    Internet Engineering Task Force (IETF)                           L. Yong
    Request for Comments: 8151                                     L. Dunbar
    Category: Informational                                           Huawei
    ISSN: 2070-1721                                                   M. Toy
                                                                     Verizon
                                                                    A. Isaac
                                                            Juniper Networks
                                                                   V. Manral
                                                                 Nano Sec Co
                                                                    May 2017

       Use Cases for Data Center Network Virtualization Overlay Networks

    Abstract

       This document describes Network Virtualization over Layer 3 (NVO3)
       use cases that can be deployed in various data centers and serve
       different data-center applications.

    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 7841.

       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/rfc8151.

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    Copyright Notice

       Copyright (c) 2017 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.

    Table of Contents

       1. Introduction ....................................................3
          1.1. Terminology ................................................4
          1.2. NVO3 Background ............................................5
       2. DC with a Large Number of Virtual Networks ......................6
       3. DC NVO3 Virtual Network and External Network Interconnection ....6
          3.1. DC NVO3 Virtual Network Access via the Internet ............7
          3.2. DC NVO3 Virtual Network and SP WAN VPN Interconnection .....8
       4. DC Applications Using NVO3 ......................................9
          4.1. Supporting Multiple Technologies ...........................9
          4.2. DC Applications Spanning Multiple Physical Zones ..........10
          4.3. Virtual Data Center (vDC) .................................10
       5. Summary ........................................................12
       6. Security Considerations ........................................12
       7. IANA Considerations ............................................12
       8. Informative References .........................................13
       Acknowledgements...................................................14
       Contributors ......................................................15
       Authors' Addresses.................................................16

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    1.  Introduction

       Server virtualization has changed the Information Technology (IT)
       industry in terms of the efficiency, cost, and speed of providing new
       applications and/or services such as cloud applications.  However,
       traditional data center (DC) networks have limits in supporting cloud
       applications and multi-tenant networks [RFC7364].  The goal of data
       center Network Virtualization over Layer 3 (NVO3) networks is to
       decouple the communication among tenant systems from DC physical
       infrastructure networks and to allow one physical network
       infrastructure to:

       o  carry many NVO3 virtual networks and isolate the traffic of
          different NVO3 virtual networks on a physical network.

       o  provide independent address space in individual NVO3 virtual
          network such as Media Access Control (MAC) and IP.

       o  Support flexible Virtual Machines (VMs) and/or workload placement
          including the ability to move them from one server to another
          without requiring VM address changes and physical infrastructure
          network configuration changes, and the ability to perform a "hot
          move" with no disruption to the live application running on those
          VMs.

       These characteristics of NVO3 virtual networks (VNs) help address the
       issues that cloud applications face in data centers [RFC7364].

       Hosts in one NVO3 VN may communicate with hosts in another NVO3 VN
       that is carried by the same physical network, or different physical
       network, via a gateway.  The use-case examples for the latter are as
       follows:

       1) DCs that migrate toward an NVO3 solution will be done in steps,
          where a portion of tenant systems in a VN are on virtualized
          servers while others exist on a LAN.

       2) many DC applications serve Internet users who are on different
          physical networks;

       3) some applications are CPU bound, such as Big Data analytics, and
          may not run on virtualized resources.

       The inter-VN policies are usually enforced by the gateway.

       This document describes general NVO3 VN use cases that apply to
       various data centers.  The use cases described here represent the DC
       provider's interests and vision for their cloud services.  The

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       document groups the use cases into three categories from simple to
       sophisticated in terms of implementation.  However, the
       implementation details of these use cases are outside the scope of
       this document.  These three categories are described below:

       o  Basic NVO3 VNs (Section 2).  All Tenant Systems (TSs) in the
          network are located within the same DC.  The individual networks
          can be either Layer 2 (L2) or Layer 3 (L3).  The number of NVO3
          VNs in a DC is much larger than the number that traditional VLAN-
          based virtual networks [IEEE802.1Q] can support.

       o  A virtual network that spans across multiple DCs and/or to
          customer premises where NVO3 virtual networks are constructed and
          interconnect other virtual or physical networks outside the DC.
          An enterprise customer may use a traditional carrier-grade VPN or
          an IPsec tunnel over the Internet to communicate with its systems
          in the DC.  This is described in Section 3.

       o  DC applications or services require an advanced network that
          contains several NVO3 virtual networks that are interconnected by
          gateways.  Three scenarios are described in Section 4:
          (1) supporting multiple technologies;
          (2) constructing several virtual networks as a tenant network; and
          (3) applying NVO3 to a virtual Data Center (vDC).

       The document uses the architecture reference model defined in
       [RFC7365] to describe the use cases.

    1.1.  Terminology

       This document uses the terminology defined in [RFC7365] and
       [RFC4364].  Some additional terms used in the document are listed
       here.

       ASBR:        Autonomous System Border Router.

       DC:          Data Center.

       DMZ:         Demilitarized Zone.  A computer or small subnetwork
                    between a more-trusted internal network, such as a
                    corporate private LAN, and an untrusted or less-trusted
                    external network, such as the public Internet.

       DNS:         Domain Name Service [RFC1035].

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       DC Operator: An entity that is responsible for constructing and
                    managing all resources in DCs, including, but not
                    limited to, computing, storage, networking, etc.

       DC Provider: An entity that uses its DC infrastructure to offer
                    services to its customers.

       NAT:         Network Address Translation [RFC3022].

       vGW:         virtual GateWay.  A gateway component used for an NVO3
                    virtual network to interconnect with another
                    virtual/physical network.

       NVO3:        Network Virtualization over Layer 3.  A virtual network
                    that is implemented based on the NVO3 architecture.

       PE:          Provider Edge.

       SP:          Service Provider.

       TS:          A Tenant System, which can be instantiated on a physical
                    server or virtual machine (VM).

       VRF-LITE:    Virtual Routing and Forwarding - LITE [VRF-LITE].

       VN:          Virtual Network

       VoIP:        Voice over IP

       WAN VPN:     Wide Area Network Virtual Private Network [RFC4364]
                    [RFC7432].

    1.2.  NVO3 Background

       An NVO3 virtual network is in a DC that is implemented based on the
       NVO3 architecture [RFC8014].  This architecture is often referred to
       as an overlay architecture.  The traffic carried by an NVO3 virtual
       network is encapsulated at a Network Virtualization Edge (NVE)
       [RFC8014] and carried by a tunnel to another NVE where the traffic is
       decapsulated and sent to a destination Tenant System (TS).  The NVO3
       architecture decouples NVO3 virtual networks from the DC physical
       network configuration.  The architecture uses common tunnels to carry
       NVO3 traffic that belongs to multiple NVO3 virtual networks.

       An NVO3 virtual network may be an L2 or L3 domain.  The network
       provides switching (L2) or routing (L3) capability to support host
       (i.e., TS) communications.  An NVO3 virtual network may be required
       to carry unicast traffic and/or multicast or broadcast/unknown-

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       unicast (for L2 only) traffic to/from TSs.  There are several ways to
       transport NVO3 virtual network Broadcast, Unknown Unicast, and
       Multicast (BUM) traffic [NVO3MCAST].

       An NVO3 virtual network provides communications among TSs in a DC.  A
       TS can be a physical server/device or a VM on a server end-device
       [RFC7365].

    2.  DC with a Large Number of Virtual Networks

       A DC provider often uses NVO3 virtual networks for internal
       applications where each application runs on many VMs or physical
       servers and the provider requires applications to be segregated from
       each other.  A DC may run a larger number of NVO3 virtual networks to
       support many applications concurrently, where a traditional VLAN
       solution based on IEEE 802.1Q is limited to 4094 VLANs.

       Applications running on VMs may require a different quantity of
       computing resources, which may result in a computing-resource
       shortage on some servers and other servers being nearly idle.  A
       shortage of computing resources may impact application performance.
       DC operators desire VM or workload movement for resource-usage
       optimization.  VM dynamic placement and mobility results in frequent
       changes of the binding between a TS and an NVE.  The TS reachability
       update mechanisms should take significantly less time than the
       typical retransmission Timeout window of a reliable transport
       protocol such as TCP and Stream Control Transmission Protocol (SCTP),
       so that endpoints' transport connections won't be impacted by a TS
       becoming bound to a different NVE.  The capability of supporting many
       TSs in a virtual network and many virtual networks in a DC is
       critical for an NVO3 solution.

       When NVO3 virtual networks segregate VMs belonging to different
       applications, DC operators can independently assign MAC and/or IP
       address space to each virtual network.  This addressing is more
       flexible than requiring all hosts in all NVO3 virtual networks to
       share one address space.  In contrast, typical use of IEEE 802.1Q
       VLANs requires a single common MAC address space.

    3.  DC NVO3 Virtual Network and External Network Interconnection

       Many customers (enterprises or individuals) who utilize a DC
       provider's compute and storage resources to run their applications
       need to access their systems hosted in a DC through Internet or
       Service Providers' Wide Area Networks (WAN).  A DC provider can
       construct a NVO3 virtual network that provides connectivity to all
       the resources designated for a customer, and it allows the customer

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       to access the resources via a virtual GateWay (vGW).  WAN
       connectivity to the vGW can be provided by VPN technologies such as
       IPsec VPNs [RFC4301] and BGP/MPLS IP VPNs [RFC4364].

       If a virtual network spans multiple DC sites, one design using NVO3
       is to allow the network to seamlessly span the sites without DC
       gateway routers' termination.  In this case, the tunnel between a
       pair of NVEs can be carried within other intermediate tunnels over
       the Internet or other WANs, or an intra-DC tunnel and inter-DC
       tunnel(s) can be stitched together to form an end-to-end tunnel
       between the pair of NVEs that are in different DC sites.  Both cases
       will form one NVO3 virtual network across multiple DC sites.

       Two use cases are described in the following sections.

    3.1.  DC NVO3 Virtual Network Access via the Internet

       A customer can connect to an NVO3 virtual network via the Internet in
       a secure way.  Figure 1 illustrates an example of this case.  The
       NVO3 virtual network has an instance at NVE1 and NVE2, and the two
       NVEs are connected via an IP tunnel in the DC.  A set of TSs are
       attached to NVE1 on a server.  NVE2 resides on a DC Gateway device.
       NVE2 terminates the tunnel and uses the VN Identifier (VNID) on the
       packet to pass the packet to the corresponding vGW entity on the DC
       GW (the vGW is the default gateway for the virtual network).  A
       customer can access their systems, i.e., TS1 or TSn, in the DC via
       the Internet by using an IPsec tunnel [RFC4301].  The IPsec tunnel is
       configured between the vGW and the customer gateway at the customer
       site.  Either a static route or Internal Border Gateway Protocol
       (IBGP) may be used for prefix advertisement.  The vGW provides IPsec
       functionality such as authentication scheme and encryption; IBGP
       traffic is carried within the IPsec tunnel.  Some vGW features are
       listed below:

       o  The vGW maintains the TS/NVE mappings and advertises the TS prefix
          to the customer via static route or IBGP.

       o  Some vGW functions such as the firewall and load-balancer (LB) can
          be performed by locally attached network appliance devices.

       o  If the NVO3 virtual network uses different address space than
          external users, then the vGW needs to provide the NAT function.

       o  More than one IPsec tunnel can be configured for redundancy.

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       o  The vGW can be implemented on a server or VM.  In this case, IP
          tunnels or IPsec tunnels can be used over the DC infrastructure.

       o  DC operators need to construct a vGW for each customer.

       Server+---------------+
             |   TS1 TSn     |
             |    |...|      |
             |  +-+---+-+    |             Customer Site
             |  |  NVE1 |    |               +-----+
             |  +---+---+    |               | GW  |
             +------+--------+               +--+--+
                    |                           *
                L3 Tunnel                       *
                    |                           *
       DC GW +------+---------+            .--.  .--.
             |  +---+---+     |           (    '*   '.--.
             |  |  NVE2 |     |        .-.'   *          )
             |  +---+---+     |       (    *  Internet    )
             |  +---+---+.    |        ( *               /
             |  |  vGW  | * * * * * * * * '-'          '-'
             |  +-------+ |   | IPsec       \../ \.--/'
             |   +--------+   | Tunnel
             +----------------+

               DC Provider Site

               Figure 1: DC Virtual Network Access via the Internet

    3.2.  DC NVO3 Virtual Network and SP WAN VPN Interconnection

       In this case, an enterprise customer wants to use a Service Provider
       (SP) WAN VPN [RFC4364] [RFC7432] to interconnect its sites with an
       NVO3 virtual network in a DC site.  The SP constructs a VPN for the
       enterprise customer.  Each enterprise site peers with an SP PE.  The
       DC provider and VPN SP can build an NVO3 virtual network and a WAN
       VPN independently, and then interconnect them via a local link or a
       tunnel between the DC GW and WAN PE devices.  The control plane
       interconnection options between the DC and WAN are described in
       [RFC4364].  Using the option "a" specified in [RFC4364] with VRF-LITE
       [VRF-LITE], both ASBRs, i.e., DC GW and SP PE, maintain a
       routing/forwarding table (VRF).  Using the option "b" specified in
       [RFC4364], the DC ASBR and SP ASBR do not maintain the VRF table;
       they only maintain the NVO3 virtual network and VPN identifier
       mappings, i.e., label mapping, and swap the label on the packets in
       the forwarding process.  Both option "a" and option "b" allow the se
       of NVO3 VNs and VPNs using their own identifiers, and two identifiers
       are mapped at the DC GW.  With the option "c" in [RFC4364], the VN

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       and VPN use the same identifier and both ASBRs perform the tunnel
       stitching, i.e., tunnel segment mapping.  Each option has pros and
       cons [RFC4364] and has been deployed in SP networks depending on the
       application requirements.  BGP is used in these options for route
       distribution between DCs and SP WANs.  Note that if the DC is the
       SP's DC, the DC GW and SP PE can be merged into one device that
       performs the interworking of the VN and VPN within an Autonomous
       System.

       These solutions allow the enterprise networks to communicate with the
       tenant systems attached to the NVO3 virtual network in the DC without
       interfering with the DC provider's underlying physical networks and
       other NVO3 virtual networks in the DC.  The enterprise can use its
       own address space in the NVO3 virtual network.  The DC provider can
       manage which VM and storage elements attach to the NVO3 virtual
       network.  The enterprise customer manages which applications run on
       the VMs without knowing the location of the VMs in the DC.  (See
       Section 4 for more information.)

       Furthermore, in this use case, the DC operator can move the VMs
       assigned to the enterprise from one sever to another in the DC
       without the enterprise customer being aware, i.e., with no impact on
       the enterprise's "live" applications.  Such advanced technologies
       bring DC providers great benefits in offering cloud services, but add
       some requirements for NVO3 [RFC7364] as well.

    4.  DC Applications Using NVO3

       NVO3 technology provides DC operators with the flexibility in
       designing and deploying different applications in an end-to-end
       virtualization overlay environment.  The operators no longer need to
       worry about the constraints of the DC physical network configuration
       when creating VMs and configuring a network to connect them.  A DC
       provider may use NVO3 in various ways, in conjunction with other
       physical networks and/or virtual networks in the DC.  This section
       highlights some use cases for this goal.

    4.1.  Supporting Multiple Technologies

       Servers deployed in a large DC are often installed at different
       times, and they may have different capabilities/features.  Some
       servers may be virtualized, while others may not; some may be
       equipped with virtual switches, while others may not.  For the
       servers equipped with Hypervisor-based virtual switches, some may
       support a standardized NVO3 encapsulation, some may not support any
       encapsulation, and some may support a documented encapsulation
       protocol (e.g., Virtual eXtensible Local Area Network (VXLAN)
       [RFC7348] and Network Virtualization using Generic Routing

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       Encapsulation (NVGRE) [RFC7637]) or proprietary encapsulations.  To
       construct a tenant network among these servers and the Top-of-Rack
       (ToR) switches, operators can construct one traditional VLAN network
       and two virtual networks where one uses VXLAN encapsulation and the
       other uses NVGRE, and interconnect these three networks via a gateway
       or virtual GW.  The GW performs packet encapsulation/decapsulation
       translation between the networks.

       Another case is that some software of a tenant has high CPU and
       memory consumption, which only makes sense to run on standalone
       servers; other software of the tenant may be good to run on VMs.
       However, provider DC infrastructure is configured to use NVO3 to
       connect VMs and VLANs [IEEE802.1Q] to physical servers.  The tenant
       network requires interworking between NVO3 and traditional VLAN.

    4.2.  DC Applications Spanning Multiple Physical Zones

       A DC can be partitioned into multiple physical zones, with each zone
       having different access permissions and running different
       applications.  For example, a three-tier zone design has a front zone
       (Web tier) with Web applications, a mid zone (application tier) where
       service applications such as credit payment or ticket booking run,
       and a back zone (database tier) with Data.  External users are only
       able to communicate with the Web application in the front zone; the
       back zone can only receive traffic from the application zone.  In
       this case, communications between the zones must pass through one or
       more security functions in a physical DMZ zone.  Each zone can be
       implemented by one NVO3 virtual network and the security functions in
       DMZ zone can be used to between two NVO3 virtual networks, i.e., two
       zones.  If network functions (NFs), especially the security functions
       in the physical DMZ, can't process encapsulated NVO3 traffic, the
       NVO3 tunnels have to be terminated for the NF to perform its
       processing on the application traffic.

    4.3.  Virtual Data Center (vDC)

       An enterprise DC may deploy routers, switches, and network appliance
       devices to construct its internal network, DMZ, and external network
       access; it may have many servers and storage running various
       applications.  With NVO3 technology, a DC provider can construct a
       vDC over its physical DC infrastructure and offer a vDC service to
       enterprise customers.  A vDC at the DC provider site provides the
       same capability as the physical DC at a customer site.  A customer
       manages its own applications running in its vDC.  A DC provider can
       further offer different network service functions to the customer.
       The network service functions may include a firewall, DNS, LB,
       gateway, etc.

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       Figure 2 illustrates one such scenario at the service-abstraction
       level.  In this example, the vDC contains several L2 VNs (L2VNx,
       L2VNy, L2VNz) to group the tenant systems together on a per-
       application basis, and one L3 VN (L3VNa) for the internal routing.  A
       network firewall and gateway runs on a VM or server that connects to
       L3VNa and is used for inbound and outbound traffic processing.  An LB
       is used in L2VNx.  A VPN is also built between the gateway and
       enterprise router.  An Enterprise customer runs Web/Mail/Voice
       applications on VMs within the vDC.  The users at the Enterprise site
       access the applications running in the vDC via the VPN; Internet
       users access these applications via the gateway/firewall at the DC
       provider site.

                    Internet                    ^ Internet
                                                |
                       ^                     +--+---+
                       |                     |  GW  |
                       |                     +--+---+
                       |                        |
               +-------+--------+            +--+---+
               |Firewall/Gateway+--- VPN-----+router|
               +-------+--------+            +-+--+-+
                       |                       |  |
                    ...+....                   |..|
           +-------: L3 VNa :---------+        LANs
         +-+-+      ........          |
         |LB |          |             |     Enterprise Site
         +-+-+          |             |
        ...+...      ...+...       ...+...
       : L2VNx :    : L2VNy :     : L2VNz :
        .......      .......       .......
          |..|         |..|          |..|
          |  |         |  |          |  |
        Web App.     Mail App.      VoIP App.

                 DC Provider Site

                  Figure 2: Virtual Data Center Abstraction View

       The enterprise customer decides which applications should be
       accessible only via the intranet and which should be assessable via
       both the intranet and Internet, and it configures the proper security
       policy and gateway function at the firewall/gateway.  Furthermore, an
       enterprise customer may want multi-zones in a vDC (see Section 4.2)
       for the security and/or the ability to set different QoS levels for
       the different applications.

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       The vDC use case requires an NVO3 solution to provide DC operators
       with an easy and quick way to create an NVO3 virtual network and NVEs
       for any vDC design, to allocate TSs and assign TSs to the
       corresponding NVO3 virtual network and to illustrate vDC topology and
       manage/configure individual elements in the vDC in a secure way.

    5.  Summary

       This document describes some general NVO3 use cases in DCs.  The
       combination of these cases will give operators the flexibility and
       capability to design more sophisticated support for various cloud
       applications.

       DC services may vary, NVO3 virtual networks make it possible to scale
       a large number of virtual networks in a DC and ensure the network
       infrastructure not impacted by the number of VMs and dynamic workload
       changes in a DC.

       NVO3 uses tunnel techniques to deliver NVO3 traffic over DC physical
       infrastructure network.  A tunnel encapsulation protocol is
       necessary.  An NVO3 tunnel may, in turn, be tunneled over other
       intermediate tunnels over the Internet or other WANs.

       An NVO3 virtual network in a DC may be accessed by external users in
       a secure way.  Many existing technologies can help achieve this.

    6.  Security Considerations

       Security is a concern.  DC operators need to provide a tenant with a
       secured virtual network, which means one tenant's traffic is isolated
       from other tenants' traffic and is not leaked to the underlay
       networks.  Tenants are vulnerable to observation and data
       modification/injection by the operator of the underlay and should
       only use operators they trust.  DC operators also need to prevent a
       tenant application attacking their underlay DC networks; further,
       they need to protect a tenant application attacking another tenant
       application via the DC infrastructure network.  For example, a tenant
       application attempts to generate a large volume of traffic to
       overload the DC's underlying network.  This can be done by limiting
       the bandwidth of such communications.

    7.  IANA Considerations

       This document does not require any IANA actions.

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    8.  Informative References

       [IEEE802.1Q]   IEEE, "IEEE Standard for Local and metropolitan area
                      networks -- Media Access Control (MAC) Bridges and
                      Virtual Bridged Local Area Networks", IEEE Std
                      802.1Q-2011, DOI 10.1109/IEEESTD.2011.6009146.

       [NVO3MCAST]    Ghanwani, A., Dunbar, L., McBride, M., Bannai, V., and
                      R. Krishnan, "A Framework for Multicast in Network
                      Virtualization Overlays", Work in Progress,
                      draft-ietf-nvo3-mcast-framework-07, May 2016.

       [RFC1035]      Mockapetris, P., "Domain names - implementation and
                      specification", STD 13, RFC 1035,
                      DOI 10.17487/RFC1035, November 1987,
                      <http://www.rfc-editor.org/info/rfc1035>.

       [RFC3022]      Srisuresh, P. and K. Egevang, "Traditional IP Network
                      Address Translator (Traditional NAT)", RFC 3022,
                      DOI 10.17487/RFC3022, January 2001,
                      <http://www.rfc-editor.org/info/rfc3022>.

       [RFC4301]      Kent, S. and K. Seo, "Security Architecture for the
                      Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
                      December 2005,
                      <http://www.rfc-editor.org/info/rfc4301>.

       [RFC4364]      Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
                      Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364,
                      February 2006,
                      <http://www.rfc-editor.org/info/rfc4364>.

       [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,
                      DOI 10.17487/RFC7348, August 2014,
                      <http://www.rfc-editor.org/info/rfc7348>.

       [RFC7364]      Narten, T., Ed., Gray, E., Ed., Black, D., Fang, L.,
                      Kreeger, L., and M. Napierala, "Problem Statement:
                      Overlays for Network Virtualization", RFC 7364,
                      DOI 10.17487/RFC7364, October 2014,
                      <http://www.rfc-editor.org/info/rfc7364>.

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    RFC 8151                      NVO3 Use Case                     May 2017

       [RFC7365]      Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
                      Rekhter, "Framework for Data Center (DC) Network
                      Virtualization", RFC 7365, DOI 10.17487/RFC7365,
                      October 2014,
                      <http://www.rfc-editor.org/info/rfc7365>.

       [RFC7432]      Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
                      Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-
                      Based Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432,
                      February 2015,
                      <http://www.rfc-editor.org/info/rfc7432>.

       [RFC7637]      Garg, P., Ed., and Y. Wang, Ed., "NVGRE: Network
                      Virtualization Using Generic Routing Encapsulation",
                      RFC 7637, DOI 10.17487/RFC7637, September 2015,
                      <http://www.rfc-editor.org/info/rfc7637>.

       [RFC8014]      Black, D., Hudson, J., Kreeger, L., Lasserre, M., and
                      T. Narten, "An Architecture for Data-Center Network
                      Virtualization over Layer 3 (NVO3)", RFC 8014,
                      DOI 10.17487/RFC8014, December 2016,
                      <http://www.rfc-editor.org/info/rfc8014>.

       [VRF-LITE]     Cisco, "Configuring VRF-lite",
                      <http://www.cisco.com/c/en/us/td/docs/switches/lan/
                      catalyst4500/12-2/31sg/configuration/guide/conf/
                      vrf.pdf>.

    Acknowledgements

       The authors would like to thank Sue Hares, Young Lee, David Black,
       Pedro Marques, Mike McBride, David McDysan, Randy Bush, Uma Chunduri,
       Eric Gray, David Allan, Joe Touch, Olufemi Komolafe, Matthew Bocci,
       and Alia Atlas for the reviews, comments, and suggestions.

    Yong, et al.                  Informational                    [Page 14]

    RFC 8151                      NVO3 Use Case                     May 2017

    Contributors

       David Black
       Dell EMC
       176 South Street
       Hopkinton, MA 01748
       United States of America

       Email: David.Black@dell.com

       Vinay Bannai
       PayPal
       2211 N. First Street
       San Jose, CA 95131
       United States of America

       Phone: +1-408-967-7784
       Email: vbannai@paypal.com

       Ram Krishnan
       Brocade Communications
       San Jose, CA 95134
       United States of America

       Phone: +1-408-406-7890
       Email: ramk@brocade.com

       Kieran Milne
       Juniper Networks
       1133 Innovation Way
       Sunnyvale, CA 94089
       United States of America

       Phone: +1-408-745-2000
       Email: kmilne@juniper.net

    Yong, et al.                  Informational                    [Page 15]

    RFC 8151                      NVO3 Use Case                     May 2017

    Authors' Addresses

       Lucy Yong
       Huawei Technologies
       Phone: +1-918-808-1918

       Email: lucy.yong@huawei.com

       Linda Dunbar
       Huawei Technologies,
       5340 Legacy Drive
       Plano, TX 75025
       United States of America

       Phone: +1-469-277-5840
       Email: linda.dunbar@huawei.com

       Mehmet Toy
       Verizon

       Email: mehmet.toy@verizon.com

       Aldrin Isaac
       Juniper Networks
       1133 Innovation Way
       Sunnyvale, CA 94089
       United States of America

       Email: aldrin.isaac@gmail.com

       Vishwas Manral
       Nano Sec Co
       3350 Thomas Rd.
       Santa Clara, CA
       United States of America

       Email: vishwas@nanosec.io

    Yong, et al.                  Informational                    [Page 16]