An Architecture for Overlay Networks (NVO3)
draft-ietf-nvo3-arch-02

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10.  Control Protocol Work Areas

   The NVO3 architecture consists of two major distinct entities: NVEs
   and NVAs.  In order to provide isolation and independence between
   these two entities, the NVO3 architecture calls for well defined
   protocols for interfacing between them.  For an individual NVA, the
   architecture calls for a logically centralized entity that could be
   implemented in a distributed or replicated fashion.  While the IETF
   may choose to define one or more specific architectural approaches to
   building individual NVAs, there is little need for it to pick exactly
   one approach to the exclusion of others.  An NVA for a single domain
   will likely be deployed as a single vendor product and thus their is
   little benefit in standardizing the internal structure of an NVA.

   Individual NVAs peer with each other in a federated manner.  The NVO3
   architecture calls for a well-defined interface between NVAs.

   Finally, a hypervisor-to-NVE protocol is needed to cover the split-
   NVE scenario described in Section 4.2.

11.  NVO3 Data Plane Encapsulation

   When tunneling tenant traffic, NVEs add encapsulation header to the
   original tenant packet.  The exact encapsulation to use for NVO3 does
   not seem to be critical.  The main requirement is that the
   encapsulation support a Context ID of sufficient size
   [I-D.ietf-nvo3-dataplane-requirements].  A number of encapsulations
   already exist that provide a VN Context of sufficient size for NVO3.
   For example, VXLAN [RFC7348] has a 24-bit VXLAN Network Identifier
   (VNI).  NVGRE [I-D.sridharan-virtualization-nvgre] has a 24-bit
   Tenant Network ID (TNI).  MPLS-over-GRE provides a 20-bit label
   field.  While there is widespread recognition that a 12-bit VN
   Context would be too small (only 4096 distinct values), it is
   generally agreed that 20 bits (1 million distinct values) and 24 bits
   (16.8 million distinct values) are sufficient for a wide variety of
   deployment scenarios.

12.  Operations and Management

   The simplicity of operating and debugging overlay networks will be
   critical for successful deployment.  Some architectural choices can
   facilitate or hinder OAM.  Related OAM drafts include
   [I-D.ashwood-nvo3-operational-requirement].

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13.  Summary

   This document presents the overall architecture for overlays in NVO3.
   The architecture calls for three main areas of protocol work:

   1.  A hypervisor-to-NVE protocol to support Split NVEs as discussed
       in Section 4.2.

   2.  An NVE to NVA protocol for disseminating VN information (e.g.,
       inner to outer address mappings).

   3.  An NVA-to-NVA protocol for exchange of information about specific
       virtual networks between federated NVAs.

   It should be noted that existing protocols or extensions of existing
   protocols are applicable.

14.  Acknowledgments

   Helpful comments and improvements to this document have come from
   Lizhong Jin, Anton Ivanov, Dennis (Xiaohong) Qin, Erik Smith, Ziye
   Yang and Lucy Yong.

15.  IANA Considerations

   This memo includes no request to IANA.

16.  Security Considerations

   Yep, kind of sparse.  But we'll get there eventually. :-)

17.  Informative References

   [I-D.ashwood-nvo3-operational-requirement]
              Ashwood-Smith, P., Iyengar, R., Tsou, T., Sajassi, A.,
              Boucadair, M., Jacquenet, C., and M. Daikoku, "NVO3
              Operational Requirements", draft-ashwood-nvo3-operational-
              requirement-03 (work in progress), July 2013.

   [I-D.ietf-nvo3-dataplane-requirements]
              Bitar, N., Lasserre, M., Balus, F., Morin, T., Jin, L.,
              and B. Khasnabish, "NVO3 Data Plane Requirements", draft-
              ietf-nvo3-dataplane-requirements-03 (work in progress),
              April 2014.

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   [I-D.ietf-nvo3-nve-nva-cp-req]
              Kreeger, L., Dutt, D., Narten, T., and D. Black, "Network
              Virtualization NVE to NVA Control Protocol Requirements",
              draft-ietf-nvo3-nve-nva-cp-req-02 (work in progress),
              April 2014.

   [I-D.sridharan-virtualization-nvgre]
              Sridharan, M., Greenberg, A., Wang, Y., Garg, P.,
              Venkataramiah, N., Duda, K., Ganga, I., Lin, G., Pearson,
              M., Thaler, P., and C. Tumuluri, "NVGRE: Network
              Virtualization using Generic Routing Encapsulation",
              draft-sridharan-virtualization-nvgre-06 (work in
              progress), October 2014.

   [IEEE-802.1Q]
              IEEE 802.1Q-2011, , "IEEE standard for local and
              metropolitan area networks: Media access control (MAC)
              bridges and virtual bridged local area networks,", August
              2011.

   [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.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, February 2006.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

   [RFC7348]  Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
              L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
              eXtensible Local Area Network (VXLAN): A Framework for
              Overlaying Virtualized Layer 2 Networks over Layer 3
              Networks", RFC 7348, August 2014.

   [RFC7364]  Narten, T., Gray, E., Black, D., Fang, L., Kreeger, L.,
              and M. Napierala, "Problem Statement: Overlays for Network
              Virtualization", RFC 7364, October 2014.

   [RFC7365]  Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
              Rekhter, "Framework for Data Center (DC) Network
              Virtualization", RFC 7365, October 2014.

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Appendix A.  Change Log

A.1.  Changes From draft-ietf-nvo3-arch-01 to -02

   1.  Minor editorial improvements after a close re-reading; references
       to problem statement and framework updated to point to recently-
       published RFCs.

   2.  Added text making it more clear that other virtualization
       approaches, including Linux Containers are intended to be fully
       supported in NVO3.

A.2.  Changes From draft-ietf-nvo3-arch-00 to -01

   1.  Miscellaneous text/section additions, including:

       *  New section on VLAN tag Handling (Section 3.1.1).

       *  New section on tenant VLAN handling in Split-NVE case
          (Section 4.2.1).

       *  New section on TTL handling (Section 3.1.2).

       *  New section on multi-homing of NVEs (Section 4.4).

       *  2 paragraphs new text describing L2/L3 Combined service
          (Section 3.1).

       *  New section on VAPs (and error handling) (Section 4.5).

       *  New section on ARP and ND handling (Section 5.5)

       *  New section on NVE-to-NVE interactions (Section 6)

   2.  Editorial cleanups from careful review by Erik Smith, Ziye Yang.

   3.  Expanded text on Distributed Inter-VN Gateways.

A.3.  Changes From draft-narten-nvo3 to draft-ietf-nvo3

   1.  No changes between draft-narten-nvo3-arch-01 and draft-ietf-nvoe-
       arch-00.

A.4.  Changes From -00 to -01 (of draft-narten-nvo3-arch)

   1.  Editorial and clarity improvements.

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   2.  Replaced "push vs. pull" section with section more focused on
       triggers where an event implies or triggers some action.

   3.  Clarified text on co-located NVE to show how offloading NVE
       functionality onto adapters is desirable.

   4.  Added new section on distributed gateways.

   5.  Expanded Section on NVA external interface, adding requirement
       for NVE to support multiple IP NVA addresses.

Authors' Addresses

   David Black
   EMC

   Email: david.black@emc.com

   Jon Hudson
   Brocade
   120 Holger Way
   San Jose, CA  95134
   USA

   Email: jon.hudson@gmail.com

   Lawrence Kreeger
   Cisco

   Email: kreeger@cisco.com

   Marc Lasserre
   Alcatel-Lucent

   Email: marc.lasserre@alcatel-lucent.com

   Thomas Narten
   IBM

   Email: narten@us.ibm.com

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