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Versions: 01 02 03

INTERNET-DRAFT                                               Luyuan Fang
Intended Status: Standards track                              John Evans
Expires: August 25, 2013                                      David Ward
                                                            Rex Fernando
                                                           John Mullooly
                                                                   Cisco
                                                                 Ning So
                                                     Tata Communications
                                                             Nabil Bitar
                                                                 Verizon
                                                         Maria Napierala
                                                                    AT&T

                                                       February 25, 2013


                         BGP IP VPN Virtual CE
                     draft-fang-l3vpn-virtual-ce-01


Abstract

   This document describes the architecture and solutions of using
   virtual Customer Edge (vCE) of BGP IP VPN. The solution is aimed at
   providing efficient service delivery capability through CE
   virtualization, and is especially beneficial in virtual Private Cloud
   (vPC) environments for extending IP VPN into tenant virtual Data
   Center containers. This document includes: BGP IP VPN virtual CE
   architecture; Control plane and forwarding options; Data Center
   orchestration processes; integration with existing WAN enterprise
   VPNs; management capability requirements; and security
   considerations. The solution is generally applicable to any BGP IP
   VPN deployment. The virtual CE solution is complementary to the
   virtual PE solutions.

   Today's data center's require multi-tenancy and mechanisms to
   establish overlay network connectivity. This document describes one
   approach to enabling data center network connectivity.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.



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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
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Copyright and License Notice

   Copyright (c) 2013 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
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   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 . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1 Terminology  . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2 Problem statement  . . . . . . . . . . . . . . . . . . . . .  6
     1.3 Scope of the document  . . . . . . . . . . . . . . . . . . .  6
   2. Virtual CE Architecture and Reference Model . . . . . . . . . .  7
     2.1 Virtual CE . . . . . . . . . . . . . . . . . . . . . . . . .  7
     2.2 Architecture . . . . . . . . . . . . . . . . . . . . . . . .  8
   3. Control Plane . . . . . . . . . . . . . . . . . . . . . . . . . 10
     3.1 vCE Control Plane  . . . . . . . . . . . . . . . . . . . . . 10
   4. Forwarding Plane  . . . . . . . . . . . . . . . . . . . . . . . 11
     4.1 Forwarding between vCE and PE/vPE  . . . . . . . . . . . . . 11
     4.2 Forwarding between vCE and VM  . . . . . . . . . . . . . . . 11
   5. Addressing and QoS  . . . . . . . . . . . . . . . . . . . . . . 11
     5.1 Addressing . . . . . . . . . . . . . . . . . . . . . . . . . 11
     5.2 QoS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
   6.  Management plane . . . . . . . . . . . . . . . . . . . . . . . 12
     6.1 Network abstraction and management . . . . . . . . . . . . . 12
     6.2 Service VM Management  . . . . . . . . . . . . . . . . . . . 12



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   7. Orchestration and IP VPN inter-provisioning . . . . . . . . . . 12
     7.1 DC Instance to WAN IP VPN instance "binding" Requirements  . 12
     7.2. Provisioning/Orchestration  . . . . . . . . . . . . . . . . 13
       7.2.1 vCE Push model . . . . . . . . . . . . . . . . . . . . . 13
         7.2.1.1 Inter-domain provisioning vCE Push Model . . . . . . 14
         7.2.1.2 Cross-domain provisioning vCE Push Model . . . . . . 14
       7.1.1 vCE Pull model . . . . . . . . . . . . . . . . . . . . . 15
   8. vCE and vPE interaction . . . . . . . . . . . . . . . . . . . . 16
     8.1 Traditional vCE-PE connectivity  . . . . . . . . . . . . . . 16
     8.2 vCE-vPE connectivity . . . . . . . . . . . . . . . . . . . . 17
       8.2.1 Co-located vCE-vPE connectivity with vPE Model 1 . . . . 17
       8.2.2 Co-located vCE-vPE connectivity with vPE Model 2 . . . . 18
   8. Security Considerations . . . . . . . . . . . . . . . . . . . . 18
   9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 18
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     10.1  Normative References . . . . . . . . . . . . . . . . . . . 18
     10.2  Informative References . . . . . . . . . . . . . . . . . . 19
   11. Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . . 20
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
































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1.  Introduction

   In the typical enterprise BGP/MPLS IP VPN [RFC4364] deployment, the
   Provider Edge (PE) and Customer Edge (CE) are physical routers which
   support the PE and CE functions. With the recent development of cloud
   services, using virtual instances of PE or CE functions, which reside
   in a compute device such as a server,  can be beneficial to emulate
   the same logical functions as the physical deployment model but now
   achieved via cloud based network virtualization principles.

   This document describes IP VPN virtual CE (vCE) solutions, while
   Virtual PE (vPE) concept and implementation options are discussed in
   [I-D.fang-l3vpn-virtual-pe], [I-D.ietf-l3vpn-end-system]. vPE and vCE
   solutions provide two avenues to realize network virtualization.


1.1 Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].


   Term              Definition
   -----------       --------------------------------------------------
   AAA               Authentication, Authorization, and Accounting
   ACL               Access Control List
   3GPP              3rd Generation Partnership Project (3GPP)
   AS                Autonomous Systems
   ASBR              Autonomous Systems Border Router
   BFD               Bidirectional Forwarding Detection
   BGP               Border Gateway Protocol
   CE                Customer Edge
   DB                Data Base
   DMZ               Demilitarized Zone, a.k.a. perimeter networking
   ED                End device: where Guest OS, Host OS/Hypervisor,
                     applications, VMs, and virtual router may reside
   FE                Front End
   FIB               Forwarding Information Base
   Forwarder         L3VPN forwarding function
   FRR               Fast Re-Route
   FTP               File Transfer Protocol
   GRE               Generic Routing Encapsulation
   HTTP              Hypertext Transfer Protocol
   Hypervisor        Virtual Machine Manager
   I2RS              Interface to Routing System
   LDAP              Lightweight Directory Access Protocol
   MP-BGP            Multi-Protocol Border Gateway Protocol



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   NVGRE             Network Virtualization using GRE
   OSPF              Open Shortest Path First
   PE                Provider Edge
   QinQ              Provider Bridging, stacked VLANs
   RR                Route Reflector
   SDN               Software Defined Network
   SLA               Service Level Agreement
   SMTP              Simple Mail Transfer Protocol
   ToR               Top of the Rack switch
   VI                Virtual Interface
   vCE               virtual Customer Edge Router
   vLB               virtual Load Balancer
   VM                Virtual Machine
   VLAN              Virtual Local Area Network
   vPC               virtual Private Cloud
   vPE               virtual Provider Edge Router
   VPN               Virtual Private Network
   vRR               virtual Route Reflector
   vSG               virtual Security Gateway
   VXLAN             Virtual eXtensible Local Area Network
   WAN               Wide Area Network


   Definitions:

   Virtual CE (vCE): A virtual instance of the Customer Edge (CE)
   routing function which resides in one or more network or compute
   devices. For example, the vCE data plane may reside in an end device,
   such as a server, and as co-resident with application Virtual
   Machines (VMs) on the server; the vCE control plane may reside in the
   same device or in a separate entity such as a controller.

   Network Container/Tenant Container: An abstraction of a set of
   network and compute resources which can be physical and virtual,
   providing the cloud services for a tenant. One tenant can have more
   than one Tenant Containers.

   Zone: A logical grouping of VMs and service assets within a tenant
   container.  Different security policies may be applied within and
   between zones.

   DMZ: Demilitarized zone, a.k.a. perimeter networking. It is often a
   machine or a small subnet that sits between a trusted internal
   network, such as a corporate private LAN, and an un-trusted external
   network, such as the public Internet. Typically, the DMZ contains
   devices accessible to Internet traffic, such as Web (HTTP) servers,
   FTP servers, SMTP (e-mail) servers and DNS servers.




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1.2 Problem statement

   With the growth of cloud services and the increase in the number of
   CE devices, routers/switches, and appliances, such as Firewalls (FWs)
   and Load Balancers (LBs), that need to be supported, there are
   benefits to virtualize the Data Center tenant container. The
   virtualized container can increase resource sharing, optimize routing
   and forwarding of inter-segment and inter-service traffic, and
   simplify design, provisioning, and management.

   The following two aspects of the virtualized Data Center tenant
   container for the IP VPN CE solution are discussed in this document.

   1. Architecture re-design for virtualized DC.

   The optimal architecture of the virtualized container includes
   virtual CE, virtual appliances, application VMs. All these functions
   are co-resitents on virtualized servers. In this arrangement, CEs and
   appliances can be created and removed easily on demand, and the
   virtual CE can interconnect the virtual appliances (e.g., FW, LB,
   NAT), applications (e.g., Web, App., and DB) in a co-located fashion
   for simplicity, routing/forwarding optimization, and easier service
   chaining. Virtualizing these functions on a per-tenant basis provides
   simplicity for the network operator in regards to managing per tenant
   service orchestration, tenant container moves, capacity planning
   across tennants and per-tenant policies.

   2. Provisioning/orchestration. Two issues need to be addressed:

   a) The provisioning/orchestration system of the virtualized data
   center need to support VM life cycle and VM migration.

   b) The provisioning/orchestration systems of the DC and the WAN
   networks need to be coordinated to support end-to-end IP VPN from DC
   to DC or from DC to enterprise remote office in the same VPN. The DC
   and the WAN network are often operated by separate departments, even
   if they belong to the same provider. Today, the process of inter-
   connecting is slow and painful, and automation is highly desirable.

1.3 Scope of the document

   It is assumed that the readers are familiar with BGP/MPLS IP VPN
   [RFC4364] terms and technologies, the base technology and its
   operation are not reviewed in details in this document.

   As the majority (all in some networks) of applications are IP, this
   vCE solution is focusing on IP VPN solutions to cover the most common
   cases and keep matters as simple as possible.



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2. Virtual CE Architecture and Reference Model

2.1 Virtual CE

   As described in [RFC4364], IP uses a "peer model" - the customers'
   edge routers (CE routers) exchange routes with the Service Provider's
   edge routers (PE routers); the CEs do not peer with each other. MP-
   BGP [RFC4271, RFC4760] is used between the PEs (often with RRs) which
   have a particular VPN attached to them to exchange the VPN routes. A
   CE sends IP packets to the PE; no VPN labels for packets forwarded
   between CE and PE.

   A virtual CE (vCE) as defined in this document is a software instance
   of IP VPN CE function which can reside in ANY network or compute
   devices. For example, a vCE MAY reside in an end device, such as a
   server in a Data Center, where the application VMs reside. The CE
   functionality and management models remain the same as defined in
   [RFC4364] regardless of whether the CE is physical or virtual.

   Using the virtual CE model, the CE functions CAN easily co-located
   with the VM/applications, e.g., in the same server. This allows
   tenant inter-segment and inter-service routing to be optimized.
   Likewise the vCE can be in a separate server (in the same DC rack or
   across racks) than the application VMs, in which case VMs would
   typically use standard L2 technologies to access the vCE via the DC
   network.

   Similar to the virtual PE solution, the control and forwarding of a
   virtual CE can be on the same device, or decoupled and reside on
   different physical devices. The provisioning of a virtual CE,
   associated applications, and the tenant network container can be
   supported through DC orchestration systems.

   Unlike a physical or virtual PE which can support multi-tenants, a
   physical or virtual CE supports a single tenant only. A single tenant
   CAN use multiple physical or virtual CEs. An end device, such as a
   server, CAN support one or more vCE(s). While the vCE is defined as a
   single tenant device, each tenant can have multiple logical
   departments which are under the tenants administrative control,
   requiring logical separation, this is the same model as today's
   physical CE deployments.

   Virtual CE and virtual PE are complimentary approaches for extending
   IP VPN into tenant containers. In the vCE solution, there is no IP
   VPN within the data center or other type of service network, the vCE
   can connect to the PE which is a centralized IP VPN PE/Gateway/ASBR,
   or connect to distributed vPE on a server or on the Top of the Rack
   switch (ToR). Virtual CE can be used to extend the SP managed CE



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   solution to create new cloud enabled services and provide the same
   topological model and features that are consistent with the physical
   CE systems.

2.2 Architecture

   Figure 1 illustrates the topology where vCE is resident in the
   servers where the applications are hosted.

                         .''---'''---''.
                        (               )
                       (     IP/MPLS     )
                        (      WAN      )
          WAN             '--,,,_,,,--'
          ----------------|----------|------------------
          Service/DC      |          |
          Network     +-------+   +-------+
                      |Gateway|---|Gateway|
                      |  PE   |   |  PE   |
                      +-------+   +-------+
                          |    ,---. |
                        .---. (     '.---.
                       (     '      '     ')
                     ('     Data Center     )
                      (.      Fabric      .)
                        (     (       ).--'
                     /   ''--' '-''--'       \
                   /      /          \        \
           +-------+   +---+---+   +-------+   +-------+
           |  vCE  |   |vCE|vCE|   |  vCE  |   |vCE|vCE|
           +---+---+   +---+---+   +---+---+   +---+---+
           |VM |VM |   |VM |VM |   |VM |VM |   |VM |VM |
           +---+---+   +---+---+   +---+---+   +---+---+
           |VM |VM |   |VM |VM |   |VM |VM |   |VM |VM |
           +---+---+   +---+---+   +---+---+   +---+---+

           End Device  End Device  End Device  End Device

           Figure 1. Virtualized Data Center with vCE


   Figure 1 shows above vCE solution in a virtualized Data Center with
   application VMs on the servers. One or more vCEs MAY be used on each
   server.

   The vCEs logically connect to the PEs/Gateway PEs to join the
   particular IP VPN which the tenant belongs to. Gateway PEs connect to
   the IP MPLS WAN network for inter-DC and DC to enterprise VPN sites



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   connection. The server physically connects to the DC Fabric for
   packet forwarding.

                        ,---.                  ,---.
                   .--.(     )            .--.(     )
                  (     '   '.---.       (     '   '.---.
                 ('     L3VPN     )     ('   Internet    )
                  '..(         ).'       '..(         ).'
                      '--'---''              '--'---''
                   +---+   +---+          +---+   +---+
                   |PE |   |PE |          | R |   | R |
                   +---+   +---+          +---+   +---+
                     |       |              |       |
   """"""""""""""""""|"""""""|""""""""""""""|"""""""|"""""""""""""""""
   " End Device      |       |            +----+    |                "
   " (e.g. a server) +-------+-----+ +----|vSG |----+                "
   "                               | |    +----+                     "
   "                              +----+                             "
   "        +---------------------|vCE |-----------+                 "
   "        |                     +----+           |                 "
   " +----+ |   +----+              |              |  +----+         "
   " |vLB |-|   |vLB |--+-----------+              +--|vLB |         "
   " +----+ |   +----+  |                          |  +----+         "
   "        |           |                   +----+ |                 "
   "        |           |            +------|vSG |-+------+          "
   "        |           |            |      +----+        |          "
   " '''''''|'''''''''''|''''' ''''''|'''''''''|''''''''''|''''''''' "
   " ' +--------+ +--------+ ' ' +-------+ +-------+ +-----------+ ' "
   " ' | Apps/  | | Apps/  | ' ' | Apps/ | | Apps/ | |Apps |Apps | ' "
   " ' | VMs    | | VMs    | ' ' | VMs   | | VMs   | |VMs  |VMs  | ' "
   " ' |        | |        | ' ' |       | |       | |ZONE3|ZONE4| ' "
   " ' | Public | |Protect-| ' ' |       | |       | +-----+-----+ ' "
   " ' | Zone   | | ed FE  | ' ' | ZONE1 | | ZONE2 | |Apps |Apps | ' "
   " ' | (DMZ)  | |        | ' ' |       | |       | |VMs  |VMs  | ' "
   " ' |        | |        | ' ' |       | |       | |ZONE5|ZONE6| ' "
   " ' +--------+ +--------+ ' ' +-------+ +-------+ +-----------+ ' "
   " '     Front-end Zone    ' '           Back-end Zone           ' "
   " '                       ' '                                   ' "
   " ''''''''''''''''''''''''' ''''''''''''''''''''''''''''''''''''' "
   """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""

        Figure 2. A Virtualized Container with vCE in an End Device

   An end device shown in Figure 2 is a physical server supporting
   multiple virtualized appliances and application, and hosts multiple
   client VMs. An end device shown in Figure 2 is a physical server
   supporting multiple In the traditional deployment, the topology often
   involves multiple physical CEs, physical Security Gateways and Load



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   Balancers residing in the same Data Center.

   The virtualized approach provides the benefit of reduced number of
   physical devices, simplified management, optimal routing due to the
   co-location of vCE, services, and client VMs.

   While the above diagram represents a simplified view of all of the
   tenant service and application VMs residing in the same physical
   server, the above model can also be represented with the VMs spread
   across many physical servers and the DC network would provide the
   physical inter-connectivity while the vCE and the VMs connected to
   the vCE form the logical connections.

3. Control Plane

3.1 vCE Control Plane

   The vCE control plane can be distributed or centralized.

   1) Distributed control plane

   vCE CAN exchange BGP routes with PE or vPE for the particular IP VPN
   as described in [RFC4364].

   The vCE needs to support BGP if this approach is used.

   The advantage of distributed protocols is to avoid single point of
   failure and bottleneck. Service chaining can be easily and
   efficiently supported in this approach.

   BGP as PE-CE protocol is used in about 70% of cases in typical
   Enterprise IP VPN PE-CE connections. BGP supports rich policy
   compared to other alternatives.

   2) Static routing. It is used in about 30% of cases in Enterprise IP
   VPN PE-CE connections. It MAY be used if the operator prefers.

   2. Using controller approach

   Using controller is the Software Defined Nework (SDN) approach. A
   controller can be distributed or centralized. The central controller
   performs the control plane functions, and sends instructions to the
   vCE on the end devices to configure the data plane.

   This requires standard interface to routing system (I2RS). The
   Interface to Routing System (I2RS) is work in progress in IETF [I-
   D.ward-irs-framework], [I-D.draft-rfernando-irs-framework-
   requirement].



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4. Forwarding Plane

4.1 Forwarding between vCE and PE/vPE

   No MPLS forwarding is required between PE and CE in typical PE-CE
   connection scenarios, though MPLS label forwarding is required for
   implementing Carriers' Carrier (CSC) model.

   IPv4 and IPv6 packet forwarding MUST be supported.

   Native fabric CAN be used to support isolation between vCEs to PE
   connections.

   Examples of native fabric include:

         - VLANs [IEEE 802.1Q], Virtual Local Area Network- IEEE 802.1ad
         [IEEE 802.1ad]/QinQ, Provider Bridge

         Or overlay segmentation with better scalability:

         - VXLANs [I-D.mahalingam-dutt-dcops-vxlan], Virtual Extensible
         LAN- NVGRE [I-D.sridharan-virtualization-nvgre], Network
         Virtualization using GRE

   Note the the above references for overlay network are currently work
   in progress in IETF.

4.2 Forwarding between vCE and VM

   If the vCE and the VM the vCE is connecting are co-located in the
   same server, the connection is internal to the server, no external
   protocol involved.

   If the vCE and the VM the vCE is connecting are located in different
   devices, standard external protocols are needed. The forwarding can
   be native or overlay techniques as listed in the above sub-section.


5. Addressing and QoS

5.1 Addressing

   IPv4 and IPv6 addressing MUST be supported.

   IP address allocation for vCEs and applications/client:

      1) IP address MAY be assigned by central management/provisioning
         with predetermined blocks through planning process.



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      2) IP address MAY be obtained through DHCP server.

   Address space separation: The IP addresses used for clients in the IP
   VPNs in the Data Center SHOULD be in separate address blocks outside
   the blocks used for the underlay infrastructure of the Data Center.
   The purpose is to protect the Data Center infrastructure from being
   attacked if the attacker gain access of the tenant VPNs.

5.2 QoS

   Differentiated Services [RFC2475] Quality of Service (QoS) is
   standard functionality for physical CEs and MUST be supported on vCE.
   This is important to ensure seamless end-to-end SLA from IP VPN in
   the WAN into service network/Data center.  The use of MPLS Diffserv
   tunnel model Pipe Mode (RFC3270) with explicit null LSP must be
   supported.


6.  Management plane

6.1 Network abstraction and management

   The use of vCE with single tenant virtual service instances can
   simplify management requirements as there is no need to discover
   device capabilities, track tenant dependencies and manage service
   resources.

   vCE North bound interface SHOULD be standards based.

   The Interface to Routing System (I2RS) is work in progress in IETF
   [I-D.ward-irs-framework], [I-D.draft-rfernando-irs-framework-
   requirement].

   vCE element management MUST be supported, it can be in the similar
   fashion as for physical CE, without the hardware aspects.

6.2 Service VM Management

   Service VM Management SHOULD be hypervisor agnostic, e.g. On demand
   service VMs turning-up SHOULD be supported.

   The management tool SHOULD be open standards.

7. Orchestration and IP VPN inter-provisioning

7.1 DC Instance to WAN IP VPN instance "binding" Requirements

   - MUST support service activation in the physical and virtual



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   environment.

     For example, assign VLAN to correct VRF.

   - MUST support per VLAN Authentication, Authorization, and Accounting
   (AAA).

     The PE function is an OA&M boundary.

   - MUST be able to apply other policies to VLAN.

     For example, per VLAN QOS, ACLs.

   - MUST ensure that WAN IP VPN state and Data cCentre state are
   dynamically synchronized.

     Ensure that there is no possibility of customer being connected to
   the wrong VRF. For example, remove all tenant state when service
   instance terminated.

   - MUST integrate with existing WAN IP VPN provisioning processes.

   - MUST scale to at least 10,000 tenant service instances.

   - MUST cope with rapid (sub minute) tenant mobility.

   - MAY support Automated cross provisioning accounting correlation
   between WAN IP VPN and cloud/DC for the same tenant.

   - MAY support Automated cross provisioning state correlation between
   WAN IP VPN and cloud/DC/extended Data Center for the same tenant.


7.2. Provisioning/Orchestration

   There are two primary approaches for IP VPN provisioning - push and
   pull, both CAN be used for provisioning/orchestration.

7.2.1 vCE Push model

   Push model: It is a top down approach - push IP VPN provisioning from
   network management system or other central control provisioning
   systems to the IP VPN network elements.

   This approach supports service activation and it is commonly used in
   the existing IP VPN enterprise deployment. When existing the IP VPN
   solution into the cloud/data center or separate Data Center, it MUST
   support off-line accounting correlation between the WAN IP VPN and



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   the cloud/DC IP VPN for the tenant, the systems SHOULD be able to
   bind interface accounting to particular tenant. It MAY requires
   offline state correlation as well, for example, bind interface state
   to tenant.

7.2.1.1 Inter-domain provisioning vCE Push Model

   Provisioning process:

   1) Cloud/DC orchestration configures vCE.

   2) Orchestration initiates WAN IP VPN provisioning; passes connection
   IDs (e.g., of VLAN/VXLAN) and tenant context to WAN IP VPN
   provisioning systems.

   3) WAN IP VPN provisioning system provisions PE VRF and other
   policies per normal enterprise IP VPN provisioning processes.

   This model requires the following:

   - The DC Orchestration system or the WAN IP VPN provisioning system
     know the topology inter-connecting the DC and WAN VPN. For
     example, which interface on the WAN core device connects to which
     interface on the DC PE.

   - Offline state correlation.

   - Offline accounting correlation.

   - Per SP integration.

   Dynamic BGP session between PE/vPE and vCE MAY be used to automate
   the PE provisioning in the PE-vCE model, that will remove the needs
   for PE configuration. Other protocols can be used for this purpose as
   well, for example, use Enhanced Interior Gateway Routing Protocol
   (EIGRP) for dynamic neighbour relationship establishment.

   The dynamic routing Prevents the need to configure the PEs in PE-vCE
   model.

   Caution: This is only under the assumption that the DC provisioning
   system is trusted and could support dynamic establishment of PE-vCE
   BGP neighbor relationships, for example, the WAN network and the
   cloud/DC belongs to the same Service Provider.

7.2.1.2 Cross-domain provisioning vCE Push Model

   Provisioning Process:



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   1) Cross-domain orchestration system initiates DC orch.

   2) DC orchestration system configures vCE

   3) DC orchestration system passes back VLAN/VXLAN and tenant context
      to Cross-domain orchestration system

   4) Cross-domain orchestration system initiates WAN IP VPN
      provisioning

   5) WAN IP VPN provisioning system provisions PE VRF and other
      policies as per normal enterprise IP VPN provisioning processes.

   This model requires the following:

   - Cross-domain orchestration system knows the topology connecting the
   DC and WAN IP VPN, for example, which interface on core device
   connects to which interface on DC PE.- Offline state correlation.

   - Offline accounting correlation.

   - Per SP integration.

7.1.1 vCE Pull model

   Pull model: It is a bottom-up approach - pull from network elements
   to network management/AAA based upon data plane or control plane
   activity. It supports service activation, this approach is often used
   in broadband deployment. Dynamic accounting correlation and dynamic
   state correlation are supported. For example, session based
   accounting is implicitly includes tenant context state correlation,
   as well as session based state which implicitly includes tenant
   context.

   Inter-domain Provisioning:

   Process:

   1) Cloud/DC orchestration system configures vCE

   2) Cloud/DC Orchestration system primes WAN IP VPN provisioning/AAA
   for new service, passes connection IDs (e.g., VLAN/VXLAN) and tenant
   context WAN IP VPN provisioning systems.

   3) Cloud/DC PE detects new VLAN, send Radius Access-Request.

   4) Radius Access-Accept with VRF and other policies.




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   This model requires VLAN/VLAN information and tenant context to
   passed on a per transaction basis. In practice, it may simplify to
   use DC orchestration updating LDAP directory

   Auto accounting correlation and auto state correlation is supported.

8. vCE and vPE interaction

   A vPE ([I-D.fang-l3vpn-virtual-pe] [I-D.ietf-l3vpn-end-system]) is
   treating the VMs in the server as a virtual CE. In this section, the
   relationship between the vPE and such vCE is discussed. vPE can
   support one of the following two models:

      Model 1: a limited control-plane functionality that advertises
      local VPN routes to a controller and receive VPN routes from the
      controller.

      Model 2: a control plane component physically separated from the
      forwarding component that fully performs the control plane routing
      functionality and communicate FIB entries to the vPE forwarding
      entity implemented on servers.

   A vCE provides subnet routing, firewalling or SLB services to host
   VMs. The underlying connectivity between the vCE and these VMs can be
   at layer 2 or layer 3. In addition, the vCE can be connected to other
   vCEs over Layer 2 or using an IP VPN infrastructure. In this section,
   the focus is on IP VPN connectivity and more importantly on the
   interaction between a vCE, a traditional PE (simply referred to as
   PE), and between a vCE and a vPE.

8.1 Traditional vCE-PE connectivity

   This connectivity is described in BGP/MPLS IPVPN [RFC4364]. The only
   distinction being that the VE is a virtual CE.  The vCE attaches to
   the layer 3 PE using a layer2 logical connection, e.g., Ethernet
   VLAN, or a tunnel (e.g., IP/GRE, VXLAN) that are presented as IP
   interfaces to a corresponding VRF at the PE. Routing between the vCE
   and PE can be static or based on a dynamic routing protocol (e.g.,
   OSPF, BGP). A routing protocol, in addition to enabling the exchange
   of routing information between the PE and vCE, provides liveliness
   check between the vCE and the PE. In the absence of a dynamic routing
   protocol, the vCE must support a mechanism that provides for
   liveliness check, or an out-of-band mechanism must be implemented to
   monitor the liveliness of a vCE and a connected PE, and effect
   routing changes upon a failure. Options for in-band liveliness check
   include IP BFD [RFC5880],  Ethernet Continuity Check (CC) [IEEE
   802.1ag], and IP ping [RFC4560]. IP BFD must be supported while the
   other mechanisms are optional.



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8.2 vCE-vPE connectivity

   In this model, the vcE and vPE forwarding plane can be: (1) co-
   located on the same end device, e.g., a server, or (2) located on
   different servers. In addition, the control plane interaction differs
   between vPE model 1 and model 2.

8.2.1 Co-located vCE-vPE connectivity with vPE Model 1

   In vPE Model 1, there is a control plane component of the vPE
   implemented on the end-server (e.g., [I-D.ietf-l3vpn-end-system], [I-
   D.fang-l3vpn-virtual-pe]). In addition, there is a control plane
   component implemented on a separate control plane entity (out-of-
   band) that enables the exchange of routing information among vPEs. In
   [I-D.ietf-l3vpn-end-system], the out-of-band control plane component
   is referred to as router server; in [I-D.fang-l3vpn-virtual-pe], it
   is referred as vPE-C.  There are two cases that must be considered:

   Case 1-A: vCE to vPE local route exchange on a server / vPE-C

   Case 1-B: vCE to route server / vPE-C route exchange.

   In these two cases, the vPE control plane or route server must send
   the CE a default route with next hop being the co-located vPE
   forwarding plane entity.

   In case 1-A, the vCE must send local routes to the vPE control plane
   with itself being the next hop. The vPE control plane entity in turn
   updates the out-of-band control entity (e.g., route server) with
   routes reachable via the local CE, as VPN routes, with itself being
   the next hop for these routes. The vPE also receives from the route
   server VPN routes reachable via other vPEs [end-system]. It should be
   noted in this case, that the vCE must be able support one or more
   routing contexts, each with separate attachment circuit to the vPE.
   Each such routing context must be associated with a VPN and one or
   more VPNs must be supported.

   In case 1-B, the vCE must have a control channel with a route server.
   There must be a control channel per vCE routing context or
   alternatively must allow the unambiguous multiplexing of routes that
   belong to different routing context on the same channel. The vCE
   sends routes reachable via the vCE to the route server with itself
   being the next hop. The route server must learn from the co-located
   vPE control plane component reachability to the local vCE IP address
   used as next hop. This IP address must be exchanged between the vCE
   and vPE in-band over a corresponding attachment circuit that
   identifies the routing context . Alternatively, the route server/vPE-
   C must be programmed with the association of the vCE control channel,



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   a VPN and an end-device IP address. As a result, the route
   server/vPE-C must populate the vPE distributed control plane with the
   corresponding routes as non-VPN routes and the vPE must respond with
   VPN routes that correspond to each of these routes. Alternatively,
   routes reachable via a vCE must be defined via in portal per routing
   context and therefore VPN, and then correlated upon instantiation of
   the vCE on an end-system with the end-system IP address and the
   appropriate VRF on that end-system. In addition, the vCE must be
   configured with default routes per routing context with the next hop
   being the vPE.

8.2.2 Co-located vCE-vPE connectivity with vPE Model 2

   In this model, there is no control plane routing component
   implemented on the end-system. That, is the end-system does not
   generate VPN routes and only receives VPN FIB entries from the out-
   of-band control plane component for routes reachable locally and for
   remote routes. The vCE-control plane interaction is similar to that
   of the interaction in Model 1 case 1-B described in the previous
   section whereby route population is management-driven.

8. Security Considerations

   vCE creation on server - is server owned by the the operator? is this
   managed CE model? how to authenticate?

   vCE in DC connecting VPN in WAN IP - are the DC and WAN IP VPN belong
   to the same SP or different? How much info are permitted to pass
   through auto-provisioning? How to authenticate connections,
   especially in pull models?

   How vCE protects itself from attach from client VMs?

   Additional security procedures in all virtualized cloud/DC
   environment, FW placement. All virtualized appliances need to be
   protected against attack.

   Three tier (Web, App, DB) interaction access control.

   Details to be added.

9. IANA Considerations

   None.

10. References

10.1  Normative References



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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271, January
              2006.

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

   [RFC4560]  Quittek, J., Ed., and K. White, Ed., "Definitions of
              Managed Objects for Remote Ping, Traceroute, and Lookup
              Operations", RFC 4560, June 2006.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760, January
              2007.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, June 2010.

              [I-D.ietf-l3vpn-end-system] Marques, P., Fang, L., Pan,
              P., Shukla, A., Napierala, M., "BGP-signaled end-system
              IP/VPNs", draft-ietf-l3vpn-end-system-00, October 2012.

              [IEEE 802.1ad] IEEE, "Provider Bridges", 2005.

              [IEEE 802.1q] IEEE, "802.1Q - Virtual LANs", 2006.

              [IEEE 802.1ag] IEEE "802.1ag - Connectivity Fault
              Management", 2007.


10.2  Informative References

   [RFC2475]  Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
              and W. Weiss, "An Architecture for Differentiated
              Services", RFC 2475, December 1998.


   [I-D.fang-l3vpn-virtual-pe] Fang, L., Ward, D., Fernando, R.,
              Napierala, M., Bitar, N., Rao, D., Rijsman, B., So, N.,
              "BGP IP VPN Virtual PE", draft-fang-l3vpn-virtual-pe-00,
              Feb. 2013.

   [I-D.ward-irs-framework] Atlas, A., Nadeau, T., Ward. D., "Interface
              to the Routing System Framework", draft-ward-irs-
              framework-00, July 2012.



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   [I-D.rfernando-irs-framework-requirement] Fernando, R., Medved, J.,
              Ward, D., Atlas, A., Rijsman, B., "IRS Framework
              Requirements", draft-rfernando-irs-framework-requirement-
              00, Oct. 2012.

   [I-D.mahalingam-dutt-dcops-vxlan]: Mahalingam, M, Dutt, D.., et al.,
              "A Framework for Overlaying Virtualized Layer 2 Networks
              over Layer 3 Networks" draft-mahalingam-dutt-dcops-vxlan-
              03, Feb. 2013.

   [I-D.sridharan-virtualization-nvgre]: SridharanNetwork, M., et al.,
              "Virtualization using Generic Routing Encapsulation",
              draft-sridharan-virtualization-nvgre-02.txt, Feb. 2013.


11. Acknowledgement

   The authors would like to thank Vaughn Suazo for his review and
   comments.

Authors' Addresses


   Luyuan Fang
   Cisco
   111 Wood Ave. South
   Iselin, NJ 08830
   US
   Email: lufang@cisco.com

   John Evans
   Cisco
   16-18 Finsbury Circus
   London, EC2M 7EB
   UK
   Email: joevans@cisco.com

   David Ward
   Cisco
   170 W Tasman Dr
   San Jose, CA 95134
   US
   Email: wardd@cisco.com

   Rex Fernando
   Cisco
   170 W Tasman Dr
   San Jose, CA



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   US
   Email: rex@cisco.com

   John Mullooly
   Cisco
   111 Wood Ave. South
   Iselin, NJ 08830
   US
   Email: jmullool@cisco.com

   Ning So
   Tata Communications
   Plano, TX 75082, USA
   Email: ning.so@tatacommunications.com

   Nabil Bitar
   Verizon
   40 Sylvan Road
   Waltham, MA 02145
   Email: nabil.bitar@verizon.com

   Maria Napierala
   AT&T
   200 Laurel Avenue
   Middletown, NJ 07748
   Email: mnapierala@att.com

























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