Basic Requirements for IPv6 Customer Edge Routers
Author(s): Wes Beebee, Barbara Stark, Chris Donley, Hemant Singh
This document specifies requirements for an IPv6 Customer Edge (CE) router. Specifically, the current version of this document focuses on the basic provisioning of an IPv6 CE router and the provisioning of IPv6 hosts attached to it. The...
Network Working Group H. Singh Internet-Draft W. Beebee Obsoletes: 6204 (if approved) Cisco Systems, Inc. Intended status: Informational C. Donley Expires: May 3, 2013 CableLabs B. Stark AT&T October 30, 2012 Basic Requirements for IPv6 Customer Edge Routers draft-ietf-v6ops-6204bis-12 Abstract This document specifies requirements for an IPv6 Customer Edge (CE) router. Specifically, the current version of this document focuses on the basic provisioning of an IPv6 CE router and the provisioning of IPv6 hosts attached to it. The document also covers IP transition technologies. Two transition technologies in RFC 5969's 6rd and RFC 6333's DS-Lite are covered in the document. The document obsoletes RFC 6204, if approved. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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 May 3, 2013. Copyright Notice Copyright (c) 2012 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 (http://trustee.ietf.org/license-info) in effect on the date of Singh, et al. Expires May 3, 2013 [Page 1] Internet-Draft IPv6 CE Router Requirements October 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Current IPv4 End-User Network Architecture . . . . . . . . 4 3.2. IPv6 End-User Network Architecture . . . . . . . . . . . . 5 3.2.1. Local Communication . . . . . . . . . . . . . . . . . 6 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. General Requirements . . . . . . . . . . . . . . . . . . . 7 4.2. WAN-Side Configuration . . . . . . . . . . . . . . . . . . 8 4.3. LAN-Side Configuration . . . . . . . . . . . . . . . . . . 12 4.4. Transition Technologies Support . . . . . . . . . . . . . 14 4.4.1. 6rd . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.4.2. Dual-Stack Lite (DS-Lite) . . . . . . . . . . . . . . 15 4.5. Security Considerations . . . . . . . . . . . . . . . . . 16 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 17 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1. Normative References . . . . . . . . . . . . . . . . . . . 17 8.2. Informative References . . . . . . . . . . . . . . . . . . 20 Appendix A. Changes from RFC 6204 . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22 Singh, et al. Expires May 3, 2013 [Page 2] Internet-Draft IPv6 CE Router Requirements October 2012 1. Introduction This document defines basic IPv6 features for a residential or small- office router, referred to as an IPv6 CE router, in order to establish an industry baseline for features to be implemented on such a router. These routers typically also support IPv4. Mixed environments of dual-stack hosts and IPv6-only hosts (behind the CE router) can be more complex if the IPv6-only devices are using a translator to access IPv4 servers [RFC6144]. Support for such mixed environments is not in scope of this document. This document specifies how an IPv6 CE router automatically provisions its WAN interface, acquires address space for provisioning of its LAN interfaces, and fetches other configuration information from the service provider network. Automatic provisioning of more complex topology than a single router with multiple LAN interfaces is out of scope for this document. See [RFC4779] for a discussion of options available for deploying IPv6 in service provider access networks. The document also covers the IP transition technologies that were available at the time this document was written. Two transition technologies in 6rd [RFC 5969] and DS-Lite [RFC6333] are covered in the document. 1.1. Requirements Language Take careful note: Unlike other IETF documents, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are not used as described in RFC2119 [RFC2119]. This document uses these keyword not strictly for the purpose of interoperability, but rather for the purpose of establishing industry-common baseline functionality. As such, the document points to several other specifications (preferable in RFC or stable form) to provide additional guidance to implementers regarding any protocol implementation required to produce a successful CPE router that interoperates successfully with a particular subset of currently deploying and planned common IPv6 access networks. 2. Terminology Singh, et al. Expires May 3, 2013 [Page 3] Internet-Draft IPv6 CE Router Requirements October 2012 End-User Network one or more links attached to the IPv6 CE router that connect IPv6 hosts. IPv6 Customer Edge Router a node intended for home or small-office use that forwards IPv6 packets not explicitly addressed to itself. The IPv6 CE router connects the end-user network to a service provider network. IPv6 Host any device implementing an IPv6 stack receiving IPv6 connectivity through the IPv6 CE router. LAN Interface an IPv6 CE router's attachment to a link in the end-user network. Examples are Ethernet (simple or bridged), 802.11 wireless, or other LAN technologies. An IPv6 CE router may have one or more network-layer LAN interfaces. Service Provider an entity that provides access to the Internet. In this document, a service provider specifically offers Internet access using IPv6, and may also offer IPv4 Internet access. The service provider can provide such access over a variety of different transport methods such as DSL, cable, wireless, and others. WAN Interface an IPv6 CE router's attachment to a link used to provide connectivity to the service provider network; example link technologies include Ethernet (simple or bridged), PPP links, Frame Relay, or ATM networks, as well as Internet-layer (or higher-layer) "tunnels", such as tunnels over IPv4 or IPv6 itself. 3. Architecture 3.1. Current IPv4 End-User Network Architecture An end-user network will likely support both IPv4 and IPv6. It is not expected that an end-user will change their existing network topology with the introduction of IPv6. There are some differences in how IPv6 works and is provisioned; these differences have implications for the network architecture. A typical IPv4 end-user Singh, et al. Expires May 3, 2013 [Page 4] Internet-Draft IPv6 CE Router Requirements October 2012 network consists of a "plug and play" router with NAT functionality and a single link behind it, connected to the service provider network. A typical IPv4 NAT deployment by default blocks all incoming connections. Opening of ports is typically allowed using a Universal Plug and Play Internet Gateway Device (UPnP IGD) [UPnP-IGD] or some other firewall control protocol. Another consequence of using private address space in the end-user network is that it provides stable addressing; i.e., it never changes even when you change service providers, and the addresses are always there even when the WAN interface is down or the customer edge router has not yet been provisioned. Many existing routers support dynamic routing (which learns routes from other routers), and advanced end-users can build arbitrary, complex networks using manual configuration of address prefixes combined with a dynamic routing protocol. 3.2. IPv6 End-User Network Architecture 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. Figure 1 illustrates the model topology for the end-user network. Singh, et al. Expires May 3, 2013 [Page 5] Internet-Draft IPv6 CE Router Requirements October 2012 +-------+-------+ \ | Service | \ | Provider | | Service | Router | | Provider +-------+-------+ | network | / | Customer / | Internet connection / | +------+--------+ \ | IPv6 | \ | Customer Edge | \ | Router | / +---+-------+-+-+ / Network A | | Network B | End-User ---+-------------+----+- --+--+-------------+--- | network(s) | | | | \ +----+-----+ +-----+----+ +----+-----+ +-----+----+ \ |IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | / | | | | | | | | / +----------+ +-----+----+ +----------+ +----------+ / Figure 1: An Example of a Typical End-User Network This architecture describes the: o Basic capabilities of an IPv6 CE router o Provisioning of the WAN interface connecting to the service provider o Provisioning of the LAN interfaces For IPv6 multicast traffic, the IPv6 CE router may act as a Multicast Listener Discovery (MLD) proxy [RFC4605] and may support a dynamic multicast routing protocol. The IPv6 CE router may be manually configured in an arbitrary topology with a dynamic routing protocol. Automatic provisioning and configuration are described for a single IPv6 CE router only. 3.2.1. Local Communication Link-local IPv6 addresses are used by hosts communicating on a single link. Unique Local IPv6 Unicast Addresses (ULAs) [RFC4193] are used by hosts communicating within the end-user network across multiple links, but without requiring the application to use a globally routable address. The IPv6 CE router defaults to acting as the Singh, et al. Expires May 3, 2013 [Page 6] Internet-Draft IPv6 CE Router Requirements October 2012 demarcation point between two networks by providing a ULA boundary, a multicast zone boundary, and ingress and egress traffic filters. At the time of this writing, several host implementations do not handle the case where they have an IPv6 address configured and no IPv6 connectivity, either because the address itself has a limited topological reachability (e.g., ULA) or because the IPv6 CE router is not connected to the IPv6 network on its WAN interface. To support host implementations that do not handle multihoming in a multi-prefix environment [MULTIHOMING-WITHOUT-NAT], the IPv6 CE router should not, as detailed in the requirements below, advertise itself as a default router on the LAN interface(s) when it does not have IPv6 connectivity on the WAN interface or when it is not provisioned with IPv6 addresses. For local IPv6 communication, the mechanisms specified in [RFC4191] are used. ULA addressing is useful where the IPv6 CE router has multiple LAN interfaces with hosts that need to communicate with each other. If the IPv6 CE router has only a single LAN interface (IPv6 link), then link-local addressing can be used instead. Coexistence with IPv4 requires any IPv6 CE router(s) on the LAN to conform to these recommendations, especially requirements ULA-5 and L-4 below. 4. Requirements 4.1. General Requirements The IPv6 CE router is responsible for implementing IPv6 routing; that is, the IPv6 CE router must look up the IPv6 destination address in its routing table to decide to which interface it should send the packet. In this role, the IPv6 CE router is responsible for ensuring that traffic using its ULA addressing does not go out the WAN interface, and does not originate from the WAN interface. G-1: An IPv6 CE router is an IPv6 node according to the IPv6 Node Requirements [RFC6434] specification. G-2: The IPv6 CE router MUST implement ICMPv6 according to [RFC4443]. In particular, point-to-point links MUST be handled as described in Section 3.1 of [RFC4443]. Singh, et al. Expires May 3, 2013 [Page 7] Internet-Draft IPv6 CE Router Requirements October 2012 G-3: The IPv6 CE router MUST NOT forward any IPv6 traffic between its LAN interface(s) and its WAN interface until the router has successfully completed the IPv6 address and the delegated prefix acquisition process. G-4: By default, an IPv6 CE router that has no default router(s) on its WAN interface MUST NOT advertise itself as an IPv6 default router on its LAN interfaces. That is, the "Router Lifetime" field is set to zero in all Router Advertisement messages it originates [RFC4861]. G-5: By default, if the IPv6 CE router is an advertising router and loses its IPv6 default router(s) and/or detects loss of connectivity on the WAN interface, it MUST explicitly invalidate itself as an IPv6 default router on each of its advertising interfaces by immediately transmitting one or more Router Advertisement messages with the "Router Lifetime" field set to zero [RFC4861]. 4.2. WAN-Side Configuration The IPv6 CE router will need to support connectivity to one or more access network architectures. This document describes an IPv6 CE router that is not specific to any particular architecture or service provider and that supports all commonly used architectures. IPv6 Neighbor Discovery and DHCPv6 protocols operate over any type of IPv6-supported link layer, and there is no need for a link-layer- specific configuration protocol for IPv6 network-layer configuration options as in, e.g., PPP IP Control Protocol (IPCP) for IPv4. This section makes the assumption that the same mechanism will work for any link layer, be it Ethernet, the Data Over Cable Service Interface Specification (DOCSIS), PPP, or others. WAN-side requirements: W-1: When the router is attached to the WAN interface link, it MUST act as an IPv6 host for the purposes of stateless [RFC4862] or stateful [RFC3315] interface address assignment. W-2: The IPv6 CE router MUST generate a link-local address and finish Duplicate Address Detection according to [RFC4862] prior to sending any Router Solicitations on the interface. The source address used in the subsequent Router Solicitation MUST be the link-local address on the WAN interface. Singh, et al. Expires May 3, 2013 [Page 8] Internet-Draft IPv6 CE Router Requirements October 2012 W-3: Absent other routing information, the IPv6 CE router MUST use Router Discovery as specified in [RFC4861] to discover a default router(s) and install default route(s) in its routing table with the discovered router's address as the next hop. W-4: The router MUST act as a requesting router for the purposes of DHCPv6 prefix delegation ([RFC3633]). W-5: The IPv6 CE router MUST use a persistent DHCP Unique Identifier (DUID) for DHCPv6 messages. The DUID MUST NOT change between network interface resets or IPv6 CE router reboots. W-6: The WAN interface of the CE router SHOULD support a PCP client as specified in [I-D.ietf-pcp-base] for use by applications on the CE Router. The PCP client SHOULD follow the procedure specified in Section 8.1 of [I-D.ietf-pcp-base] to discover its PCP server. This document takes no position on whether such functionality is enabled by default or mechanisms by which users would configure the functionality. Handling PCP requests from PCP clients in the LAN side of the CE Router is out of scope. Link-layer requirements: WLL-1: If the WAN interface supports Ethernet encapsulation, then the IPv6 CE router MUST support IPv6 over Ethernet [RFC2464]. WLL-2: If the WAN interface supports PPP encapsulation, the IPv6 CE router MUST support IPv6 over PPP [RFC5072]. WLL-3: If the WAN interface supports PPP encapsulation, in a dual- stack environment with IPCP and IPV6CP running over one PPP logical channel, the Network Control Protocols (NCPs) MUST be treated as independent of each other and start and terminate independently. Address assignment requirements: WAA-1: The IPv6 CE router MUST support Stateless Address Autoconfiguration (SLAAC) [RFC4862]. WAA-2: The IPv6 CE router MUST follow the recommendations in Section 4 of [RFC5942], and in particular the handling of the L flag in the Router Advertisement Prefix Information option. Singh, et al. Expires May 3, 2013 [Page 9] Internet-Draft IPv6 CE Router Requirements October 2012 WAA-3: The IPv6 CE router MUST support DHCPv6 [RFC3315] client behavior. WAA-4: The IPv6 CE router MUST be able to support the following DHCPv6 options: IA_NA, Reconfigure Accept [RFC3315], and DNS_SERVERS [RFC3646]. The IPv6 CE router SHOULD be able to support the DNS Search List DNSSL option as specified in [RFC3646]. WAA-5: The IPv6 CE router SHOULD implement the Network Time Protocol (NTP) as specified in [RFC5905] to provide a time reference common to the service provider for other protocols, such as DHCPv6, to use. If the CE router implements NTP, it requests the NTP Server DHCPv6 option [RFC5908] and uses the received list of servers as primary time reference, unless explicitly configured otherwise. LAN side support of NTP is out of scope for this document. WAA-6: If the IPv6 CE router receives a Router Advertisement message (described in [RFC4861]) with the M flag set to 1, the IPv6 CE router MUST do DHCPv6 address assignment (request an IA_NA option). WAA-7: If the IPv6 CE router does not acquire global IPv6 address(es) from either SLAAC or DHCPv6, then it MUST create global IPv6 address(es) from its delegated prefix(es) and configure those on one of its internal virtual network interfaces, unless configured to require a global IPv6 address on the WAN interface. WAA-8: The CE router must support the SOL_MAX_RT option [I-D.droms-dhc-dhcpv6-solmaxrt-update] and request the SOL_MAX_RT option in an ORO. WAA-9: As a router, the IPv6 CE router MUST follow the weak host (Weak ES) model [RFC1122]. When originating packets from an interface, it will use a source address from another one of its interfaces if the outgoing interface does not have an address of suitable scope. WAA-10: The IPv6 CE router SHOULD implement the Information Refresh Time option and associated client behavior as specified in [RFC4242]. Prefix delegation requirements: Singh, et al. Expires May 3, 2013 [Page 10] Internet-Draft IPv6 CE Router Requirements October 2012 WPD-1: The IPv6 CE router MUST support DHCPv6 prefix delegation requesting router behavior as specified in [RFC3633] (IA_PD option). WPD-2: The IPv6 CE router MAY indicate as a hint to the delegating router the size of the prefix it requires. If so, it MUST ask for a prefix large enough to assign one /64 for each of its interfaces, rounded up to the nearest nibble, and SHOULD be configurable to ask for more. WPD-3: The IPv6 CE router MUST be prepared to accept a delegated prefix size different from what is given in the hint. If the delegated prefix is too small to address all of its interfaces, the IPv6 CE router SHOULD log a system management error. [RFC6177] covers the recommendations for service providers for prefix allocation sizes. WPD-4: By default, the IPv6 CE router MUST initiate DHCPv6 prefix delegation when either the M or O flags are set to 1 in a received Router Advertisement (RA) message. Behavior of the CE router to use DHCPv6 prefix delegation when the CE router has not received any RA or received an RA with the M and the O bits set to zero is out of scope for this document. WPD-5: Any packet received by the CE router with a destination address in the prefix(es) delegated to the CE router but not in the set of prefixes assigned by the CE router to the LAN must be dropped. In other words, the next hop for the prefix(es) delegated to the CE router should be the null destination. This is necessary to prevent forwarding loops when some addresses covered by the aggregate are not reachable [RFC4632]. (a) The IPv6 CE router SHOULD send an ICMPv6 Destination Unreachable message in accordance with Section 3.1 of [RFC4443] back to the source of the packet, if the packet is to be dropped due to this rule. WPD-6: If the IPv6 CE router requests both an IA_NA and an IA_PD option in DHCPv6, it MUST accept an IA_PD option in DHCPv6 Advertise/Reply messages, even if the message does not contain any addresses, unless configured to only obtain its WAN IPv6 address via DHCPv6. See [I-D.ietf-dhc-dhcpv6-stateful-issues] Singh, et al. Expires May 3, 2013 [Page 11] Internet-Draft IPv6 CE Router Requirements October 2012 WPD-7: By default, an IPv6 CE router MUST NOT initiate any dynamic routing protocol on its WAN interface. WPD-8: The IPv6 CE Router SHOULD support the [I-D.ietf-dhc-pd-exclude] PD-Exclude option. 4.3. LAN-Side Configuration The IPv6 CE router distributes configuration information obtained during WAN interface provisioning to IPv6 hosts and assists IPv6 hosts in obtaining IPv6 addresses. It also supports connectivity of these devices in the absence of any working WAN interface. An IPv6 CE router is expected to support an IPv6 end-user network and IPv6 hosts that exhibit the following characteristics: 1. Link-local addresses may be insufficient for allowing IPv6 applications to communicate with each other in the end-user network. The IPv6 CE router will need to enable this communication by providing globally scoped unicast addresses or ULAs [RFC4193], whether or not WAN connectivity exists. 2. IPv6 hosts should be capable of using SLAAC and may be capable of using DHCPv6 for acquiring their addresses. 3. IPv6 hosts may use DHCPv6 for other configuration information, such as the DNS_SERVERS option for acquiring DNS information. Unless otherwise specified, the following requirements apply to the IPv6 CE router's LAN interfaces only. ULA requirements: ULA-1: The IPv6 CE router SHOULD be capable of generating a ULA prefix [RFC4193]. ULA-2: An IPv6 CE router with a ULA prefix MUST maintain this prefix consistently across reboots. ULA-3: The value of the ULA prefix SHOULD be configurable. ULA-4: By default, the IPv6 CE router MUST act as a site border router according to Section 4.3 of [RFC4193] and filter packets with local IPv6 source or destination addresses accordingly. Singh, et al. Expires May 3, 2013 [Page 12] Internet-Draft IPv6 CE Router Requirements October 2012 ULA-5: An IPv6 CE router MUST NOT advertise itself as a default router with a Router Lifetime greater than zero whenever all of its configured and delegated prefixes are ULA prefixes. LAN requirements: L-1: The IPv6 CE router MUST support router behavior according to Neighbor Discovery for IPv6 [RFC4861]. L-2: The IPv6 CE router MUST assign a separate /64 from its delegated prefix(es) (and ULA prefix if configured to provide ULA addressing) for each of its LAN interfaces. L-3: An IPv6 CE router MUST advertise itself as a router for the delegated prefix(es) (and ULA prefix if configured to provide ULA addressing) using the "Route Information Option" specified in Section 2.3 of [RFC4191]. This advertisement is independent of having or not having IPv6 connectivity on the WAN interface. L-4: An IPv6 CE router MUST NOT advertise itself as a default router with a Router Lifetime [RFC4861] greater than zero if it has no prefixes configured or delegated to it. L-5: The IPv6 CE router MUST make each LAN interface an advertising interface according to [RFC4861]. L-6: In Router Advertisement messages ([RFC4861]), the Prefix Information option's A and L flags MUST be set to 1 by default. L-7: The A and L flags' ([RFC4861]) settings SHOULD be user- configurable. L-8: The IPv6 CE router MUST support a DHCPv6 server capable of IPv6 address assignment according to [RFC3315] OR a stateless DHCPv6 server according to [RFC3736] on its LAN interfaces. L-9: Unless the IPv6 CE router is configured to support the DHCPv6 IA_NA option, it SHOULD set the M flag to 0 and the O flag to 1 in its Router Advertisement messages [RFC4861]. L-10: The IPv6 CE router MUST support providing DNS information in the DHCPv6 DNS_SERVERS and DOMAIN_LIST options [RFC3646]. Singh, et al. Expires May 3, 2013 [Page 13] Internet-Draft IPv6 CE Router Requirements October 2012 L-11: The IPv6 CE router MUST support providing DNS information in the Router Advertisement Recursive DNS Server (RDNSS) and DNS Search List options. Both options are specified in [RFC6106]. L-12: The IPv6 CE router SHOULD make available a subset of DHCPv6 options (as listed in Section 5.3 of [RFC3736]) received from the DHCPv6 client on its WAN interface to its LAN-side DHCPv6 server. L-13: If the delegated prefix changes, i.e., the current prefix is replaced with a new prefix without any overlapping time period, then the IPv6 CE router MUST immediately advertise the old prefix with a Preferred Lifetime of zero and a Valid Lifetime of either a) zero, or b) the lower of the current Valid Lifetime and two hours (which must be decremented in real time) in a Router Advertisement message as described in Section 5.5.3, (e) of [RFC4862]. L-14: The IPv6 CE router MUST send an ICMPv6 Destination Unreachable message, code 5 (Source address failed ingress/egress policy) for packets forwarded to it that use an address from a prefix that has been invalidated. 4.4. Transition Technologies Support 4.4.1. 6rd 6rd [RFC 5969] specifies an automatic tunneling mechanism tailored to advance deployment of IPv6 to end users via a service provider's IPv4 network infrastructure. Key aspects include automatic IPv6 prefix delegation to sites, stateless operation, simple provisioning, and service that is equivalent to native IPv6 at the sites that are served by the mechanism. It is expected that such traffic is forwarded over the CE Router's native IPv4 WAN interface, and not encapsulated in another tunnel. The CE Router SHOULD support 6rd functionality. If 6rd is supported, it MUST be implemented according to [RFC 5969]. The following CE Requirements also apply: 6rd requirements: 6RD-1: The IPv6 CE router MUST support 6rd configuration via the 6rd DHCPv4 Option (212). If the CE router has obtained an IPv4 network address through some other means such as PPP, it SHOULD use the DHCPINFORM request message [RFC2131] to request the 6rd DHCPv4 Option. The IPv6 CE router MAY use other mechanisms to configure 6rd parameters. Such Singh, et al. Expires May 3, 2013 [Page 14] Internet-Draft IPv6 CE Router Requirements October 2012 mechanisms are outside the scope of this document. 6RD-2: If the IPv6 CE router is capable of automated configuration of IPv4 through IPCP (i.e., over a PPP connection), it MUST support user-entered configuration of 6rd. 6RD-3: If the CE router supports configuration mechanisms other than the 6rd DHCPv4 Option 212 (user-entered, TR-69, etc.), the CE router MUST support 6rd in "hub and spoke" mode. 6rd in "hub and spoke" requires all IPv6 traffic to go to the 6rd Border Relay. In effect, this requirement removes the "direct connect to 6rd" route defined in Section 7.1.1 of [RFC 5969]. 6RD-4: A CE router MUST allow 6rd and native IPv6 WAN interfaces to be active alone as well as simultaneously in order to support coexistence of the two technologies during an incremental migration period such as a migration from 6rd to native IPv6. 6RD-5: Each packet sent on a 6rd or native WAN interface MUST be directed such that its source IP address is derived from the delegated prefix associated with the particular interface from which the packet is being sent[Section 4.3 [RFC3704]]. 6RD-6: The CE router MUST allow different as well as identical delegated prefixes to be configured via each (6rd or native) WAN interface. 6RD-7: In the event that forwarding rules produce a tie between 6rd and native IPv6, by default, the IPv6 CE Router MUST prefer native IPv6. 4.4.2. Dual-Stack Lite (DS-Lite) Dual-Stack Lite [RFC6333] enables both continued support for IPv4 services and incentives for the deployment of IPv6. It also de- couples IPv6 deployment in the Service Provider network from the rest of the Internet, making incremental deployment easier. Dual-Stack 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 CE Router's native IPv6 WAN interface, and not encapsulated in another tunnel. The IPv6 CE Router SHOULD implement DS-Lite functionality. If DS- Lite is supported, it MUST be implemented according to [RFC6333]. This document takes no position on simultaneous operation of Dual- Stack Lite and native IPv4. The following CE Router requirements also apply: Singh, et al. Expires May 3, 2013 [Page 15] Internet-Draft IPv6 CE Router Requirements October 2012 WAN requirements: DLW-1: The CE Router MUST support configuration of DS-Lite via the DS-Lite DHCPv6 option [RFC6334]. The IPv6 CE Router MAY use other mechanisms to configure DS-Lite parameters. Such mechanisms are outside the scope of this document. DLW-2: IPv6 CE Router MUST NOT perform IPv4 Network Address Translation (NAT) on IPv4 traffic encapsulated using DS-Lite. DLW-3: If the IPv6 CE Router is configured with an IPv4 address on its WAN interface then the IPv6 CE Router SHOULD disable the DS-Lite B4 element. 4.5. Security Considerations It is considered a best practice to filter obviously malicious traffic (e.g., spoofed packets, "Martian" addresses, etc.). Thus, the IPv6 CE router ought to support basic stateless egress and ingress filters. The CE router is also expected to offer mechanisms to filter traffic entering the customer network; however, the method by which vendors implement configurable packet filtering is beyond the scope of this document. Security requirements: S-1: The IPv6 CE router SHOULD support [RFC6092]. In particular, the IPv6 CE router SHOULD support functionality sufficient for implementing the set of recommendations in [RFC6092], Section 4. This document takes no position on whether such functionality is enabled by default or mechanisms by which users would configure it. S-2: The IPv6 CE router SHOULD support ingress filtering in accordance with BCP 38 [RFC2827]. Note that this requirement was downgraded from a MUST from RFC 6204 due to the difficulty of implementation in the CE router and the feature's redundancy with upstream router ingress filtering. S-3: If the IPv6 CE router firewall is configured to filter incoming tunneled data, the firewall SHOULD provide the capability to filter decapsulated packets from a tunnel. 5. IANA Considerations This document has no actions for IANA. Singh, et al. Expires May 3, 2013 [Page 16] Internet-Draft IPv6 CE Router Requirements October 2012 6. Acknowledgements Thanks to the following people (in alphabetical order) for their guidance and feedback: Mikael Abrahamsson, Tore Anderson, Merete Asak, Rajiv Asati, Scott Beuker, Mohamed Boucadair, Rex Bullinger, Brian Carpenter, Tassos Chatzithomaoglou, Lorenzo Colitti, Remi Denis-Courmont, Gert Doering, Alain Durand, Katsunori Fukuoka, Brian Haberman, Tony Hain, Thomas Herbst, Ray Hunter, Kevin Johns, Joel Jaeggli, Erik Kline, Stephen Kramer, Victor Kuarsingh, Francois-Xavier Le Bail, Arifumi Matsumoto, David Miles, Shin Miyakawa, Jean-Francois Mule, Michael Newbery, Carlos Pignataro, John Pomeroy, Antonio Querubin, Daniel Roesen, Hiroki Sato, Teemu Savolainen, Matt Schmitt, David Thaler, Mark Townsley, Sean Turner, Bernie Volz, Dan Wing, Timothy Winters, James Woodyatt, Carl Wuyts, and Cor Zwart. This document is based in part on CableLabs' eRouter specification. The authors wish to acknowledge the additional contributors from the eRouter team: Ben Bekele, Amol Bhagwat, Ralph Brown, Eduardo Cardona, Margo Dolas, Toerless Eckert, Doc Evans, Roger Fish, Michelle Kuska, Diego Mazzola, John McQueen, Harsh Parandekar, Michael Patrick, Saifur Rahman, Lakshmi Raman, Ryan Ross, Ron da Silva, Madhu Sudan, Dan Torbet, and Greg White. 7. Contributors The following people have participated as co-authors or provided substantial contributions to this document: Ralph Droms, Kirk Erichsen, Fred Baker, Jason Weil, Lee Howard, Jean-Francois Tremblay, Yiu Lee, John Jason Brzozowski, and Heather Kirksey. Thanks to Ole Troan for editorship in the original RFC 6204 document. 8. References 8.1. Normative References [I-D.droms-dhc-dhcpv6-solmaxrt-update] Droms, R., "Modification to Default Value of SOL_MAX_RT", draft-droms-dhc-dhcpv6-solmaxrt-update-03 (work in progress), August 2012. [I-D.ietf-dhc-pd-exclude] Korhonen, J., Savolainen, T., Krishnan, S., and O. Troan, Singh, et al. Expires May 3, 2013 [Page 17] Internet-Draft IPv6 CE Router Requirements October 2012 "Prefix Exclude Option for DHCPv6-based Prefix Delegation", draft-ietf-dhc-pd-exclude-04 (work in progress), December 2011. [I-D.ietf-pcp-base] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", draft-ietf-pcp-base-28 (work in progress), October 2012. [RFC1122] Braden, R., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC1122, October 1989. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC2119, March 1997. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC2131, March 1997. [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC2464, December 1998. [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: Defeating Denial of Service Attacks which employ IP Source Address Spoofing", BCP 38, RFC2827, May 2000. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC3315, July 2003. [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6", RFC3633, December 2003. [RFC3646] Droms, R., "DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC3646, December 2003. [RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed Networks", BCP 84, RFC3704, March 2004. [RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6", RFC3736, April 2004. [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC4191, November 2005. [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast Addresses", RFC4193, October 2005. Singh, et al. Expires May 3, 2013 [Page 18] Internet-Draft IPv6 CE Router Requirements October 2012 [RFC4242] Venaas, S., Chown, T., and B. Volz, "Information Refresh Time Option for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC4242, November 2005. [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC4443, March 2006. [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, "Internet Group Management Protocol (IGMP) / Multicast Listener Discovery (MLD)-Based Multicast Forwarding ("IGMP/MLD Proxying")", RFC4605, August 2006. [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan", BCP 122, RFC4632, August 2006. [RFC4779] Asadullah, S., Ahmed, A., Popoviciu, C., Savola, P., and J. Palet, "ISP IPv6 Deployment Scenarios in Broadband Access Networks", RFC4779, January 2007. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC4861, September 2007. [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC4862, September 2007. [RFC4864] Van de Velde, G., Hain, T., Droms, R., Carpenter, B., and E. Klein, "Local Network Protection for IPv6", RFC4864, May 2007. [RFC5072] S.Varada, Haskins, D., and E. Allen, "IP Version 6 over PPP", RFC5072, September 2007. [RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC5905, June 2010. [RFC5908] Gayraud, R. and B. Lourdelet, "Network Time Protocol (NTP) Server Option for DHCPv6", RFC5908, June 2010. [RFC5942] Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet Model: The Relationship between Links and Subnet Prefixes", RFC5942, July 2010. [RFC 5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) -- Protocol Specification", Singh, et al. Expires May 3, 2013 [Page 19] Internet-Draft IPv6 CE Router Requirements October 2012 RFC 5969, August 2010. [RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in Customer Premises Equipment (CPE) for Providing Residential IPv6 Internet Service", RFC6092, January 2011. [RFC6106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, "IPv6 Router Advertisement Options for DNS Configuration", RFC6106, November 2010. [RFC6177] Narten, T., Huston, G., and L. Roberts, "IPv6 Address Assignment to End Sites", BCP 157, RFC6177, March 2011. [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4 Exhaustion", RFC6333, August 2011. [RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite", RFC6334, August 2011. [RFC6434] Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node Requirements", RFC6434, December 2011. 8.2. Informative References [I-D.ietf-dhc-dhcpv6-stateful-issues] Troan, O. and B. Volz, "Issues with multiple stateful DHCPv6 options", draft-ietf-dhc-dhcpv6-stateful-issues-00 (work in progress), May 2012. [MULTIHOMING-WITHOUT-NAT] Troan, O., Ed., Miles, D., Matsushima, S., Okimoto, T., and D. Wing, "IPv6 Multihoming without Network Address Translation", Work in Progress, December 2010. [RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for IPv4/IPv6 Translation", RFC6144, March 2011. [UPnP-IGD] UPnP Forum, "Universal Plug and Play (UPnP) Internet Gateway Device (IGD)", November 2001, <http://www.upnp.org/>. Singh, et al. Expires May 3, 2013 [Page 20] Internet-Draft IPv6 CE Router Requirements October 2012 Appendix A. Changes from RFC 6204 1. Added IP transition technologies available in RFC form. 2. Changed requirement G-5 to augment the condition of losing IPv6 default router(s) with loss of connectivity. 3. Removed requirement WAA-7 due to not reaching consensus by various service provider standards bodies. The removal of text does not remove any critical functionality from the CE specification. 4. Changed requirement WAA-8 to qualify WAN behavior only if not configured to perform DHCPv6. This way a deployment specific profile can mandate DHCPv6 numbered WAN without conflicting with this document. 5. Changed the WPD-2 requirement from MUST be configurable to SHOULD be configurable. 6. Changed requirement WPD-4 for a default behavior without compromising any prior specification of the CE device. The change was needed by a specific layer 2 deployment which wanted to specify a MUST for DHCPv6 in their layer 2 profile and not conflict with this document. 7. Changed requirement WPD-7 to qualify text for DHCPv6. Removed W-5 and WPD-5 because the text does not have consensus from the IETF DHC Working Group for what the final solution related to the removed requirements will be. 8. Added a new WAN DHCPv6 requirement for SOL_MAX_RT of DHCPv6 so that if an service provider does not have DHCPv6 service enabled CE routers do not send too frequent DHCPv6 requests to the service provider DHCPv6 server. 9. Changed requirement L-11 from SHOULD provide DNS options in the RA to MUST provide DNS option in the RA. 10. New requirement added to the Security Considerations section due to addition of transition technology. The CE router filters decapsulated 6rd data. 11. Minor change involved changing ICMP to ICMPv6. 12. Added PCP client requirement for the WAN. Singh, et al. Expires May 3, 2013 [Page 21] Internet-Draft IPv6 CE Router Requirements October 2012 13. Added a requirement for the DHCPv6 pd-exclude option. Authors' Addresses Hemant Singh Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 1622 EMail: firstname.lastname@example.org URI: http://www.cisco.com/ Wes Beebee Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 2030 EMail: email@example.com URI: http://www.cisco.com/ Chris Donley CableLabs 858 Coal Creek Circle Louisville, CO 80027 USA EMail: firstname.lastname@example.org Barbara Stark AT&T 725 W Peachtree St. Atlanta, GA 30308 USA EMail: email@example.com Singh, et al. Expires May 3, 2013 [Page 22]