Problem Statement: Overlays for Network Virtualization
RFC 7364

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Internet Engineering Task Force (IETF)                    T. Narten, Ed.
Request for Comments: 7364                                           IBM
Category: Informational                                     E. Gray, Ed.
ISSN: 2070-1721                                                 Ericsson
                                                                D. Black
                                                                     EMC
                                                                 L. Fang
                                                               Microsoft
                                                              L. Kreeger
                                                                   Cisco
                                                            M. Napierala
                                                                    AT&T
                                                            October 2014

         Problem Statement: Overlays for Network Virtualization

Abstract

   This document describes issues associated with providing multi-
   tenancy in large data center networks and how these issues may be
   addressed using an overlay-based network virtualization approach.  A
   key multi-tenancy requirement is traffic isolation so that one
   tenant's traffic is not visible to any other tenant.  Another
   requirement is address space isolation so that different tenants can
   use the same address space within different virtual networks.
   Traffic and address space isolation is achieved by assigning one or
   more virtual networks to each tenant, where traffic within a virtual
   network can only cross into another virtual network in a controlled
   fashion (e.g., via a configured router and/or a security gateway).
   Additional functionality is required to provision virtual networks,
   associating a virtual machine's network interface(s) with the
   appropriate virtual network and maintaining that association as the
   virtual machine is activated, migrated, and/or deactivated.  Use of
   an overlay-based approach enables scalable deployment on large
   network infrastructures.

Narten, et al.                Informational                     [Page 1]
RFC 7364           Overlays for Network Virtualization      October 2014

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7364.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Narten, et al.                Informational                     [Page 2]
RFC 7364           Overlays for Network Virtualization      October 2014

Table of Contents

   1. Introduction ....................................................4
   2. Terminology .....................................................6
   3. Problem Areas ...................................................6
      3.1. Need for Dynamic Provisioning ..............................6
      3.2. Virtual Machine Mobility Limitations .......................7
      3.3. Inadequate Forwarding Table Sizes ..........................7
      3.4. Need to Decouple Logical and Physical Configuration ........7
      3.5. Need for Address Separation between Virtual Networks .......8
      3.6. Need for Address Separation between Virtual Networks and ...8
      3.7. Optimal Forwarding .........................................9
   4. Using Network Overlays to Provide Virtual Networks .............10
      4.1. Overview of Network Overlays ..............................10
      4.2. Communication between Virtual and Non-virtualized
           Networks ..................................................12
      4.3. Communication between Virtual Networks ....................12
      4.4. Overlay Design Characteristics ............................13