PCP Working Group M. Boucadair
Internet-Draft France Telecom
Intended status: Standards Track R. Penno
Expires: October 03, 2014 D. Wing
Cisco
April 01, 2014

DHCP Options for the Port Control Protocol (PCP)
draft-ietf-pcp-dhcp-11

Abstract

This document specifies DHCP (IPv4 and IPv6) options to configure hosts with Port Control Protocol (PCP) server IP addresses. The use of DHCPv4 or DHCPv6 depends on the PCP deployment scenarios. The set of deployment scenarios to which use of DHCPv4 or DHCPv6 apply are outside the scope of this document.

Requirements Language

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].

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 October 03, 2014.

Copyright Notice

Copyright (c) 2014 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

This document defines DHCPv4 [RFC2131] and DHCPv6 [RFC3315] options that can be used to provision PCP server [RFC6887] IP addresses.

This specification assumes a PCP server is reachable with one or multiple IP addresses. As such, a list of IP addresses can be returned in the DHCP PCP server option.

This specification allows returning one or multiple lists of PCP server IP addresses. This is used as a hint to guide the PCP client when determining whether to send PCP requests to one or multiple PCP servers. For guidelines on how a PCP client can use multiple IP addresses and multiple PCP servers, see [I-D.ietf-pcp-server-selection].

The use of DHCPv4 or DHCPv6 depends on the PCP deployment scenarios. The set of deployment scenarios to which use of DHCPv4 or DHCPv6 apply are out of scope.

2. Terminology

This document makes use of the following terms:

3. DHCPv6 PCP Server Option

3.1. Format

The DHCPv6 PCP server option can be used to configure a list of IPv6 addresses of a PCP server.

The format of this option is shown in Figure 1.

    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_V6_PCP_SERVER      |         Option-length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                         ipv6-address                          |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                         ipv6-address                          |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ...                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: DHCPv6 PCP server option

3.2. DHCPv6 Client Behavior

To discover one or more PCP servers, the DHCPv6 client requests PCP server IP addresses by including OPTION_V6_PCP_SERVER in an Option Request Option (ORO), as described in Section 22.7 of [RFC3315].

The DHCPv6 client MUST be prepared to receive multiple instances of OPTION_V6_PCP_SERVER; each instance is to be treated as a separate PCP server.

If an IPv4-mapped IPv6 address is received in OPTION_V6_PCP_SERVER, it indicates that the PCP server has the corresponding IPv4 address.

4. DHCPv4 PCP Option

4.1. Format

The DHCPv4 PCP server option can be used to configure a list of IPv4 addresses of a PCP server. The format of this option is illustrated in Figure 2.

    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Code         |     Length    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | List-Length   |   List of     |
   +-+-+-+-+-+-+-+-+  PCP server   |
   /              IPv4 Addresses   /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   ---
   | List-Length   |   List of     |    |
   +-+-+-+-+-+-+-+-+  PCP server   |    |
   /              IPv4 Addresses   /    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |
   .             ...               . optional
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |
   | List-Length   |   List of     |    |
   +-+-+-+-+-+-+-+-+  PCP server   |    |
   /              IPv4 Addresses   /    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   ---

Figure 2: DHCPv4 PCP server option

   0     8     16    24    32    40    48
   +-----+-----+-----+-----+-----+-----+--
   |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 | ...
   +-----+-----+-----+-----+-----+-----+--
        IPv4 Address 1          IPv4 Address 2 ...

The description of the fields is as follows:

  • Code: OPTION_V4_PCP_SERVER (TBA, see Section 9.2);
  • Length: Length of all included data in octets. The minimum length is 5.
  • List-Length: Length of the "List of PCP server IPv4 Addresses" field in octets; MUST be a multiple of 4.
  • List of PCP server IPv4 Addresses: Contains one or more IPv4 addresses of the PCP server to be used by the PCP client. The format of this field is shown in Figure 3.
  • OPTION_V4_PCP_SERVER can include multiple lists of PCP server IPv4 addresses; each list is treated as a separate PCP server. When several lists of PCP server IPv4 addresses are to be included, "List-Length" and "PCP server IPv4 Addresses" fields are repeated.

This format assumes that an IPv4 address is encoded as a1.a2.a3.a4.

Figure 3: Format of the List of PCP server IPv4 Addresses

[RFC3396] MUST be used if OPTION_V4_PCP_SERVER exceeds the maximum DHCPv4 option size of 255 octets.

4.2. DHCPv4 Client Behavior

To discover one or more PCP servers, the DHCPv4 client requests PCP server IP addresses by including OPTION_V4_PCP_SERVER in a Parameter Request List Option [RFC2132].

The DHCPv4 client MUST be prepared to receive multiple lists of PCP server IPv4 addresses in the same DHCPv4 PCP server option; each list is to be treated as a separate PCP server.

5. DHCP Server Configuration Guidelines

DHCP servers supporting the DHCP PCP server option can be configured with a list of IP addresses of the PCP server(s). If multiple IP addresses are configured, the DHCP server MUST be explicitly configured whether all or some of these addresses refer to:

  1. the same PCP server: the DHCP server returns multiple addresses in the same instance of the DHCP PCP server option.
  2. distinct PCP servers: the DHCP server returns multiple lists of PCP server IP addresses to the requesting DHCP client (encoded as multiple OPTION_V6_PCP_SERVER or in the same OPTION_V4_PCP_SERVER); each list is referring to a distinct PCP server. For example, multiple PCP servers may be configured to a PCP client in some deployment contexts such as multi-homing. It is out of scope of this document to enumerate all deployment scenarios that require multiple PCP servers to be returned.

Precisely how DHCP servers are configured to separate lists of IP addresses according to which PCP server they address is out of scope for this document. However, DHCP servers MUST NOT treat IP addresses returned from a single Fully Qualified Domain Name (FQDN) lookup as belonging to more than one PCP server.

DHCPv6 servers that implement this option and that can populate the option by resolving FQDNs will need a mechanism for indicating whether to query for A records or only AAAA records. When a query returns A records, the IP addresses in those records are returned in the DHCPv6 response as IPv4-mapped IPv6 addresses.

  • Discussion: The motivation for this design is to accommodate deployment cases where an IPv4 connectivity service is provided while only DHCPv6 is in use (e.g., an IPv4-only PCP server in a DS-Lite context [RFC6333]).

Since this option requires support for IPv4-mapped IPv6 addresses, a DHCPv6 server implementation will not be complete if it does not query for A records and represent any that are returned as IPv4-mapped IPv6 addresses in DHCPv6 responses. This behavior is neither required nor suggested for DHCPv6 options in general: it is specific to OPTION_V6_PCP_SERVER. The mechanism whereby DHCPv6 implementations provide this functionality is beyond the scope of this document.

For guidelines on providing context-specific configuration information (e.g., returning a regional-based configuration), and information on how a DHCP server might be configured with FQDNs that get resolved on demand, see [I-D.ietf-dhc-topo-conf].

6. Dual-Stack Hosts

A Dual-Stack host might receive PCP server option via both DHCPv4 and DHCPv6. For guidance on how a DHCP client can handle PCP server IP lists for the same network but obtained via different mechanisms, see [I-D.ietf-pcp-server-selection].

7. Hosts with Multiple Interfaces

A host may have multiple network interfaces (e.g, 3G, IEEE 802.11, etc.); each configured differently. Each PCP server learned MUST be associated with the interface via which it was learned. Refer to [I-D.ietf-pcp-server-selection] and Section 8.4 of [RFC6887] for more discussion on multi-interface considerations.

8. Security Considerations

The security considerations in [RFC2131] and [RFC3315] are to be considered. PCP-related security considerations are discussed in [RFC6887].

9. IANA Considerations

9.1. DHCPv6 Option

IANA is requested to assign the following new DHCPv6 Option Code in the registry maintained in http://www.iana.org/assignments/dhcpv6-parameters:

Option Name Value
OPTION_V6_PCP_SERVER TBA

9.2. DHCPv4 Option

IANA is requested to assign the following new DHCPv4 Option Code in the registry maintained in http://www.iana.org/assignments/bootp-dhcp-parameters/:

Option Name Value Data length Meaning
OPTION_V4_PCP_SERVER TBA Variable; the minimum length is 5. Includes one or multiple lists of PCP server IP addresses; each list is treated as a separate PCP server.

10. Acknowledgements

Many thanks to C. Jacquenet, R. Maglione, D. Thaler, T. Mrugalski, T. Reddy, S. Cheshire, M. Wasserman, and C. Holmberg for their review and comments.

Special thanks to T. Lemon and B. Volz for the review and their effort to enhance this specification.

11. References

11.1. 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 IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997.
[RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R. and P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, April 2013.
[RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002.

11.2. Informative References

[I-D.ietf-dhc-topo-conf] Lemon, T. and T. Mrugalski, "Customizing DHCP Configuration on the Basis of Network Topology", Internet-Draft draft-ietf-dhc-topo-conf-01, February 2014.
[I-D.ietf-pcp-server-selection] Boucadair, M., Penno, R., Wing, D., Patil, P. and T. Reddy, "PCP Server Selection", Internet-Draft draft-ietf-pcp-server-selection-02, January 2014.
[RFC6333] Durand, A., Droms, R., Woodyatt, J. and Y. Lee, "Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion", RFC 6333, August 2011.

Authors' Addresses

Mohamed Boucadair France Telecom Rennes, 35000 France EMail: mohamed.boucadair@orange.com
Reinaldo Penno Cisco USA EMail: repenno@cisco.com
Dan Wing Cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134 USA EMail: dwing@cisco.com