Rebind Capability in DHCPv6 Reconfigure Messages
draft-ietf-dhc-dhcpv6-reconfigure-rebind-02.txt

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Abstract

This document updates RFC 3315 to allow the Rebind message type to appear in the Reconfigure Message option of a Reconfigure message, which allows DHCPv6 servers to instruct clients to perform a Rebind operation as well as a Renew operation.

1.  Introduction

DHCPv6 (Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, “Dynamic Host Configuration Protocol for IPv6 (DHCPv6),” July 2003.) [RFC3315] allows a server to send an unsolicited Reconfigure message to a client. The client's response to a Reconfigure message, according to [RFC3315] (Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, “Dynamic Host Configuration Protocol for IPv6 (DHCPv6),” July 2003.) is either a Renew or an Information-Request message, depending on the contents of the msg-type field in the Reconfigure Message option of the Reconfigure message.

In a network with multiple DHCPv6 servers, the Reconfigure message may not be sent by the same server as the one from which the client last obtained configuration and/or addressing information. If the Reconfigure message commands the client to perform a Renew, [RFC3315] (Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, “Dynamic Host Configuration Protocol for IPv6 (DHCPv6),” July 2003.) does not specify to which server the client should send the Renew. This difficulty is avoided if the server commands the client to perform an Information-Request, since such messages are multicast. However, Information-Request messages do not cause addressing configuration to be returned.

This document expands the allowed values of the msg-type field to allow the server to indicate that the client is to attempt to perform a Rebind; since Rebind messages are multicast, this avoids the necessity of the client contacting a particular server. Rebind messages also cause all configuration information, including addresses, to be returned from a server.

This document updates section 19 of RFC 3315.

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] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).

3.  The Reconfigure Message option of the DHCPv6 Reconfigure Message

A server includes a Reconfigure Message option in a Reconfigure message to indicate to the client whether the client responds with a Renew, an Information-request, or a Rebind message.

The format of this option is:

     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_RECONF_MSG        |         option-len            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    msg-type   |
    +-+-+-+-+-+-+-+-+

option-code

OPTION_RECONF_MSG (19).

option-len

1.

msg-type

5 for Renew message, 6 for Rebind, 11 for Information-request message.

4.  Security Considerations

This document adds no new security considerations beyond those present in [RFC3315] (Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, “Dynamic Host Configuration Protocol for IPv6 (DHCPv6),” July 2003.).

5.  IANA Considerations

There are no actions for IANA associated with this document.

6. Normative References

Authors' Addresses

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