IPv6 Operations (v6ops)Internet Engineering Task Force (IETF) J. Palet MartinezInternet-DraftRequest for Comments: 8585 The IPv6 CompanyIntended status:Category: Informational H. M.-H. LiuExpires: August 1, 2019ISSN: 2070-1721 D-Link Systems, Inc. M. Kawashima NEC Platforms, Ltd.January 28,May 2019 Requirements for IPv6 Customer Edge Routers to SupportIPv4 Connectivity as-a-Service draft-ietf-v6ops-transition-ipv4aas-15IPv4-as-a-Service Abstract This document specifies the IPv4 service continuity requirements foranIPv6 Customer Edge (CE)router, eitherrouters that are provided either by the service provider or by vendors who sell through the retail market. Specifically, this document extends the"Basic Requirementsbasic requirements for IPv6Customer Edge Routers" (RFC7084)CE routers as described inorderRFC 7084 to allow the provisioning of IPv6 transition services for the support of"IPv4 as-a-Service"IPv4-as-a-Service (IPv4aaS) by means of new transition mechanisms. The document only covers IPv4aaS, i.e., transition technologies for delivering IPv4 in IPv6-only accessnetworks, commonly called "IPv4 as-a-Service" (IPv4aaS). Thisnetworks. IPv4aaS is necessary because there aren't sufficient IPv4 addresses available for every possiblecustomer/device.customer/ device. However, devices or applications in the customerLANs (LocalLocal AreaNetworks)Networks (LANs) may be IPv4-only or IPv6-only and still need to communicate with IPv4-only servicesaton the Internet. Status of This Memo ThisInternet-Draftdocument issubmitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documentsnot an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force (IETF).Note that other groups may also distribute working documents as Internet-Drafts. The listIt represents the consensus ofcurrent Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draftthe IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documentsvalidapproved by the IESG are candidates fora maximumany level of Internet Standard; see Section 2 of RFC 7841. Information about the current status ofsix monthsthis document, any errata, and how to provide feedback on it may beupdated, replaced, or obsoleted by other documentsobtained atany time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 1, 2019.https://www.rfc-editor.org/info/rfc8585. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . .32 1.1. Requirements Language . . . . . . . . . . . . . . . . . .54 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . .54 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . .65 3.1. LAN-Side Configuration . . . . . . . . . . . . . . . . .65 3.2. Transition Technologies Support for IPv4 Service Continuity(IPv4 as-a-Service - IPv4aaS)(IPv4-as-a-Service) . . . . . . . . . . .6. . 5 3.2.1. 464XLAT . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.2. Dual-Stack Lite (DS-Lite) . . . . . . . . . . . . . .98 3.2.3. Lightweight 4over6 (lw4o6) . . . . . . . . . . . . .109 3.2.4. MAP-E . . . . . . . . . . . . . . . . . . . . . . . .109 3.2.5. MAP-T . . . . . . . . . . . . . . . . . . . . . . . .1110 4. IPv4 Multicast Support . . . . . . . . . . . . . . . . . . .1110 5. UPnP Support . . . . . . . . . . . . . . . . . . . . . . . .1211 6. Comparison toRFC7084 .RFC 7084 . . . . . . . . . . . . . . . . . . .1211 7. Code Considerations . . . . . . . . . . . . . . . . . . . . .1211 8. Security Considerations . . . . . . . . . . . . . . . . . . .1312 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . .1312 10.Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 11. Annex A: Usage Scenarios . . . . . . . . . . . . . . . . . . 14 12. Annex B: End-User Network Architecture . . . . . . .References . . . .15 13. ANNEX C: Changes from -00. . . . . . . . . . . . . . . . . .18 14. ANNEX D: Changes from -01. . . 12 10.1. Normative References . . . . . . . . . . . . . . .18 15. ANNEX E: Changes from -02. . . 12 10.2. Informative References . . . . . . . . . . . . . . .18 16. ANNEX F: Changes from -03. . 15 Appendix A. Usage Scenarios . . . . . . . . . . . . . . . .19 17. ANNEX G: Changes from -04. . 16 Appendix B. End-User Network Architecture . . . . . . . . . . . 17 Acknowledgements . . . . .19 18. ANNEX H: Changes from -05. . . . . . . . . . . . . . . . . .19 19. ANNEX I: Changes from -06 . . . . . . . . . . . . . . . . . . 19 20. ANNEX J: Changes from -07 . . . . . . . . . . . . . . . . . . 19 21. ANNEX K: Changes from -08, -09 and -10 . . . . . . . . . . . 20 22. ANNEX L: Changes from -11, -12, -13 and -14 . . . . . . . . . 20 23. References .. 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 2023.1. Normative References . . . . . . . . . . . . . . . . . . 20 23.2. Informative References . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 231. Introduction This document defines IPv4 service continuity features over an IPv6-onlynetwork,network foraresidential orsmall-office router, referredsmall office routers (referred to asan"IPv6 Transition CERouter",Routers") in order to establish an industry baseline for transition features to be implemented on sucha router.routers. These routers rely upon"Basic Requirementsrequirements for IPv6Customer Edge Routers"CE routers defined in [RFC7084]. The scope of this document is to ensuretheIPv4"service continuity" support,service continuity support for devices in the LAN side. This ensures that remote IPv4-only services continue to be accessible,from an IPv6-only Internet Service Provider (ISP) access network from both,for both IPv4-only and IPv6-only applications anddevicesdevices, located in the LANside.side behind an IPv6 Transition CE Router connected to an IPv6-only access network. These ISP access networks are typically referred to as Wide Area Networks (WANs), even ifin some casesthey may be metropolitan orregional.regional in some cases. Figure 1 presents a simplified view of this architecture. +------------+ +------------+ \ | IPv4-only | | IPv4/IPv6 | \ | Remote | | Remote | | | Host | | Host | | Internet +--------+---+ +---+--------+ | | | / | | / +-+-----------+-+ \ | Service | \ | Provider | \ | Router | | Service +-------+-------+ | Provider | IPv6-only | Network | Customer / | Internet Connection / | / +------+--------+ \ | IPv6 | \ |Customer EdgeTransition CE | \ | Router | | +---+-------+---+ | LAN A | | LAN B | End-User -+----------------+- -+-----+-------------+- | Network(s) | | | | +---+------+ +----+-----+ +-----+----+ | | IPv6-only| | IPv4-only| |IPv4/IPv6 | / | Host | | Host | | Host | / +----------+ +----------+ +----------+ / Figure 1: Simplified TypicalIPv6-onlyIPv6-Only Access Network This document covers a set of IP transition techniques required when ISPs have, or want to have, an IPv6-only access network. This is a common situation when sufficient IPv4 addresses are no longer available for every possible customer and device,causingwhich causes IPv4 addresses to become prohibitively expensive. This, in turn, may result in service providers provisioning IPv6-only WAN access. At the same time, they need to ensure that both IPv4-only and IPv6-only devices and applications in the customer networks can still reach IPv4-only devices and applicationsinon the Internet. This document specifies the IPv4 service continuity mechanisms to be supported by an IPv6 Transition CERouter,Router and relevant provisioning or configuration information differences from [RFC7084]. This document is not a recommendation for service providers to use any specific transition mechanism. Automatic provisioning of more complex topology than a single router with multiple LAN interfaces may be handled by means ofHNCP [RFC7788] (Homethe Home Networking ControlProtocol),Protocol (HNCP) [RFC7788], which is out of the scope of this document. Since it is impossible to know prior to sale which transition mechanism a device will need over its lifetime, an IPv6 Transition CE Router intended for the retail market MUST support all the IPv4aaS transition mechanisms listed in this document. Service providerswhothat specify feature sets for the IPv6 Transition CERouter,Router may define a different set of featuresthanfrom those included in this document, forexample supportingexample, features that support only some of the transition mechanisms enumerated in this document. Appendices A and B contain a complete description of"Usage Scenarios" and "End-User Network Architecture" is provided in Annexes Athe usage scenarios andB, respectively, which togetherend-user network architecture, respectively. These appendices, along with [RFC7084], will facilitatethe reader to havea clearer understanding of this document. 1.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described inBCP14BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2. Terminology This document uses the same terms as in [RFC7084], with minor clarifications. "IPv4aaS" stands for"IPv4 as-a-Service","IPv4-as-a-Service", meaning transition technologies for delivering IPv4 in IPv6-only connectivity. The term "IPv6 transition Customer Edge Router with IPv4aaS" (shortened as "IPv6 Transition CE Router") is defined as an"IPv6IPv6 Customer EdgeRouter"Router that provides features for the delivery of IPv4 services over an IPv6-only WAN network, including IPv6-IPv4 communications. The term "WAN Interface"termas usedacrossin thisdocument, definesdocument is defined as an IPv6 Transition CE Router attachment to an IPv6-only link used to provide connectivity to a service provider network, including linkInternet- layerInternet-layer (or higher layers)"tunnels",tunnels, such as IPv4-in-IPv6 tunnels. 3. Requirements The IPv6 Transition CE Router MUST comply with [RFC7084](Basic("Basic Requirements for IPv6 Customer EdgeRouters) and thisRouters"). This document adds new requirements, as described in the followingsub-sections.subsections. 3.1. LAN-Side Configuration A new LAN requirement is added, which is, infact isfact, common in regular IPv6 Transition CE Routers, anditis required by most of the transition mechanisms: L-1: The IPv6 Transition CE Router MUST implement a DNS proxy as described in [RFC5625](DNS("DNS Proxy ImplementationGuidelines).Guidelines"). 3.2. Transition Technologies Support for IPv4 Service Continuity(IPv4 as-a-Service - IPv4aaS)(IPv4- as-a-Service) The main target of this document is the support of IPv6-only WAN access. To enable legacy IPv4 functionality, this document also includes the support of IPv4-only devices and applications in thecustomerscustomer LANs, as well as IPv4-only services on the Internet. Thus, both IPv4-only andtheIPv6-only devices in the customer-side LANs of the IPv6 Transition CE Router are able to reach the IPv4-only services. Note that this documentisonlyconfiguring theconfigures IPv4aaS in the IPv6 Transition CE Routeritself, and not forwardingitself; it does not forward such information to devices attached to theLANs, soLANs. Thus, the WANconfiguration,configuration and availability of native IPv4 orIPv4aaS, isIPv4aaS are transparent forthem.the devices attached to the LANs. This document takes no position on simultaneous operation of one or several transition mechanisms and/or native IPv4. In order to seamlessly provide IPv4 service continuity in the customerLANs,LANs and allow automated IPv6 transition mechanism provisioning, the following general transition requirements are defined. General transition requirements: TRANS-1: The IPv6 Transition CE Router MUST support the DHCPv6 S46 priority options described in [RFC8026](Unified("Unified IPv4-in- IPv6 Softwire Customer Premises Equipment (CPE): A DHCPv6-Based PrioritizationMechanism).Mechanism"). TRANS-2: The IPv6 Transition CE Router MUST have a GUI and either a CLI or API (or both) to manually enable/disable each of the supported transition mechanisms. TRANS-3: If an IPv6 Transition CE Router supports more than one LAN subnet, the IPv6 Transition CE Router MUST allow appropriate subnetting and configuration of the address space amongtheseveral interfaces. In some transition mechanisms, this may require differentiating mappings/ translations on a per-interface basis. In order to allow the service provider to disable all the transition mechanisms and/or choose the most convenient one, the IPv6 Transition CE Router MUST follow the following configuration steps: CONFIG-1: Request the relevant configuration options for each supported transition mechanisms, which MUST remain disabled at this step. CONFIG-2: Following the steps in Section 1.4 of [RFC8026], MUST check for a valid match in OPTION_S46_PRIORITY, which allowsenabling/ disablingenabling/disabling a transition mechanism. CONFIG-3: Keep disabled all the transition mechanisms if no match is found between the priority list and the candidate list, unless a NAT64 [RFC6146] prefix has been configured, in which case, 464XLAT [RFC6877] MUST be enabled. Because 464XLAT hasnotno DHCPv6 configuration options, it can't currently beincluded, at the time being,included in the OPTION_S46_PRIORITY. In the future, an update of [RFC8026] or a NAT64 DHCPv6 configurationoption,option may enable it. Meanwhile, if an operator provides 464XLAT, it needs to ensure that OPTION_S46_PRIORITY is not sent for any other transition mechanism to the relevant customers. The followingsectionssubsections describe the requirements for supporting each one of the transition mechanisms. An IPv6 Transition CE Router intended for the retail market MUST support all of them. 3.2.1. 464XLAT 464XLAT [RFC6877] is a technique to provide IPv4 service over an IPv6-only access network without encapsulation. This architecture assumes a Stateful NAT64 [RFC6146](Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers)function deployed at the service provider or a third-party network. The IPv6 Transition CE Router MUST supportCLATcustomer-side translator (CLAT) functionality [RFC6877] if intended for the retail market. If 464XLAT is supported, it MUST be implemented according to [RFC6877]. The following IPv6 Transition CE Router requirements alsoapply:apply. 464XLAT requirements: 464XLAT-1: Unless a dedicated /64 prefix has been acquired, either by using DHCPv6-PD[RFC8415] (IPv6 Prefix Options(Dynamic Host Configuration Protocol forDHCPv6)IPv6 Prefix Delegation) or by alternative means, the IPv6 Transition CE Router MUST perform IPv4 Network Address Translation (NAT) on IPv4 traffic translated using the CLAT. 464XLAT-2: The IPv6 Transition CE Router SHOULD support IGD-PCP IWF [RFC6970](UPnP("Universal Plug and Play (UPnP) Internet Gateway Device - Port Control Protocol InterworkingFunction).Function (IGD-PCP IWF)"). 464XLAT-3: IfPCPthe Port Control Protocol (PCP) [RFC6887] is implemented, the IPv6 Transition CE Router MUST also implement [RFC7291](DHCP("DHCP Options for thePCP).Port Control Protocol (PCP)"). Following [RFC6887], if no PCP server is configured, the IPv6 Transition CE Router MAY verify if the defaultgateway,gateway or the NAT64 is the PCP server. The IPv6 Transition CE Router MUST use plain IPv6 mode (i.e.,nonot IPv4-in-IPv6encapsulation is used)encapsulation) to send PCP requests to the server. 464XLAT-4: The IPv6 Transition CE Router MUST implement [RFC7050](Discovery("Discovery of the IPv6 Prefix Used for IPv6 AddressSynthesis)Synthesis") in order to discover thePLAT-sideprovider-side translator (PLAT) translation IPv4 and IPv6 prefix(es)/suffix(es). 464XLAT-5: If PCP is implemented, the IPv6 Transition CE Router MUST follow [RFC7225](Discovering("Discovering NAT64 IPv6 Prefixes Using thePCP),Port Control Protocol (PCP)") in order to learn the PLAT-side translation IPv4 and IPv6 prefix(es)/suffix(es) used by an upstream PCP-controlled NAT64 device. 464XLAT-6:The priorityIf the network provides several choices for the discovery/learning of the NAT64 prefix,in casethenetwork provides several choices,priority to use one or the other MUSTbe:follow this order: 1)[RFC7225],[RFC7225] and 2) [RFC7050]. The NAT64 prefix could be discovered by means of the method defined in [RFC7050] onlyin the caseif the service provider uses DNS64 [RFC6147]. It may be the case that the service provider does not use or does not trust DNS64 [RFC6147] because the DNS configuration at the CE (or hosts behind the CE) can be modified by the customer. In that case, the service provider may opt to configure the NAT64 prefix by means of the option defined in [RFC7225]. This can also be used if the service provider uses DNS64 [RFC6147]. 3.2.2. Dual-Stack Lite (DS-Lite)Dual-Stack LiteDS-Lite [RFC6333] enables continued support for IPv4 services.Dual-Stack LiteDS-Lite enables a broadband service provider to share IPv4 addresses among customers by combining two well-known technologies: IP in IP (IPv4-in-IPv6) and Network Address Translation (NAT). It is expected that DS-Lite traffic is forwarded over the IPv6 Transition CE Router's native IPv6 WANinterface,interface and not encapsulated in another tunnel. The IPv6 Transition CE Router MUST implement DS-Lite B4 functionality [RFC6333] if intended for the retail market. If DS-Lite is supported, it MUST be implemented according to [RFC6333]. The following IPv6 Transition CE Router requirements alsoapply:apply. DS-Lite requirements: DSLITE-1: The IPv6 Transition CE Router MUST support configuration of DS-Lite via the DS-Lite DHCPv6 option [RFC6334](DHCPv6("Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Option for Dual-StackLite).Lite"). The IPv6 Transition CE Router MAY use other mechanisms to configure DS-Lite parameters. Such mechanisms are outside the scope of this document. DSLITE-2: The IPv6 Transition CE Router SHOULD support IGD-PCP IWF[RFC6970] (UPnP Internet Gateway Device - Port Control Protocol Interworking Function).[RFC6970]. DSLITE-3: If PCP [RFC6887] is implemented, the IPv6 Transition CE Router SHOULD implement[RFC7291] (DHCP Options for the PCP).[RFC7291]. If PCP [RFC6887] is implemented and a PCP server is not configured, the IPv6 Transition CE Router MUST assume, by default, that theAFTRAddress Family Transition Router (AFTR, commonly called "CGN" - Carrier-Grade NAT) is the PCP server. The IPv6 Transition CE Router MUST use plain IPv6 mode (i.e.,nonot IPv4-in-IPv6encapsulation is used)encapsulation) to send PCP requests to the server. The term "default" above is to be interpreted as pertaining to a configuration as applied by avendor,vendor prior to the administrator changing it for its initial activation. DSLITE-4: The IPv6 Transition CE Router MUST NOT perform IPv4 Network Address Translation (NAT) on IPv4 traffic encapsulated using DS-Lite [RFC6333]. 3.2.3. Lightweight 4over6 (lw4o6) lw4o6 [RFC7596] specifies an extension to DS-Litewhichthat moves the NAPT function from the DS-Lite tunnel concentrator to the tunnel client located in the IPv6 Transition CE Router, removing the requirement fora CGN (Carrier Grade NAT,an AFTR- Address Family Transition Router)(CGN) function in the tunnel concentrator and reducing the amount of centralized state. The IPv6 Transition CE Router MUST implement lwB4 functionality [RFC7596] if intended for the retail market. If DS-Lite is implemented, lw4o6 SHOULD be implemented as well. If lw4o6 is supported, it MUST be implemented according to [RFC7596]. The following IPv6 Transition CE Router requirements alsoapply:apply. lw4o6 requirements: LW4O6-1: The IPv6 Transition CE Router MUST support configuration of lw4o6 via the lw4o6 DHCPv6 options [RFC7598](DHCPv6("DHCPv6 Options for Configuration of Softwire Address and Port- MappedClients).Clients"). The IPv6 Transition CE Router MAY use other mechanisms to configure lw4o6 parameters. Such mechanisms are outside the scope of this document. LW4O6-2: The IPv6 Transition CE Router MUST support the DHCPv4-over- DHCPv6 (DHCP 4o6) transport described in [RFC7341](DHCPv4- over-DHCPv6 Transport).("DHCPv4-over-DHCPv6 (DHCP 4o6) Transport"). LW4O6-3: The IPv6 Transition CE Router MAY support Dynamic Allocation of Shared IPv4 Addresses as described in [RFC7618](Dynamic("Dynamic Allocation of Shared IPv4Addresses).Addresses"). 3.2.4. MAP-EMAP-EMapping of Address and Port with Encapsulation (MAP-E) [RFC7597] is a mechanism for transporting IPv4 packets across an IPv6 network using IPencapsulation, includingencapsulation. MAP-E includes an algorithmic mechanism for mapping between IPv6 and IPv4 addresses. The IPv6 Transition CE Router MUST support MAP-E CE functionality [RFC7597] if intended for the retail market. If MAP-E is supported, it MUST be implemented according to [RFC7597]. The following IPv6 Transition CE Router requirements alsoapply:apply. MAP-E requirements: MAPE-1: The IPv6 Transition CE Router MUST support configuration of MAP-E via the MAP-E DHCPv6 options[RFC7598] (DHCPv6 Options for Configuration of Softwire Address and Port-Mapped Clients).[RFC7598]. The IPv6 Transition CE Router MAY use other mechanisms to configure MAP-E parameters. Such mechanisms are outside the scope of this document. MAPE-2: The IPv6 Transition CE Router MAY support Dynamic Allocation of Shared IPv4 Addresses as described in[RFC7618] (Dynamic Allocation of Shared IPv4 Addresses).[RFC7618]. 3.2.5. MAP-T MAP-T [RFC7599] is a mechanism similar to MAP-E, differing from it in that MAP-T uses IPv4-IPv6 translation, instead of encapsulation, as the form of IPv6 domain transport. The IPv6 Transition CE Router MUST support MAP-T CE functionality [RFC7599] if intended for the retail market. If MAP-T is supported, it MUST be implemented according to [RFC7599]. The following IPv6 Transition CE Router requirements alsoapply:apply. MAP-T requirements: MAPT-1: The IPv6 Transition CE Router MUST support configuration of MAP-T via the MAP-T DHCPv6 options[RFC7598] (DHCPv6 Options for Configuration of Softwire Address and Port-Mapped Clients).[RFC7598]. The IPv6 Transition CE Router MAY use other mechanisms to configure MAP-T parameters. Such mechanisms are outside the scope of this document. MAPT-2: The IPv6 Transition CE Router MAY support Dynamic Allocation of Shared IPv4 Addresses as described in[RFC7618] (Dynamic Allocation of Shared IPv4 Addresses).[RFC7618]. 4. IPv4 Multicast Support Existing IPv4 deployments support IPv4 multicast for services such as IPTV. In the transition phase, it is expected that multicast services will still be provided using IPv4 to the customer LANs. If the IPv6 Transition CE Router supports delivery of IPv4 multicast services, then it MUST support [RFC8114](Delivery("Delivery of IPv4 Multicast Services to IPv4 Clients over an IPv6 MulticastNetwork)Network") and [RFC8115](DHCPv6("DHCPv6 Option for IPv4-Embedded Multicast and Unicast IPv6Prefixes).Prefixes"). 5. UPnP Support If the UPnP WANIPConnection:2 service[UPnP-WANIPC][UPnP-WANIPC][OCF-IGD] is enabled on a CE router, but cannot be associated with an IPv4 interface established by an IPv4aaS mechanism or cannot determine which ports are available, an AddPortMapping() or AddAnyPortMapping() action MUST be rejected with error code 729"ConflictWithOtherMechanisms".("ConflictWithOtherMechanisms"). Port availability could be determined through PCP or access to a configured port set (if the IPv4aaS mechanism limits the available ports). An AddPortMapping() request for a port that is not available MUST result in "ConflictInMappingEntry". An AddAnyPortMapping() request for a port that is not available SHOULD result in a successful mapping with an alternative "NewReservedPort" value from within the configured port setrange,range or as assigned by PCP as per[RFC6970],Section5.6.1.5.6.1 of [RFC6970]. Note that IGD:1 and its WANIPConnection:1 service have been deprecated by OCF (Open ConnectivityFoundation).Foundation) [OCF-IGD]. 6. Comparison toRFC7084RFC 7084 This document doesn't include support for 6rd[RFC5969],[RFC5969] because it is an IPv6-in-IPv4 tunneling. Regarding DS-LITE [RFC6333], this document includes slightly differentrequirements,requirements related to the support of PCP [RFC6887],IGD- PCPIGD-PCP IWF[RFC6970][RFC6970], and the prioritization of the transition mechanisms, including dual-stack. 7. Code Considerations At the time of this writing, one of the apparent main issues for vendors with regard toincludeincluding new functionalities, such as support for new transition mechanisms, is the lack of space in the flash (or equivalent) memory. However, it has been confirmed from existingopen sourceopen-source implementations(OpenWRT/LEDE,(e.g., OpenWRT/LEDE, Linux,VPP, others),and VPP) that adding the support for the new transitionmechanisms,mechanisms requires around 10-12Kbytes,KBs because most of the code base is shared among several transition mechanisms, which are already supported by [RFC7084]. A single data plane is common to all of them, which typically means, in popular CEs already in the market [OpenWRT], the new required code is only about 0.15% of the total existing code size. In general, the new requirements don't have extra cost in terms of RAM memory, nor other hardware requirements such as more powerful CPUs, if compared to the cost of NAT44code, socode. Thus, existing hardware should be able to support all of them with minimal impact. The other issue seems to be the cost of developing the code for those new functionalities. However, at the time of writing this document, it has been confirmed that there are severalopen sourceopen-source versions of the required code for supporting all the new transition mechanisms, and several vendors already have implementations andprovide itprovided them toISPs, soISPs. Therefore, the development cost is negligible, and only integration and testing cost may become an issue. Finally, in some cases, operators supporting several transition mechanisms may need to consider training costs for staff in all the techniques fortheirthe operation andmanagement,management of these mechanisms, even ifthis isthe costs are not directly caused by supporting thisdocument,document but becausetheof businessdecisions behind that.decisions. 8. Security Considerations The IPv6 Transition CE Router must comply with the Security Considerationsas statedin[RFC7084],[RFC7084] as well as thosestated byfor each transition mechanism implemented by the IPv6 Transition CE Router. As described in[RFC8026] and [RFC8415]the SecurityConsideration sections,Considerations of [RFC8026] and [RFC8415], there are generic DHCP security issues,whichwhich, in the case of thisdocument meansdocument, mean that malicious nodes may alter the priority of the transition mechanisms. Access network architecture for securing DHCP within the access network is out of scopeoffor this document. Securing DHCP in the LAN is also not in scope. DHCP packets MUST NOT be forwarded between LAN and WAN interfaces of an IPv6 Transition CErouter.Router. 9. IANA Considerations This documentdoes not have any new specifichas no IANAconsiderations.actions. 10.Acknowledgements ThanksReferences 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs toMikael Abrahamsson, Fred Baker, Mohamed Boucadair, Brian Carpenter, Ian Farrer, Lee Howard, Richard Patterson, Barbara Stark, OleIndicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines", BCP 152, RFC 5625, DOI 10.17487/RFC5625, August 2009, <https://www.rfc-editor.org/info/rfc5625>. [RFC5969] Townsley, W. and O. Troan,James Woodyatt, Lorenzo Colitti"IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) -- Protocol Specification", RFC 5969, DOI 10.17487/RFC5969, August 2010, <https://www.rfc-editor.org/info/rfc5969>. [RFC6146] Bagnulo, M., Matthews, P., andAlejandro D'Egidio, for their reviewI. van Beijnum, "Stateful NAT64: Network Address andcomments in this and/or previous versions of this document, as well asProtocol Translation from IPv6 Clients tothe Last Call reviewers by the Ops-dir (Dan Romascanu), Sec-dir (Christian Huitema), Rtg-dir (Daniele Ceccarelli), Tsv-art (Martin Stiemerling), Gen-art (Matthew Miller) and IESG (Alissa Cooper, Benjamin Kaduk, Suresh Krishnan, Ben Campbell, Spencer Dawkins, Mirja Kuhlewind,IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, April 2011, <https://www.rfc-editor.org/info/rfc6146>. [RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., andAdam Roach). 11. Annex A: Usage Scenarios The situation previously described, where there is ongoingI. van Beijnum, "DNS64: DNS Extensions for Network Address Translation from IPv6deploymentClients to IPv4 Servers", RFC 6147, DOI 10.17487/RFC6147, April 2011, <https://www.rfc-editor.org/info/rfc6147>. [RFC6333] Durand, A., Droms, R., Woodyatt, J., andlack ofY. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4addresses, is not happening at the same pace in every country,Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, <https://www.rfc-editor.org/info/rfc6333>. [RFC6334] Hankins, D. andeven within every country,T. Mrugalski, "Dynamic Host Configuration Protocol forevery ISP. For different technical, financial, commercial/marketingIPv6 (DHCPv6) Option for Dual-Stack Lite", RFC 6334, DOI 10.17487/RFC6334, August 2011, <https://www.rfc-editor.org/info/rfc6334>. [RFC6877] Mawatari, M., Kawashima, M., andsocio- economic reasons, each network is transitioning at their own pace; the global transition timings cannot be reliably estimated. Different studies (for example [IPv6Survey]) also show thatC. Byrne, "464XLAT: Combination of Stateful and Stateless Translation", RFC 6877, DOI 10.17487/RFC6877, April 2013, <https://www.rfc-editor.org/info/rfc6877>. [RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, DOI 10.17487/RFC6887, April 2013, <https://www.rfc-editor.org/info/rfc6887>. [RFC6970] Boucadair, M., Penno, R., and D. Wing, "Universal Plug and Play (UPnP) Internet Gateway Device - Port Control Protocol Interworking Function (IGD-PCP IWF)", RFC 6970, DOI 10.17487/RFC6970, July 2013, <https://www.rfc-editor.org/info/rfc6970>. [RFC7050] Savolainen, T., Korhonen, J., and D. Wing, "Discovery of the IPv6deployment is a changing situation. In a single country, not all operators will necessarily providePrefix Used for IPv6support. Consumers may also switch ISPs,Address Synthesis", RFC 7050, DOI 10.17487/RFC7050, November 2013, <https://www.rfc-editor.org/info/rfc7050>. [RFC7084] Singh, H., Beebee, W., Donley, C., anduse the same IPv6 Transition CE Router with either an ISP that provides IPv4-only or an ISP that providesB. Stark, "Basic Requirements for IPv6with IPv4aaS. So, to cover all those evolving situations, anCustomer Edge Routers", RFC 7084, DOI 10.17487/RFC7084, November 2013, <https://www.rfc-editor.org/info/rfc7084>. [RFC7225] Boucadair, M., "Discovering NAT64 IPv6Transition CE Router is required, at least fromPrefixes Using theperspective ofPort Control Protocol (PCP)", RFC 7225, DOI 10.17487/RFC7225, May 2014, <https://www.rfc-editor.org/info/rfc7225>. [RFC7291] Boucadair, M., Penno, R., and D. Wing, "DHCP Options for thetransition support. Moreover, because some services will remain IPv4-only for an undetermined time,Port Control Protocol (PCP)", RFC 7291, DOI 10.17487/RFC7291, July 2014, <https://www.rfc-editor.org/info/rfc7291>. [RFC7341] Sun, Q., Cui, Y., Siodelski, M., Krishnan, S., andsome service providers will remain IPv4-only for an undetermined period of time, IPv4 will be needed for an undetermined periodI. Farrer, "DHCPv4-over-DHCPv6 (DHCP 4o6) Transport", RFC 7341, DOI 10.17487/RFC7341, August 2014, <https://www.rfc-editor.org/info/rfc7341>. [RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I. Farrer, "Lightweight 4over6: An Extension to the Dual- Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596, July 2015, <https://www.rfc-editor.org/info/rfc7596>. [RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S., Murakami, T., and T. Taylor, Ed., "Mapping oftime. There will be a need for CEsAddress and Port withsupport "IPv4 as-a-Service"Encapsulation (MAP-E)", RFC 7597, DOI 10.17487/RFC7597, July 2015, <https://www.rfc-editor.org/info/rfc7597>. [RFC7598] Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec, W., Bao, C., Yeh, L., and X. Deng, "DHCPv6 Options foran undetermined periodConfiguration oftime. This document, based on those premises, ensures that the IPv6 Transition CE Router allows the continued transition from networks that today may provide access with dual-stack or IPv6-in-IPv4, as described in [RFC7084], and as an "extension" to it, evolve to an IPv6-only access with IPv4-as-a-Service. Considering that situationSoftwire Address anddifferent possible usage cases, the IPv6 Transition CE Router described in this document is expected to be used typically, in residential/household, Small Office/Home Office (SOHO)Port-Mapped Clients", RFC 7598, DOI 10.17487/RFC7598, July 2015, <https://www.rfc-editor.org/info/rfc7598>. [RFC7599] Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S., andSmall/Medium Enterprise (SME). Common usage is any kindT. Murakami, "Mapping ofInternet access (web, email, streaming, online gaming, etc.)Address andeven more advanced requirements including inbound connections (IP cameras, web, DNS, email, VPN, etc.). The above is not intended to be a comprehensive list of all the possible usage cases, just an overall view. In fact, combinations of the above usages are also possible, as well as situations where the same CE is used at different times in different scenarios or even different with services providers that may use a different transition mechanism. The mechanisms for allowing inbound connections are "naturally" available in any IPv6 router whenPort usingGUA (IPv6 Global Unicast Addresses), unless they are blocked by firewall rules, which may require some manual configuration. However, in the case of IPv4aaS, because the usageTranslation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July 2015, <https://www.rfc-editor.org/info/rfc7599>. [RFC7618] Cui, Y., Sun, Q., Farrer, I., Lee, Y., Sun, Q., and M. Boucadair, "Dynamic Allocation ofprivate addressesShared IPv4 Addresses", RFC 7618, DOI 10.17487/RFC7618, August 2015, <https://www.rfc-editor.org/info/rfc7618>. [RFC8026] Boucadair, M. andNATI. Farrer, "Unified IPv4-in-IPv6 Softwire Customer Premises Equipment (CPE): A DHCPv6-Based Prioritization Mechanism", RFC 8026, DOI 10.17487/RFC8026, November 2016, <https://www.rfc-editor.org/info/rfc8026>. [RFC8114] Boucadair, M., Qin, C., Jacquenet, C., Lee, Y., andeven depending on the specific transition mechanism, inbound connections typically require some degreeQ. Wang, "Delivery ofmore complex manual configuration such as setting up a DMZ, virtual servers, or port/protocol forwarding. In general,IPv4CE Routers already provide a GUI, CLI or API to manually configure them, or the possibilityMulticast Services tosetup the CE in bridge mode, so another CE behind it takes care of that. The requirements for that support are out of the scope of this document. It is not relevant who provides theIPv4 Clients over an IPv6Transition CE Router. In most of the cases it is the service provider,Multicast Network", RFC 8114, DOI 10.17487/RFC8114, March 2017, <https://www.rfc-editor.org/info/rfc8114>. [RFC8115] Boucadair, M., Qin, J., Tsou, T., andin fact they are responsible, typically, of provisioning/managing at least the WAN side. Commonly, the user has access to configure the LAN interfaces, firewall, DMZ,X. Deng, "DHCPv6 Option for IPv4-Embedded Multicast andmany other features. However, in many cases, the user must supply or may replace theUnicast IPv6Transition CE Router. This underscores the importancePrefixes", RFC 8115, DOI 10.17487/RFC8115, March 2017, <https://www.rfc-editor.org/info/rfc8115>. [RFC8174] Leiba, B., "Ambiguity ofthe IPv6 Transition CE Routers fulfilling the same requirements definedUppercase vs Lowercase inthis document.RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., Richardson, M., Jiang, S., Lemon, T., and T. Winters, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 8415, DOI 10.17487/RFC8415, November 2018, <https://www.rfc-editor.org/info/rfc8415>. 10.2. Informative References [IPv6Survey] Palet Martinez, J., "Best Current Operational Practice for operators: IPv6 Prefix Assignment for end-customers -- persistent vs non-persistent and what size to choose", January 2018, <https://indico.uknof.org.uk/event/41/contribution/5/ material/slides/0.pdf>. [OCF-IGD] Open Connectivity Foundation, "Internet Gateway Device (IGD) V 2.0", March 2015, <https://openconnectivity.org/developer/specifications/ upnp-resources/upnp/internet-gateway-device-igd-v-2-0>. [OpenWRT] OpenWRT, "Packages", <https://openwrt.org/packages/start>. [RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April 2016, <https://www.rfc-editor.org/info/rfc7788>. [UPnP-IGD] UPnP Forum, "InternetGatewayDevice:2 Device Template Version 1.01", December 2010, <http://upnp.org/specs/gw/ UPnP-gw-InternetGatewayDevice-v2-Device.pdf>. [UPnP-WANIPC] UPnP Forum, "WANIPConnection:2 Service", September 2010, <http://upnp.org/specs/gw/ UPnP-gw-WANIPConnection-v2-Service.pdf>. Appendix A. Usage Scenarios The situation of ongoing IPv6Transition CE Router described in this documentdeployment and a lack of IPv4 addresses is notintended for usage in other scenarios such as large Enterprises, Data Centers, Content Providers, etc. So even ifhappening at thedocumented requirements meet their needs, they may have additional requirements, which are out of the scope of this document. 12. Annex B: End-User Network Architecture According to the descriptionssame pace inthe preceding sections, an end-user network will likely support both IPv4every country andIPv6. Iteven within every country for every ISP. For different technical, financial, commercial/marketing, and socio-economic reasons, each network isnot expected that an end-user will changetransitioning at theirexisting network topology withown pace; theintroduction of IPv6. There are some differences in howglobal transition timings cannot be reliably estimated. Different studies (for example, [IPv6Survey]) also show that IPv6works anddeployment isprovisioned; these differences have implications for the network architecture. A typical IPv4 end-user network consists ofa"plug and play" router with NAT functionality andchanging situation. In a singlelink upstream, connected to the service provider network. From the perspective of an "IPv4 user" behind an IPv6 transition Customer Edge Router with IPv4aaS, this doesn't change. However, while a typical IPv4 NAT deployment by default blockscountry, not allincoming connections andoperators will necessarily provide IPv6 support. Consumers mayallow opening of ports using a Universal Plugalso switch ISPs andPlay Internet Gateway Device (UPnP IGD) [UPnP-IGD] or some other firewall control protocol, inuse thecase ofsame IPv6 Transition CE Router with either anIPv6-only access and IPv4aaS,ISP thatmay not be feasible depending on specific transition mechanism details. PCP (Port Control Protocol, [RFC6887]) may beprovides IPv4-only or analternative solution. Another consequence of using IPv4 private address space in the end- user network isISP thatitprovidesstable addressing; that is, it doesn't change, even when you change service providers, and the addresses are always usable even when the WAN interfaceIPv6 with IPv4aaS. So, to cover all those evolving situations, an IPv6 Transition CE Router isdown or the customer edge router has not yet been provisioned. Inrequired, at least from thecaseperspective ofan IPv6-only access, private IPv4 addresses are also available if the IPv4aaStransitionmechanism keeps running the NAT interface towards the LAN side when the WAN interface is down. More advanced routers support dynamic routing (which learns routes from other routers),support. Moreover, because some services andadvanced end-users can build arbitrary, complex networks using manual configurationservice providers will remain IPv4-only for an undetermined period ofaddress prefixes combined with a dynamic routing protocol. Once again, thistime, IPv4 service continuity istruerequired. Thus, there is a need forboth IPv4 and IPv6. In general,CEs to support IPv4aaS indefinitely. Based on these premises, this document ensures that theend-user network architecture forIPv6shouldTransition CE Router allows the continued transition from networks that today may provideequivalentaccess with dual-stack orbetter capabilitiesIPv6-in-IPv4 (as described in [RFC7084]) to networks that provide IPv6-only access with IPv4aaS. Considering that situation andfunctionality thandifferent possible usage cases, thecurrent IPv4 architecture. The end-user networkIPv6 Transition CE Router described in this document isa stub network,expected to be used inthe sense thatresidential/household; small office, home office (SOHO); and small/medium enterprise (SME). Common usage is any kind of Internet access (web, email, streaming, online gaming, etc.), and more advanced requirements include inbound connections (IP cameras, web, DNS, email, VPN, etc.). The above is notproviding transitintended toother external networks. However, HNCP [RFC7788] allows support for automatic provisioning of downstream routers. Figure 2 illustrates the model topology for the end-user network. +---------------+ \ | Service | \ | Provider | \ | Router | | Service +-------+-------+ | Provider | IPv6-only | Network | Customer / | Internet Connection / | / +------+--------+ \ | IPv6 | \ | Customer Edge | \ | Router | | +---+-------+---+ | Network A | | Network B | -+----------------+-+- -+---+-------------+- | | | | | | +---+------+ | +----+-----+ +-----+----+ | | IPv6 | | | IPv4 | |IPv4/IPv6 | | | Host | | | Host | | Host | | +----------+ | +----------+ +----------+ | End-User | | Network(s) +------+--------+ | | IPv6 | | | Router | | +------+--------+ | Network C | | -+-------------+--+- | | | | +---+------+ +----+-----+ | | IPv6 | | IPv6 | / | Host | | Host | / +----------+ +----------+ / Figure 2: An Example ofbe aTypical End-User Network This architecture describes the: o Basic capabilitiescomprehensive list of all theIPv6 Transition CE Router o Provisioningpossible usage cases, just an overview. In fact, combinations of theWAN interface connecting to the service provider o Provisioning ofabove usages are also possible, along with situations where theLAN interfaces The IPv6 Transitionsame CERouter may be manually configuredis used at different times inan arbitrary topology with a dynamic routing protocoldifferent scenarios orusing HNCP [RFC7788]. Automatic provisioning and configuration is describedeven with different IPv4aaSes at different service providers. The mechanisms fora singleallowing inbound connections are naturally available in any IPv6Transition CE Router only. 13. ANNEX C: Changes from -00 Section to be removed by RFC Editor. Significant updates are: 1. ID-Nits: IANA section. 2. ID-Nits: RFC7084 reference removed from Abstract. 3. This document no longer updates RFC7084. 4. UPnP section reworded. 5. "CE Router" changed to "IPv6 Transition CE Router". 6. Reduced text in Annex A. 14. ANNEX D: Changes from -01 Section to be removed by RFC Editor. Significant updates are: 1. TRANS requirements reworked in order to increase operator control and allow gradual transitioning from dual-stack to IPv6-only on specific customers. 2. New TRANS requirement so all the supported transition mechanismsrouter when using IPv6 Global Unicast Addresses (GUAs), unless they aredisabledblocked bydefault,firewall rules, which may require some manual configuration. However, inorder to facilitatetheoperator management. 3. New TRANS requirement in order to allow turning on/off each transition mechanism bycase of IPv4aaS, because of theuser. 4. Clarification on how to obtain multiple /64 for 464XLAT. 5. S46 priority update to RFC8026 for including 464XLATusage of private IPv4 addresses andrelated changes in several sections. 15. ANNEX E: Changes from -02 Section to be removed by RFC Editor. Significant updates are: 1. RFC8026 update removed, not needed with new approach. 2. TRANSNAT and464XLAT requirements reworded in order to match new approach to allow operator controldepending oneach/allthe specific transitionmechanisms. 3. Added text in 464XLATmechanism, inbound connections typically require some degree of more complex manual configuration, such as setting up a DMZ, setting up virtual servers, or setting up port/protocol forwarding. In general, IPv4 CE Routers already provide a GUI, CLI, or API toclarifymanually configure them, or provide theusage. 16. ANNEX F: Changes from -03 Sectionpossibility tobe removed by RFC Editor. Significant updates are: 1. Several editorial changes acrossset up thedocument, specially TRANS requirements. 2. DNS proxy MUST instead of SHOULD. 17. ANNEX G: Changes from -04 Section to be removed by RFC Editor. Significant updates are: 1. Removed G-1. 2. Added support for draft-pref64folks-6man-ra-pref64. 3. General text clarifications. 18. ANNEX H: Changes from -05 Section to be removed by RFC Editor. Significant updates are: 1. Reworded and shorter UPnP section and new informative reference. 2. New general transition requirementCE incase multiple public IPv4 prefixes are provided,bridge mode, soto run multiple instances according to each specific transition mechanism. 3. General text clarifications. 19. ANNEX I: Changes from -06 Section to be removed by RFC Editor. Significant updates are: 1. Removed reference and text related to pref64folks-6man-ra-pref64. 2. General text clarifications. 20. ANNEX J: Changes from -07 Section to be removed by RFC Editor. Significant updates are: 1. Added text to UPnP section. 21. ANNEX K: Changes from -08, -09 and -10 Section to be removed by RFC Editor. Significant updates are: 1. Editorial edits. 22. ANNEX L: Changes from -11, -12, -13 and -14 Section to be removed by RFC Editor. Significant updates are: 1. Changes related to suggestions by Ops-dir, Sec-dir, Rtg-dir, Tsv- art and Gen-art, as well as comments from IESG review. 2. IANA section removed as a consequence ofanother Router behind theremovaloriginal CE, takes care of inbound connections. The requirements for that support are out of theinclusionscope of464XLAT inthis document. Who provides theRFC8026 priority mechanism. 23. References 23.1. Normative References [RFC2119] Bradner, S., "Key wordsIPv6 Transition CE Router is not relevant. In most cases, the service provider is responsible foruse in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines", BCP 152, RFC 5625, DOI 10.17487/RFC5625, August 2009, <https://www.rfc-editor.org/info/rfc5625>. [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deploymentprovisioning/managing, at least onIPv4 Infrastructures (6rd) -- Protocol Specification", RFC 5969, DOI 10.17487/RFC5969, August 2010, <https://www.rfc-editor.org/info/rfc5969>. [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clientsthe WAN side. Commonly, the user has access toIPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, April 2011, <https://www.rfc-editor.org/info/rfc6146>. [RFC6147] Bagnulo, M., Sullivan, A., Matthews, P.,configure the LAN interfaces, firewall, DMZ, andI. van Beijnum, "DNS64: DNS Extensions for Network Address Translation frommany other features. However, in many cases, the user must supply or may replace the IPv6Clients to IPv4 Servers", RFC 6147, DOI 10.17487/RFC6147, April 2011, <https://www.rfc-editor.org/info/rfc6147>. [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4 Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, <https://www.rfc-editor.org/info/rfc6333>. [RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration Protocol forTransition CE Router. This underscores the importance of the IPv6(DHCPv6) OptionTransition CE Routers fulfilling the requirements defined in this document. The IPv6 Transition CE Router described in this document is not intended forDual-Stack Lite", RFC 6334, DOI 10.17487/RFC6334, August 2011, <https://www.rfc-editor.org/info/rfc6334>. [RFC6877] Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT: Combinationusage in other scenarios, such as large enterprises, data centers, content providers, etc. Even if the documented requirements meet their needs, they may have additional requirements, which are out ofStateful and Stateless Translation", RFC 6877, DOI 10.17487/RFC6877, April 2013, <https://www.rfc-editor.org/info/rfc6877>. [RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, DOI 10.17487/RFC6887, April 2013, <https://www.rfc-editor.org/info/rfc6887>. [RFC6970] Boucadair, M., Penno, R., and D. Wing, "Universal Plugthe scope of this document. Appendix B. End-User Network Architecture An end-user network will likely support both IPv4 andPlay (UPnP) Internet Gateway Device - Port Control Protocol Interworking Function (IGD-PCP IWF)", RFC 6970, DOI 10.17487/RFC6970, July 2013, <https://www.rfc-editor.org/info/rfc6970>. [RFC7050] Savolainen, T., Korhonen, J.,IPv6 (see Section 1 andD. Wing, "Discovery ofAppendix A). It is not expected that end users will change their existing network topology with the introduction of IPv6. There are some differences in how IPv6Prefix Used for IPv6 Address Synthesis", RFC 7050, DOI 10.17487/RFC7050, November 2013, <https://www.rfc-editor.org/info/rfc7050>. [RFC7084] Singh, H., Beebee, W., Donley, C.,works andB. Stark, "Basic Requirements for IPv6 Customer Edge Routers", RFC 7084, DOI 10.17487/RFC7084, November 2013, <https://www.rfc-editor.org/info/rfc7084>. [RFC7225] Boucadair, M., "Discovering NAT64 IPv6 Prefixes Using the Port Control Protocol (PCP)", RFC 7225, DOI 10.17487/RFC7225, May 2014, <https://www.rfc-editor.org/info/rfc7225>. [RFC7291] Boucadair, M., Penno, R., and D. Wing, "DHCP Optionsis provisioned; these differences have implications for thePort Control Protocol (PCP)", RFC 7291, DOI 10.17487/RFC7291, July 2014, <https://www.rfc-editor.org/info/rfc7291>. [RFC7341] Sun, Q., Cui, Y., Siodelski, M., Krishnan, S.,network architecture. A typical IPv4 end-user network consists of a "plug andI. Farrer, "DHCPv4-over-DHCPv6 (DHCP 4o6) Transport", RFC 7341, DOI 10.17487/RFC7341, August 2014, <https://www.rfc-editor.org/info/rfc7341>. [RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y.,play" router with NAT functionality andI. Farrer, "Lightweight 4over6: An Extensiona single link upstream, connected to theDual- Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596, July 2015, <https://www.rfc-editor.org/info/rfc7596>. [RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S., Murakami, T., and T. Taylor, Ed., "Mappingservice provider network. From the perspective ofAddress and Port with Encapsulation (MAP-E)", RFC 7597, DOI 10.17487/RFC7597, July 2015, <https://www.rfc-editor.org/info/rfc7597>. [RFC7598] Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec, W., Bao, C., Yeh, L.,an IPv4 user behind an IPv6 Transition CE Router, this doesn't change. However, while a typical IPv4 NAT deployment, by default, blocks all incoming connections andX. Deng, "DHCPv6 Options for Configurationmay allow opening ofSoftwire Address and Port-Mapped Clients", RFC 7598, DOI 10.17487/RFC7598, July 2015, <https://www.rfc-editor.org/info/rfc7598>. [RFC7599] Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S.,ports using a Universal Plug andT. Murakami, "MappingPlay Internet Gateway Device (UPnP IGD) [UPnP-IGD][OCF-IGD] or some other firewall control protocol, in the case of an IPv6-only access and IPv4aaS, that may not be feasible depending on specific transition mechanism details. PCP [RFC6887] may be an alternative solution. Another consequence ofAddress and PortusingTranslation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July 2015, <https://www.rfc-editor.org/info/rfc7599>. [RFC7618] Cui, Y., Sun, Q., Farrer, I., Lee, Y., Sun, Q.,IPv4 private address space in the end- user network is that it provides stable addressing; that is, it doesn't change, even when you change service providers, andM. Boucadair, "Dynamic Allocationthe addresses are always usable even when the WAN interface is down or the customer edge router has not yet been provisioned. In the case ofSharedIPv6-only access, private IPv4Addresses", RFC 7618, DOI 10.17487/RFC7618, August 2015, <https://www.rfc-editor.org/info/rfc7618>. [RFC8026] Boucadair, M.addresses are also available if the IPv4aaS transition mechanism keeps running the NAT interface towards the LAN side when the WAN interface is down. More advanced routers support dynamic routing (which learns routes from other routers), andI. Farrer, "Unified IPv4-in-IPv6 Softwireadvanced end users can build arbitrary, complex networks using manual configuration of address prefixes combined with a dynamic routing protocol. Once again, this is true for both IPv4 and IPv6. In general, the end-user network architecture for IPv6 should provide equivalent or better capabilities and functionality than the current IPv4 architecture. The end-user network is a stub network in the sense that is not providing transit to other external networks. However, HNCP [RFC7788] allows support for automatic provisioning of downstream routers. Figure 2 illustrates the model topology for the end-user network. +---------------+ \ | Service | \ | Provider | \ | Router | | Service +-------+-------+ | Provider | IPv6-only | Network | CustomerPremises Equipment (CPE):/ | Internet Connection / | / +------+--------+ \ | IPv6 | \ | Transition CE | \ | Router | | +---+-------+---+ | Network ADHCPv6-Based Prioritization Mechanism", RFC 8026, DOI 10.17487/RFC8026, November 2016, <https://www.rfc-editor.org/info/rfc8026>. [RFC8114] Boucadair, M., Qin, C., Jacquenet, C., Lee, Y., and Q. Wang, "Delivery| | Network B | -+----------------+-+- -+---+-------------+- | | | | | | +---+------+ | +----+-----+ +-----+----+ | | IPv6 | | | IPv4 | |IPv4/IPv6 | | | Host | | | Host | | Host | | +----------+ | +----------+ +----------+ | End-User | | Network(s) +------+--------+ | | IPv6 | | | Router | | +------+--------+ | Network C | | -+-------------+--+- | | | | +---+------+ +----+-----+ | | IPv6 | | IPv6 | / | Host | | Host | / +----------+ +----------+ / Figure 2: Example of a Typical End-User Network This architecture describes the: o Basic capabilities ofIPv4 Multicast Servicesthe IPv6 Transition CE Router o Provisioning of the WAN interface connecting toIPv4 Clients overthe service provider o Provisioning of the LAN interfaces The IPv6 Transition CE Router may be manually configured in an arbitrary topology with a dynamic routing protocol or HNCP [RFC7788]. Automatic provisioning and configuration are described for a single IPv6Multicast Network", RFC 8114, DOI 10.17487/RFC8114, March 2017, <https://www.rfc-editor.org/info/rfc8114>. [RFC8115]Transition CE Router only. Acknowledgements Thanks to Mikael Abrahamsson, Fred Baker, Mohamed Boucadair,M., Qin, J., Tsou, T.,Brian Carpenter, Lorenzo Colitti, Alejandro D'Egidio, Ian Farrer, Lee Howard, Richard Patterson, Barbara Stark, Ole Troan, andX. Deng, "DHCPv6 OptionJames Woodyatt forIPv4-Embedded Multicasttheir review andUnicast IPv6 Prefixes", RFC 8115, DOI 10.17487/RFC8115, March 2017, <https://www.rfc-editor.org/info/rfc8115>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercasecomments inRFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., Richardson, M., Jiang, S., Lemon, T., and T. Winters, "Dynamic Host Configuration Protocolthis and/or previous draft versions of this document. Thanks also forIPv6 (DHCPv6)", RFC 8415, DOI 10.17487/RFC8415, November 2018, <https://www.rfc-editor.org/info/rfc8415>. 23.2. Informative References [IPv6Survey] Palet Martinez, J., "IPv6 Deployment Survey", January 2018, <https://indico.uknof.org.uk/event/41/contribution/5/ material/slides/0.pdf>. [OpenWRT] OpenWRT, "OpenWRT Packages", January 2018, <https://openwrt.org/packages/start>. [RFC7788] Stenberg, M., Barth, S.,the Last Call reviews by Dan Romascanu (OPS-DIR); Christian Huitema (SEC-DIR); Daniele Ceccarelli (RTG-DIR); Martin Stiemerling (TSV-ART); Matthew Miller (Gen-ART); andP. Pfister, "Home Networking Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April 2016, <https://www.rfc-editor.org/info/rfc7788>. [UPnP-IGD] UPnP Forum, "InternetGatewayDevice:2 Device Template Version 1.01", December 2010, <http://upnp.org/specs/gw/igd2/>. [UPnP-WANIPC] UPnP Forum, "WANIPConnection:2 Service", December 2010, <http://upnp.org/specs/gw/ UPnP-gw-WANIPConnection-v2-Service.pdf>.Alissa Cooper, Benjamin Kaduk, Suresh Krishnan, Ben Campbell, Spencer Dawkins, Mirja Kuhlewind, and Adam Roach (all IESG). Authors' Addresses Jordi Palet Martinez The IPv6 Company Molino de la Navata, 75 La Navata - Galapagar, Madrid 28420 Spain Email: jordi.palet@theipv6company.com URI: http://www.theipv6company.com/ Hans M.-H. Liu D-Link Systems, Inc. 17595 Mount Herrmann St. Fountain Valley, California 92708USUnited States of America Email: hans.liu@dlinkcorp.com URI:http://www.dlink.com/https://www.dlink.com/ Masanobu Kawashima NEC Platforms, Ltd.800, Shimomata Kakegawa-shi, Shizuoka 436-85012-3, Kanda-Tsukasamachi Chiyoda-ku, Tokyo 101-8532 Japan Email: kawashimam@vx.jp.nec.com URI: https://www.necplatforms.co.jp/en/