single person or department of 115 administrators). Administrators generally support an internal 116 network, consisting of users' workstations, personal computers, other 117 computing devices and related peripherals, a server network, 118 consisting of accounting and business application servers, and an 119 external network, consisting of Internet-accessible services such as 120 web servers, email servers, VPN systems, and customer applications. 121 This document is intended as guidance for network architects and 122 administrators in planning their IPv6 deployments. 124 The business reasons for spending time, effort, and money on IPv6 125 will be unique to each enterprise. The most common drivers are due 126 to the fact that when Internet service providers, including mobile 127 wireless carriers, run out of IPv4 addresses, they will provide 128 native IPv6 and non-native IPv4. The non-native IPv4 service may be 129 NAT64, NAT444, Dual-stack Lite, or other transition technologies. 130 Compared to tunneled or translated, native traffic typically performs 131 better and more reliably than non-native. For example, for client 132 networks trying to reach enterprise networks, the IPv6 experience 133 will be better than the transitional IPv4 if the enterprise deploys 134 IPv6 in its public-facing services. The native IPv6 network path 135 should also be simpler to manage and, if necessary, troubleshoot. 136 Further, enterprises doing business in growing parts of the world may 137 find IPv6 growing faster there, where again potential new customers, 138 employees and partners are using IPv6. It is thus in the 139 enterprise's interests to deploy native IPv6, at the very least in 140 its public-facing services, but ultimately across the majority or all 141 of its scope. 143 The text in this document provides specific guidance for enterprise 144 networks, and complements other related work in the IETF, including 145 [I-D.ietf-v6ops-design-choices] and [RFC5375]. 147 1.1. Enterprise Assumptions 149 For the purpose of this document, we assume: 151 o The administrator is considering deploying IPv6 (but see 152 Section 1.2 below). 154 o The administrator has existing IPv4 networks and devices which 155 will continue to operate and be supported. 157 o The administrator will want to minimize the level of disruption to 158 the users and services by minimizing number of technologies and 159 functions that are needed to mediate any given application. In 160 other words, provide native IP wherever possible. 162 Based on these assumptions, an administrator will want to use 163 technologies which minimize the number of flows being tunnelled, 164 translated or intercepted at any given time. The administrator will 165 choose transition technologies or strategies which allow most traffic 166 to be native, and will manage non-native traffic. This will allow 167 the administrator to minimize the cost of IPv6 transition 168 technologies, by containing the number and scale of transition 169 systems. 171 1.2. IPv4-only Considerations 173 As described in [RFC6302] administrators should take certain steps 174 even if they are not considering IPv6. Specifically, Internet-facing 175 servers should log the source port number, timestamp (from a reliable 176 source), and the transport protocol. This will allow investigation 177 of malefactors behind address-sharing technologies such as NAT444 or 178 Dual-stack Lite. 180 Other IPv6 considerations may impact ostensibly IPv4-only networks, 181 e.g. [RFC6104] describes the rogue IPv6 RA problem, which may cause 182 problems in IPv4-only networks where IPv6 is enabled in end systems 183 on that network. Further discussion of the security implications of 184 IPv6 in IPv4-only networks can be found in 185 [I-D.ietf-opsec-ipv6-implications-on-ipv4-nets]). 187 1.3. Reasons for a Phased Approach 189 Given the challenges of transitioning user workstations, corporate 190 systems, and Internet-facing servers, a phased approach allows 191 incremental deployment of IPv6, based on the administrator's own 192 determination of priorities. The Preparation Phase is highly 193 recommended to all administrators, as it will save errors and 194 complexity in later phases. Each administrator must decide whether 195 to begin with the External Phase (as recommended in [RFC5211]) or the 196 Internal Phase. There is no "correct" answer here; the decision is 197 one for each enterprise to make. 199 Each scenario is likely to be different to some extent, but we can 200 highlight some considerations: 202 o In many cases, customers outside the network will have IPv6 before 203 the internal enterprise network. For these customers, IPv6 may 204 well perform better, especially for certain applications, than 205 translated or tunneled IPv4, so the administrator may want to 206 prioritize the External Phase such that those customers have the 207 simplest and most robust connectivity to the enterprise, or at 208 least its external-facing elements. 210 o Employees who access internal systems by VPN may find that their 211 ISPs provide translated IPv4, which does not support the required 212 VPN protocols. In these cases, the administrator may want to 213 prioritize the External Phase, and any other remotely-accessible 214 internal systems. It is worth noting that a number of emerging 215 VPN solutions provide dual-stack connectivity; thus a VPN service 216 may be useful for employees in IPv4-only access networks to access 217 IPv6 resources in the enterprise network (much like many public 218 tunnel broker services, but specifically for the enterprise). 220 o Internet-facing servers cannot be managed over IPv6 unless the 221 management systems are IPv6-capable. These might be Network 222 Management Systems (NMS), monitoring systems, or just remote 223 management desktops. Thus in some cases, the Internet-facing 224 systems are dependent on IPv6-capable internal networks. However, 225 dual-stack Internet-facing systems can still be managed over IPv4. 227 o Virtual machines may enable a faster rollout once initial system 228 deployment is complete. Management of VMs over IPv6 is still 229 dependent on the management software supporting IPv6. 231 o IPv6 is enabled by default on all modern operating systems, so it 232 may be more urgent to manage and have visibility on the internal 233 traffic. It is important to manage IPv6 for security purposes, 234 even in an ostensibly IPv4-only network, as described in 235 [I-D.ietf-opsec-ipv6-implications-on-ipv4-nets]. 237 o In many cases, the corporate accounting, payroll, human resource, 238 and other internal systems may only need to be reachable from the 239 internal network, so they may be a lower priority. As enterprises 240 require their vendors to support IPv6, more internal applications 241 will support IPv6 by default and it can be expected that 242 eventually new applications will only support IPv6. The 243 inventory, as described in Section 2.2, will help determine the 244 systems' readiness, as well as the readiness of the supporting 245 network elements and security, which will be a consideration in 246 prioritization of these corporate systems. 248 o Some large organizations (even when using private IPv4 249 addresses[RFC1918]) are facing IPv4 address exhaustion because of 250 the internal network growth (for example the vast number of 251 virtual machines) or because of the acquisition of other companies 252 that often raise private IPv4 address overlapping issues. 254 o IPv6 restores end to end transparency even for internal 255 applications (of course security policies must still be enforced). 256 When two organizations or networks merge 257 [I-D.ietf-6renum-enterprise], the unique addressing of IPv6 can 258 make the merger much easier and faster. A merger may, therefore, 259 prioritize IPv6 for the affected systems. 261 These considerations are in conflict; each administrator must 262 prioritize according to their company's conditions. It is worth 263 noting that the reasons given in one "Large Corporate User's View of 264 IPng", described in [RFC1687], for reluctance to deploy have largely 265 been satisfied or overcome in the intervening 18 years. 267 2. Preparation and Assessment Phase 269 2.1. Program Planning 271 As with any project, an IPv6 deployment project will have its own 272 phases. Generally, one person is identified as the project sponsor 273 or champion, who will make sure time, people and other resources are 274 committed appropriately for the project. Because enabling IPv6 can 275 be a project with many interrelated tasks, identifying a project 276 manager is also recommended. The project manager and sponsor can 277 initiate the project, determining the scope of work, the 278 corresponding milestones and deliverables, and identifying whose 279 input is required, and who will be affected by work. The scope will 280 generally include the Preparation Phase, and may include the Internal 281 Phase, the External Phase, or both, and may include any or all of the 282 Other Phases identified. It may be necessary to complete the 283 Preparation Phase before determining which of the other phases will 284 be prioritized, since needs and readiness assessments are part of 285 that phase. 287 The project manager will need to spend some time on planning. It is 288 often useful for the sponsor to communicate with stakeholders at this 289 time, to explain why IPv6 is important to the enterprise. Then, as 290 the project manager is assessing what systems and elements will be 291 affected, the stakeholders will understand why it is important for 292 them to support the effort. Well-informed project participants can 293 help significantly by explaining the relationships between 294 components. For a large enterprise, it may take several iterations 295 to really understand the level of effort required; some systems will 296 require additional development, some might require software updates, 297 and others might need new versions or alternative products from other 298 vendors. Once the projects are understood, the project manager can 299 develop a schedule and a budget, and work with the project sponsor to 300 determine what constraints can be adjusted, if necessary. 302 It is tempting to roll IPv6 projects into other architectural 303 upgrades - this can be an excellent way to improve the network and 304 reduce costs. Project participants are advised that by increasing 305 the scope of projects, the schedule is often affected. For instance, 306 a major systems upgrade may take a year to complete, where just 307 patching existing systems may take only a few months. Understanding 308 and evaluating these trade-offs are why a project manager is 309 important. 311 The deployment of IPv6 will not generally stop all other technology 312 work. Once IPv6 has been identified as an important initiative, all 313 projects will need to evaluate their ability to support IPv6. If 314 expansions or new deployments fail to include IPv6, then additional 315 work will be required after all initial IPv6 has been completed. It 316 may not be possible to delay regular projects for IPv6, if their IPv6 317 support is dependent on network elements that have not yet been 318 upgraded, but the projects need to include a return to IPv6 support 319 in their eventual timeline. 321 It is very common for assessments to continue in some areas even as 322 execution of the project begins in other areas. This is fine, as 323 long as recommendations in other parts of this document are 324 considered, especially regarding security (for instance, one should 325 not deploy IPv6 on a system before security has been evaluated). The 326 project manager will need to continue monitoring the progress of 327 discrete projects and tasks, to be aware of changes in schedule, 328 budget, or scope. "Feature creep" is common, where engineers or 329 management wish to add other features while IPv6 development or 330 deployment is ongoing; each feature will need to be individually 331 evaluated for its effect on the schedule and budget, and whether 332 expanding the scope increases risk to any other part of the project. 334 As projects are completed, the project manager will confirm that work 335 has been completed, often by means of seeing a completed test plan, 336 and will report back to the project sponsor on completed parts of the 337 project. A good project manager will remember to thank the people 338 who executed the project. 340 2.2. Inventory Phase 342 To comprehend the scope of the inventory phase we recommend dividing 343 the problem space in two: network infrastructure readiness and 344 applications readiness. 346 2.2.1. Network infrastructure readiness assessment 348 The goal of this assessment is to identify the level of IPv6 349 readiness of network equipment. This is an important step as it will 350 help identify the effort required to move to an infrastructure that 351 supports IPv6 with the same functional service capabilities as the 352 existing IPv4 network. This may also require a feature comparison 353 and gap analysis between IPv4 and IPv6 functionality on the network 354 equipment and software. 356 Be able to understand which network devices are already capable, 357 which devices can be made IPv6 ready with a code/firmware upgrade, 358 and which devices will need to be replaced. The data collection 359 consists of a network discovery to gain an understanding of the 360 topology and inventory network infrastructure equipment and code 361 versions with information gathered from static files and IP address 362 management, DNS and DHCP tools. 364 Since IPv6 might already be present in the environment, through 365 default configurations or VPNs, an infrastructure assessment (at 366 minimum) is essential to evaluate potential security risks. 368 2.2.2. Applications readiness assessment 370 Just like network equipment, application software needs to support 371 IPv6. This includes OS, firmware, middleware and applications 372 (including internally developed applications). Vendors will 373 typically handle IPv6 enablement of off-the-shelf products, but often 374 enterprises need to request this support from vendors. For 375 internally developed applications it is the responsibility of the 376 enterprise to enable them for IPv6. Analyzing how a given 377 application communicates over the network will dictate the steps 378 required to support IPv6. Applications should be made to use APIs 379 which hide the specifics of a given IP address family. Any 380 applications that use APIs, such as the C language, which exposes the 381 IP version specificity, need to be modified to also work with IPv6. 383 There are two ways to IPv6-enable applications. The first approach 384 is to have separate logic for IPv4 and IPv6, thus leaving the IPv4 385 code path mainly untouched. This approach causes the least 386 disruption to the existing IPv4 logic flow, but introduces more 387 complexity, since the application now has to deal with two logic 388 loops with complex race conditions and error recovery mechanisms 389 between these two logic loops. The second approach is to create a 390 combined IPv4/IPv6 logic, which ensures operation regardless of the 391 IP version used on the network. Knowing whether a given 392 implementation will use IPv4 or IPv6 in a given deployment is a 393 matter of some art; see Source Address Selection [RFC6724] and Happy 394 Eyeballs [RFC6555]. It is generally recommend that the application 395 developer use industry IPv6-porting tools to locate the code that 396 needs to be updated. Some discussion of IPv6 application porting 397 issues can be found in [RFC4038]. 399 2.2.3. Importance of readiness validation and testing 401 Lastly IPv6 introduces a completely new way of addressing endpoints, 402 which can have ramifications at the network layer all the way up to 403 the applications. So to minimize disruption during the transition 404 phase we recommend complete functionality, scalability and security 405 testing to understand how IPv6 impacts the services and networking 406 infrastructure. 408 2.3. Training 410 IPv6 planning and deployment in the enterprise does not only affect 411 the network. IPv6 adoption will be a multifaceted undertaking that 412 will touch everyone in the organization unlike almost any other 413 project. While technology and process transformations are taking 414 place, it is critical that personnel training takes place as well. 415 Training will ensure that people and skill gaps are assessed 416 proactively and managed accordingly. We recommend that training 417 needs be analyzed and defined in order to successfully inform, train, 418 and prepare staff for the impacts of the system or process changes. 419 Better knowledge of the requirements to deploy IPv6 may also help 420 inform procurement processes. 422 2.4. Security Policy 424 It is obvious that IPv6 networks should be deployed in a secure way. 425 The industry has learnt a lot about network security with IPv4, so, 426 network operators should leverage this knowledge and expertise when 427 deploying IPv6. IPv6 is not so different than IPv4: it is a 428 connectionless network protocol using the same lower layer service 429 and delivering the same service to the upper layer. Therefore, the 430 security issues and mitigation techniques are mostly identical with 431 same exceptions that are described further. 433 2.4.1. IPv6 is no more secure than IPv4 434 Some people believe that IPv6 is inherently more secure than IPv4 435 because it is new. Nothing can be more wrong. Indeed, being a new 436 protocol means that bugs in the implementations have yet to be 437 discovered and fixed and that few people have the operational 438 security expertise needed to operate securely an IPv6 network. This 439 lack of operational expertise is the biggest threat when deploying 440 IPv6: the importance of training is to be stressed again. 442 One security myth is that thanks to its huge address space, a network 443 cannot be scanned by enumerating all IPv6 address in a /64 LAN hence 444 a malevolent person cannot find a victim. [RFC5157] describes some 445 alternate techniques to find potential targets on a network, for 446 example enumerating all DNS names in a zone. Additional advice in 447 this area is also given in [I-D.ietf-opsec-ipv6-host-scanning]. 449 Another security myth is that IPv6 is more secure because it mandates 450 the use of IPsec everywhere. While the original IPv6 specifications 451 may have implied this, [RFC6434] clearly states that IPsec support is 452 not mandatory. Moreover, if all the intra-enterprise traffic is 453 encrypted, then this renders a lot of the network security tools 454 (IPS, firewall, ACL, IPFIX, etc) blind and pretty much useless. 455 Therefore, IPsec should be used in IPv6 pretty much like in IPv4 (for 456 example to establish a VPN overlay over a non-trusted network or 457 reserved for some specific applications). 459 The last security myth is that amplification attacks (such as 460 [SMURF]) do not exist in IPv6 because there is no more broadcast. 461 Alas, this is not true as ICMP error (in some cases) or information 462 messages can be generated by routers and hosts when forwarding or 463 receiving a multicast message (see Section 2.4 of [RFC4443]). 464 Therefore, the generation and the forwarding rate of ICMPv6 messages 465 must be limited as in IPv4. 467 It should be noted that in a dual-stack network the security 468 implementation for both IPv4 and IPv6 needs to be considered, in 469 addition to security considerations related to the interaction of 470 (and transition between) the two, while they coexist. 472 2.4.2. Similarities between IPv6 and IPv4 security 474 As mentioned earlier, IPv6 is quite similar to IPv4, therefore 475 several attacks apply for both protocol families: 477 o Application layer attacks: such as cross-site scripting or SQL 478 injection 480 o Rogue device: such as a rogue Wi-Fi Access Point 481 o Flooding and all traffic-based denial of services (including the 482 use of control plane policing for IPv6 traffic see [RFC6192]) 484 o Etc. 486 A specific case of congruence is IPv6 Unique Local Addresses (ULAs) 487 [RFC4193] and IPv4 private addressing [RFC1918], which do not provide 488 any security by 'magic'. In both cases, the edge router must apply 489 strict filters to block those private addresses from entering and, 490 just as importantly, leaving the network. This filtering can be done 491 by the enterprise or by the ISP, but the cautious administrator will 492 prefer to do it in the enterprise. 494 IPv6 addresses can be spoofed as easily as IPv4 addresses and there 495 are packets with bogon IPv6 addresses (see [CYMRU]). Anti-bogon 496 filtering must be done in the data and routing planes. It can be 497 done by the enterprise or by the ISP, or both, but again the cautious 498 administrator will prefer to do it in the enterprise. 500 2.4.3. Specific Security Issues for IPv6 502 Even if IPv6 is similar to IPv4, there are some differences that 503 create some IPv6-only vulnerabilities or issues. We give examples of 504 such differences in this section. 506 Privacy extension addresses [RFC4941] are usually used to protect 507 individual privacy by periodically changing the interface identifier 508 part of the IPv6 address to avoid tracking a host by its otherwise 509 always identical and unique MAC-based EUI-64. While this presents a 510 real advantage on the Internet, moderated by the fact that the prefix 511 part remains the same, it complicates the task of following an audit 512 trail when a security officer or network operator wants to trace back 513 a log entry to a host in their network, because when the tracing is 514 done the searched IPv6 address could have disappeared from the 515 network. Therefore, the use of privacy extension addresses usually 516 requires additional monitoring and logging of the binding of the IPv6 517 address to a data-link layer address (see also the monitoring section 518 of [I-D.ietf-opsec-v6]). Some early enterprise deployments have 519 taken the approach to use tools that harvest IP/MAC address mappings 520 from switch and router devices to provide address accountability; 521 this approach has been shown to work, though it can involve gathering 522 significantly more address data than in equivalent IPv4 networks. An 523 alternative is to try to prevent the use of privacy extension 524 addresses by enforcing the use of DHCPv6, such that hosts only get 525 addresses assigned by a DHCPv6 server. This can be done by 526 configuring routers to set the M-bit in Router Advertisements, 527 combined with all advertised prefixes being included without the 528 A-bit set (to prevent the use of stateless auto-configuration). This 529 technique of course requires that all hosts support stateful DHCPv6. 530 It is important to note that not all operating systems exhibit the 531 same behavior when processing RAs with the M-Bit set. The varying OS 532 behavior is related to the lack of prescriptive definition around the 533 A, M and O-bits within the ND protocol. 534 [I-D.liu-bonica-dhcpv6-slaac-problem] provides a much more detailed 535 analysis on the interaction of the M-Bit and DHCPv6. 537 Extension headers complicate the task of stateless packet filters 538 such as ACLs. If ACLs are used to enforce a security policy, then 539 the enterprise must verify whether its ACL (but also stateful 540 firewalls) are able to process extension headers (this means 541 understand them enough to parse them to find the upper layers 542 payloads) and to block unwanted extension headers (e.g., to implement 543 [RFC5095]). This topic is discussed further in 544 [I-D.carpenter-6man-ext-transmit]. 546 Fragmentation is different in IPv6 because it is done only by source 547 host and never during a forwarding operation. This means that ICMPv6 548 packet-too-big messages must be allowed to pass through the network 549 and not be filtered [RFC4890]. Fragments can also be used to evade 550 some security mechanisms such as RA-guard [RFC6105]. See also 551 [RFC5722], and [I-D.ietf-v6ops-ra-guard-implementation]. 553 One of the biggest differences between IPv4 and IPv6 is the 554 introduction of the Neighbor Discovery Protocol [RFC4861], which 555 includes a variety of important IPv6 protocol functions, including 556 those provided in IPv4 by ARP [RFC0826]. NDP runs over ICMPv6 (which 557 as stated above means that security policies must allow some ICMPv6 558 messages to pass, as described in RFC 4890), but has the same lack of 559 security as, for example, ARP, in that there is no inherent message 560 authentication. While Secure Neighbour Discovery (SeND) [RFC3971] 561 and CGA [RFC3972] have been defined, they are not widely 562 implemented). The threat model for Router Advertisements within the 563 NDP suite is similar to that of DHCPv4 (and DHCPv6), in that a rogue 564 host could be either a rogue router or a rogue DHCP server. An IPv4 565 network can be made more secure with the help of DHCPv4 snooping in 566 edge switches, and likewise RA snooping can improve IPv6 network 567 security (in IPv4-only networks as well). Thus enterprises using 568 such techniques for IPv4 should use the equivalent techniques for 569 IPv6, including RA-guard (RFC 6105) and all work in progress from the 570 SAVI WG, e.g. [I-D.ietf-savi-threat-scope], which is similar to the 571 protection given by dynamic ARP monitoring in IPv4. Other DoS 572 vulnerabilities are related to NDP cache exhaustion, and mitigation 573 techniques can be found in ([RFC6583]). 575 As stated previously, running a dual-stack network doubles the attack 576 exposure as a malevolent person has now two attack vectors: IPv4 and 577 IPv6. This simply means that all routers and hosts operating in a 578 dual-stack environment with both protocol families enabled (even if 579 by default) must have a congruent security policy for both protocol 580 versions. For example, permit TCP ports 80 and 443 to all web 581 servers and deny all other ports to the same servers must be 582 implemented both for IPv4 and IPv6. It is thus important that the 583 tools available to administrators readily support such behaviour. 585 2.5. Routing 587 An important design choice to be made is what IGP to use inside the 588 network. A variety of IGPs (IS-IS, OSPFv3 and RIPng) support IPv6 589 today and picking one over the other is a design choice that will be 590 dictated mostly by existing operational policies in an enterprise 591 network. As mentioned earlier, it would be beneficial to maintain 592 operational parity between IPv4 and IPv6 and therefore it might make 593 sense to continue using the same protocol family that is being used 594 for IPv4. For example, in a network using OSPFv2 for IPv4, it might 595 make sense to use OSPFv3 for IPv6. It is important to note that 596 although OSPFv3 is similar to OSPFv2, they are not the same. On the 597 other hand, some organizations may chose to run different routing 598 protocols for different IP versions. For example, one may chose to 599 run OSPFv2 for IPv4 and IS-IS for IPv6. An important design question 600 to consider here is whether to support one IGP or two different IGPs 601 in the longer term. [I-D.ietf-v6ops-design-choices] presents advice 602 on the design choices that arise when considering IGPs and discusses 603 the advantages and disadvantages to different approaches in detail. 605 2.6. Address Plan 607 The most common problem encountered in IPv6 networking is in applying 608 the same principles of conservation that are so important in IPv4. 609 IPv6 addresses do not need to be assigned conservatively. In fact, a 610 single larger allocation is considered more conservative than 611 multiple non-contiguous small blocks, because a single block occupies 612 only a single entry in a routing table. The advice in [RFC5375] is 613 still sound, and is recommended to the reader. If considering ULAs, 614 give careful thought to how well it is supported, especially in 615 multiple address and multicast scenarios, and assess the strength of 616 the requirement for ULA. If using ULAs in a ULA-only deployment 617 model, instead of using them in conjunction with Globally Unique 618 Addressing for hosts, note that Network Prefix Translation will be 619 required [RFC6296] for Internet based communication; the implications 620 of which must be well understood before deploying. 621 [I-D.ietf-v6ops-ula-usage-recommendations] provides much more 622 detailed analysis and recommendations on the usage of ULAs. 624 The enterprise administrator will want to evaluate whether the 625 enterprise will request address space from a LIR (Local Internet 626 Registry, such as an ISP), a RIR (Regional Internet Registry, such as 627 AfriNIC, APNIC, ARIN, LACNIC, or RIPE-NCC) or a NIR (National 628 Internet Registry, operated in some countries). The normal 629 allocation is Provider Aggregatable (PA) address space from the 630 enterprise's ISP, but use of PA space implies renumbering when 631 changing provider. Instead, an enterprise may request Provider 632 Independent (PI) space; this may involve an additional fee, but the 633 enterprise may then be better able to be multihomed using that 634 prefix, and will avoid a renumbering process when changing ISPs 635 (though it should be noted that renumbering caused by outgrowing the 636 space, merger, or other internal reason would still not be avoided 637 with PI space). 639 The type of address selected (PI vs. PA) should be congruent with the 640 routing needs of the enterprise. The selection of address type will 641 determine if an operator will need to apply new routing techniques 642 and may limit future flexibility. There is no right answer, but the 643 needs of the external phase may affect what address type is selected. 645 Each network location or site will need a prefix assignment. 646 Depending on the type of site/location, various prefix sizes may be 647 used. In general, historical guidance suggests that each site should 648 get at least a /48, as documented in RFC 5375 and [RFC6177]. In 649 addition to allowing for simple planning, this can allow a site to 650 use its prefix for local connectivity, should the need arise, and if 651 the local ISP supports it. 653 When assigning addresses to end systems, the enterprise may use 654 manually-configured addresses (common on servers) or SLAAC or DHCPv6 655 for client systems. Early IPv6 enterprise deployments have used 656 SLAAC, both for its simplicity but also due to the time DHCPv6 has 657 taken to mature. However, DHCPv6 is now very mature, and thus 658 workstations managed by an enterprise may use stateful DHCPv6 for 659 addressing on corporate LAN segments. DHCPv6 allows for the 660 additional configuration options often employed by enterprise 661 administrators, and by using stateful DHCPv6, administrators 662 correlating system logs know which system had which address at any 663 given time. Such an accountability model is familiar from IPv4 664 management, though for DHCPv6 hosts are identified by DUID rather 665 than MAC address. For equivalent accountability with SLAAC (and 666 potentially privacy addresses), a monitoring system that harvests IP/ 667 MAC mappings from switch and router equipment could be used. 669 A common deployment consideration for any enterprise network is how 670 to get host DNS records updated. In a traditional IPv4 network, the 671 two commonly used methods are to either have the host send DNS 672 updates itself or have the DHCPv4 server update DNS records. The 673 former implies that there is sufficient trust between the hosts and 674 the DNS server while the latter implies a slightly more controlled 675 environment where only DHCP servers are trusted to make these 676 updates. If the enterprise uses the first model, then SLAAC is a 677 perfectly valid option to assign addresses to end systems. However, 678 an enterprise network with a more controlled environment will need to 679 disable SLAAC and force end hosts to use DHCPv6 only. 681 In the data center or server room, assume a /64 per VLAN. This 682 applies even if each individual system is on a separate VLAN. In a / 683 48 assignment, typical for a site, there are then still 65,535 /64 684 blocks. Addresses are either configured manually on the server, or 685 reserved on a DHCPv6 server, which may also synchronize forward and 686 reverse DNS. Because of the need to synchronize RA timers and DNS 687 TTLs, SLAAC is rarely, if ever, used for servers, and would require 688 tightly coupled dynamic DNS updates. 689 [I-D.ietf-6renum-static-problem] 691 All user access networks should be a /64. Point-to-point links where 692 Neighbor Discovery Protocol is not used may also utilize a /127 (see 693 [RFC6164]). 695 Plan to aggregate at every layer of network hierarchy. There is no 696 need for VLSM [RFC1817] in IPv6, and addressing plans based on 697 conservation of addresses are short-sighted. Use of prefixes longer 698 then /64 on network segments will break common IPv6 functions such as 699 SLAAC[RFC4862]. Where multiple VLANs or other layer two domains 700 converge, allow some room for expansion. Renumbering due to 701 outgrowing the network plan is a nuisance, so allow room within it. 702 Generally, plan to grow to about twice the current size that can be 703 accommodated; where rapid growth is planned, allow for twice that 704 growth. Also, if DNS (or reverse DNS) authority may be delegated to 705 others in the enterprise, assignments need to be on nibble boundaries 706 (that is, on a multiple of 4 bits, such as /64, /60, /56, ..., /48, / 707 44), to ensure that delegated zones align with assigned prefixes. 709 2.7. Tools Assessment 711 Enterprises will often have a number of operational tools and support 712 systems which are used to provision, monitor, manage and diagnose the 713 network and systems within their environment. These tools and 714 systems will need to be assessed for compatibility with IPv6. The 715 compatibility may be related to the addressing and connectivity of 716 various devices as well as IPv6 awareness the tools and processing 717 logic. 719 The tools within the organization fall into two general categories, 720 those which focus on managing the network, and those which are 721 focused on managing systems and applications on the network. In 722 either instance, the tools will run on platforms which may or may not 723 be capable of operating in an IPv6 network. This lack in 724 functionality may be related to Operating System version, or based on 725 some hardware constraint. Those systems which are found to be 726 incapable of utilizing an IPv6 connection, or which are dependent on 727 an IPv4 stack, may need to be replaced or upgraded. 729 In addition to devices working on an IPv6 network natively, or via a 730 tunnel, many tools and support systems may require additional 731 software updates to be IPv6 aware, or even a hardware upgrade 732 (usually for additional memory: IPv6 as the addresses are larger and 733 for a while, IPv4 and IPv6 addresses will coexist in the tool). This 734 awareness may include the ability to manage IPv6 elements and/or 735 applications in addition to the ability to store and utilize IPv6 736 addresses. 738 Considerations when assessing the tools and support systems may 739 include the fact that IPv6 addresses are significantly larger than 740 IPv4, requiring data stores to support the increased size. Such 741 issues are among those discussed in [RFC5952]. Many organizations 742 may also run dual-stack networks, therefore the tools need to not 743 only support IPv6 operation, but may also need to support the 744 monitoring, management and intersection with both IPv6 and IPv4 745 simultaneously. It is important to note that managing IPv6 is not 746 just constrained to using large IPv6 addresses, but also that IPv6 747 interfaces and nodes are likely to use two or more addresses as part 748 of normal operation. Updating management systems to deal with these 749 additional nuances will likely consume time and considerable effort. 751 For networking systems, like node management systems, it is not 752 always necessary to support local IPv6 addressing and connectivity. 753 Operations such as SNMP MIB polling can occur over IPv4 transport 754 while seeking responses related to IPv6 information. Where this may 755 seem advantageous to some, it should be noted that without local IPv6 756 connectivity, the management system may not be able to perform all 757 expected functions - such as reachability and service checks. 759 Organizations should be aware that changes to older IPv4-only SNMP 760 MIB specifications have been made by the IETF related to legacy 761 operation in [RFC2096] and [RFC2011]. Updated specifications are now 762 available in [RFC4296] and [RFC4293] which modified the older MIB 763 framework to be IP protocol agnostic, supporting both IPv4 and IPv6. 764 Polling systems will need to be upgraded to support these updates as 765 well as the end stations which are polled. 767 3. External Phase 769 The external phase for enterprise IPv6 adoption covers topics which 770 deal with how an organization connects its infrastructure to the 771 external world. These external connections may be toward the 772 Internet at large, or to other networks. The external phase covers 773 connectivity, security and monitoring of various elements and outward 774 facing or accessible services. 776 How an organization connects to the outside worlds is very important 777 as it is often a critical part of how a business functions, therefore 778 it must be dealt accordingly. 780 3.1. Connectivity 782 The enterprise will need to work with one or more Service Providers 783 to gain connectivity to the Internet or transport service 784 infrastructure such as a BGP/MPLS IP VPN as described in [RFC4364] 785 and [RFC4659]. One significant factor that will guide how an 786 organization may need to communicate with the outside world will 787 involve the use of PI (Provider Independent) and/or PA (Provider 788 Aggregatable) IPv6 space. 790 Enterprises should be aware that depending on which address type they 791 selected (PI vs. PA) in their planning section, they may need to 792 implement new routing functions and/or behaviours to support their 793 connectivity to the ISP. In the case of PI, the upstream ISP may 794 offer options to route the prefix (typically a /48) on the 795 enterprise's behalf and update the relevant routing databases. In 796 other cases, the enterprise may need to perform this task on their 797 own and use BGP to inject the prefix into the global BGP system. 798 This latter case is not how many enterprises operate today and is an 799 important consideration. 801 Note that the rules set by the RIRs for an enterprise acquiring PI 802 address space have changed over time. For example, in the European 803 region the RIPE-NCC no longer requires an enterprise to be multihomed 804 to be eligible for an IPv6 PI allocation. Requests can be made 805 directly or via an LIR. It is possible that the rules may change 806 again, and may vary between RIRs. 808 When seeking IPv6 connectivity to a Service Provider, the Enterprise 809 will prefer to use native IPv6 connectivity. Native IPv6 810 connectivity is preferred since it provides the most robust and 811 efficient form of connectivity. If native IPv6 connectivity is not 812 possible due to technical or business limitations, the enterprise may 813 utilize readily available tunnelled IPv6 connectivity. There are 814 IPv6 transit providers which provide robust tunnelled IPv6 815 connectivity which can operate over IPv4 networks. It is important 816 to understand the tunneling mechanism used, and to consider that it 817 will have higher latency than native IPv4 or IPv6, and may have other 818 problems, e.g. related to MTUs. 820 The use of ULAs may provide some flexibility when an enterprise is 821 using PA space from two or more providers in a multihoming scenario, 822 by providing an independent local prefix for internal use, while 823 using the PA prefix for external communication in conjunction with 824 NPTv6 at the egress [RFC6296]. While NPTv6 can provide for 825 simplified renumbering in certain scenarios, as described in 826 [I-D.ietf-6renum-enterprise], it must be noted that many of the well- 827 known issues with NAT still apply, in particular handling IPv6 828 addresses embedded in payloads. As mentioned earlier, if considering 829 ULAs, give careful thought to how well it is supported, especially in 830 multiple address and multicast scenarios, and assess the strength of 831 the requirement for ULA.[I-D.ietf-v6ops-ula-usage-recommendations] 832 provides much more detailed analysis and recommendations on the usage 833 of ULAs. 835 It should be noted that the use of PI space obviates the need for 836 using ULAs just in order to achieve multihoming. 838 It is important to evaluate MTU considerations when adding in IPv6 to 839 an existing IPv4 network. It is generally desirable to have the IPv6 840 and IPv4 MTU congruent to simplify operations. If the enterprise 841 uses tunnelling inside or externally for IPv6 connectivity, then 842 modification of the MTU on hosts/routers may be needed as mid-stream 843 fragmentation is no longer supported in IPv6. It is preferred that 844 pMTUD is used to optimize the MTU, so erroneous filtering of the 845 related ICMPv6 message types should be monitored. Adjusting the MTU 846 may be the only option if undesirable upstream ICMPv6 filtering 847 cannot be removed. 849 3.2. Security 851 The most important part of security for external IPv6 deployment is 852 filtering and monitoring. Filtering can be done by stateless ACLs or 853 a stateful firewall. The security policies must be consistent for 854 IPv4 and IPv6 (else the attacker will use the less protected protocol 855 stack), except that certain ICMPv6 messages must be allowed through 856 and to the filtering device (see [RFC4890]): 858 o Unreachable packet-too-big: it is very important to allow Path MTU 859 discovery to work 861 o Unreachable parameter-problem 862 o Neighbor solicitation 864 o Neighbor advertisement 866 It could also be safer to block all fragments where the transport 867 layer header is not in the first fragment to avoid attacks as 868 described in [RFC5722]. Some filtering devices allow this filtering. 869 To be fully compliant with [RFC5095], all packets containing the 870 routing extension header type 0 must be dropped. 872 If an Intrusion Prevention System (IPS) is used for IPv4 traffic, 873 then an IPS should also be used for IPv6 traffic. In general, make 874 sure IPv6 security is at least as good as IPv4. This also includes 875 all email content protection (anti-spam, content filtering, data 876 leakage prevention, etc.). 878 The edge router must also implement anti-spoofing techniques based on 879 [RFC2827] (also known as BCP 38). 881 In order to protect the networking devices, it is advised to 882 implement control plane policing as per [RFC6192]. 884 The potential NDP cache exhaustion attack (see [RFC6538]) can be 885 mitigated by two techniques: 887 o Good NDP implementation with memory utilization limits as well as 888 rate-limiters and prioritization of requests. 890 o Or, as the external deployment usually involves just a couple of 891 exposed statically configured IPv6 addresses (virtual addresses of 892 web, email, and DNS servers), then it is straightforward to build 893 an ingress ACL allowing traffic for those addresses and denying 894 traffic to any other addresses. This actually prevents the attack 895 as a packet for a random destination will be dropped and will 896 never trigger a neighbor resolution. 898 3.3. Monitoring 900 Monitoring the use of the Internet connectivity should be done for 901 IPv6 as it is done for IPv4. This includes the use of IP Flow 902 Information eXport (IPFIX) [RFC5102] to detect abnormal traffic 903 patterns (such as port scanning, SYN-flooding) and SNMP MIB [RFC4293] 904 (another way to detect abnormal bandwidth utilization). Where using 905 Netflow, version 9 is required for IPv6 support. 907 3.4. Servers and Applications 908 The path to the servers accessed from the Internet usually involves 909 security devices (firewall, IPS), server load balancing (SLB) and 910 real physical servers. The latter stage is also multi-tiered for 911 scalability and security between presentation and data storage. The 912 ideal transition is to enable dual-stack on all devices but this may 913 seem too time-consuming and too risky. 915 Operators have used the following approaches with success: 917 o Use a network device to apply NAT64 and basically translate an 918 inbound TCP connection (or any other transport protocol) over IPv6 919 into a TCP connection over IPv4. This is the easiest to deploy as 920 the path is mostly unchanged but it hides all IPv6 remote users 921 behind a single IPv4 address which leads to several audit trail 922 and security issues (see [RFC6302]). 924 o Use the server load balancer which acts as an application proxy to 925 do this translation. Compared to the NAT64, it has the potential 926 benefit of going through the security devices as native IPv6 (so 927 more audit and trace abilities) and is also able to insert a HTTP 928 X-Forward-For header which contains the remote IPv6 address. The 929 latter feature allows for logging, and rate-limiting on the real 930 servers based on the IPV6 address even if those servers run only 931 IPv4. 933 3.5. Network Prefix Translation for IPv6 935 Network Prefix Translation for IPv6, or NPTv6 as described in 936 [RFC6296] provides a framework to utilize prefix ranges within the 937 internal network which are separate (address-independent) from the 938 assigned prefix from the upstream provider or registry. As mentioned 939 above, while NPTv6 has potential use-cases in IPv6 networks, the 940 implications of its deployment need to be fully understood, 941 particularly where any applications might embed IPv6 addresses in 942 their payloads. 944 Use of NTPv6 can be chosen independently from how addresses are 945 assigned and routed within the internal network and how prefixes are 946 routed towards the Internet (included both PA and PI address 947 assignment options). 949 4. Internal Phase 951 This phase deals with the delivery of IPv6 to the internal user- 952 facing side of the IT infrastructure, which comprises various 953 components such as network devices (routers, switches, etc.), end 954 user devices and peripherals (workstations, printers, etc.), and 955 internal corporate systems. 957 An important design paradigm to consider during this phase is "dual- 958 stack when you can, tunnel when you must". Dual-stacking allows a 959 more robust, production-quality IPv6 network than is typically 960 facilitated by internal use of tunnels that are harder to 961 troubleshoot and support, and that may introduce scalability and 962 performance issues. Tunnels may of course still be used in 963 production networks, but their use needs to be carefully considered, 964 e.g. where the tunnel may be run through a security or filtering 965 device. Tunnels do also provide a means to experiment with IPv6 and 966 gain some operational experience with the protocol. [RFC4213] 967 describes various transition mechanisms in more detail. 968 [I-D.templin-v6ops-isops] suggests operational guidance when using 969 ISATAP tunnels [RFC5214], though we would recommend use of dual-stack 970 wherever possible. 972 4.1. Security 974 IPv6 must be deployed in a secure way. This means that all existing 975 IPv4 security policies must be extended to support IPv6; IPv6 976 security policies will be the IPv6 equivalent of the existing IPv4 977 ones (taking into account the difference for ICMPv6 [RFC4890]). As 978 in IPv4, security policies for IPv6 will be enforced by firewalls, 979 ACL, IPS, VPN, and so on. 981 Privacy extension addresses [RFC4941] raise a challenge for an audit 982 trail as explained in section Section 2.4.3. The enterprise may 983 choose to attempt to enforce use of DHCPv6, or deploy monitoring 984 tools that harvest accountability data from switches and routers 985 (thus making the assumption that devices may use any addresses inside 986 the network). 988 But the major issue is probably linked to all threats against 989 Neighbor Discovery. This means, for example, that the internal 990 network at the access layer (where hosts connect to the network over 991 wired or wireless) should implement RA-guard [RFC6105] and the 992 techniques being specified by SAVI WG [I-D.ietf-savi-threat-scope]; 993 see also Section 2.4.3 for more information. 995 4.2. Network Infrastructure 997 The typical enterprise network infrastructure comprises a combination 998 of the following network elements - wired access switches, wireless 999 access points, and routers (although it is fairly common to find 1000 hardware that collapses switching and routing functionality into a 1001 single device). Basic wired access switches and access points 1002 operate only at the physical and link layers, and don't really have 1003 any special IPv6 considerations other than being able to support IPv6 1004 addresses themselves for management purposes. In many instances, 1005 these devices possess a lot more intelligence than simply switching 1006 packets. For example, some of these devices help assist with link 1007 layer security by incorporating features such as ARP inspection and 1008 DHCP Snooping, or they may help limit where multicast floods by using 1009 IGMP (or, in the case of IPv6, MLD) snooping. 1011 Another important consideration in enterprise networks is first hop 1012 router redundancy. This directly ties into network reachability from 1013 an end host's point of view. IPv6 Neighbor Discovery (ND), 1014 [RFC4861], provides a node with the capability to maintain a list of 1015 available routers on the link, in order to be able to switch to a 1016 backup path should the primary be unreachable. By default, ND will 1017 detect a router failure in 38 seconds and cycle onto the next default 1018 router listed in its cache. While this feature provides a basic 1019 level of first hop router redundancy, most enterprise IPv4 networks 1020 are designed to fail over much faster. Although this delay can be 1021 improved by adjusting the default timers, care must be taken to 1022 protect against transient failures and to account for increased 1023 traffic on the link. Another option to provide robust first hop 1024 redundancy is to use the Virtual Router Redundancy Protocol for IPv6 1025 (VRRPv3), [RFC5798]. This protocol provides a much faster switchover 1026 to an alternate default router than default ND parameters. Using 1027 VRRPv3, a backup router can take over for a failed default router in 1028 around three seconds (using VRRPv3 default parameters). This is done 1029 without any interaction with the hosts and a minimum amount of VRRP 1030 traffic. 1032 Last but not the least, one of the most important design choices to 1033 make while deploying IPv6 on the internal network is whether to use 1034 Stateless Automatic Address Configuration (SLAAC), [RFC4862], or 1035 Dynamic Host Configuration Protocol for IPv6 (DHCPv6), [RFC3315], or 1036 a combination thereof. Each option has advantages and disadvantages, 1037 and the choice will ultimately depend on the operational policies 1038 that guide each enterprise's network design. For example, if an 1039 enterprise is looking for ease of use, rapid deployment, and less 1040 administrative overhead, then SLAAC makes more sense for 1041 workstations. Manual or DHCPv6 assignments are still needed for 1042 servers, as described in the External Phase and Address Plan sections 1043 of this document. However, if the operational policies call for 1044 precise control over IP address assignment for auditing then DHCPv6 1045 may be preferred. DHCPv6 also allows you tie into DNS systems for 1046 host entry updates and gives you the ability to send other options 1047 and information to clients. It is worth noting that in general 1048 operation RAs are still needed in DHCPv6 networks, as there is no 1049 DHCPv6 Default Gateway option. Similarly, DHCPv6 is needed in RA 1050 networks for other configuration information, e.g. NTP servers or, 1051 in the absence of support for DNS resolvers in RAs [RFC6106], DNS 1052 resolver information. 1054 4.3. End user devices 1056 Most operating systems (OSes) that are loaded on workstations and 1057 laptops in a typical enterprise support IPv6 today. However, there 1058 are various out-of-the-box nuances that one should be mindful about. 1059 For example, the default behavior of OSes vary; some may have IPv6 1060 turned off by default, some may only have certain features such as 1061 privacy extensions to IPv6 addresses (RFC 4941) turned off while 1062 others have IPv6 fully enabled. Further, even when IPv6 is enabled, 1063 the choice of which address is used may be subject to Source Address 1064 Selection (RFC 6724) and Happy Eyeballs (RFC 6555). Therefore, it is 1065 advised that enterprises investigate the default behavior of their 1066 installed OS base and account for it during the Inventory phases of 1067 their IPv6 preparations. Furthermore, some OSes may have tunneling 1068 mechanisms turned on by default and in such cases it is recommended 1069 to administratively shut down such interfaces unless required. 1071 It is important to note that it is recommended that IPv6 be deployed 1072 at the network and system infrastructure level before it is rolled 1073 out to end user devices; ensure IPv6 is running and routed on the 1074 wire, and secure and correctly monitored, before exposing IPv6 to end 1075 users. 1077 Smartphones and tablets are poised to become one of the major 1078 consumers of IP addresses and enterprises, and should be ready to 1079 support IPv6 on various networks that serve such devices. In 1080 general, support for IPv6 in these devices, albeit in its infancy, 1081 has been steadily rising. Most of the leading smartphone OSes have 1082 some level of support for IPv6. However, the level of configurable 1083 options are mostly at a minimum and are not consistent across all 1084 platforms. Also, it is fairly common to find IPv6 support on the Wi- 1085 Fi connection alone and not on the radio interface in these devices. 1086 This is sometimes due to the radio network not being IPv6 ready, or 1087 it may be device-related. An IPv6-enabled enterprise Wi-Fi network 1088 will allow the majority of these devices to connect via IPv6. Much 1089 work is still being done to bring the full IPv6 feature set across 1090 all interfaces (802.11, 3G, LTE, etc.) and platforms. 1092 IPv6 support in peripheral equipment such as printers, IP cameras, 1093 etc., has been steadily rising as well, although at a much slower 1094 pace than traditional OSes and smartphones. Most newer devices are 1095 coming out with IPv6 support but there is still a large installed 1096 base of legacy peripheral devices that might need IPv4 for some time 1097 to come. The audit phase mentioned earlier will make it easier for 1098 enterprises to plan for equipment upgrades, in line with their 1099 corporate equipment refresh cycle. 1101 4.4. Corporate Systems 1103 No IPv6 deployment will be successful without ensuring that all the 1104 corporate systems that an enterprise uses as part of its IT 1105 infrastructure support IPv6. Examples of such systems include, but 1106 are not limited to, email, video conferencing, telephony (VoIP), DNS, 1107 RADIUS, etc. All these systems must have their own detailed IPv6 1108 rollout plan in conjunction with the network IPv6 rollout. It is 1109 important to note that DNS is one of the main anchors in an 1110 enterprise deployment, since most end hosts decide whether or not to 1111 use IPv6 depending on the presence of IPv6 AAAA records in a reply to 1112 a DNS query. It is recommended that system administrators 1113 selectively turn on AAAA records for various systems as and when they 1114 are IPv6 enabled; care must be taken though to ensure all services 1115 running on that host name are IPv6-enabled before adding the AAAA 1116 record. Additionally, all monitoring and reporting tools across the 1117 enterprise would need to be modified to support IPv6. 1119 5. IPv6-only 1121 Early IPv6 enterprise deployments have generally taken a dual-stack 1122 approach to enabling IPv6, i.e. the existing IPv4 services have not 1123 been turned off. Although IPv4 and IPv6 networks will coexist for a 1124 long time, the long term enterprise network roadmap should include 1125 steps on gradually deprecating IPv4 from the dual-stack network. In 1126 some extreme cases, deploying dual-stack networks may not even be a 1127 viable option for very large enterprises due to the RFC 1918 address 1128 space not being large enough to support the network's growth. In 1129 such cases, deploying IPv6-only networks might be the only choice 1130 available to sustain network growth. In other cases, there may be 1131 elements of an otherwise dual-stack network that may be run 1132 IPv6-only. 1134 If nodes in the network don't need to talk to an IPv4-only node, then 1135 deploying IPv6-only networks should be fairly trivial. However, in 1136 the current environment, given that IPv4 is the dominant protocol on 1137 the Internet, an IPv6-only node most likely needs to talk to an 1138 IPv4-only node on the Internet. It is therefore important to provide 1139 such nodes with a translation mechanism to ensure communication 1140 between nodes configured with different address families. As 1141 [RFC6144] points out, it is important to look at address translation 1142 as a transition strategy towards running an IPv6-only network. 1144 There are various stateless and stateful IPv4/IPv6 translation 1145 methods available today that help IPv6 to IPv4 communication. RFC 1146 6144 provides a framework for IPv4/IPv6 translation and describes in 1147 detail various scenarios in which such translation mechanisms could 1148 be used. [RFC6145] describes stateless address translation. In this 1149 mode, a specific IPv6 address range will represent IPv4 systems 1150 (IPv4-converted addresses), and the IPv6 systems have addresses 1151 (IPv4-translatable addresses) that can be algorithmically mapped to a 1152 subset of the service provider's IPv4 addresses. [RFC6146], NAT64, 1153 describes stateful address translation. As the name suggests, the 1154 translation state is maintained between IPv4 address/port pairs and 1155 IPv6 address/port pairs, enabling IPv6 systems to open sessions with 1156 IPv4 systems. [RFC6147], DNS64, describes a mechanism for 1157 synthesizing AAAA resource records (RRs) from A RRs. Together, RFCs 1158 6146 and RFC 6147 provide a viable method for an IPv6-only client to 1159 initiate communications to an IPv4-only server. 1161 The address translation mechanisms for the stateless and stateful 1162 translations are defined in [RFC6052]. It is important to note that 1163 both of these mechanisms have limitations as to which protocols they 1164 support. For example, RFC 6146 only defines how stateful NAT64 1165 translates unicast packets carrying TCP, UDP, and ICMP traffic only. 1166 The classic problems of IPv4 NAT also apply, e.g. handling IP 1167 literals in application payloads. The ultimate choice of which 1168 translation mechanism to chose will be dictated mostly by existing 1169 operational policies pertaining to application support, logging 1170 requirements, etc. 1172 There is additional work being done in the area of address 1173 translation to enhance and/or optimize current mechanisms. For 1174 example, [I-D.xli-behave-divi] describes limitations with the current 1175 stateless translation, such as IPv4 address sharing and application 1176 layer gateway (ALG) problems, and presents the concept and 1177 implementation of dual-stateless IPv4/IPv6 translation (dIVI) to 1178 address those issues. 1180 It is worth noting that for IPv6-only access networks that use 1181 technologies such as NAT64, the more content providers (and 1182 enterprises) that make their content available over IPv6, the less 1183 the requirement to apply NAT64 to traffic leaving the access network. 1185 6. Considerations For Specific Enterprises 1187 6.1. Content Delivery Networks 1189 Some guidance for Internet Content and Application Service Providers 1190 can be found in [I-D.ietf-v6ops-icp-guidance], which includes a 1191 dedicated section on CDNs. An enterprise that relies on CDN to 1192 deliver a 'better' e-commerce experience needs to ensure that their 1193 CDN provider also supports IPv4/IPv6 traffic selection so that they 1194 can ensure 'best' access to the content. 1196 6.2. Data Center Virtualization 1198 IPv6 Data Center considerations are described in 1199 [I-D.lopez-v6ops-dc-ipv6]. 1201 6.3. University Campus Networks 1203 A number of campus networks around the world have made some initial 1204 IPv6 deployment. This has been encouraged by their National Research 1205 and Education Network (NREN) backbones having made IPv6 available 1206 natively since the early 2000's. Universities are a natural place 1207 for IPv6 deployment to be considered at an early stage, perhaps 1208 compared to other enterprises, as they are involved by their very 1209 nature in research and education. 1211 Campus networks can deploy IPv6 at their own pace; their is no need 1212 to deploy IPv6 across the entire enterprise from day one, rather 1213 specific projects can be identified for an initial deployment, that 1214 are both deep enough to give the university experience, but small 1215 enough to be a realistic first step. There are generally three areas 1216 in which such deployments are currently made. 1218 In particular those initial areas commonly approached are: 1220 o External-facing services. Typically the campus web presence and 1221 commonly also external-facing DNS and MX services. This ensures 1222 early IPv6-only adopters elsewhere can access the campus services 1223 as simply and as robustly as possible. 1225 o Computer science department. This is where IPv6-related research 1226 and/or teaching is most likely to occur, and where many of the 1227 next generation of network engineers are studying, so enabling 1228 some or all of the campus computer science department network is a 1229 sensible first step. 1231 o The eduroam wireless network. Eduroam [I-D.wierenga-ietf-eduroam] 1232 is the de facto wireless roaming system for academic networks, and 1233 uses 802.1X-based authentication, which is agnostic to the IP 1234 version used (unlike web-redirection gateway systems). Making a 1235 campus' eduroam network dual-stack is a very viable early step. 1237 The general IPv6 deployment model in a campus enterprise will still 1238 follow the general principles described in this document. While the 1239 above early stage projects are commonly followed, these still require 1240 the campus to acquire IPv6 connectivity and address space from their 1241 NREN (or other provider in some parts of the world), and to enable 1242 IPv6 on the wire on at least part of the core of the campus network. 1243 This implies a requirement to have an initial address plan, and to 1244 ensure appropriate monitoring and security measures are in place, as 1245 described elsewhere in this document. 1247 Campuses which have deployed to date do not use ULAs, nor do they use 1248 NPTv6. In general, campuses have very stable PA-based address 1249 allocations from their NRENs (or their equivalent). However, campus 1250 enterprises may consider applying for IPv6 PI; some have already done 1251 so. The discussions earlier in this text about PA vs. PI still 1252 apply. 1254 Finally, campuses may be more likely than many other enterprises to 1255 run multicast applications, such as IP TV or live lecture or seminar 1256 streaming, so may wish to consider support for specific IPv6 1257 multicast functionality, e.g. Embedded-RP [RFC3956] in routers and 1258 MLDv1 and MLDv2 snooping in switches. 1260 7. Security Considerations 1262 This document has multiple security sections detailing how to 1263 securely deploy an IPv6 network within an enterprise network. 1265 8. Acknowledgements 1267 The authors would like to thank Chris Grundemann, Ray Hunter, Brian 1268 Carpenter, Tina Tsou, Christian Jaquenet, and Fred Templin for their 1269 substantial comments and contributions. 1271 9. IANA Considerations 1273 There are no IANA considerations or implications that arise from this 1274 document. 1276 10. Informative References 1278 [RFC0826] Plummer, D., "Ethernet Address Resolution Protocol: Or 1279 converting network protocol addresses to 48.bit Ethernet 1280 address for transmission on Ethernet hardware", STD 37, 1281 RFC 826, November 1982. 1283 [RFC1687] Fleischman, E., "A Large Corporate User's View of IPng", 1284 RFC 1687, August 1994. 1286 [RFC1817] Rekhter, Y., "CIDR and Classful Routing", RFC 1817, August 1287 1995. 1289 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 1290 E. Lear, "Address Allocation for Private Internets", BCP 1291 5, RFC 1918, February 1996. 1293 [RFC2011] McCloghrie, K., "SNMPv2 Management Information Base for 1294 the Internet Protocol using SMIv2", RFC 2011, November 1295 1996. 1297 [RFC2096] Baker, F., "IP Forwarding Table MIB", RFC 2096, January 1298 1997. 1300 [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: 1301 Defeating Denial of Service Attacks which employ IP Source 1302 Address Spoofing", BCP 38, RFC 2827, May 2000. 1304 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 1305 and M. Carney, "Dynamic Host Configuration Protocol for 1306 IPv6 (DHCPv6)", RFC 3315, July 2003. 1308 [RFC3956] Savola, P. and B. Haberman, "Embedding the Rendezvous 1309 Point (RP) Address in an IPv6 Multicast Address", RFC 1310 3956, November 2004. 1312 [RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure 1313 Neighbor Discovery (SEND)", RFC 3971, March 2005. 1315 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 1316 RFC 3972, March 2005. 1318 [RFC4038] Shin, M-K., Hong, Y-G., Hagino, J., Savola, P., and E. 1319 Castro, "Application Aspects of IPv6 Transition", RFC 1320 4038, March 2005. 1322 [RFC4057] Bound, J., "IPv6 Enterprise Network Scenarios", RFC 4057, 1323 June 2005. 1325 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 1326 Addresses", RFC 4193, October 2005. 1328 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 1329 for IPv6 Hosts and Routers", RFC 4213, October 2005. 1331 [RFC4293] Routhier, S., "Management Information Base for the 1332 Internet Protocol (IP)", RFC 4293, April 2006. 1334 [RFC4296] Bailey, S. and T. Talpey, "The Architecture of Direct Data 1335 Placement (DDP) and Remote Direct Memory Access (RDMA) on 1336 Internet Protocols", RFC 4296, December 2005. 1338 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 1339 Networks (VPNs)", RFC 4364, February 2006. 1341 [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control 1342 Message Protocol (ICMPv6) for the Internet Protocol 1343 Version 6 (IPv6) Specification", RFC 4443, March 2006. 1345 [RFC4659] De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur, 1346 "BGP-MPLS IP Virtual Private Network (VPN) Extension for 1347 IPv6 VPN", RFC 4659, September 2006. 1349 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1350 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1351 September 2007. 1353 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1354 Address Autoconfiguration", RFC 4862, September 2007. 1356 [RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering 1357 ICMPv6 Messages in Firewalls", RFC 4890, May 2007. 1359 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 1360 Extensions for Stateless Address Autoconfiguration in 1361 IPv6", RFC 4941, September 2007. 1363 [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation 1364 of Type 0 Routing Headers in IPv6", RFC 5095, December 1365 2007. 1367 [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J. 1368 Meyer, "Information Model for IP Flow Information Export", 1369 RFC 5102, January 2008. 1371 [RFC5157] Chown, T., "IPv6 Implications for Network Scanning", RFC 1372 5157, March 2008. 1374 [RFC5211] Curran, J., "An Internet Transition Plan", RFC 5211, July 1375 2008. 1377 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 1378 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 1379 March 2008. 1381 [RFC5375] Van de Velde, G., Popoviciu, C., Chown, T., Bonness, O., 1382 and C. Hahn, "IPv6 Unicast Address Assignment 1383 Considerations", RFC 5375, December 2008. 1385 [RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments", 1386 RFC 5722, December 2009. 1388 [RFC5798] Nadas, S., "Virtual Router Redundancy Protocol (VRRP) 1389 Version 3 for IPv4 and IPv6", RFC 5798, March 2010. 1391 [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 1392 Address Text Representation", RFC 5952, August 2010. 1394 [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. 1395 Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, 1396 October 2010. 1398 [RFC6104] Chown, T. and S. Venaas, "Rogue IPv6 Router Advertisement 1399 Problem Statement", RFC 6104, February 2011. 1401 [RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J. 1402 Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105, 1403 February 2011. 1405 [RFC6106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, 1406 "IPv6 Router Advertisement Options for DNS Configuration", 1407 RFC 6106, November 2010. 1409 [RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for 1410 IPv4/IPv6 Translation", RFC 6144, April 2011. 1412 [RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation 1413 Algorithm", RFC 6145, April 2011. 1415 [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful 1416 NAT64: Network Address and Protocol Translation from IPv6 1417 Clients to IPv4 Servers", RFC 6146, April 2011. 1419 [RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van 1420 Beijnum, "DNS64: DNS Extensions for Network Address 1421 Translation from IPv6 Clients to IPv4 Servers", RFC 6147, 1422 April 2011. 1424 [RFC6177] Narten, T., Huston, G., and L. Roberts, "IPv6 Address 1425 Assignment to End Sites", BCP 157, RFC 6177, March 2011. 1427 [RFC6164] Kohno, M., Nitzan, B., Bush, R., Matsuzaki, Y., Colitti, 1428 L., and T. Narten, "Using 127-Bit IPv6 Prefixes on Inter- 1429 Router Links", RFC 6164, April 2011. 1431 [RFC6192] Dugal, D., Pignataro, C., and R. Dunn, "Protecting the 1432 Router Control Plane", RFC 6192, March 2011. 1434 [RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix 1435 Translation", RFC 6296, June 2011. 1437 [RFC6302] Durand, A., Gashinsky, I., Lee, D., and S. Sheppard, 1438 "Logging Recommendations for Internet-Facing Servers", BCP 1439 162, RFC 6302, June 2011. 1441 [RFC6434] Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node 1442 Requirements", RFC 6434, December 2011. 1444 [RFC6538] Henderson, T. and A. Gurtov, "The Host Identity Protocol 1445 (HIP) Experiment Report", RFC 6538, March 2012. 1447 [RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown, 1448 "Default Address Selection for Internet Protocol Version 6 1449 (IPv6)", RFC 6724, September 2012. 1451 [RFC6555] , "Happy Eyeballs: Success with Dual-Stack Hosts", . 1453 [RFC6583] , "Operational Neighbor Discovery Problems", . 1455 [I-D.xli-behave-divi] 1456 Bao, C., Li, X., Zhai, Y., and W. Shang, "dIVI: Dual- 1457 Stateless IPv4/IPv6 Translation", draft-xli-behave-divi-05 1458 (work in progress), June 2013. 1460 [I-D.wierenga-ietf-eduroam] 1461 Wierenga, K., Winter, S., and T. Wolniewicz, "The eduroam 1462 architecture for network roaming", draft-wierenga-ietf- 1463 eduroam-00 (work in progress), October 2012. 1465 [I-D.ietf-savi-threat-scope] 1466 McPherson, D., Baker, F., and J. Halpern, "SAVI Threat 1467 Scope", draft-ietf-savi-threat-scope-08 (work in 1468 progress), April 2013. 1470 [I-D.lopez-v6ops-dc-ipv6] 1471 Lopez, D., Chen, Z., Tsou, T., Zhou, C., and A. Servin, 1472 "IPv6 Operational Guidelines for Datacenters", draft- 1473 lopez-v6ops-dc-ipv6-04 (work in progress), February 2013. 1475 [I-D.templin-v6ops-isops] 1476 Templin, F., "Operational Guidance for IPv6 Deployment in 1477 IPv4 Sites using ISATAP", draft-templin-v6ops-isops-19 1478 (work in progress), April 2013. 1480 [I-D.carpenter-6man-ext-transmit] 1481 Carpenter, B. and S. Jiang, "Transmission of IPv6 1482 Extension Headers", draft-carpenter-6man-ext-transmit-02 1483 (work in progress), February 2013. 1485 [I-D.ietf-6renum-enterprise] 1486 Jiang, S., Liu, B., and B. Carpenter, "IPv6 Enterprise 1487 Network Renumbering Scenarios, Considerations and 1488 Methods", draft-ietf-6renum-enterprise-06 (work in 1489 progress), January 2013. 1491 [I-D.ietf-6renum-static-problem] 1492 Carpenter, B. and S. Jiang, "Problem Statement for 1493 Renumbering IPv6 Hosts with Static Addresses in Enterprise 1494 Networks", draft-ietf-6renum-static-problem-03 (work in 1495 progress), December 2012. 1497 [I-D.ietf-v6ops-design-choices] 1498 Matthews, P., "Design Choices for IPv6 Networks", draft- 1499 ietf-v6ops-design-choices-00 (work in progress), February 1500 2013. 1502 [I-D.ietf-opsec-v6] 1503 Chittimaneni, K., Kaeo, M., and E. Vyncke, "Operational 1504 Security Considerations for IPv6 Networks", draft-ietf- 1505 opsec-v6-02 (work in progress), February 2013. 1507 [I-D.ietf-opsec-ipv6-host-scanning] 1508 Gont, F. and T. Chown, "Network Reconnaissance in IPv6 1509 Networks", draft-ietf-opsec-ipv6-host-scanning-01 (work in 1510 progress), April 2013. 1512 [I-D.ietf-opsec-ipv6-implications-on-ipv4-nets] 1513 Gont, F. and W. Liu, "Security Implications of IPv6 on 1514 IPv4 Networks", draft-ietf-opsec-ipv6-implications-on- 1515 ipv4-nets-05 (work in progress), July 2013. 1517 [I-D.ietf-v6ops-ra-guard-implementation] 1518 Gont, F., "Implementation Advice for IPv6 Router 1519 Advertisement Guard (RA-Guard)", draft-ietf-v6ops-ra- 1520 guard-implementation-07 (work in progress), November 2012. 1522 [I-D.ietf-v6ops-icp-guidance] 1523 Carpenter, B. and S. Jiang, "IPv6 Guidance for Internet 1524 Content and Application Service Providers", draft-ietf- 1525 v6ops-icp-guidance-05 (work in progress), January 2013. 1527 [I-D.liu-bonica-dhcpv6-slaac-problem] 1528 Liu, B. and R. Bonica, "DHCPv6/SLAAC Address Configuration 1529 Interaction Problem Statement", draft-liu-bonica-dhcpv6 1530 -slaac-problem-01 (work in progress), February 2013. 1532 [I-D.ietf-v6ops-ula-usage-recommendations] 1533 Liu, B., Jiang, S., and C. Byrne, "Recommendations of 1534 Using Unique Local Addresses", draft-ietf-v6ops-ula-usage- 1535 recommendations-00 (work in progress), May 2013. 1537 [SMURF] , "CERT Advisory CA-1998-01 Smurf IP Denial-of-Service 1538 Attacks", , 1539 . 1541 [CYMRU] , "THE BOGON REFERENCE", , 1542 . 1544 Authors' Addresses 1546 Kiran K. Chittimaneni 1547 Google Inc. 1548 1600 Amphitheater Pkwy 1549 Mountain View, California CA 94043 1550 USA 1552 Email: kk@google.com 1554 Tim Chown 1555 University of Southampton 1556 Highfield 1557 Southampton, Hampshire SO17 1BJ 1558 United Kingdom 1560 Email: tjc@ecs.soton.ac.uk 1562 Lee Howard 1563 Time Warner Cable 1564 13820 Sunrise Valley Drive 1565 Herndon, VA 20171 1566 US 1568 Phone: +1 703 345 3513 1569 Email: lee.howard@twcable.com 1571 Victor Kuarsingh 1572 Rogers Communications 1573 8200 Dixie Road 1574 Brampton, Ontario 1575 Canada 1577 Email: victor.kuarsingh@rci.rogers.com 1578 Yanick Pouffary 1579 Hewlett Packard 1580 950 Route Des Colles 1581 Sophia-Antipolis 06901 1582 France 1584 Email: Yanick.Pouffary@hp.com 1586 Eric Vyncke 1587 Cisco Systems 1588 De Kleetlaan 6a 1589 Diegem 1831 1590 Belgium 1592 Phone: +32 2 778 4677 1593 Email: evyncke@cisco.com