Softwire WGInternet Engineering Task Force (IETF) T. MrugalskiInternet-DraftRequest for Comments: 7598 ISCIntended status:Category: Standards Track O. TroanExpires: September 10, 2015ISSN: 2070-1721 Cisco Systems I. Farrer Deutsche Telekom AG S. PerreaultViagenieJive Communications W. Dec Cisco Systems C. Bao Tsinghua University L. YehCNNICFreelancer Technologies X. DengMarch 09,The University of New South Wales July 2015 DHCPv6 Options forconfigurationConfiguration of Softwire Address andPort MappedPort-Mapped Clientsdraft-ietf-softwire-map-dhcp-12Abstract This document specifies DHCPv6 options, termed Softwire46 options, for the provisioning of Softwire46 Customer Edge (CE) devices. Softwire46 is a collective term used to refer to architectures based on the notion of IPv4Address+PortAddress plus Port (A+P) for providing IPv4 connectivity across an IPv6 network. Status of This Memo ThisInternet-Draftissubmitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documentsan Internet Standards Track document. 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 http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents validthe IETF community. It has received public review and has been approved fora maximumpublication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. 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 September 10, 2015.http://www.rfc-editor.org/info/rfc7598. Copyright Notice Copyright (c) 2015 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 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. . . . . . . . . . . . . . . . . . . . . . . . 2....................................................3 2. Conventions. . . . . . . . . . . . . . . . . . . . . . . . . 3.....................................................3 3. Softwire46 Overview. . . . . . . . . . . . . . . . . . . . . 3.............................................4 4. Common Softwire46 DHCPv6 Options. . . . . . . . . . . . . . 4................................5 4.1. S46 Rule Option. . . . . . . . . . . . . . . . . . . . . 5............................................5 4.2. S46 BR Option. . . . . . . . . . . . . . . . . . . . . . 7..............................................7 4.3. S46 DMR Option. . . . . . . . . . . . . . . . . . . . . 7.............................................8 4.4. S46 IPv4/IPv6 Address Binding Option. . . . . . . . . . 8.......................9 4.5. S46 Port Parameters Option. . . . . . . . . . . . . . . 9................................10 5. Softwire46 Containers. . . . . . . . . . . . . . . . . . . . 10..........................................11 5.1.Softwire46S46 MAP-E Container Option. . . . . . . . . . . . 10................................11 5.2.Softwire46S46 MAP-T Container Option. . . . . . . . . . . . 11................................12 5.3.Softwire46 LightWeight 46S46 Lightweight 4over6 Container Option. . . . . . . 11...................13 6. Softwire46 OptionsFormatting . . . . . . . . . . . . . . . . 12Encapsulation ...............................14 7. DHCPv6 Server Behavior. . . . . . . . . . . . . . . . . . . 13.........................................14 8. DHCPv6 Client Behavior. . . . . . . . . . . . . . . . . . . 13.........................................14 9. Security Considerations. . . . . . . . . . . . . . . . . . . 14........................................15 10. IANA Considerations. . . . . . . . . . . . . . . . . . . . . 14...........................................16 11.Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 12.References. . . . . . . . . . . . . . . . . . . . . . . . . 15 12.1.....................................................16 11.1. Normative References. . . . . . . . . . . . . . . . . . 15 12.2......................................16 11.2. Informative References. . . . . . . . . . . . . . . . . 15...................................17 Acknowledgements ..................................................18 Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . . 16................................................19 1. Introduction A number of architectural solution proposals discussed in the IETF Softwire Working Group use Addressandplus Port (A+P) [RFC6346] as their technology base for providing IPv4 connectivity to end users usingCECustomer Edge (CE) devices across aService Provider'sservice provider's IPv6 network, while allowing for shared or dedicated IPv4 addressing of CEs. An example is Mapping of Address and Port(MAP)with Encapsulation (MAP-E) as defined in[I-D.ietf-softwire-map].[RFC7597]. The MAP solution consists of one or more MAP Border Relay (BR)routers,routers responsible for stateless forwarding between a MAP IPv6 domain and an IPv4 network, and one or more MAP Customer Edge (CE)routers,routers responsible for forwarding between a user's IPv4 network and the MAP IPv6 network domain. Collectively, the MAP CE and BR form a domain when configured with common service parameters. This characteristic is common to all of the Softwire46 mechanisms. To function in such a domain, a CE needs to be provisioned with the appropriate A+P service parameters for that domain. These consist primarily of the CE's IPv4 address andtransport layer port-range(s).transport-layer port range(s). Furthermore, the IPv6 transport mode(i.e.(i.e., encapsulation or translation) needs to be specified. Provisioning of other IPv4 configuration information not derived directly from the A+P service parameters is not covered in this document. It is expected that provisioning of other IPv4 configuration information will continue to use DHCPv4 [RFC2131]. This memo specifies a set of DHCPv6 [RFC3315] options to provision Softwire46 configuration information to CE routers. Although the focus is to deliver IPv4 service to an end-user network (such as a residential home network), it can equally be applied to an individual host acting as a CE. Configuration of the BR is out of scopeoffor this document. 2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 3. Softwire46 Overview This document describes a set of common DHCPv6 options for configuring theMAP-E [I-D.ietf-softwire-map], MAP-T [I-D.ietf-softwire-map-t]Mapping of Address and Port with Encapsulation (MAP-E) [RFC7597], Mapping of Address and Port using Translation (MAP-T) [RFC7599], and Lightweight 4over6[I-D.ietf-softwire-lw4over6][RFC7596] mechanisms. Fordefinitiondefinitions of the terminology used in thisdocumentdocument, please see the relevant terminology sections inthe above references.[RFC7597], [RFC7599], and [RFC7596]. MAP-E,MAP-TMAP-T, and Lightweight 4over6 are essentially providing the same functionality: IPv4 service to a CE router over anIPv6 onlyIPv6-only access network. MAP-E and MAP-T may embed parts of the IPv4 address in IPv6 prefixes, thereby supporting many clients with a fixed set of mapping rules andmeshMesh mode (directCE to CECE-to-CE communication). MAP-E and MAP-T CEs may also be provisioned inhub and spoke mode,hub-and-spoke mode and in 1:1 mode (with no embedded address bits). The difference between MAP-E and MAP-T is that they use different means to connect to the IPv6 domain. MAP-E uses[RFC2473] IPv4 over IPv6 tunnelling,IPv4-over-IPv6 tunneling [RFC2473], while MAP-T usesNAT64 [RFC6145]IPv4-to-IPv6 translation basedtranslation.on [RFC6145]. Lightweight 4over6 is ahub and spoke IPv4 over IPv6hub-and-spoke IPv4-over-IPv6 tunneling mechanism, with complete independence of IPv4 and IPv6 addressing (zero embedded address bits). TheDHCPDHCPv6 options described here tie the provisioning parameters, and hence the IPv4 service itself, to the End-user IPv6 prefix lifetime. The validity of a Softwire46's IPv4 address,prefixprefix, or shared IPv4address,address; portsetset; and any authorization and accounting are tied to the lifetime of its associated End-user IPv6 prefix. To support more than one mechanism at a time and to allow for a possibility of transition between them, the DHCPv6 Option Request Option (ORO) [RFC3315] is used. Each mechanism has a corresponding DHCPv6 container option. A DHCPv6 client can request a particular mechanism by including the option code for a particular container option in itsORO option.ORO. The provisioning parameters for that mechanism are expressed by embedding the common format options within the respective container option. This approach implies that all of the provisioning optionsMUSTappear only within the container options.The client MUST NOT request any of the provisioning options directly within an ORO. MAP- DHCPSoftwire46 DHCPv6 clients that receive provisioning options that are not encapsulated in container options MUST silently ignore these options.DHCPDHCPv6 server administrators are advised to ensure thatDHCPDHCPv6 servers are configured to send these options in the proper encapsulation.TheThis document is organized with the commonsub-optionsencapsulated options describedfirst,first (Section 4), followed by the three containeroptions.options (Section 5). Somesub-optionsencapsulated options are mandatory in some containers, some areoptionaloptional, and some are notpermitted at all.permitted. This is shown in Table1.1 (Section 6). 4. Common Softwire46 DHCPv6 Options The DHCPv6 protocol is used for Softwire46 CE provisioning following regular DHCPv6 notions, with the CE assuming the role of a DHCPv6 client, and the DHCPv6 server providing options following DHCPv6server sideserver-side policies. The format and usage of the options are defined in the followingsub-sections.subsections. Each CE needs to be provisioned with enough information to calculate its IPv4 address, IPv4prefixprefix, or shared IPv4 address. MAP-E and MAP-T use theOPTION_S46_RULE,OPTION_S46_RULE option, while Lightweight 4over6 uses the OPTION_S46_V4V6BIND option. A CE that needs to communicate outside of the A+P domain also needs the address or prefix of the BR. MAP-E and Lightweight 4over6 use the OPTION_S46_BR option to communicate the IPv6 address of the BR. MAP-T forms an IPv6 destination address by embedding an IPv4 destination address into the BR's IPv6 prefix conveyed via the OPTION_S46_DMR option. Optionally, all mechanisms can include the OPTION_S46_PORTPARAMS option to specify parameters and port sets for theport rangeport-range algorithm. Softwire46 options use addresses rather thanFQDNs.Fully Qualified Domain Names (FQDNs). For the rationale behind this design choice, see Section 8 of [RFC7227]. 4.1. S46 Rule Option Figure 1 shows the format of the S46 Rule option (OPTION_S46_RULE) used for conveying the Basic Mapping Rule (BMR) and Forwarding Mapping Rule (FMR). This option follows behavior described in Sections 17.1.1 and 18.1.1 of [RFC3315]. Clients caninsertsend thoseoptionsoptions, encapsulated in their respective container options, with specific values as hints for the server. See Section 5 for details. Depending on the server configuration and policy, it may accept or ignore the hints.ClientClients MUST be able to process received values that are different than the hints it sent earlier. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_S46_RULE | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | flags | ea-len | prefix4-len | ipv4-prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | (continued) | prefix6-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ipv6-prefix | | (variable length) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . S46_RULE-options . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: S46 Rule Option o option-code: OPTION_S46_RULE(TBD1)(89) o option-length: length of the option, excluding option-code and option-length fields, including length of all encapsulatedoptions,options; expressed inbytes.octets. o flags: 8 bitslong field carryinglong; carries flags applicable to the rule. Themeaningmeanings of the specific bits are explained in Figure 2. o ea-len: 8 bitslong field thatlong; specifies theEmbedded-AddressEmbedded Address (EA) bit length. Allowed values range from 0 to 48. o prefix4-len: 8 bitslong field expressinglong; expresses the prefix length of the Rule IPv4 prefix specified in therule-ipv4-prefixipv4-prefix field.ValidAllowed values range from 0 to 32. o ipv4-prefix: afixed length 32 bitfixed-length 32-bit field that specifies the IPv4 prefix for the S46 rule. The bits in the prefix after prefix4-len number of bits are reserved and MUST be initialized to zero by the sender and ignored by the receiver. o prefix6-len: 8 bitslong field expressinglong; expresses the length of the Rule IPv6 prefix specified in therule-ipv6-prefixipv6-prefix field. Allowed values range from 0 to 128. o ipv6-prefix: avariable lengthvariable-length field that specifies the IPv6 domain prefix for the S46 rule. The field is padded on the right with zero bits up to the nearest octet boundary when prefix6-len is not evenly divisible by 8. o S46_RULE-options: avariablevariable-length field that may contain zero or more options that specify additional parameters for this S46 rule. This document specifies one suchoption,option: OPTION_S46_PORTPARAMS. TheFormatformat of the S46 Rule Flags field is: 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |Reserved |F| +-+-+-+-+-+-+-+-+ Figure 2: S46 Rule Flags o Reserved:7-bits7 bits; reserved for future use as flags. oF-Flag: 1 bitF-flag: 1-bit field that specifies whether the rule is to be used for forwarding (FMR). If set, this rule is used asa FMR,an FMR; if notsetset, this rule is a BMR only and MUST NOT be used for forwarding. Note: A BMR can also be used as an FMR for forwarding if the F-flag is set. The BMRruleis determined by a longest-prefix match of theRule-IPv6-prefixRule IPv6 prefix against theEnd-UserEnd-user IPv6 prefix(es). It is expected that in a typical mesh deploymentscenario,scenario there will be a single BMR, which could also be designated as an FMR using theF-Flag.F-flag. 4.2. S46 BR Option The S46 BROptionoption (OPTION_S46_BR) is used to convey the IPv6 address of the Border Relay. Figure43 shows the format of the OPTION_S46_BR option. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_S46_BR | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | br-ipv6-address | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: S46 BR Option o option-code: OPTION_S46_BR(TBD2)(90) o option-length: 16 o br-ipv6-address: afixed lengthfixed-length field of 16 octets that specifies the IPv6 address for the S46 BR. BR redundancy can be implemented by using an anycast address for the BR IPv6 address. Multiple OPTION_S46_BR options MAY be included in the container; this document does not further explore the use of multiple BR IPv6 addresses. 4.3. S46 DMR Option The S46 DMROptionoption (OPTION_S46_DMR) is used to convey values for the Default Mapping Rule (DMR). Figure 4 shows the format of the OPTION_S46_DMR option used for conveying a DMR. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_S46_DMR | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |dmr-prefix6-len| dmr-ipv6-prefix | +-+-+-+-+-+-+-+-+ (variable length) | . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: S46 DMR Option o option-code: OPTION_S46_DMR(TBD3)(91) o option-length: 1 + length of dmr-ipv6-prefix specified inbytes.octets. o dmr-prefix6-len: 8 bitslong field expressinglong; expresses thebit maskbitmask length of the IPv6 prefix specified in the dmr-ipv6-prefix field. Allowed values range from 0 to 128. o dmr-ipv6-prefix: avariable lengthvariable-length field specifying the IPv6 prefix or address for the BR. This field isright paddedright-padded with zeros to the nearest octet boundary when dmr-prefix6-len is not divisible by 8. 4.4. S46 IPv4/IPv6 Address Binding Option TheIPv4 address OptionS46 IPv4/IPv6 Address Binding option (OPTION_S46_V4V6BIND) MAY be used to specify the full or shared IPv4 address of the CE. The IPv6 prefix field is used by the CE to identify the correct prefix to use for the tunnel source. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_S46_V4V6BIND | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ipv4-address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |bindprefix6-len| bind-ipv6-prefix | +-+-+-+-+-+-+-+-+ (variable length) | . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . S46_V4V6BIND-options . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: S46 IPv4/IPv6 Address Binding Option o option-code: OPTION_S46_V4V6BIND(TBD4)(92) o option-length: length of the option, excluding option-code and option-length fields, including length of all encapsulatedoptions,options; expressed inbytes.octets. o ipv4-address:A fixeda fixed-length field of 4 octets specifying an IPv4 address. o bindprefix6-len: 8 bitslong field expressinglong; expresses thebit maskbitmask length of the IPv6 prefix specified in the bind-ipv6-prefix field. Allowed values range from 0 to 128. o bind-ipv6-prefix: avariable lengthvariable-length field specifying the IPv6 prefix or address for the S46 CE. This field isright paddedright-padded with zeros to the nearest octet boundary when bindprefix6-len is not divisible by 8. o S46_V4V6BIND-options: avariablevariable-length field that may contain zero or more options that specify additional parameters. This document specifies one suchoption,option: OPTION_S46_PORTPARAMS. 4.5. S46 Port Parameters Option The S46 Port ParametersOptionoption (OPTION_S46_PORTPARAMS) specifies optionalPort Setport set information that MAY be provided to CEs. See[I-D.ietf-softwire-map],Section 5.1 of [RFC7597] for a description of the MAPalgorithm, explainingalgorithm and detailed explanation of all of theparameters in detail.parameters. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_S46_PORTPARAMS | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | offset | PSID-len | PSID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6: S46 Port Parameters Option o option-code: OPTION_S46_PORTPARAMS(TBD5)(93) o option-length: 4 o offset:(PSID offset)Port Set Identifier (PSID) offset. 8 bitslong field thatlong; specifies the numeric value for the S46 algorithm's excluded portrange/offsetrange/ offset bits (a-bits), as persection 5.1.1Section 5.1 of[I-D.ietf-softwire-map].[RFC7597]. Allowed values are between 0 and 15. Default values for this field are specific to the softwire mechanism being implemented and are defined in the relevant specification document. o PSID-len:Bit length value of8 bits long; specifies the number of significant bits in the PSIDfield.field (also known as 'k'). When set to 0, the PSID field is to be ignored. After the first 'a' bits, there are k bits in the port number representing the value of thePort Set Identifier (PSID).PSID. Consequently, theaddress sharingaddress-sharing ratio would be 2^k. o PSID:Explicit 16-bit (unsigned word) PSID value.16 bits long. The PSID value algorithmically identifies a set of ports assigned to a CE. The first k bits on the left of this field contain the PSID binary value. The remaining(16-k)(16 - k) bits on the right are padding zeros. When receiving the OPTION_S46_PORTPARAMS option with an explicit PSID, the client MUST use this explicit PSIDinwhen configuring its softwire interface. The OPTION_S46_PORTPARAMS option with an explicit PSID MUST be discarded if the S46 CE isn't configured with a full IPv4 address(e.g. IPv4 prefix). The OPTION_S46_PORTPARAMS option with an explicit PSID MUST be discarded if the S46 CE isn't configured with a full IPv4 address (e.g.(e.g., IPv4 prefix). The OPTION_S46_PORTPARAMS option is contained within an OPTION_S46_RULE option or an OPTION_S46_V4V6BIND option. 5. Softwire46 Containers 5.1.Softwire46S46 MAP-E Container Option The S46 MAP-E ContainerOptionoption (OPTION_S46_CONT_MAPE) specifies the container used to group all rules and optional port parameters for a specified domain. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_S46_CONT_MAPE | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . encapsulated-options (variable length) . . . +---------------------------------------------------------------+ Figure 7: S46 MAP-E Container Option o option-code: OPTION_S46_CONT_MAPE(TBD6)(94) o option-length:Lengthlength of encapsulatedoptionsoptions, expressed in octets. o encapsulated-options: options associated with this Softwire46 MAP-E domain. Theencapsulated optionsencapsulated-options field conveys options specific to theOPTION_S46_CONT_MAPE. CurrentlyOPTION_S46_CONT_MAPE option. Currently, there are twosub-options specified,encapsulated options specified: OPTION_S46_RULE and OPTION_S46_BR. There MUST be at least one OPTION_S46_RULE option and at least one OPTION_S46_BR option. Other options applicable to a domain may be defined in the future. ADHCPDHCPv6 message MAY include multiple OPTION_S46_CONT_MAPE options (representing multiple domains). 5.2.Softwire46S46 MAP-T Container Option The S46 MAP-T Container option (OPTION_S46_CONT_MAPT) specifies the container used to group all rules and optional port parameters for a specified domain. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_S46_CONT_MAPT | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . encapsulated-options (variable length) . . . +---------------------------------------------------------------+ Figure 8:MAP-ES46 MAP-T Container Option o option-code: OPTION_S46_CONT_MAPT(TBD7)(95) o option-length:Lengthlength of encapsulatedoptionsoptions, expressed in octets. o encapsulated-options: options associated with this Softwire46 MAP-T domain.The encapsulated optionsThe encapsulated-options field conveys options specific to the OPTION_S46_CONT_MAPT option.CurrentlyCurrently, there are two optionsspecified,specified: the OPTION_S46_RULE and OPTION_S46_DMR options. There MUST be at least one OPTION_S46_RULE option and exactly one OPTION_S46_DMR option. 5.3.Softwire46 LightWeight 46S46 Lightweight 4over6 Container Option TheLW46S46 Lightweight 4over6 Container option (OPTION_S46_CONT_LW) specifies the container used to group all rules and optional port parameters for a specified domain. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_S46_CONT_LW | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + encapsulated-options (variable length) . . . +---------------------------------------------------------------+ Figure 9:LW46S46 Lightweight 4over6 Container Option o option-code: OPTION_S46_CONT_LW(TBD8)(96) o option-length:Lengthlength of encapsulatedoptionsoptions, expressed in octets. o encapsulated-options: options associated with this Softwire46 Lightweight 4over6 domain. Theencapsulated optionsencapsulated-options field conveys options specific to the OPTION_S46_CONT_LW option.CurrentlyCurrently, there are two optionsspecified,specified: OPTION_S46_V4V6BIND and OPTION_S46_BR. There MUST be at most one OPTION_S46_V4V6BIND option and at least one OPTION_S46_BR option. 6. Softwire46 OptionsFormattingEncapsulation Thebelowtable below shows whichsub-optionsencapsulated options are mandatory,optionaloptional, or not permitted for each defined container option. +-----------------------+-------+-------+--------------------+ | Option | MAP-E | MAP-T | Lightweight 4over6 | +-----------------------+-------+-------+--------------------+ | OPTION_S46_RULE | M | M |N/A | | | | |N/P | | OPTION_S46_BR | M |N/AN/P | M | || | | | |OPTION_S46_PORTPARAMS | O | O | O | || | | | |OPTION_S46_DMR |N/AN/P | M |N/A | | | | |N/P | | OPTION_S46_V4V6BIND |N/AN/P |N/AN/P | O | +-----------------------+-------+-------+--------------------+ M - Mandatory, O - Optional,N/AN/P - NotApplicablePermitted Table 1:Option toOptions for Container MappingsMAP-DHCPSoftwire46 DHCPv6 clients that receive container options that violate any of the above rules MUST silently ignore such container options. 7. DHCPv6 Server Behavior[RFC3315]Section 17.2.2 of [RFC3315] describes how a DHCPv6 client and server negotiate configuration values using the ORO. As a conveniencetofor the reader, we mention here that bydefault,default a server will not reply with a Softwire46Container Optioncontainer option if the client has not explicitly enumerated one in itsOption Request Option.ORO. A CE router may support several (or all) of the mechanisms mentioned here. In the case where a client requests multiple mechanisms in itsORO option,ORO, the server will reply with the corresponding Softwire46Containercontainer options for which it has configuration information. 8. DHCPv6 Client Behavior An S46 CE acting as a DHCPv6 client will request S46 configuration parameters from the DHCPv6 server located in the IPv6 network. Such a client MUST request the S46Containercontainer option(s) that it is configured for in its ORO in SOLICIT, REQUEST, RENEW,REBINDREBIND, and INFORMATION-REQUEST messages. When processing received S46 containeroptionsoptions, the followingbehaviourbehavior is expected: o A client MUST support processing multiple received OPTION_S46_RULE options in a container OPTION_S46_CONT_MAPE or OPTION_S46_CONT_MAPToptionoption. o A client receiving an unsupported S46option,option or an invalid parameter value SHOULD discard that S46Containercontainer option and log the event. The behavior of a clientsupportingthat supports multiple Softwire46mechanisms,mechanisms is out of scopeoffor this document.[I-D.ietf-softwire-unified-cpe][Unified-v4-in-v6] describes clientbehaviourbehavior for the prioritization and handling of multiple mechanisms simultaneously. Note that a system implementing CE functionality may have multiple network interfaces, and these interfaces may be configured differently; some may be connected to networks using a Softwire46 mechanism, and some may be connected to networks that are using normaldual stackdual-stack or other means. The CE should approach this specification on an interface-by-interface basis. For example, if the CE system is MAP-E capable and is attached to multiple networks that provide the OPTION_S46_CONT_MAPE option, then the CE MUST configure MAP-E for each interface separately. Failure modes are out of scope for this document. Failure recovery mechanisms may be defined in the future. See Section 5 of[I-D.ietf-softwire-map][RFC7597] for a discussiononof valid MAPruleRule combinations. See Section 11 of[RFC7227],[RFC7227] and Sections 18.1.3,18.1.418.1.4, and 19.1 of [RFC3315] forparameters updateparameter-update mechanisms in DHCPv6 that can be leveraged to update configuration after a failure. 9. Security Considerations Section 23 of [RFC3315] discusses DHCPv6-related security issues. As with all DHCPv6-derived configurationstate,states, it is possible that configuration is actually being delivered by a third party (ManIn Thein the Middle). As such, there is no basis on which access over MAP orlw4o6Lightweight 4over6 can be trusted. Therefore, softwires should not bypass any security mechanisms such as IP firewalls. In IPv6-only networks that lackanyIPv4 firewalls, a devicesupportingthat supports MAP could be tricked into enabling its IPv4 stack anddirectdirecting IPv4 traffic to the attacker, thus exposing itself to previously infeasible IPv4 attack vectors. Section1110 of[I-D.ietf-softwire-map][RFC7597] discusses security issues related to the MAP-E mechanism, Section 9 of [RFC7596] discusses security issues related to theMAPLightweight 4over6 mechanism, and Section 13 of [RFC7599] discusses security issues related to the MAP-T mechanism. Readers concerned with the security ofMAPSoftwire46 provisioning over DHCPv6 are encouraged to read[I-D.ietf-dhc-sedhcpv6].[Secure-DHCPv6]. 10. IANA Considerations IANAis kindly requested to allocatehas allocated the following DHCPv6 option codes:TBD189 for OPTION_S46_RULETBD290 for OPTION_S46_BRTBD391 for OPTION_S46_DMRTBD492 for OPTION_S46_V4V6BINDTBD593 for OPTION_S46_PORTPARAMSTBD694 for OPTION_S46_CONT_MAPETBD795 for OPTION_S46_CONT_MAPTTBD896 for OPTION_S46_CONT_LW All valuesshould behave been added to theDHCPv6"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)" option code space defined in Section 24.3 of [RFC3315]. 11.Acknowledgements This document was created as a product of a MAP design team. Following people were members of that team: Congxiao Bao, Mohamed Boucadair, Gang Chen, Maoke Chen, Wojciech Dec, Xiaohong Deng, Jouni Korhonen, Xing Li, Satoru Matsushima, Tomasz Mrugalski, Tetsuya Murakami, Jacni Qin, Necj Scoberne, Qiong Sun, Tina Tsou, Dan Wing, Leaf Yeh and Jan Zorz. The authors would like to thank Bernie Volz and Tom Taylor for their insightful comments and suggestions. 12.References12.1.11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ RFC2119, March1997.1997, <http://www.rfc-editor.org/info/rfc2119>. [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC3315, July 2003. 12.2. Informative References [I-D.ietf-dhc-sedhcpv6]3315, DOI 10.17487/RFC3315, July 2003, <http://www.rfc-editor.org/info/rfc3315>. 11.2. Informative References [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, DOI 10.17487/RFC2131, March 1997, <http://www.rfc-editor.org/info/rfc2131>. [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, December 1998, <http://www.rfc-editor.org/info/rfc2473>. [RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation Algorithm", RFC 6145, DOI 10.17487/RFC6145, April 2011, <http://www.rfc-editor.org/info/rfc6145>. [RFC6346] Bush, R., Ed., "The Address plus Port (A+P) Approach to the IPv4 Address Shortage", RFC 6346, DOI 10.17487/ RFC6346, August 2011, <http://www.rfc-editor.org/info/rfc6346>. [RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S.,Shen, S., Zhang, D.,andT. Jinmei, "SecureS. Krishnan, "Guidelines for Creating New DHCPv6with Public Key", draft-ietf-dhc-sedhcpv6-03 (work in progress), June 2014. [I-D.ietf-softwire-lw4over6]Options", BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014, <http://www.rfc-editor.org/info/rfc7227>. [RFC7596] Cui, Y.,Qiong,Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I. Farrer, "Lightweight 4over6: An Extension to theDS-Dual-Stack Lite Architecture",draft-ietf-softwire-lw4over6-03 (work in progress), November 2013. [I-D.ietf-softwire-map-t]RFC 7596, DOI 10.17487/RFC7596, July 2015, <http://www.rfc-editor.org/info/rfc7596>. [RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C.,Dec, W., Troan, O.,Matsushima, S., Murakami, T., and T.Murakami,Taylor, Ed., "Mapping of Address and Portusing Translation (MAP-T)", draft-ietf-softwire-map-t-04 (work in progress), September 2013. [I-D.ietf-softwire-map] Troan, O., Dec, W.,with Encapsulation (MAP-E)", RFC 7597, DOI 10.17487/ RFC7597, July 2015, <http://www.rfc-editor.org/info/rfc7597>. [RFC7599] Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S.,Murakami, T.,and T.Taylor,Murakami, "Mapping of Address and Portwith Encapsulation (MAP)", draft-ietf-softwire-map-08 (workusing Translation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July 2015, <http://www.rfc-editor.org/info/rfc7599>. [Secure-DHCPv6] Jiang, S., Ed., Shen, S., Zhang, D., and T. Jinmei, "Secure DHCPv6", Work inprogress), August 2013. [I-D.ietf-softwire-unified-cpe]Progress, draft-ietf-dhc-sedhcpv6-08, June 2015. [Unified-v4-in-v6] Boucadair, M., Farrer, I., Perreault, S., Ed., and S. Sivakumar, Ed., "Unified IPv4-in-IPv6 Softwire CPE",draft- ietf-softwire-unified-cpe-01 (workWork inprogress),Progress, draft-ietf-softwire-unified-cpe-01, May 2013.[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC 2473, December 1998. [RFC6145] Li, X.,Acknowledgements This document was created as a product of a MAP design team. The following people were members of that team: Congxiao Bao,C., and F. Baker, "IP/ICMP Translation Algorithm", RFC 6145, April 2011. [RFC7227] Hankins, D.,Mohamed Boucadair, Gang Chen, Maoke Chen, Wojciech Dec, Xiaohong Deng, Jouni Korhonen, Xing Li, Satoru Matsushima, Tomek Mrugalski,T., Siodelski, M., Jiang, S.,Tetsuya Murakami, Jacni Qin, Necj Scoberne, Qiong Sun, Tina Tsou, Dan Wing, Leaf Yeh, andS. Krishnan, "GuidelinesJan Zorz. The authors would like to thank Bernie Volz and Tom Taylor forCreating New DHCPv6 Options", BCP 187, RFC 7227, May 2014.their insightful comments and suggestions. Authors' AddressesTomaszTomek Mrugalski Internet Systems Consortium, Inc. 950 Charter Street Redwood City, CA 94063USAUnited States Phone: +1 650 423 1345 Email: tomasz.mrugalski@gmail.com URI: http://www.isc.org/ Ole Troan CiscoSystems, Inc.Systems Philip Pedersens vei 1 Lysaker 1366 Norway Email: ot@cisco.com Ian Farrer Deutsche Telekom AG CTO-ATI, Landgrabenweg 151 Bonn, NRW 53227 Germany Email: ian.farrer@telekom.de Simon PerreaultViagenie 246 AberdeenJive Communications Quebec, QCG1R 2E1CanadaPhone: +1 418 656 9254Email:simon.perreault@viagenie.casperreault@jive.com Wojciech Dec Cisco Systems, Inc. The Netherlands Email: wdec@cisco.com URI: http://cisco.com Congxiao Bao CERNET Center/Tsinghua University Room 225, Main Building, Tsinghua University Beijing 100084CNChina Phone: +86 10-62785983 Email: congxiao@cernet.edu.cn Leaf Y. YehCNNIC 4, South 4th Street, Zhong_Guan_Cun Beijing 100190 P. R.Freelancer Technologies China Email:leaf.yeh.sdo@gmail.comleaf.y.yeh@hotmail.com Xiaohong Deng6 Floor, C Block, DaCheng International Center Chaoyang District Beijing 100124 China Phone: +61 3858 3128The University of New South Wales Sydney NSW 2052 Australia Email: dxhbupt@gmail.com URI: https://www.unsw.edu.au/