--- 1/draft-ietf-dhc-host-gen-id-02.txt 2012-08-21 09:14:05.245341559 +0200 +++ 2/draft-ietf-dhc-host-gen-id-03.txt 2012-08-21 09:14:05.265342194 +0200 @@ -1,45 +1,46 @@ Network Working Group S. Jiang Internet-Draft F. Xia Intended status: Standards Track B. Sarikaya -Expires: November 24, 2012 Huawei Technologies - May 23, 2012 +Expires: February 22, 2013 Huawei Technologies + August 21, 2012 Prefix Assignment in DHCPv6 - draft-ietf-dhc-host-gen-id-02 + draft-ietf-dhc-host-gen-id-03 Abstract - This document introduce a procedure for configuring hosts' IPv6 - address which the prefix is assigned from a DHCPv6 server through - DHCPv6 protocol while the interface identifiers are independently - generated by the hosts. The method is applicable to - Cryptographically Generated Addresses (CGA), and other IPv6 addresses - with host-generated interface identifiers. + This document introduces a generic prefix announcement mechanism + using DHCPv6. In this new address configuration procedure, the + prefix is propagated from a DHCPv6 server to hosts through DHCPv6 + message exchanging while the interface identifiers are independently + generated by the hosts. It enables both integral address assignment + and self-generated addresses in one single mechanism, DHCPv6. It + also enables stateless address configuration without RA attendance. 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 November 24, 2012. + This Internet-Draft will expire on February 22, 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 publication of this document. Please review these documents @@ -49,81 +50,86 @@ the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Address Auto-configuration . . . . . . . . . . . . . . . . . . 4 4. DHCPv6 Operation . . . . . . . . . . . . . . . . . . . . . . . 5 5. DHCPv6 IA_PA Option . . . . . . . . . . . . . . . . . . . . . 6 - 5.1. Identity Association for Prefix Assignment Option . . . . 6 - 5.2. IA_PA Prefix Option . . . . . . . . . . . . . . . . . . . 7 + 5.1. Identity Association for Prefix Assignment Option . . . . 7 + 5.2. IA_PA Prefix Option . . . . . . . . . . . . . . . . . . . 8 6. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 8 - 7. IANA consideration . . . . . . . . . . . . . . . . . . . . . . 8 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 + 7. IANA consideration . . . . . . . . . . . . . . . . . . . . . . 9 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 10.1. Normative References . . . . . . . . . . . . . . . . . . . 9 - 10.2. Informative references . . . . . . . . . . . . . . . . . . 9 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 + 10.2. Informative references . . . . . . . . . . . . . . . . . . 10 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction A host IPv6 address is combined by a prefix and an interface identifier. Currently, there are two mechanisms to configure a host IPv6 address. [RFC3315] describes the operation of address assignment by a DHCPv6 server. The operation assumes that the server is responsible for the assignment of an integral address which - includes prefix and interface identifier parts as described in + includes both prefix and interface identifier parts as described in [RFC4291]. In the Stateless Address Autoconfiguration (SLACC, [RFC4862]) model, the interface Identifier is generated by the host itself while the prefix is configured through Router Advertisement message defined in [RFC4861]. - Up to now, there is no mechanism that allows host self-generated - addresses to be used in the DHCPv6-managed network. + However, in a DHCPv6-managed network, assigning 128-bit address is + insufficient. Some hosts may want to use self-generated address, + which are combined by prefixes obtained from network configuration + and interface identifiers generated by hosts. The examples include + CGA [RFC3972], modified EUI-64 interface identifier [EUI-64], + temporary addresses for privacy [RFC4941] and etc. - [RFC3633] defines Prefix Delegation options providing a mechanism for - automated delegation of IPv6 prefixes using the DHCPv6. This - mechanism is intended for delegating a long-lived prefix from a - delegating router to a requesting router. This mechanism "is not - bound to the assignment of IP addresses or other configuration - information to hosts" [RFC3633]. It delegates prefixes to a routable - device for itself use only. It does not support the host-genarated - interface identifiers model, in which prefix(es) need to be - advertised or assigned to hosts. + In these scenarios, the address configuration precedure has to be + splitted in two motheds: integral address assignment through DHCPv6 + and prefix announcement by RA advertisement. Some ISPs desire to + manage address configuration using one set of protocol, rather than + mixture of DHCPv6 and Neighbor Discovery. - This document introduces a new DHCPv6 procedure to configure hosts' - IPv6 addresses. In this new procedure, the prefix is advertised from - a DHCPv6 server through DHCPv6 protocol while the interface - identifiers are independently generated by the hosts. The usage of - DHCPv6 for assigning prefixes separats prefix assignment and - interface identifier generation. + There are also some network environments in that perfix annoucement + through RAs may not be the best choice. For example, hosts may + connect through tunnels, either layer 2 tunnels or layer 3 tunnels. - [RFC3972] describes a method for binding a public signature key to an - IPv6 address. The basic idea is to generate the interface identifier - (i.e., the rightmost 64 bits) of the IPv6 address by computing a - cryptographic hash of the public key. That is, the host decides its - interface identifier. As for the prefix part of the CGA, it is - probably got through Router Advertisement message defined in - [RFC4861], or through DHCPv6 operations defined in this document. + While a RA is only able to announce prefix on a single link, DHCPv6 + configuration can be used to manage multiple links by setup DHCPv6 + relay. - There are also other host-generated IPv6 addresses, which are - combined by prefixes obtained from network configuration and - ingerface identifiers generated by hosts, such as modified EUI-64 - interface identifier [EUI-64], temporary addresses for privacy - [RFC4941],etc. The DHCPv6 operations defined in this document also - supports such address methods. + Up to now, there is no mechanism for the prefix announcement/ + assignment in DHCPv6. [RFC3633] defines Prefix Delegation options + providing a mechanism for automated delegation of IPv6 prefixes using + the DHCPv6. This mechanism is intended for delegating a long-lived + prefix from a delegating router to a requesting router. This + mechanism "is not bound to the assignment of IP addresses or other + configuration information to hosts" [RFC3633]. It delegates prefixes + to a routable device for itself use only. It does not support the + host-generated interface identifiers model, in which prefix(es) need + to be advertised or assigned to hosts. - The DHCPv6 operations defined in this document also supports the - assigned prefix to be shared across multiple hosts. + This document introduces a generic prefix announcement mechanism + using DHCPv6. In this new address configuration procedure, the + prefix is propagated from a DHCPv6 server to hosts through DHCPv6 + message exchanging while the interface identifiers are independently + generated by the hosts. It is alternative of RA prefix assignment/ + announcement. It enables both integral address assignment and self- + generated addresses in one single mechanism, DHCPv6. Note, in many + scenarios, neighbor discovery is still needed for routing and + reachability. In other scenarios, this mechanism enables stateless + address configuration while RA absents. 2. Terminology 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 [RFC2119]. The terminology in this document is based on the definitions in [RFC3315], in addition to the ones specified in this section @@ -160,79 +166,95 @@ o An interface identifier. Modified EUI-64 interface identifier [EUI-64] is a widely-used host generated interface identifier. It generates interface identifier from the host MAC address. The interface identifier of [RFC3972] is generated by computing a cryptographic hash of a public key of a host. The host is responsible for interface identifier generation. In the ND-managed environment, RA is used to assign the prefix. So far, there is no mechanism to support the scenario that prefixes - are managed by a DHCPv6 server. The DHCPv6 operation defined in this - document enables the DHCPv6 server to assign a prefix, rather than a - integral address, to the host, so that the host can obtain an IPv6 - address by combining the prefix with its own generated interface - identifier. It actually enables the auto address configuration - through DHCPv6. - - This document targets to meet this gap. + are managed by a DHCPv6 server. This document targets to meet this + gap. The DHCPv6 operation defined in this document enables the + DHCPv6 server to assign a prefix, rather than a integral address, to + the host, so that the host can obtain an IPv6 address by combining + the prefix with its own generated interface identifier. It actually + enables the auto address configuration through DHCPv6. 4. DHCPv6 Operation Figure 1 shows the operation of separating prefix assignment and interface identifier generation in the DHCPv6. +------------+ +-------------+ |Host(Client)| |DHCPv6 Server| +------------+ +-------------+ - | 1 Solicit | + | 1 Solicit/Request | |---------------------> | - | 2 Advertise | + | 2 Advertise/Reply | + | with IA_PA Option | |<--------------------- | 3 Combination of Prefix | and Interface Identifier | | | Figure 1: DHCPv6 Operation 1. A host uses a Solicit message to discover DHCPv6 servers that have been configured to assign prefixes for the host. Identity Association for Prefix Delegation Option (IA_PD) is defined in [RFC3633] for prefix delegation between a requesting router and delegating router. Referring to the definition, a new Identity Association for Prefix Assignment (IA-PA) option is defined in Section 5.1 to enable the prefix assignment from a DHCPv6 server - to a host. + to a host. A host MAY include a Option Request Option requesting + IA_PA in a Solicit or a IA_PA Option in a Request message to + request prefix assignment explicitly. + 2. The DHCPv6 server assigns one or more prefixes to the host in - Advertise messages or in the Reply messages to the prefix - requests from the hosts. The assigned prefixes SHOULD be a + Advertise messages or in the Reply messages responding to the + prefix requests from the hosts. When the prefix assignment in + advertise model, even if a host does not request, DHCPv6 server + can push it initiatively. The assigned prefixes SHOULD be a subset of the authorized prefixes or derivative prefixes of the authorized prefixes. Identity Association for Prefix Assignment Option in Section 5.1 is used for conveying the assigned - prefixes. If there is not a proper prefix available, a status- - code is returned to the host and the procedure is terminated. - When receiving multiple prefixes, the host may use pre-configured - hints for prefix assignment preference. The hints are authorized - prefixes advertised by an authorized router through Certification - Path Advertisement defined in [RFC3971]. + prefixes. If there is not a proper prefix available, a + NoPrefixAvail (defined in [RFC3633])status-code is returned to + the host and the procedure is terminated. When receiving + multiple prefixes, the host may use pre-configured hints for + prefix assignment preference. The hints are authorized prefixes + advertised by an authorized router through Certification Path + Advertisement defined in [RFC3971]. 3. The host generates an interface identifier and formulates a combined IPv6 address by concatenating the assigned prefix and the self-generated interface identifier. There are many ways to generate interface identifier. [RFC3972] defines a method to generate the interface identifier by computing a cryptographic hash of a public key of the host. Modified EUI-64 interface identifier [EUI-64] is generated based on the host MAC address. After the host generates an IPv6 address using the above procedure, the host may send a Request message to the DHCPv6 server in order to confirm the usage of the new address. The confirmation procedure may - be completed together with the address registration procedure. - However, the confirmation procedure is out of scope. + be completed together with the address registration procedure + [I-D.ietf-dhc-addr-registration]. However, the confirmation + procedure is out of scope. + + When the host reaches T1 or T2 defined in Section 5.1, it SHOULD use + the same message exchanges, as described in section 18, "DHCP Client- + Initiated Configuration Exchange" of [RFC3315], to obtain or update + prefix(es) from a DHCPv6 server. + + A DHCPv6 server MAY initiatively send a reconfiguration message to + the host, as described in section 19, "DHCP Server-Initiated + Configuration Exchange" of [RFC3315], to cause prefix(es) information + update. 5. DHCPv6 IA_PA Option In this section, one new option is defined, Identity Association for Prefix Assignment Option . The format of this new DHCPv6 IA_PA Option has been deliberately designed to be the same with IA_PD option[RFC3633]. The IA_PD Prefix and IA Address sub-options from IA_PD option are also reused. However, the two options are different on the semantics and usage models. @@ -335,22 +358,23 @@ Security considerations in DHCPv6 are described in [RFC3315]. To guard against attacks through prefix assignment, a host and a DHCPv6 server SHOULD use DHCPv6 authentication as described in Section 21, "Authentication of DHCP messages" of [RFC3315] or Secure DHCPv6 [I-D.ietf-dhc-secure-dhcpv6] . 9. Acknowledgements - The authors would like to thanks Suresh Krishnan, Ted Lemon and other - members of DHC WG for their valuable comments. + The authors would like to thanks Suresh Krishnan, Ted Lemon, Bing + Liu, Andre Kostur, Gaurav Halwasia, Bernie Volz and other members of + DHC WG for their valuable comments. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for @@ -387,20 +411,26 @@ RFC 3314, September 2002. [RFC4968] Madanapalli, S., "Analysis of IPv6 Link Models for 802.16 Based Networks", RFC 4968, August 2007. [I-D.ietf-dhc-secure-dhcpv6] Jiang, S. and S. Shen, "Secure DHCPv6 Using CGAs", draft-ietf-dhc-secure-dhcpv6-06 (work in progress), March 2012. + [I-D.ietf-dhc-addr-registration] + Jiang, S. and G. Chen, "A Generic IPv6 Addresses + Registration Solution Using DHCPv6", + draft-ietf-dhc-addr-registration-00 (work in progress), + May 2012. + [EUI-64] "Guidelines for 64-bit Global Identifier (EUI-64) Registration Authority", http://standards.ieee.org/ regauth/oui/tutorials/EUI64.html", March 1997. Authors' Addresses Sheng Jiang Huawei Technologies Q14, Huawei Campus, No.156, BeiQing Road Hai-Dian District, Beijing 100095