Network Working Group F. Templin Internet-Draft Boeing Research & Technology Intended status: Standards Track December 4, 2009 Expires: June 7, 2010 Dynamic Host Configuration Protocol (DHCPv4) Option for the Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) draft-templin-isatap-dhcp-04.txt Abstract This document specifies a Dynamic Host Configuration Protocol (DHCPv4) option for nodes that implement the Intra-Site Automatic Tunnel Addressing Protocol (ISATAP). Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 June 7, 2010. Copyright Notice Copyright (c) 2009 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 Templin Expires June 7, 2010 [Page 1]
Internet-Draft ISATAP DHCP Option December 2009 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 BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology and Requirements . . . . . . . . . . . . . . . . . 3 3. ISATAP DHCPv4 Option . . . . . . . . . . . . . . . . . . . . . 3 4. Anycast Services . . . . . . . . . . . . . . . . . . . . . . . 4 5. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 10.1. Normative References . . . . . . . . . . . . . . . . . . . 5 10.2. Informative References . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Templin Expires June 7, 2010 [Page 2]
Internet-Draft ISATAP DHCP Option December 2009 1. Introduction This document specifies a Dynamic Host Configuration Protocol option [RFC2131][RFC2132] for nodes that implement the Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) [RFC5214]. The option encodes configuration information used by clients to initialize the Potential Router List as specified in [RFC5214], section 8.3.2. The option format is similar to that specified in [RFC3361], and includes a list of IPv4 addresses and domain names that form the Potential Router List. 2. Terminology and Requirements The terminology of ISATAP [RFC5214] applies to this document. The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in [RFC2119]. 3. ISATAP DHCPv4 Option The ISATAP DHCPv4 option encodes a list of IPv4 addresses followed by a list of DNS [RFC1035] fully-qualified domain names (FQDNs). The ISATAP DHCPv4 option encodes a sequence of octets using the following format: Code Len M <- IPv4 addr's -> <- FQDN's -> +----+----+----+----+----+----+----+----+----+----+----+ | TBD| Len| M | a1 | a2 | ...| aM | f1 | f2 | ...| fN | +----+----+----+----+----+----+----+----+----+----+----+ Figure 1: ISATAP DHCPv4 Option Format As shown in Figure 1, the DHCPv4 option code is followed immediately by a 'Len' octet that indicates the total number of option octets that follow. The 'Len' octet is followed by an 'M' octet that indicates the total number of IPv4 addresses that follow, and the 'M' octet is then followed by a list of 'M' 4-octet IPv4 addresses. The final IPv4 address is followed by a list of 'N' DNS FQDN's encoded exactly as specified in Section 3.1 of [RFC1035], where 'N' is implicitly derived by parsing the remaining portion of the option beyond the final IPv4 address. For example, if the administrator wishes to advertise the IPv4 addresses '192.0.2.3' and '192.0.2.3', and the FQDNs "isatap.com", "isatap.org" and "isatap.net", the DHCPv4 option is encoded as shown Templin Expires June 7, 2010 [Page 3]
Internet-Draft ISATAP DHCP Option December 2009 in Figure 2 (with numeric values represented as decimal): +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |TBD| 45| 2 |192| 00| 02| 02|192| 00| 02| 03| 6 |'i'|'s'|'a'| +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |'t'|'a'|'p'| 3 |'c'|'o'|'m'| 0 | 6 |'i'|'s'|'a'|'t'|'a'|'p'| +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | 3 |'o'|'r'|'g'| 0 | 6 |'i'|'s'|'a'|'t'|'a'|'p'| 3 |'n'|'e'| +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |'t'| 0 | +---+---+ Figure 2: ISATAP DHCPv4 Option Example ISATAP clients use the information encoded in the ISATAP DHCPv4 option to initialize the Potential Router List as specified in Section 8.3.2 of [RFC5214]. The ISATAP client itself (i.e., and not the DHCP server) resolves each FQDN into a list of IPv4 addresses, since the name resolution service available to the ISATAP client may in some cases be more responsive to dynamic updates than the name resolution service available to the DHCP server. If the length of the ISATAP DHCPv4 Option exceeds 254 octets, the option is encoded as for DHCP long options as specified in [RFC3396]. 4. Anycast Services Any of the IPv4 addresses that appear in the Potential Router List may be anycast addresses, i.e., they may be configured on the ISATAP interfaces of more than one router. In that case, each ISATAP router that configures the same anycast address must provide equivalent packet forwarding and IPv6 Neighbor Discovery services. ISATAP clients use the minimum path MTU for all routers that configure the same anycast address as the MTU for the tunnel neighbor. 5. Backward Compatibility The ISATAP DHCP option can be used in the presence of legacy ISATAP clients which typically construct a FQDN for the Potential Router List by concatenating the string "isatap" with a connection-specific DNS suffix "example.com" received from the DHCP server, e.g., as "isatap.example.com". Administrators should therefore ensure that the Potential Router Lists discovered by clients that implement the ISATAP DHCP option are consistent with the Potential Router Lists Templin Expires June 7, 2010 [Page 4]
Internet-Draft ISATAP DHCP Option December 2009 discovered by legacy clients. 6. IANA Considerations A new DHCPv4 option number for ISATAP is requested. 7. Related Work 'draft-ietf-softwire-ipv6-6rd' presents a similar DHCP option that advertises a 6RD prefix and an IPv4 anycast address. 8. Security Considerations The security considerations in [RFC2131] apply. 9. Acknowledgments The following individuals are acknowledged for their contributions: Jim Bound, Ralph Droms, Ted Lemon, Mohan Parthasarathy, Pekka Savola. 10. References 10.1. Normative References [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002. [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, March 2008. Templin Expires June 7, 2010 [Page 5]
Internet-Draft ISATAP DHCP Option December 2009 10.2. Informative References [RFC3361] Schulzrinne, H., "Dynamic Host Configuration Protocol (DHCP-for-IPv4) Option for Session Initiation Protocol (SIP) Servers", RFC 3361, August 2002. Author's Address Fred L. Templin Boeing Research & Technology P.O. Box 3707 Seattle, WA 98124 USA Email: fltemplin@acm.org Templin Expires June 7, 2010 [Page 6]