ANIMA                                                       M. Behringer
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                        October 16, 2015
Expires: April 18, 2016

                  An Autonomic IPv6 Addressing Scheme


   This document describes a generic IPv6 addressing scheme which is
   suitable for self-managing Autonomic Control Plane.  The scheme
   allows for a flat address hierarchy as well as optionally, when
   required, the definition of aggregatable zones.

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   This Internet-Draft will expire on April 18, 2016.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Fundamental Concepts of Autonomic Addressing  . . . . . . . .   2
   3.  The Base Addressing Scheme  . . . . . . . . . . . . . . . . .   3
   4.  Possible Sub-Schemes  . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Sub-Scheme 1  . . . . . . . . . . . . . . . . . . . . . .   4
     4.2.  Sub-Scheme 2  . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Usage of the Zone Field . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   In an Autonomic Network, as defined in
   [I-D.irtf-nmrg-autonomic-network-definitions], and specified in more
   detail in [I-D.behringer-anima-reference-model], one of the design
   goals is to minimise central functions.

   In an autonomic network each node receives a domain-unique
   identifier, which consists of a domain name and a unique node-ID in
   that domain.  We introduce an addressing scheme and an algorithm that
   allows the calculation of a unique IPv6 ULA address from those
   parameters.  In other words, once a device has a unique node-ID and
   domain name, this addressing scheme and algorithm allows for
   distributed self-management of addressing inside a network.

   The addressing scheme described here is specifically designed for the
   Autonomic Control Plane (ACP; see
   [I-D.ietf-anima-autonomic-control-plane]).  It is for communication
   inside the domain only, specifically to support self-management
   functions.  It may be used for OAM functions inside the ACP as well,
   as described in [I-D.eckert-anima-stable-connectivity].

2.  Fundamental Concepts of Autonomic Addressing

   We assume that each node has a unique domain name and a unique node
   ID inside that domain.  The fundamental concepts for autonomic
   addressing are:

   o  IPv6 only: Autonomic processes should use exclusively IPv6, for
      simplicity reasons.

   o  Usage: Autonomic addresses are exclusively used for self-
      management functions inside a trusted domain.  They are not used

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      for user traffic.  Communications with entities outside the
      trusted domain use another address space, for example normally
      managed routable address space.

   o  Separation: Autonomic address space is used separately from user
      address space and other address realms.  This supports the
      robustness requirement.

   o  Loopback-only: Only loopback interfaces of autonomic nodes carry a
      routable address; all other interfaces exclusively use IPv6 link
      local for autonomic functions.  The usage of IPv6 link local
      addressing is discussed in [RFC7404].

   o  Use-ULA: For loopback interfaces of autonomic nodes, we use Unique
      Local Addresses (ULA), as specified in [RFC4193].  An alternative
      scheme was discussed, using assigned ULA addressing.  The
      consensus was to use standard ULA, because it was deemed to be

   o  No external connectivity: They do not provide access to the
      Internet.  If a node requires further reaching connectivity, it
      should use another, traditionally managed address scheme in

3.  The Base Addressing Scheme

   The Base ULA addressing scheme for autonomic nodes has the following

     8      40          3                     77
   |FD| hash(domain) | Type |             (sub-scheme)                 |

                     Figure 1: Base Addressing Scheme

   The first 48 bits follow the ULA scheme, as defined in [RFC4193], to
   which a type field is added:

   o  "FD" identifies a locally defined ULA address.

   o  The "global ID" is set here to be a hash of the domain name, which
      results in a pseudo-random 40 bit value.  It is calculated as the
      first 40 bits of the MD5 hash of the domain name, in the example

   o  Type: Set to 000 (3 zero bits).  This field allows different
      address sub-schemes in the future.  The goal is to start with a

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      minimal number (ideally one) of sub-schemes initially, but to
      allow for extensions later if and when required.  This addresses
      the "upgradability" requirement.  Assignment of types for this
      field should be maintained by IANA.

4.  Possible Sub-Schemes

   The sub-schemes listed here are not intended to be all supported
   initially, but are listed for discussion.  The final document should
   define ideally only a single sub-scheme for now, and leave the other
   "types" for later assignment.

4.1.  Sub-Scheme 1

             51                 13                    64
   |    (base scheme)       | Zone ID |         Device ID              |

                       Figure 2: Addressing Scheme 1

   The fields are defined as follows: [Editor's note: The lengths of the
   fields is for discussion.]

   o  Zone ID: If set to all zero bits: The device ID bits are used as
      an identifier (as opposed to a locator).  This results in a non-
      hierarchical, flat addressing scheme.  Any other value indicates a
      zone.  See section Section 5 on how this field is used in detail.

   o  Device ID: A unique value for each device.

   The device ID is derived as follows: In an Autonomic Network, a
   registrar is enrolling new devices.  As part of the enrolment process
   the registrar assigns a number to the device, which is unique for
   this registrar, but not necessarily unique in the domain.  The 64 bit
   device ID is then composed as:

   o  48 bit: Registrar ID, a number unique inside the domain that
      identifies the registrar which assigned the name to the device.  A
      MAC address of the registrar can be used for this purpose.

   o  16 bit: Device number, a number which is unique for a given
      registrar, to identify the device.  This can be a sequentially
      assigned number.

   The "device ID" itself is unique in a domain (i.e., the Zone-ID is
   not required for uniqueness).  Therefore, a device can be addressed
   either as part of a flat hierarchy (zone ID = 0), or with an

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   aggregation scheme (any other zone ID).  A address with zone-ID could
   be interpreted as an identifier, with another zone-ID as a locator.
   See Section 5 for a description of the zone bits.

4.2.  Sub-Scheme 2

             51                 13                    64-V           ?
   |    (base scheme)       | Zone ID |         Device ID          | V |

                       Figure 3: Addressing Scheme 2

   The fields are defined as follows: [Editor's note: The lengths of the
   fields is for discussion.]

   o  Zone ID: As in sub-scheme 1.

   o  Device ID: As in sub-scheme 1.

   o  V: Virtualization bit(s): 1 or more bits that indicate a virtual
      context on an autonomic node.

   In addition the scheme 1 (Section 4.1), this scheme allows the direct
   addressing of specific virtual containers / VMs on an autonomic node.
   An increasing number of hardware platforms have a distributed
   architecture, with a base OS for the node itself, and the support for
   hardware blades with potentially different OSs.  The VMs on the
   blades could be considered as separate autonomic nodes, in which case
   it would make sense to be able to address them directly.  Autonomic
   Service Agents (ASAs) could be instantiated in either the base OS, or
   one of the VMs on a blade.  This addressing scheme allows for the
   easy separation of the hardware context.

   The location of the V bit(s) at the end of the address allows to
   announce a single prefix for each autonomic node, while having
   separate virtual contexts addressable directly.

5.  Usage of the Zone Field

   The "zone ID" allows for the introduction of structure in the
   addressing scheme.

   Zone = zero is the default addressing scheme in an autonomic domain.
   Every autonomic node MUST respond to its ACP address with zone=0.
   Used on its own this leads to a non-hierarchical address scheme,
   which is suitable for networks up to a certain size.  In this case,

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   the addresses primarily act as identifiers for the nodes, and
   aggregation is not possible.

   If aggregation is required, the 13 bit value allows for up to 8191
   zones.  The allocation of zone numbers may either happen
   automatically through a to-be-defined algorithm; or it could be
   configured and maintained manually.  [We could divide the zone space
   into manual and automatic space - to be discussed.]

   If a device learns through an autonomic method or through
   configuration that it is part of a zone, it MUST also respond to its
   ACP address with that zone number.  In this case the ACP loopback is
   configured with two ACP addresses: One for zone 0 and one for the
   assigned zone.  This method allows for a smooth transition between a
   flat addressing scheme and an hierarchical one.

   (Theoretically, the 13 bits for the zone ID would allow also for two
   levels of zones, introducing a sub-hierarchy.  We do not think this
   is required at this point, but a new type could be used in the future
   to support such a scheme.)

   Note: Another way to introduce hierarchy is to use sub-domains in the
   naming scheme.  The node names "" and
   "" would automatically lead to different
   ULA prefixes, which can be used to introduce a routing hierarchy in
   the network, assuming that the subdomains are aligned with routing

6.  IANA Considerations

   The type field in the base addressing scheme should be maintained by

7.  Security Considerations


8.  Acknowledgements

   The following people have been involved in developing this scheme:
   Toerless Eckert, Steinthor Bjarnason, BL Balaji, Ravi Kumar

9.  References

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              Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
              Liu, B., Jeff, J., and J. Strassner, "A Reference Model
              for Autonomic Networking", draft-behringer-anima-
              reference-model-03 (work in progress), June 2015.

              Eckert, T. and M. Behringer, "Using Autonomic Control
              Plane for Stable Connectivity of Network OAM", draft-
              eckert-anima-stable-connectivity-01 (work in progress),
              March 2015.

              Behringer, M., Bjarnason, S., BL, B., and T. Eckert, "An
              Autonomic Control Plane", draft-ietf-anima-autonomic-
              control-plane-01 (work in progress), October 2015.

              Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
              Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
              Networking - Definitions and Design Goals", draft-irtf-
              nmrg-autonomic-network-definitions-07 (work in progress),
              March 2015.

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,

   [RFC7404]  Behringer, M. and E. Vyncke, "Using Only Link-Local
              Addressing inside an IPv6 Network", RFC 7404,
              DOI 10.17487/RFC7404, November 2014,

Author's Address

   Michael H. Behringer
   Cisco Systems
   Building D, 45 Allee des Ormes
   Mougins  06250


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