Network Working Group                                         F. Templin
Internet-Draft                                                S. Russert
Intended status: Informational                               I. Chakeres
Expires: August 5, 2007                                            S. Yi
                                                    Boeing Phantom Works
                                                        February 1, 2007


                        MANET Autoconfiguration
                   draft-templin-autoconf-dhcp-04.txt

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 August 5, 2007.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   Mobile Ad-hoc Networks (MANETs) consist of routers operating over
   wireless channels and may or may not connect to other networks.
   Routers in MANETs that connect to the Internet must have a way to
   automatically provision globally routable and unique IP addresses/
   prefixes.  This document specifies mechanisms for MANET
   autoconfiguration.  Both IPv4 and IPv6 are discussed.



Templin, et al.          Expires August 5, 2007                 [Page 1]


Internet-Draft           MANET Autoconfiguration           February 2007


1.  Introduction

   Mobile Ad-hoc Networks (MANETs) comprise links with asymmetric
   reachability link characteristics (see: [RFC2461], Section 2.2) that
   connect MANET Routers (MRs).  MRs participate in a routing protocol
   such that packets can be forwarded via multiple hops across the MANET
   if necessary.  MANETs may connect to other networks via MANET Border
   Routers (MBRs), and MRs may be multiple IP hops away from their
   nearest MBR in some scenarios.  A MANET may be as large as an
   Autonomous System (AS) or as small as an individual site, and may
   contain other MANETs and/or fixed networks.  MRs with hosts on
   downstream-attached links that require global Internet access must
   have a means to automatically provision global IP addresses/prefixes
   and/or other configuration information.

   Conceptually, MRs comprise a router entity and a host entity that are
   connected via a virtual point-to-point VLAN (e.g., a loopback
   interface) configured over an imaginary shared link for the MANET.
   The imaginary shared link provides a conceptual model of a fully-
   connected shared link to which all MRs attach, and has an associated
   identifier (e.g., a prefix associated with the imaginary shared link)
   that "names" the MANET.  An MR (and its downstream-attached links) is
   a "site" unto itself, and a MANET is therefore a "site-of-sites".

   MANETs that comprise homogeneous link types can configure the routing
   protocol to operate as a sub-IP layer mechanism such that IP (i.e.,
   Layer-3) sees the MANET as an ordinary shared link the same as for a
   (bridged) campus LAN.  In that case, a single IP hop is sufficient to
   traverse the MANET.

   MANETs that comprise heterogeneous link types must configure the
   routing protocol to operate as a Layer-3 mechanism such that routing
   protocol operation is based on MANET-Local Addresses (MLAs) or other
   Layer-3 identifiers that are unique within the MANET to avoid issues
   associated with bridging media types with dissimilar Layer-2 address
   formats and maximum transmission units (MTUs).  In that case,
   multiple IP hops may be necessary to traverse the MANET.

   This document specifies mechanisms and operational practices for
   MANET autoconfiguration.  Operation using standard BOOTP/DHCP
   [RFC0951][RFC2131][RFC3315][RFC3633] and neighbor discovery
   [RFC0826][RFC1256][RFC2461][RFC2462] mechanisms is assumed unless
   otherwise specified.  Both IPv4 [RFC0791] and IPv6 [RFC2460] are
   discussed.







Templin, et al.          Expires August 5, 2007                 [Page 2]


Internet-Draft           MANET Autoconfiguration           February 2007


2.  Terminology

   The terminology in the normative references apply; the following
   terms are defined within the scope of this document:

   Mobile Ad-hoc Network (MANET)
      a connected network region that comprises MANET routers that
      maintain a routing structure among themselves in a relatively
      arbitrary fashion over links with asymmetric reachability
      characteristics (see: [RFC2461], Section 2.2).  MANETs may be
      large as an Autonomous System (AS) or as small as an individual
      site.  Further information on the characteristics of MANETs can be
      found in [RFC2501].

   MANET Interface
      a MANET router's attachment to a link within the MANET.

   MANET Router (MR)
      a node that participates in a routing protocol over its MANET
      interface(s) and forwards packets on behalf of its downstream-
      attached nodes and other MRs.  Conceptually, an MR comprises a
      router entity and a host entity connected via a virtual point-to-
      point VLAN (e.g., a loopback interface) configured over an
      imaginary shared link for the MANET.  An MR (and its downstream-
      attached links) is a "site" unto itself, and a MANET is therefore
      a "site-of-sites".  For the purpose of this specification, an MR's
      host entity configures a DHCP client and its router entity
      configures a DHCP relay.

   MANET Border Router (MBR)
      an MR that connects the MANET to other networks.  For the purpose
      of this specification, MBRs are assumed to configure a DHCP relay
      and/or a DHCP server.

   MANET Local Address (MLA)
      a Layer-3 unicast address/prefix configured by an MR that is used
      for intra-MANET communications, i.e., routable only within the
      scope of the MANET.  For IPv6, Unique Local Addresses (ULAs)
      [RFC4193][I-D.jelger-autoconf-mla] provide a natural MLA
      mechanism.

   Extended Router Advertisement/Solicitation (ERA/ERS)
      an IP Router Advertisement/Solicitation (RA/RS) message [RFC1256]
      [RFC2461] with an MLA source address and with destination address
      set to an MLA or a site-scoped multicast address that spans the
      MANET via a broadcast/multicast flooding mechanism (see:
      Section 3.5).  Unlike ordinary RA/RS messages, ERA/ERS messages
      use a non-link-local source address and may travel multiple IP



Templin, et al.          Expires August 5, 2007                 [Page 3]


Internet-Draft           MANET Autoconfiguration           February 2007


      hops.


3.  MANET Autoconfiguration

   The following sections specify autoconfiguration mechanisms and
   operational practices that allow MRs to participate in the routing
   protocol and obtain addresses/prefixes for Intra-MANET and global
   Internet communications.

3.1.  MANET Router (MR) Operation

   Each MR configures MLAs on each of its MANET interfaces.  For IPv6,
   MLAs are generated using Unique Local Addresses
   [RFC4193][I-D.jelger-autoconf-mla] with interface identifiers that
   are either managed for uniqueness (e.g., per [RFC4291], Appendix A)
   or self-generated using a suitable random interface identifier
   generation mechanism that is compatible with EUI-64 format (e.g.,
   Cryptographically Generated Addresses (CGAs) [RFC3972]).  For IPv4,
   MLAs are generated using a corresponding unique local address
   configuration mechanism.

   Each MR next engages in the routing protocol and discovers an
   identifier for the MANET.  The identifier could be an IP prefix, a
   DNS Fully-Qualified Domain Name (FQDN), an IEEE MAC address, etc. but
   in any case provides a name for the MANET.  MRs can discover this
   identifier by receiving ERAs that contain a prefix associated with
   the imaginary shared link (see: Section 3.2), via an out-of-band
   service discovery protocol, via information conveyed in the routing
   protocol itself, or through some other means associated with the
   particular link technology.

   After a MR discovers an identifier for the MANET, the DHCP client
   associated with its host function sends a DHCP DISCOVER (DHCPv4) or
   Solicit (DHCPv6) request across the virtual interface to the DHCP
   relay associated with its router function to request global IP
   address and/or prefix delegations (see also: Section 3.6).  The relay
   function then forwards the request to or more MBRs, to other known
   DHCP servers, or to a site-scoped "All-DHCP-Servers" multicast
   address.

   For DHCPv4, the MR's relay function writes an MLA from the outgoing
   MANET interface (i.e., the relay's upstream-attached interface) in
   the 'giaddr' field and also includes the MLA in a DHCPv4 MLA option
   (see: Section 3.4).  If necessary to identify the downstream-attached
   virtual interface, the relay also includes a link selection sub-
   option [RFC3527] with an address from the prefix associated with the
   MANET's imaginary shared link (if such a prefix is available).



Templin, et al.          Expires August 5, 2007                 [Page 4]


Internet-Draft           MANET Autoconfiguration           February 2007


   For DHCPv6, the MR's relay function writes an MLA from the outgoing
   MANET interface in the "peer-address" field and also writes an
   address from the prefix associated with the MANET's imaginary shared
   link in the "link-address" field (if such a prefix is available).
   The MR can also use DHCP prefix delegation [RFC3633] to obtain
   prefixes for further sub-delegation to nodes on its downstream-
   attached links.

   The DHCP request will elicit a DHCP reply from a server with IP
   address/prefix delegations.  When addresses are delegated, the MR
   assigns the resulting addresses to the virtual interface that
   connects its host and router functions, i.e., the addresses are *not*
   assigned on the upstream MANET interface.  When prefixes are
   delegated, the MR can assign and/or further sub-delegate the prefixes
   to its downstream-attached links, including physical links and
   virtual links of the MR itself.  If the MANET uses a proactive
   routing protocol, the MR advertises the delegated addresses/prefixes
   into the routing protocol during the duration of the delegation
   lifetimes.

   The DHCP server ensures unique IP address/prefix delegations.  By
   assigning global IP addresses/prefixes only on downstream-attached
   interfaces (and not the upstream MANET interface) there is no
   requirement for the MR to perform Duplicate Address Detection (DAD)
   for global addresses on the MANET interface.  See Appendix A for
   further DAD considerations.

   After the MR configures global IP addresses/prefixes, it can send IP
   packets with global IP source addresses to off-MANET destinations
   using any of the MBRs as egress gateways.  For MANETs in which MBRs
   can advertise a 'default' route that propagates throughout the
   routing protocol, the MR can send the IP packets without
   encapsulation at the expense of extra TTL (IPv4) or Hop Limit (IPv6)
   decrementation.  For MANETs in which the routing protocol cannot
   propagate a default route, the MR either: a) encapsulates IP packets
   with an MLA for an MBR as the destination address in the outer header
   (i.e., tunnels the packets to the MBR), or b) inserts an IPv4 source
   routing header (likewise IPv6 routing header) to ensure that the
   packets will be forwarded through an MBR.

3.2.  MANET Border Router Operation

   MBRs can send periodic and/or solicited ERAs associated with the
   imaginary shared link for the MANET on their attached MANET links.
   For IPv6, MBRs can advertise prefixes in ERAs that MRs can consider
   as an identifier for the MANET.  Such prefixes should be advertised
   as not to be used for on-link determination or StateLess Address
   AutoConfiguration (SLAAC) [RFC2462] by setting the 'A', 'L' bits in



Templin, et al.          Expires August 5, 2007                 [Page 5]


Internet-Draft           MANET Autoconfiguration           February 2007


   Prefix Information Options to 0.  (See: Appendix B for further
   considerations on using SLAAC for MANET Autoconfiguration.)

   MBRs act as BOOTP/DHCP relays and/or servers for a MR's DHCP
   requests/replies.  For DHCPv4, when a MBR acting as a relay forwards
   a DHCP request that includes an MLA option, it writes its own address
   in the 'giaddr' field, i.e., it overwrites the value that was written
   into 'giaddr' by the MR's relay function.

   For MANETs in which MRs cannot proactively advertise delegated
   addresses/prefixes via the routing protocol, the MBR creates a tunnel
   for each DHCP reply message it processes pertaining to address/prefix
   delegation with the tunnel's destination address set to the MLA for
   the MR encoded in the DHCPv4 MLA option or the DHCPv6 "peer-address"
   field (see: Section 3.4).  The MBR then creates entries in its IP
   forwarding table that point to the tunnel for each delegated IP
   address/prefix and relays the reply to the MLA for the MR.

   For MANETs in which MRs will advertise delegated addresses/prefixes
   via the routing protocol, tunneling from the MBR is not required
   since standard IP routing within the MANET will direct packets to the
   correct MR.

3.3.  DHCP Server Extensions

   No MANET autoconfiguration-specific extensions are required for
   DHCPv6 servers.

   DHCPv4 servers examine DHCPv4 requests for a DHCPv4 MLA option (see:
   Section 3.4).  If a DHCPv4 MLA option is present, the DHCPv4 server
   copies the option into the corresponding DHCPv4 reply message(s).

3.4.  MLA Encapsulation

   For DHCPv6, the MLA is encoded directly in the "peer-address" field
   of DHCPv6 requests/replies.

   For DHCPv4, a new DHCPv4 option [RFC2132] called the 'MLA option' is
   required to encode an MLA for DHCP transactions that will traverse a
   MBR, i.e., so that the MBR has a MANET-relevant address to direct
   DHCPv4 replies to the correct MR, which may be multiple Layer-3 hops
   away.  The format of the DHCPv4 MLA option is given below:

     Code  Len   Ether Type      MLA
   +-----+-----+-----+-----+-----+-----+---
   | TBD |  n  |    type   |  a1 |  a2 | ...
   +-----+-----+-----+-----+-----+-----+---




Templin, et al.          Expires August 5, 2007                 [Page 6]


Internet-Draft           MANET Autoconfiguration           February 2007


   Code
      a one-octet field that identifies the option type (see:
      Section 5).

   Len
      a one-octet field that encodes the remaining option length.

   Ether Type
      a type value from the IANA "ethernet-numbers" registry.

   MLA
      a variable-length MANET Local Address (MLA).

3.5.  MANET Flooding

   When multicast service discovery is required, Layer-3 MANETs that
   implement this specification must use a MANET flooding mechanism
   (e.g., Simplified Multicast Forwarding (SMF) [I-D.ietf-manet-smf]) so
   that site-scoped multicast messages can be propagated across multiple
   Layer-3 hops.

3.6.  Self-Generated Addresses

   MR's can self-generate an address (e.g., an IPv6 Cryptographically-
   Generated Address (CGA) [RFC3972]) then propose the address to the
   DHCP server.  If the DHCP server determines that the self-generated
   address is unique and can be assigned to MR's virtual interface
   configured over the imaginary shared link, it will delegate the
   address for the MR's use.


4.  Operation with Multiple MBRs

   For a set of MANETs and MBRs that attach to the same backbone
   network, MRs can retain their global IP address/prefix delegations as
   they move if the backbone network participates with the MBRs and MRs
   in a localized mobility management scheme, e.g., see:
   [I-D.templin-autoconf-netlmm-dhcp].

   For a set of MBRs that attach to different backbone networks and/or
   serve different global IP prefixes from within the same network, MRs
   must configure new global IP addresses/prefixes as they change
   between different MBRs unless inter-MBR tunnels and routing protocol
   exchanges are supported, e.g., see:
   [I-D.templin-autoconf-netlmm-dhcp], Appendix A.

   Global mobility management mechanisms for MRs that configure new
   global IP addresses/prefixes as they move between different MBRs are



Templin, et al.          Expires August 5, 2007                 [Page 7]


Internet-Draft           MANET Autoconfiguration           February 2007


   beyond the scope of this document.


5.  IANA Considerations

   A new DHCP option code is requested for the DHCP MLA Option in the
   IANA "bootp-dhcp-parameters" registry.


6.  Security Considerations

   Threats relating to MANET routing protocols also apply to this
   document.


7.  Related Work

   Telcordia has proposed DHCP-related solutions for the CECOM MOSAIC
   program.  Various IETF AUTOCONF working group proposals have
   suggested similar mechanisms for address configuration.


8.  Acknowledgements

   The Naval Research Lab (NRL) Information Technology Division uses
   DHCP in their MANET research testbeds.  Many of the ideas on this
   document originated from IETF AUTOCONF working group discussions on
   various aspects of autoconfiguration for MANETs.

   Thomas Henderson provided valuable input; Jinmei Tatuya reminded that
   address duplication can occur when multiple mechanisms (i.e. manual
   configuration, stateless and DHCP) are used within the same network.


9.  References

9.1.  Normative References

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              September 1981.

   [RFC0826]  Plummer, D., "Ethernet Address Resolution Protocol: Or
              converting network protocol addresses to 48.bit Ethernet
              address for transmission on Ethernet hardware", STD 37,
              RFC 826, November 1982.

   [RFC0951]  Croft, B. and J. Gilmore, "Bootstrap Protocol", RFC 951,
              September 1985.



Templin, et al.          Expires August 5, 2007                 [Page 8]


Internet-Draft           MANET Autoconfiguration           February 2007


   [RFC1256]  Deering, S., "ICMP Router Discovery Messages", RFC 1256,
              September 1991.

   [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.

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, December 1998.

   [RFC2461]  Narten, T., Nordmark, E., and W. Simpson, "Neighbor
              Discovery for IP Version 6 (IPv6)", RFC 2461,
              December 1998.

   [RFC2462]  Thomson, S. and T. Narten, "IPv6 Stateless Address
              Autoconfiguration", RFC 2462, December 1998.

   [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.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

9.2.  Informative References

   [I-D.ietf-manet-smf]
              Macker, J., "Simplified Multicast Forwarding for MANET",
              draft-ietf-manet-smf-03 (work in progress), October 2006.

   [I-D.jelger-autoconf-mla]
              Jelger, C., "MANET Local IPv6 Addresses",
              draft-jelger-autoconf-mla-01 (work in progress),
              October 2006.

   [I-D.templin-autoconf-netlmm-dhcp]
              Templin, F., "Network Localized Mobility Management using
              DHCP", draft-templin-autoconf-netlmm-dhcp-04 (work in
              progress), October 2006.

   [I-D.thaler-autoconf-multisubnet-manets]
              Thaler, D., "Multi-Subnet MANETs",
              draft-thaler-autoconf-multisubnet-manets-00 (work in
              progress), February 2006.




Templin, et al.          Expires August 5, 2007                 [Page 9]


Internet-Draft           MANET Autoconfiguration           February 2007


   [I-D.thaler-intarea-multilink-subnet-issues]
              Thaler, D., "Issues With Protocols Proposing Multilink
              Subnets", draft-thaler-intarea-multilink-subnet-issues-00
              (work in progress), March 2006.

   [RFC2501]  Corson, M. and J. Macker, "Mobile Ad hoc Networking
              (MANET): Routing Protocol Performance Issues and
              Evaluation Considerations", RFC 2501, January 1999.

   [RFC3527]  Kinnear, K., Stapp, M., Johnson, R., and J. Kumarasamy,
              "Link Selection sub-option for the Relay Agent Information
              Option for DHCPv4", RFC 3527, April 2003.

   [RFC3972]  Aura, T., "Cryptographically Generated Addresses (CGA)",
              RFC 3972, March 2005.

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, October 2005.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.


Appendix A.  IPv6 Neighbor Discovery and Duplicate Address Detection

   IPv6 Neighbor Discovery (ND) and Duplicate Address Detection (DAD)
   for MANETs is for further study.

   In terms of ND, [RFC2461][RFC4291] require that a node configure a
   link-local address on each of its IPv6-enabled interfaces, and the
   primary requirement for link-locals seems to be for the purpose of
   uniquely identifying routers on the link.  But, it is for further
   study as to whether MRs should send RAs on MANET links at all, since
   the MANET is a peering point between distinct sites and not the link
   of a single site with a clear set of serving routers and dependent
   end-hosts.  In particular, since MANET interfaces configure MLAs
   which already provide a statistically-unique identifier, link-local
   addresses may be of little/no value on MANET interfaces and hence
   strict enforcement of link-local address uniqueness may not be
   necessary

   In terms of DAD, pre-service DAD on a MANET link (such as specified
   in [RFC2462]) would require either flooding the entire MANET or
   somehow discovering a targeted region of the MANET on which a node
   that configures a duplicate address resides and sending a directed
   DAD message toward that region.  But, the control message overhead
   for such a MANET-wide DAD would be substantial and prone to false-
   negatives due to packet loss.  Note also that link-local addresses



Templin, et al.          Expires August 5, 2007                [Page 10]


Internet-Draft           MANET Autoconfiguration           February 2007


   using Cryptographically Generated Addresses (CGAs) [RFC3972] provide
   random generation only in 59 bits of the lower 64 bits of the IPv6
   address, while MLAs using CGAs also use 40/56 bits of random
   generation in the upper 64 bits of the IPv6 address.  Since such MLAs
   are highly unlikely to collide, pre-service DAD can be avoided and a
   passive in-service DAD (e.g., one that monitors routing protocol
   messages) can be used instead.

   Statistical properties can assure uniqueness for the MLAs assigned on
   a MR's MANET interfaces, and careful operational practices can assure
   uniqueness for the global addresses/prefixes assigned on a MR's
   downstream-attached links (since the DHCP server assures unique
   assignments).  However, a passive in-service DAD mechanism should
   still be used to detect duplicates that were assigned via other
   means, e.g., manual configuration.


Appendix B.  IPv6 StateLess Address AutoConfiguration (SLAAC)

   The use of StateLess Address AutoConfiguration (SLAAC) [RFC2462]
   could be indicated by prefix information options in ERAs with the 'A'
   bit set to 1.  MRs that receive such ERAs could then self-generate an
   address from the prefix and assign it to the virtual interface
   configured over the imaginary shared link for the MANET, then use a
   passive in-service DAD approach to detect duplicates within the
   MANET.  But, if the MANET partitions, DAD might not be able to
   monitor the routing exchanges occurring in other partitions and
   address duplication could result.


Appendix C.  Change Log

   Changed from -03 to -04:

   o  introduced conceptual "imaginary shared link" as a representation
      for a MANET.

   o  discussion of autonomous system and site abstractions for MANETs

   o  discussion of autoconfiguration of CGAs

   o  new appendix on IPv6 StateLess Address AutoConfiguration

   Changes from -02 to -03:

   o  updated terminology based on RFC2461 "asymmetric reachability"
      link type; IETF67 MANET Autoconf wg discussions.




Templin, et al.          Expires August 5, 2007                [Page 11]


Internet-Draft           MANET Autoconfiguration           February 2007


   o  added new appendix on IPv6 Neighbor Discovery and Duplicate
      Address Detection

   o  relaxed DHCP server deployment considerations allow DHCP servers
      within the MANET itself

   Changes from -01 to -02:

   o  minor updates for consistency with recent developments

   Changes from -00 to -01:

   o  new text on DHCPv6 prefix delegation and multilink subnet
      considerations.

   o  various editorial changes


Authors' Addresses

   Fred L. Templin
   Boeing Phantom Works
   P.O. Box 3707 MC 7L-49
   Seattle, WA  98124
   USA

   Email: fred.l.templin@boeing.com


   Steven W. Russert
   Boeing Phantom Works
   P.O. Box 3707 MC 7L-49
   Seattle, WA  98124
   USA

   Email: steven.w.russert@boeing.com


   Ian D. Chakeres
   Boeing Phantom Works
   P.O. Box 3707 MC 7L-49
   Seattle, WA  98124
   USA

   Email: ian.chakeres@gmail.com






Templin, et al.          Expires August 5, 2007                [Page 12]


Internet-Draft           MANET Autoconfiguration           February 2007


   Seung Yi
   Boeing Phantom Works
   P.O. Box 3707 MC 7L-49
   Seattle, WA  98124
   USA

   Email: seung.yi@boeing.com












































Templin, et al.          Expires August 5, 2007                [Page 13]


Internet-Draft           MANET Autoconfiguration           February 2007


Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.


Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





Templin, et al.          Expires August 5, 2007                [Page 14]