2.3.2 Dynamic Host Configuration (dhc)

In addition to this official charter maintained by the IETF Secretariat, there is additional information about this working group on the Web at:

       http://www.dhcp.org -- Additional DHC Page
NOTE: This charter is a snapshot of the 56th IETF Meeting in San Francisco, California USA. It may now be out-of-date.

Last Modified: 2003-02-21

Ralph Droms <rdroms@cisco.com>
Internet Area Director(s):
Thomas Narten <narten@us.ibm.com>
Erik Nordmark <erik.nordmark@sun.com>
Internet Area Advisor:
Thomas Narten <narten@us.ibm.com>
Mailing Lists:
General Discussion: dhcwg@ietf.org
To Subscribe: http://www1.ietf.org/mailman/listinfo/dhcwg
Archive: http://www1.ietf.org/mailman/listinfo/dhcwg
Description of Working Group:
Other Lists:

The dhc working group (DHC WG) has developed DHCP for automated allocation, configuration and management of IP addresses and TCP/IP protocol stack parameters. DHCP is currently a "Draft Standard". The base protocol is documented in RFC2131 and RFC2132 (DHCP for IPv4) and RFCxxxx (DHCP for IPv6). Additional options are documented in subsequent RFCs.

The DHC WG is responsible for reviewing (and sometimes developing) DHCP options or other extensions (for both IPv4 and IPv6). The DHC WG is expected to review all proposed extensions to DHCP to ensure that they are consistent with the DHCP specification and other option formats, that they do not duplicate existing mechanisms, etc. The DHC WG will not (generally) be responsible for evaluating the semantic content of proposed options. The DHC WG will not adopt new proposals for extensions to DHCP as working group documents without first coordinating with other relevant working groups and determining who has the responsibility for reviewing the semantic content of an option.

The DHC WG has the following main objectives:

The DHC WG will address security in DHCP

o Develop and document security requirements for DHCP. RFC 3118 defines current security mechanisms for DHCPv4. Unfortunately, RFC 3118 has neither been implemented nor deployed to date. Specific issues to be considered include:

- Improved key management and scalability

- Security for messages passed between relay agents and servers

- Threats of DoS attacks through FORCERENEW

- The increased usage of DHC on unsecured (e.g., wireless) and public LANs

- The need for clients to be able to authenticate servers, without simultaneously requiring client authentication by the server.

o Develop and document a roadmap of any new documents or protocols needed to meet the security requirements for DHCP

Write an analysis of the DHCP specification, including RFC2131, RFC2132 and other RFCs defining additional options, which identifies ambiguities, contradictory specifications and other obstacles to development of interoperable implementations. Recommend a process for resolving identified problems and incorporating the resolutions into the DHCP specification.

Complete or abandon work on DHCPv6 options that are currently work in progress:

o IPv6 Prefix Options for DHCPv6 (draft-troan-dhcpv6-opt-prefix-delegation-02.txt)

o DNS Configuration options for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-dnsconfig-01.txt)

o Load Balancing for DHCPv6 (draft-ietf-dhc-dhcpv6-loadb-02.txt)

o NIS Configuration Options for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-nisconfig-01.txt)

o Time Configuration Options for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-timeconfig-01.txt)

o Client Preferred Prefix option for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-cliprefprefix-00.txt)

o A Guide to Implementing Stateless DHCPv6 Service (draft-droms-dhcpv6-stateless-guide-00.txt)

o DSTM Options for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-dstm-01.txt)

o DSTM Ports Option for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-dstm-ports-01.txt)

Complete or abandon work on DHCP extensions and options that are currently work in progress:

o Failover protocol (draft-ietf-dhc-failover-11.txt)

o The DHCP Client FQDN Option (draft-ietf-dhc-fqdn-option-04.txt) o Resolution of DNS Name Conflicts Among DHCP Clients (draft-ietf-dhc-ddns-resolution-04.txt)

o DHCP Server MIB (draft-ietf-dhc-server-mib-07.txt)

o Considerations for the use of the Host Name option (draft-ietf-dhc-host-option-considerations-01.txt)

o DHCP Lease Query (draft-ietf-dhc-leasequery-04.txt)

o DHCP Options for Internet Storage Name Service (draft-ietf-dhc-isnsoption-03.txt)

o Dynamic Host Configuration Protocol (DHCP) Server MIB (draft-ietf-dhc-server-mib-07.txt)

o DHCP Option for Mobile IP Mobility Agents (draft-ietf-dhc-mipadvert-opt-00.txt)

o DHCP VPN Information Option (draft-ietf-dhc-vpn-option-02.txt)

o KDC Server Address Sub-option (draft-ietf-dhc-suboptions-kdc-serveraddress-00.txt)

o The Authentication Suboption for the DHCP Relay Agent Option (draft-ietf-dhc-auth-suboption-00.txt)

o Link Selection sub-option for the Relay Agent Information Option (draft-ietf-dhc-agent-subnet-selection-03.txt)

o VPN Identifier sub-option for the Relay Agent Information Option (draft-ietf-dhc-agent-vpn-id-02.txt)

o RADIUS Attributes Sub-option for the DHCP Relay Agent Information Option (draft-ietf-dhc-agentopt-radius-02.txt)

o DHCP Subscriber ID Suboption for the DHCP Relay Agent Option (draft-ietf-dhc-subscriber-id-00.txt)

Goals and Milestones:
Done  WG Last Call on DHCP Options for Internet Storage Name Service (draft-ietf-dhc-isnsoption-03.txt)
Done  WG Last Call on Load Balancing for DHCPv6 (draft-ietf-dhc-dhcpv6-loadb-02.txt)
Done  WG Last Call on Time Configuration Options for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-timeconfig-01.txt)
Done  WG Last Call on IPv6 Prefix Options for DHCPv6 (draft-troan-dhcpv6-opt-prefix-delegation-02.txt)
Done  WG Last Call on DNS Configuration options for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-dnsconfig-01.txt)
Done  WG Last Call on NIS Configuration Options for DHCPv6 (draft-ietf-dhc-dhcpv6-opt-nisconfig-01.txt)
Done  Resubmit draft-ietf-dhc-dhcpv6-28.txt to IESG
Done  Identify DHCPv4 authentication design team
Done  Identify DHCPv4 specification review design team
Done  Identify DHCPv4 relay agent message authentication design team
FEB 03  Submit DHCP Options for Internet Storage Name Service to IESG (draft-ietf-dhc-isnsoption-03.txt)
FEB 03  Submit DNS Configuration options for DHCPv6 to IESG (draft-ietf-dhc-dhcpv6-opt-dnsconfig-01.txt)
FEB 03  Submit NIS Configuration Options for DHCPv6 to IESG (draft-ietf-dhc-dhcpv6-opt-nisconfig-01.txt)
FEB 03  Submit Time Configuration Options for DHCPv6 to IESG (draft-ietf-dhc-dhcpv6-opt-timeconfig-01.txt)
MAR 03  Submit IPv6 Prefix Options for DHCPv6 to IESG (draft-troan-dhcpv6-opt-prefix-delegation-02.txt)
MAR 03  Submit Load Balancing for DHCPv6 to IESG (draft-ietf-dhc-dhcpv6-loadb-02.txt)
APR 03  Update milestones to include all WG documents
JUN 03  DHCPv4 authentication design team report completed
JUN 03  DHCPv4 specification review report completed
JUN 03  Select DHCPv4 relay agent message authentication mechanism
  • - draft-ietf-dhc-dhcpv6-28.txt
  • - draft-ietf-dhc-failover-12.txt
  • - draft-ietf-dhc-server-mib-08.txt
  • - draft-ietf-dhc-packetcable-06.txt
  • - draft-ietf-dhc-fqdn-option-05.txt
  • - draft-ietf-dhc-ddns-resolution-05.txt
  • - draft-ietf-dhc-leasequery-04.txt
  • - draft-ietf-dhc-agent-subnet-selection-04.txt
  • - draft-ietf-dhc-agent-vpn-id-02.txt
  • - draft-ietf-dhc-vpn-option-02.txt
  • - draft-ietf-dhc-dhcpv6-opt-dstm-01.txt
  • - draft-ietf-dhc-dhcpv6-opt-dnsconfig-03.txt
  • - draft-ietf-dhc-agentopt-radius-02.txt
  • - draft-ietf-dhc-dhcpv6-loadb-02.txt
  • - draft-ietf-dhc-dhcpv6-opt-dstm-ports-01.txt
  • - draft-ietf-dhc-dhcpv6-opt-nisconfig-02.txt
  • - draft-ietf-dhc-dhcpv6-opt-timeconfig-02.txt
  • - draft-ietf-dhc-host-option-considerations-02.txt
  • - draft-ietf-dhc-isnsoption-05.txt
  • - draft-ietf-dhc-dhcpv6-opt-cliprefprefix-00.txt
  • - draft-ietf-dhc-auth-suboption-01.txt
  • - draft-ietf-dhc-suboptions-kdc-serveraddress-03.txt
  • - draft-ietf-dhc-dhcpv6-opt-prefix-delegation-03.txt
  • - draft-ietf-dhc-mipadvert-opt-00.txt
  • - draft-ietf-dhc-subscriber-id-00.txt
  • - draft-ietf-dhc-pktc-kerb-tckt-01.txt
  • - draft-ietf-dhc-server-override-00.txt
  • - draft-ietf-dhc-unused-optioncodes-00.txt
  • - draft-ietf-dhc-dhcpv6-interop-00.txt
  • - draft-ietf-dhc-subnet-alloc-00.txt
  • - draft-ietf-dhc-implementation-00.txt
  • Request For Comments:
    RFC1531 PS Dynamic Host Configuration Protocol
    RFC1532 PS Clarifications and Extensions for the Bootstrap Protocol
    RFC1534 DS Interoperation Between DHCP and BOOTP
    RFC1533 PS DHCP Options and BOOTP Vendor Extensions
    RFC1542 DS Clarifications and Extensions for the Bootstrap Protocol
    RFC1541 PS Dynamic Host Configuration Protocol
    RFC2131 DS Dynamic Host Configuration Protocol
    RFC2132 DS DHCP Options and BOOTP Vendor Extensions
    RFC2241 PS DHCP Options for Novell Directory Services
    RFC2242 PS Netware/IP Domain Name and Information
    RFC2485 PS DHCP Option for The Open Group's User Authentication Protocol
    RFC2489BCPProcedure for Defining New DHCP Options
    RFC2563 PS DHCP Option to Disable Stateless Auto-Configuration in IPv4 Clients
    RFC2610 PS DHCP Options for Service Location Protocol
    RFC2939BCPProcedure for Defining New DHCP Options and Message Types
    RFC2937 PS The Name Service Search Option for DHCP
    RFC3004 PS The User Class Option for DHCP
    RFC3011 PS The Subnet Selection Option for DHCP
    RFC3046 PS DHCP Relay Agent Information Option
    RFC3074 PS DHC load balancing algorithm
    RFC3118 PS Authentication for DHCP Messages
    RFC3203 PS DHCP reconfigure extension
    RFC3256 PS The DOCSIS Device Class DHCP Relay Agent Information Sub-option
    RFC3396 PS Encoding Long Options in DHCPv4
    RFC3442 PS The Classless Static Route Option for Dynamic Host Configuration Protocol (DHCP) version 4

    Current Meeting Report

    Minute of dhc WG Meeting, IETF 56
    Administrivia, agenda bashing, WG progress report - Ralph Droms
    Progress report since last WG meeting:
    RFCs published:
      The Classless Static Route Option for Dynamic Host Configuration Protocol 
      (DHCP) version 4, RFC3442 Dynamic Host Configuration Protocol (DHCP) Option 
      for CableLabs Client Configuration, RFC3495
    Accepted as Draft Standard:
      Link Selection sub-option for the Relay Agent Information Option for DHCPv4
    Passed last call:
      Security Ticket Control Sub-option for the CableLabs Client Configuration Option
      DNS Configuration options for DHCPv6
      NIS Configuration Options for DHCPv6
      Time Configuration Options for DHCPv6
      DHCP Options for Internet Storage Name Service
      IPv6 Prefix Options for DHCPv6
    Review of new charter, request for milestones - Ralph Droms
    Droms announced that charter had been accepted by IESG and posted to www.ietf.org.
    He noted that draft authors will be asked to supply milestones for posting with the charter.
    DHCP security review team report - Barr Hibbs
    Review team has made progress but did not publish draft prior to pre-IETF deadline;
     team will publish initial draft after IETF blackout.  Focus is currently on DHCPv4, 
     but results may be applicable to DHCPv6 as well.  Vipul Gupta has agreed to re-publish 
     earlier draft on certificate-based DHCP authentication.  Ted Lemon and Michael 
     Richardson have published a draft using SIG(0) keys (see below).
    'Securing DHCP with DNSSEC bourne public keys' - Ted Lemon
    This draft was published just before the IETF deadline and is incomplete.  The 
    fundamental idea in this draft is to perform DHCP authentication using DNS SIG(0) 
    keys.  The WG accepted the draft as WG work item.
    Authentication of relay agent options - John Schnizlein
    Schnizlein volunteered at previous IETF to conduct comparison of two proposals for
    securing communication between a relay agent and server  (draft-ietf-dhc-auth-
    suboption-01.txt, Stapp and Lemon; draft-droms-dhcp-relay-agent-ipsec-00.txt, Droms).  
    His conclusion is that the proposals are each applicable in different situations. 
    Thomas Narten questioned whether the WG should advance two mechanisms that address 
    the same problem.  The authors of the two drafts and Schnizlein said the two proposals 
    may be appropriate in different environments, if IPsec is already available on 
    all the participating components, the IPsec-based method may be usable with no 
    additional configuration or software updates; the authentication has better scalability 
    (key management) properties when IPsec is not already deployed.  Narten suggested 
    we could flip a coin to choose between the two proposals.  Droms observed that, 
    while there is some overlap between the applicability of the two proposals, there 
    are significant cases in which only one of the two is appropriate.  The WG will 
    continue to work on both proposals.
    VPN-ID option and sub-option -  Kim Kinnear
    Narten asked about the requirements for these options - what problem spaces do 
    they apply to?  What are the situations in which the server sends the option to
    the client/relay agent and what are the situations in which the client/relay 
    agent sends the option to the server?  Erik Nordmark asked about security 
    considerations.  John Schnizlein suggested the use of "VPN" in the name might be 
    confusing - this option is intended to pass a VPN identifier as additional
    information about a client, rather than use a VPN in any kind of security.
    These two drafts are ready for WG last call after a name change and addition of
    an example case.
    DHCP server MIB - Barr Hibbs
    This draft is ready for WG last call; the MIB doctors who reviewed the draft will 
    be asked to comment during WG last call.
    Option code recovery - Ralph Droms
    This draft will be revised to edit out option codes related to PXE standard and 
    to add more words about the plan for the use of draft; the document will then be 
    ready for WG last call.
    Option code extensions - Bernie Volz
    This document resurrects an old proposal from Droms about using option codes 126 and 
    127 for options that would extend the DHCP option code space with 16-bit option codes.  
    Volz proposes redefining option codes in the range 128-223 as DHCP option codes 
    (managed by IANA), leaving option codes 224-254 as site-specific options codes.  
    The WG accepted this document as a WG work item.
    Review of DHCP RFCs - Barr Hibbs
    Hibbs is collecting references to text in the DHCP RFCs that is confusing, contradictory,
    incomplete, conflicted with other RFCs, difficult to implement, or could only be
    resolved by consensus at connectathons.  The objective is to document these issues
    and suggest clarifications and corrections where necessary.  The final document 
    will be used in moving DHCP to full Standard.  Rob Stevens is co-editor; the work
    was started three years ago by Mike Carney.  Hibbs asked for more input.
    Failover protocol - Kinnear
    Kinnear reported on changes since last revision and discussion.  There was a 
    meeting of failover authors and implementors in Atlanta, IETF 55: Kim Kinnear, 
    Scanner Luce, Bernie Volz, Mark Stapp.  Notes from that meeting are available at http://www1.ietf.org/mail-archive/working-groups/dhcwg/current/msg01902.html. 
    Narten suggested publishing as Experimental.  There are at least 6 implementations 
    and at least two implementors reported customer interest in failover that will 
    interoperate between DHCP servers from different vendors.  One vendor (Lucent) 
    noted that there has never been a request for their implementation. Droms asked 
    if Experimental could be a step towards Standards track.  Narten responded that 
    SRV started as Experimental.  Kinnear said he had no problem with Experimental; 
    the important issue is to get a stake in the ground for implementors to work 
    toward.  WG responded that Proposed Standard is appropriate.  Draft is now ready 
    for WG last call.
    Lease query protocol - Kim Kinnear
    Kinnear described changes to draft and noted that there have been questions
    about the functions provided by the most recent document relative to the problem 
    statement in the introduction.  Narten expressed concern about feature creep; that 
    is, using this mechanism to supply information to a network element that wouldn't 
    be available to the network element through DHCP messages.  Kinnear will revise 
    draft to provide information retrieval capability identical to what could be 
    obtained through reading DHCP messages.  Document will then be ready for WG last call.
    DHCPv6 status - Ralph Droms
    The base protocol specification has been accepted as Proposed Standard.  Several 
    options have passed WG last call and are ready to be forwarded to the IESG.  Two 
    rounds of interoperability testing have been conducted (TAHI and Connectathon), 
    resulting in identification of several minor editorial and clarification issues.  
    These issues have been published in draft-ietf-dhc-dhcpv6-interop-01.txt and will 
    be announced to IETF.  The changes documented with the issues in that draft will 
    be made before publication of the RFC.
    IPv4 Link Local addressing issue from zeroconf WG - Lemon
    Ted explained that there is a dependency between IPv4LL and DHCP: the current 
    specification for IPv4LL restricts an interface to be configured with either a 
    routable IPv4 address or an IPv4LL address. However, transition from DHCP-assigned 
    address to an IPv4LL address will require a change to RFC2131, to cause a DHCP 
    client to drop its routable address in favor of an IPv4LL address when INIT-REBOOT 
    fails.  Ted will publish a summary of the issue to the DHC WG mailing list.


    None received.