Network Working Group                                           L. Yong
Internet Draft                                                L. Dunbar
Category: Informational                                          Huawei
                                                                 M. Toy
                                                               A. Isaac
                                                       Juniper Networks
                                                              V. Manral
                                                         Ionos Networks

Expires: June July 2017                                 February 10, 2017                                 December 21, 2016

     Use Cases for Data Center Network Virtualization Overlay Networks




   This document describes data center network virtualization overlay
   (NVO3) network use cases that can be deployed in various data
   centers and serve different data center applications.

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Table of Contents

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

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 some limits in supporting
   cloud applications and multi tenant networks [RFC7364]. The goal goals of
   data center network virtualization overlay (NVO3) networks is are 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 network
      traffic virtual networks on a physical network that carries NVO3 network traffic. network.

   o  Independent  Provide independent address spaces space in individual NVO3 networks virtual
      network such as MAC and IP.

   o  Flexible  Support flexible Virtual Machines (VM) 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

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


   Hosts in one NVO3 virtual network may interconnect communicate with hosts in
   another NVO3 virtual network on that is carried by the same physical
   network, or another physical network (i.e., not the different physical network that the NVO3 network is carried over), network, via a gateway. The use case
   examples for the latter are: 1) DCs that migrate toward an NVO3
   solution will be done in steps, where a portion of tenant systems in
   a VN is are on virtualized servers while others exist on a LAN. 2) many
   DC applications serve to 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. Some inter-VN The inter-
   VN policies can be are usually enforced at by the gateway.

   This document describes general NVO3 virtual network use cases that
   apply to various data centers. The use cases described here
   represent DC provider's interests and vision for their cloud
   services. The document groups the use cases into three categories
   from simple to
   advance sophiscated in term terms of implementation. However the implementations
   implementation details of these use cases are outside the scope of
   this document. These three categories are highlighted below:

   o  Basic NVO3 virtual networks (Section 2). All Tenant Systems (TS)
      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 virtual networks in a DC is much higher larger than what the number
      that traditional VLAN based virtual networks [IEEE 802.1Q] can
      support. This case is often
      referred as to the DC East-West traffic.

   o  A virtual network that spans across multiple Data Centers and/or
      to customer premises where NVO3 virtual networks are constructed
      and interconnect another other virtual or physical network networks outside the
      data center. An enterprise customer may use a traditional carrier
      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 the
      gateways. Three scenarios are described in Section 4.1) 4. (1)
      supporting multiple technologies; 2) (2) constructing several
      virtual networks as a tenant network; 3) (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 terminologies terminology defined in [RFC7365] and
   [RFC4364]. Some additional terms used in the document are listed

   ASBR: Autonomous System Boarder Routers (ASBR)

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

   DNS: Domain Name Service [RFC1035]

   DC Operator: A role who An entity that is responsible to construct for constructing and manage cloud
   service instances
   managing all resources in their life-cycle and manage DC infrastructure
   that runs these cloud instances. data centers, including, but not limited
   to, compute, storage, networking, etc.

   DC Provider: A company 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.

2. Basic NVO3 Networks


   NVO3 network provides communications among Tenant Systems (TS) in virtual network: a DC. virtual network that is implemented based
   NVO3 architecture [NVO3-ARCH].

   PE:   Provider Edge

   SP:   Service Provider

   TS: A TS can be a physical server/device or a virtual machine (VM)
   on a server, i.e., end-device [RFC7365]. A DC provider often uses
   NVO3 networks for its internal applications in which each
   application runs on many VMs or physical services

   VRF-LITE: Virtual Routing and requires
   application segregation.

   A Forwarding - LITE [VRF-LITE]

   VN: NVO3 virtual network.

   WAN VPN: Wide Area Network Virtual Edge (NVE) is an Private Network [RFC4364]

1.2. NVO3 Background

   An NVO3 virtual network is a virtual network in a DC that is
   implemented based on the NV03 architecture [RFC8014]. This
   architecture component
   [RFC7365]]. It is responsible often referred to forward and encapsulate the NVO3 as an overlay architecture. The
   traffic in outbound direction; and decapsulate and forward the carried by an NVO3
   traffic in inbound direction [NVO3ARCH]. A Network Virtualization
   Authority (NVA) is another NVO3 architecture component [RFC7365]. An
   NVE obtains the reachability information of tenant systems in a NVO3
   network from the NVA. The tenant systems attached to the same NVE
   may belong to a same or different NVO3 networks.

   The network virtualization overlay in this context means that a virtual network is implemented with an overlay technology, i.e.,
   within a DC, NVO3 traffic is encapsulated at an NVE a
   Network Virtual Edge (NVE) [RFC8014] and carried by a tunnel to
   another NVE where the packet traffic is decapsulated and sent to a
   target tenant system [NVO3ARCH]. This
   destination Tenant System (TS). The NVO3 architecture decouples an NVO3
   network construction
   virtual networks from the DC physical network configuration,
   which provides the flexibility for VM placement and mobility. configuration. The
   architecture supports one tunnel uses common tunnels to carry NVO3 traffic belonging that belongs
   different NVO3 networks; thus the multiple NVO3 encapsulation header carries
   a virtual network identifier to differentiate NVO3 traffic in a
   tunnel. 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.
   (i.e., tenant systems) communications. An NVO3 virtual network may
   be required to carry unicast traffic and/or multicast, broadcast/unknown
   broadcast/unknown-unicast (for L2 only) traffic from/to tenant
   systems. There are several ways to transport NVO3 virtual network
   BUM (Broadcast, Unknown-unicast, Multicast) traffic [NVO3MCAST].

   It is worth mentioning two distinct cases regarding to NVE location.
   The first is where TSs and an NVE are co-located on

   An NVO3 virtual network provides communications among Tenant Systems
   (TS) in a single end
   host/device, which means that the NVE DC. A TS can be aware a physical server/device or a virtual
   machine (VM) on a server end-device [RFC7365].

2. DC with Large Number of the TS's state
   at any time via an Virtual Networks

   A DC provider often uses NVO3 virtual networks for internal API. The second is
   applications where TSs and an NVE
   are not co-located, with the NVE residing each application runs on a network device; in
   this case, a protocol is necessary to allow many VMs or physical
   servers and the NVE provider requires applications to be aware segregated from
   each other. A DC may run a larger number of
   the TS's state [NVO3HYVR2NVE].

  One NVO3 network can provide connectivity virtual networks to
   support many TSs that attach applications concurrently, where traditional IEEE802.1Q
   based VLAN solution is limited to
  many 4094 VLANs.

  Applications running on VMs may require different NVEs quantity of
  computing resource, which may result in a DC. TS computing resource shortage
  on some servers and other servers being nearly idle. Shortage of
  computing resource 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 need be fast enough should take significantly less time than the typical
  TCP/SCTP re-transmission Time-out window, so that
  the updates do not cause any communication disruption/interruption. end points'
  TCP/SCTP 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
  more virtual networks in a DC is critical for the an NVO3

   If a virtual network spans across multiple DC sites, one design

   When NVO3 is to allow the network virtual networks segregate VMs belonging to seamlessly span across 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 different
   applications, DC tunnel(s) operators can be stitched together independently assign MAC and/or IP
   address space to form an
   end-to-end tunnel between the pair of NVEs that are each virtual network. This addressing is more
   flexible than requiring all hosts in different DC
   sites. Both cases will form one all NVO3 virtual network across multiple DC
   sites. 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 Network virtual network and External Network Interconnection

   Many customers (an enterprise (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 allows the customer to
   access the resources via a virtual gateway (vGW). This, in turn,
   becomes WAN connectivity
   to the case of interconnecting an NVO3 network virtual gateway can be provided by VPN technologies such as
   IPsec VPNs [RFC4301] and the BGP/MPLS IP VPNs [RFC 4364].

   If a virtual
   private network (VPN) on 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 wide-area networks (WAN).
   Note 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 a VPN is not implemented by are in different DC sites. Both cases
   will form one NVO3 solution. virtual network across multiple DC sites.

   Two use cases are described here. in the following sections.

3.1. DC NVO3 Network 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 Data Center. A set of
   tenant systems are attached to NVE1 on a server. NVE2 resides on a
   DC Gateway device. NVE2 terminates the tunnel and uses the 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 iBGP Interior Border Gateway Protocol
   (iBGP) may be used for prefix advertisement. The vGW provides IPsec
   functionality such as authentication scheme and encryption; iBGP
   protocol 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 firewall and load balancer 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.

   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.

         |   TS1 TSn     |
         |    |...|      |
         |  +-+---+-+    |             Customer Site
         |  |  NVE1 |    |               +-----+
         |  +---+---+    |               | CGW 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 Network 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 Service Provider constructs a
   VPN for the enterprise customer. Each enterprise site peers with an
   SP PE. The DC Provider and VPN Service Provider 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
   Provider Edge (PE) devices. The control plane interconnection
   options between the DC and WAN are described in RFC4364 [RFC4364]. Using Option the
   option A specified in [RFC4364] with VRF-LITE [VRF-LITE], both
   Autonomous System Boarder Routers (ASBR), i.e., DC GW and SP PE,
   maintain a routing/forwarding table (VRF). Using Option B, 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 B allow the
   NVO3 virtual network and VPN using their own identifier identifiers and two
   identifiers are mapped at DC GW. With the option C, C in [RFC4364], the
   VN and VPN use the same identifier and both ASBRs perform the tunnel
   stitching, i.e., tunnel segment mapping. Each option has pros/cons
   [RFC4364] and has been deployed in SP networks depending on the applications in use.
   application requirements. BGP is used with in these options for route
   distribution between DCs and SP WANs. Note that if the DC is the
   SP's Data Center, the DC GW and SP PE in this case can be merged
   into one device that performs the interworking of the VN and VPN
   within an AS.

   The configurations above

   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)

   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 for a reason. DC. This section
   highlights some use cases for this goal.

4.1. Supporting Multiple Technologies

   Servers deployed in a large data center are often installed at
   different times, and 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. VxLAN [RFC7348], NVGRE [RFC7637]) or proprietary
   encapsulations. To construct a tenant network among these servers
   and the 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 is has high CPU and
   memory consumption, which only makes a sense to run on metal 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 to VMs and VLAN [IEEE802.1Q] connect to metal services. physical servers. The tenant
   network requires interworking between NVO3 and traditional VLAN.

4.2. DC Application with Applications Spanning Multiple Virtual Networks Physical Zones

   A DC application may necessarily can be constructed with multi-tier partitioned into multiple physical zones, where with each zone has
   having different access permissions and runs 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 GW/firewall. physical DMZ zone. Each zone can be
   implemented by one NVO3 virtual network and a GW/firewall the security functions
   in DMZ zone can be used to between two NVO3 virtual networks, i.e.,
   two zones. As a result, a tunnel carrying NVO3 If network traffic must functions (NF), especially the security
   functions in the physical DMZ can't process encapsulated NVO3
   traffic, the NVO3 tunnels have to be terminated at for the GW/firewall where NF to
   perform its processing on the NVO3
   traffic is processed. application traffic.

4.3. Virtual Data Center (vDC)

   An enterprise data center today 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 virtual Data Center (vDC) over its physical DC
   infrastructure and offer a virtual Data Center 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 firewall, DNS, load balancer,
   gateway, etc.

   Figure 2 below 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. A
   load balancer (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 provider DC site.

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

                        Provider DC 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 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.

   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 and potential NVO3 use cases in DCs. The
   combination of these cases will give operators the flexibility and
   capability to design more sophisticated cases support for various cloud

   DC services may vary, from infrastructure as a service (IaaS), to
   platform as a service (PaaS), to software as a service (SaaS).
   In these services, NVO3 virtual networks are just make it possible to
   scale a portion large number of such services. virtual networks in DC and ensure the
   network infrastructure not impacted by the number of VMs and dynamic
   workload changes in 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 as well as from 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 against a
   tenant application attacking their underlay DC network; further,
   they need to protect against 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. An NVO3 solution has to
   address these issues. This can be done by limiting
   the bandwidth of such communications.

7. IANA Considerations

   This document does not request any action from IANA.

8. Informative References

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

   [NVO3HYVR2NVE] Li, Y., et al, "Hypervisor to NVE Control Plane
             Requirements", draft-ietf-nvo3-hpvr2nve-cp-req-05, work in

   [NVO3ARCH] Black, D., et al, "An Architecture for Overlay Networks
             (NVO3)", draft-ietf-nvo3-arch-08, work in progress.

   [NIST]    National Institute of Standards and Technology, "The NIST
             Definition of Cloud Computing", SP 880-145, September,

   [NVO3MCAST] Ghanwani, A., Dunbar, L., et al, "A Framework for
             Multicast in Network Virtualization Overlays", draft-ietf-
             nvo3-mcast-framework-05, work in progress.

   [RFC1035] Mockapetris, P., "DOMAIN NAMES - Implementation and
             Specification", RFC1035, November 1987.

   [RFC3022] Srisuresh, P. and Egevang, K., "Traditional IP Network
             Address Translator (Traditional NAT)", RFC3022, January

   [RFC4301] Kent, S., "Security Architecture for the Internet
             Protocol", rfc4301, December 2005

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

   [RFC7348] Mahalingam, M., Dutt, D., et al, "Virtual eXtensible Local
             Area Network (VXLAN): A Framework for Overlaying
             Virtualized Layer 2 Networks over Layer 3 Networks",
             RFC7348 August 2014.

   [RFC7364] Narten, T., et al "Problem Statement: Overlays for Network
             Virtualization", RFC7364, October 2014.

   [RFC7365] Lasserre, M., Motin, T., et al, "Framework for DC Network
             Virtualization", RFC7365, October 2014.

   [RFC7432]  Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A. and
             J. Uttaro, "BGP MPLS Based Ethernet VPN", RFC7432,
             February 2015

   [RFC7637] Garg, P., and Wang, Y., "NVGRE: Network Virtualization
             using Generic Routing Encapsulation", RFC7637, Sept. 2015.

   [RFC8014] Black, D., et al, "An Architecture for Overlay Networks
             (NVO3)", rfc8014, January 2017.

   [VRF-LITE] Cisco, "Configuring VRF-lite",


      David Black
      Dell EMC
      176 South Street
      Hopkinton, MA 01748

      Vinay Bannai
      2211 N. First St,
      San Jose, CA 95131
      Phone: +1-408-967-7784

      Ram Krishnan
      Brocade Communications
      San Jose, CA 95134
      Phone: +1-408-406-7890

      Kieran Milne
      Juniper Networks
      1133 Innovation Way
      Sunnyvale, CA 94089
      Phone: +1-408-745-2000


   Authors 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 review, comments, and suggestions.

 Authors' Addresses

   Lucy Yong
   Huawei Technologies

   Phone: +1-918-808-1918

   Linda Dunbar
   Huawei Technologies,
   5340 Legacy Dr.
   Plano, TX 75025 US

   Phone: +1-469-277-5840

   Mehmet Toy

   E-mail :

   Aldrin Isaac
   Juniper Networks

   Vishwas Manral