Network Working Group S. Krishnan Internet-Draft Ericsson Intended status: Standards Track August 23, 2007 Expires: February 24, 2008 Neighbor Discovery Information over DHCP draft-krishnan-dhc-ndc-option-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on February 24, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Krishnan Expires February 24, 2008 [Page 1] Internet-Draft Neighbor Discovery Information over DHCP August 2007 Abstract Neighbor discovery options, in addition to being used for Neighbor Discovery, are used to convey some forms of network configuration information to the hosts attached to a network. Some centrally managed networks, that do not wish to configure their routers to advertise these pieces of information, might use a DHCP server to configure there parameters. This document defines a generic DHCP option for carrying these parameters. Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Neighbor Discovery Container(NDC) Option . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. Normative References . . . . . . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 13 Krishnan Expires February 24, 2008 [Page 2] Internet-Draft Neighbor Discovery Information over DHCP August 2007 1. Requirements notation 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]. Krishnan Expires February 24, 2008 [Page 3] Internet-Draft Neighbor Discovery Information over DHCP August 2007 2. Introduction Router Advertisements (RAs) as defined in [RFC2461] are used to deliver configuration information that is common to several nodes in the same network. The router advertisements are usually multicasted to all nodes in a given network in order to be scalable. The configuration information is contained in Neigbor Discovery (ND) options. DHCP [RFC3315] is used for delivering addressing information and other related configuration information to single clients when they request it. Since there are two mechanisms for delivering configuration information to a given node, configuration parameters need to be defined under two varying option formats. This leads to duplication of work needed to standardize these options and additional implementation complexity on hosts in order to process these option variants. In order to prevent this duplication, this document proposes a DHCP option that can be used to directly carry any neighbor discovery option. Krishnan Expires February 24, 2008 [Page 4] Internet-Draft Neighbor Discovery Information over DHCP August 2007 3. Applicability It is possible to carry any neighbor discovery option using the NDC option. This does not always make sense since there are neigbor discovery options that are not related to configuration. The NDC option SHOULD NOT be used to carry neighbor discovery options that are not related to configuration. e.g. Source Link-layer Address, Target Link-layer Address etc. Krishnan Expires February 24, 2008 [Page 5] Internet-Draft Neighbor Discovery Information over DHCP August 2007 4. Operation After a DHCP client receives a message that contains a NDC option it needs to verify if the NDC option length is at least 8 octets. If it is not, the client MUST NOT process the NDC option any further and SHOULD log an error message locally. Otherwise it needs to process the embedded Neighbor Discovery options one at a time as it would if it had received them through a Router Advertisement. It is entirely possible that the code for processing these options is shared between the RA based delivery and DHCP based delivery of these options. Krishnan Expires February 24, 2008 [Page 6] Internet-Draft Neighbor Discovery Information over DHCP August 2007 5. Neighbor Discovery Container(NDC) Option The DHCP NDC option is used to carry complete neighbor discovery options. There can be more than one neighbor discovery option that is contained in a NDC. The number of contained options is not explicitly mentioned in the NDC. The receiving node needs to process all the contained options 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_NDC | Option Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPT1_Type | OPT1_Length | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | OPT1_Data | . . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTn_Type | OPTn_Length | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | OPTn_Data | . . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ OPTION_NDC DHCP Option code allocated for the NDC option. To be allocated by IANA out of the dhcpv6 parameters for option codes. Option Length Length of the NDC option in octets not including the Option Code and the Option Length fields. i.e. Combined length of the included neighbor discovery options. OPT1_Type The neighbor discovery option type of the first included option. OPT1_Length Krishnan Expires February 24, 2008 [Page 7] Internet-Draft Neighbor Discovery Information over DHCP August 2007 The length of the first included option (including the OPT1_Type and OPT1_Length fields) in units of 8 octets. The value 0 is invalid. OPT1_Data The data field of the first included neighbor discovery option. The contents of this field are determined by the type of the option. OPTn_Type The neighbor discovery option type of the nth included option. OPTn_Length The length of the nth included option (including the OPT1_Type and OPT1_Length fields) in units of 8 octets. The value 0 is invalid. OPTn_Data The data field of the nth included neighbor discovery option. The contents of this field are determined by the type of the option. Figure 1: NDC layout Krishnan Expires February 24, 2008 [Page 8] Internet-Draft Neighbor Discovery Information over DHCP August 2007 6. IANA Considerations This document defines a new DHCPv6 option code for carrying neighbor discovery options. IANA is requested to assign the following new DHCPv6 Option Code in the registry maintained at http://www.iana.org/assignments/dhcpv6-parameters: OPTION_NDC Krishnan Expires February 24, 2008 [Page 9] Internet-Draft Neighbor Discovery Information over DHCP August 2007 7. Security Considerations The mechanism described in this document provides a method by which one or more neighbor discovery options can be carried using DHCP messages. The DHCP messages containing the NDC option may be intercepted, modified or replayed in order to communicate false configuration data to the client hosts. In order to prevent these kinds of attacks, it is recommended that authenticated DHCP [RFC3118] be used. Krishnan Expires February 24, 2008 [Page 10] Internet-Draft Neighbor Discovery Information over DHCP August 2007 8. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [RFC3118] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages", RFC 3118, June 2001. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. Krishnan Expires February 24, 2008 [Page 11] Internet-Draft Neighbor Discovery Information over DHCP August 2007 Author's Address Suresh Krishnan Ericsson 8400 Decarie Blvd. Town of Mount Royal, QC Canada Phone: +1 514 345 7900 x42871 Email: suresh.krishnan@ericsson.com Krishnan Expires February 24, 2008 [Page 12] Internet-Draft Neighbor Discovery Information over DHCP August 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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