Network Working Group                                    B. E. Carpenter
Internet-Draft                                         Univ. of Auckland
Intended status: Informational                                    B. Liu
Expires: 11 October 2020                             Huawei Technologies
                                                            9 April 2020

    Scenarios and Requirements for Layer 2 Autonomic Control Planes


   This document discusses scenarios and requirements for Autonomic
   Control Planes (ACPs) constructed and secured at Layer 2.  These
   would be alternatives to an ACP constructed and secured at the
   network layer.  A secure ACP is required as the substrate for an
   autonomic network and for the Generic Autonomic Signaling Protocol

Status of This Memo

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   as described in Section 4.e of the Trust Legal Provisions and are
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Network Scenarios Suitable for a Layer 2 ACP  . . . . . . . .   3
   3.  Requirements for a Layer 2 Technology . . . . . . . . . . . .   3
   4.  Multiple Segments . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Implementation Status [RFC Editor: please remove] . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Change log [RFC Editor: Please remove] . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   As defined in [I-D.ietf-anima-reference-model], the Autonomic Service
   Agent (ASA) is the atomic entity of an autonomic function, and it is
   instantiated on autonomic nodes.  When ASAs communicate with each
   other, they should use the Generic Autonomic Signaling Protocol
   (GRASP) [I-D.ietf-anima-grasp].  It is essential that such
   communication is strongly secured to avoid malicious interference
   with the Autonomic Network Infrastructure (ANI).

   For this reason, GRASP, and any other autonomic management traffic,
   must run over a secure substrate that is isolated from regular data
   plane traffic.  This substrate is known as the Autonomic Control
   Plane (ACP).  A method for constructing an ACP at the network layer
   is described in [I-D.ietf-anima-autonomic-control-plane].  The
   present document discusses scenarios and requirements for
   constructing an ACP at layer 2.  It is not intended to be a normative
   specification, since implementation details will depend on individual
   layer 2 technologies.

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2.  Network Scenarios Suitable for a Layer 2 ACP

   The ANI design is aimed at managed networks, as explained in the
   reference model [I-D.ietf-anima-reference-model].  For a wide area
   network (such as a large campus, a multi-site enterprise network, or
   a carrier network considered as a whole) it is appropriate to
   construct the ACP using network layer techniques and network layer
   security, which is the model described in
   [I-D.ietf-anima-autonomic-control-plane].  However, in at least two
   cases an ACP covering a smaller geographical area may be appropriate:

   1.  A small enterprise that is completely within one building or
       several adjacent buildings, which also requires autonomic network

   2.  An enterprise that prefers in any case to segment its network
       into smaller units for management purposes.

   In either case, we assume that the L2 ACP may extend into the Network
   Operations Centre (NOC) so that it can be interfaced to traditional
   tools for Operations, Administration and Maintenance, as described in
   [RFC8368].  In the terminology of that document, an L2 ACP is an
   instance of a Generalized ACP.

3.  Requirements for a Layer 2 Technology

   These requirements are intended to ensure that a layer 2 ACP can meet
   the needs of all components of the ANI.

   1.  Since GRASP is specified to run over IPv6, the technology must
       support transmission of IPv6 packets according to [RFC8200].
       Since GRASP can run on a single network segment using link-local
       addresses, there is not required to be an IPv6 router or DHCPv6

   2.  The technology must support multicast.  If the switches are not
       completely transparent to layer 2 multicast, they must support
       Multicast Listener Discovery Version 2 (MLDv2) for IPv6

   3.  The technology should have a minimum MTU of 1500 bytes.  Note
       that since GRASP is specified to run unicast operations over TCP,
       this is not an absolute requirement and the IPv6 minimum MTU of
       1280 bytes would be acceptable.  GRASP UDP multicast messages
       could in principle be fragmented but in normal operation this
       would be unusual.

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   4.  The technology must support isolation of a given set of nodes
       (the "ACP VLAN").

   5.  The technology must support secure authorization for access to
       the ACP VLAN.  If the VLAN technology in use does not support
       password protection, a VLAN access control list could be used.

   6.  The technology should support both the normal dataplane VLAN and
       the ACP VLAN on the same physical sockets.  (Possibly the
       dataplane may be the native VLAN, i.e. frames with no VLAN tag.)

   7.  The technology should support line speed encryption of the ACP

   8.  The technology should support wired/wireless bridging if

   9.  The technology should require minimal manual configuration of ACP
       nodes.  However, it is expected that the nodes will need to be
       preconfigured before deployment with the VLAN ID, and with a
       password or encryption key if necessary.  A solution which is
       both secure and self-configuring at Layer 2 is out of scope for
       this document.

   A specific security protocol that supports both authentication and
   encryption of layer 2 packets for Ethernet LANs is MACsec, i.e. the
   IEEE Standard 802.1AE-2018 [MACsec].  For multicast packets,
   authentication is on a group basis (i.e., the originator is
   guaranteed to be a member of the group, rather than a specific
   interface).  MACsec applies across all VLANs, but the ACP VLAN can be
   isolated from the data plane VLAN independently of MACsec.  This
   solution does not extend to wireless networks.  For IEEE 802.11
   networks, IEEE Standard 802.11-2016 [WiFi] "WPA2" security within a
   dedicated Basic Service Set (BSS) might be considered adequate.

   An ACP software module will be needed in each autonomic node, whose
   job is to provide the GRASP core or other autonomic management
   protocols with the following information about the L2 ACP:

   1.  A signal that the L2 ACP is available and secure.

   2.  The current global scope IPv6 address that GRASP should use as
       its primary locator, preferably a ULA, if available.  As
       mentioned, if no such address is available, GRASP will simply
       operate with link-local addresses.

   3.  A list of [interface_index, link_local_address] pairs for all
       valid IPv6 interfaces attached to the L2 ACP.  The interface

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       index (also known as a zone index [RFC4007]) is an integer for
       maximum portability between operating systems.

4.  Multiple Segments

   The L2 ACP could in principle be extended across multiple segments or
   even multiple sites by use of secure L2VPN technology.  This topic is
   out of the scope of the present document.

5.  Implementation Status [RFC Editor: please remove]

   A simple ACP software module emulating that needed for a secure L2
   ACP has been implemented, but it does not in fact verify security.
   It may be found at and is briefly documented in

6.  Security Considerations

   The assumption of this document is that any Layer 2 solution chosen
   must have adequate security against interlopers and eavesdroppers.
   It should be noted that (at least in a wired network) this also
   requires adequate physical security to prevent access by unauthorized
   persons, including physical intrusion detection.

   The fact that an IPv6 router is not required in an L2 ACP excludes
   many Layer 3 vulnerabilities by construction.  No outside entity can
   generate link-local IPv6 packets, and no outside entity can send
   global scope packets to any autonomic node.

7.  IANA Considerations

   This document makes no request of the IANA.

8.  Acknowledgements

   Excellent suggestions were made by Michael Richardson and other
   participants in the ANIMA WG.

9.  References

9.1.  Normative References

   [MACsec]   "IEEE Standard for Local and metropolitan area networks -
              Media Access Control (MAC) Security", IEEE Standard
              802.1AE-2018, 2018,

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   [RFC3810]  Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
              Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
              DOI 10.17487/RFC3810, June 2004,

   [RFC4007]  Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
              B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
              DOI 10.17487/RFC4007, March 2005,

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,

   [WiFi]     "Information technology - Telecommunications and
              information exchange between systems - Local and
              metropolitan area networks - Specific requirements - Part
              11: Wireless LAN Medium Access Control (MAC) and Physical
              Layer (PHY) specifications", IEEE Standard 802.11-2016,
              2016, <

9.2.  Informative References

              Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
              Control Plane (ACP)", Work in Progress, Internet-Draft,
              draft-ietf-anima-autonomic-control-plane-24, 9 March 2020,

              Bormann, C., Carpenter, B., and B. Liu, "A Generic
              Autonomic Signaling Protocol (GRASP)", Work in Progress,
              Internet-Draft, draft-ietf-anima-grasp-15, 13 July 2017,

              Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
              and J. Nobre, "A Reference Model for Autonomic
              Networking", Work in Progress, Internet-Draft, draft-ietf-
              anima-reference-model-10, 22 November 2018,

   [RFC8368]  Eckert, T., Ed. and M. Behringer, "Using an Autonomic
              Control Plane for Stable Connectivity of Network

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              Operations, Administration, and Maintenance (OAM)",
              RFC 8368, DOI 10.17487/RFC8368, May 2018,

Appendix A.  Change log [RFC Editor: Please remove]

   draft-carpenter-anima-l2acp-scenarios-00, 2019-02-28:

   *  Initial version

   draft-carpenter-anima-l2acp-scenarios-01, 2019-10-03:

   *  Added discussion of MACsec and WPA2
   *  Editorial improvements

   draft-carpenter-anima-l2acp-scenarios-02, 2020-04-09:

   *  Updated references
   *  Editorial improvements
   *  Converted to xml2rfc v3

Authors' Addresses

   Brian Carpenter
   The University of Auckland
   School of Computer Science
   University of Auckland
   PB 92019
   Auckland 1142
   New Zealand


   Bing Liu
   Huawei Technologies
   Q14, Huawei Campus
   No.156 Beiqing Road
   Hai-Dian District, Beijing
   P.R. China


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