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BESS Working Group                                           Weiguo Hao
                                                              Lucy Yong
                                                               S. Hares
Internet Draft                                                   Huawei
                                                              Osama Zia
                                                              Microsoft
                                                       Muhammad Durrani
                                                                  Cisco
Intended status: Standard Track                         August 11, 2015
Expires: February 2016



         Inter-AS Option C between NVO3 and BGP/MPLS IP VPN network
               draft-hao-bess-inter-nvo3-vpn-optionc-02.txt


Abstract

   This draft describes inter-as option-C solution between NVO3 network
   and MPLS/IP VPN network. Transport layer stitching solution should
   be provided. Also to ensure VPNv4 route exchange correctly between
   local NVE and remote PE, VNID space should be partitioned, only the
   VNIDs of lower 1 Million can be used for interconnection with outer
   MPLS VPN network using option-C solution, the rest 15 Million VNIDs
   can only be used for intra DC.

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
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   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
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   at any time. It is inappropriate to use Internet-Drafts as reference
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   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.




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Copyright Notice

   Copyright (c) 2015 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.

Table of Contents

   1. Introduction ................................................ 2
   2. Conventions used in this document............................ 4
   3. Reference model ............................................. 5
   4. Traditional Option-C [RFC4364] Recap......................... 6
   5. Inter-As Option-C Solution ...................................6
      5.1. EBGP process for transport layer stitching.............. 6
         5.1.1. UDP based overlay network.......................... 7
         5.1.2. GRE based overlay network.......................... 8
      5.2. VPN routes exchange..................................... 8
      5.3. Data forwarding process................................. 9
         5.3.1. Data flow from TS1 to CE1.......................... 9
         5.3.2. Data flow from CE1 to TS1......................... 10
   6. NVE-NVA architecture........................................ 10
      6.1. EBGP process for transport layer stitching............. 11
      6.2. VPN route exchange..................................... 11
   7. Security Considerations..................................... 12
   8. IANA Considerations ........................................ 12
   9. References ................................................. 12
      9.1. Normative References................................... 12
      9.2. Informative References................................. 13
   10. Acknowledgments ........................................... 13

1. Introduction

   In cloud computing era, multi-tenancy has become a core requirement
   for data centers. Since Network Virtualization Overlays (NVO3) can
   satisfy multi-tenancy key requirements, this technology is being
   deployed in an increasing number of cloud data center network. NVO3
   focuses on the construction of overlay networks that operate over an
   IP (L3) underlay transport network. It can provide layer 2 bridging
   and layer 3 IP service for each tenant. VXLAN [RFC7348] and NVGRE
   [NVGRE] are two typical NVO3 technologies. In NVO3 network, 24-bit
   VNID (or VSID) is used to identify different virtual networks,


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   theoretically 16M virtual networks can be supported in a data center.
   MPLS Over GRE and MPLS In UDP [RFC7510] are another two technologies
   to construct the overlay network, 20-bit MPLS Label is used as
   virtual networks identification. NVO3 overlay network can be
   controlled through centralized NVE-NVA architecture or through
   distributed BGP VPN protocol.

   NVO3 has good scaling properties from relatively small networks to
   networks with several million tenant systems (TSs) and hundreds of
   thousands of virtual networks within a single administrative domain.
   In a data center network, each tenant may include one or more layer
   2 virtual network. In normal case, each tenant corresponds to one
   routing domain (RD), each layer 2 virtual network corresponds to one
   or more subnets.

   To provide cloud service to external data center client, data center
   networks should be connected with WAN networks. BGP MPLS/IP VPN has
   already been widely deployed at WAN networks. Normally internal data
   center and external MPLS/IP VPN network are different Autonomous
   System (AS). This requires the setting up of inter-as connections at
   Autonomous System Border Routers(ASBRs) between NVO3 network and
   external MPLS/IP network.

   In multiple NVO3 data center inter-connecting scenario, the traffic
   across data center normally are carried over BGP MPLS/IP VPN network.
   This also requires an applicable inter-as solution between NVO3
   network and external MPLS/IP network.

   Similar to the Inter-as connection method defined in RFC4364, there
   are three different ways of handling this case, they are option-A,
   option-B and option-C respectively in order of increasing
   scalability.

   Option-A is a back-to-back VRFs solution. Using option-A, EBGP
   session per VPN is created on peering ASBRs. In the data-plane,
   VLANs are used for tenant traffic separation. It has the lowest
   scalability among the three solutions. Compared to option-A solution,
   option-B solution has more scalability. But using option-B, ASBRs
   need to maintain and distribute all VPN prefixes. In the data plane,
   ASBRs need to perform MPLS VPN Label switching. Because MPLS VPN
   Label switching table space on ASBRs is limited, it still has
   scalability limitation for large VPN network. Option-C solution is a
   most scalable option through separating VPNv4 and PE prefixes
   exchange, the ASBRs don't need to maintain and distribute the
   customers VPN prefixes. The ASBR is only used to exchange the
   service provider(SP) internal IP.



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   This draft is to propose inter-as option-C solution between NVO3
   network and external BGP MPLS/IP VPN network. Compared to the
   traditional option-C solution defined in [RFC4364], it is for
   heterogeneous network interconnection, the control plane and data
   plane procedures in NVO3 network should be newly specified.

2. Conventions used in this document

   Network Virtualization Edge (NVE) - An NVE is the network entity
   that sits at the edge of an underlay network and implements network
   virtualization functions.

   Tenant System - A physical or virtual system that can play the role
   of a host, or a forwarding element such as a router, switch,
   firewall, etc. It belongs to a single tenant and connects to one or
   more VNs of that tenant.

   VNID - Virtual Network Identifier (for VxLAN)

   VSID - Virtual Subnet Identifier (for NVGRE)

   RD - Route Distinguisher. RDs are used to maintain uniqueness among
   identical routes in different VRFs, The route distinguisher is an 8-
   octet field prefixed to the customer's IP address. The resulting 12-
   octet field is a unique "VPN-IPv4" address.

   RT - Route targets. It is used to control the import and export of
   routes between different VRFs.




















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3. Reference model

   +---------------------------------------------------+
   |  +----+           AS1                             |
   |  | TS1| -                                         |
   |  +----+  -                                        |
   |            - +----+    +----+                     |
   |            - |NVE1| -- |TOR1|---------------+     |
   |  +----+  -   +----+    +----+               |     |
   |  | TS2|-                                    |     |
   |  +----+                                     |     |
   |                                         +-------+ |
   |                           +------------ | ASBR-d|-|--|
   |  +----+                   |             +-------+ |  |
   |  | TS3| -                 |                       |  |
   |  +----+  -                |                       |  |
   |            - +----+    +----+                     |  |
   |            - |NVE2| -- |TOR2|                     |  |
   |  +----+  -   +----+    +----+                     |  |
   |  | TS4|-                                          |  |
   |  +----+                                           |  |
   ----------------------------------------------------|  |
                                        |
   |---------------------------------------------------|  |
   |                   AS2                             |  |
   |  +----+                                           |  |
   |  | CE1| -                                         |  |
   |  +----+  -                                        |  |
   |            - +----+                     +-------+ |  |
   |            - | PE1| --------------------| ASBR-w|-|--|
   |  +----+  -   +----+                     +-------+ |
   |  | CE2|-                                          |
   |  +----+                                           |
   |---------------------------------------------------|
                         Figure 1 Reference model

   Figure 1 shows an arbitrary Multi-AS VPN interconnectivity scenario
   between NVO3 network and BGP MPLS/IP VPN network. NVE1, NVE2, and
   ASBR-d forms NVO3 overlay network in internal DC. TS1 and TS2
   connect to NVE1, TS3 and TS4 connect to NVE2. PE1 and ASBR-w forms
   MPLS IP/VPN network in external DC. CE1 and CE2 connect to PE1. The
   NVO3 network is in AS 1, the MPLS/IP VPN network is in AS 2.

   There are two tenants in NVO3 network, TSs in tenant 1 can freely
   communicate with CEs in VPN-Red, TSs in tenant 2 can freely
   communicate with CEs in VPN-Green. TS1 and TS3 belong to tenant 1,
   TS2 and TS4 belong to tenant 2. CE1 belongs to VPN-Red , CE2 belongs


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   to VPN-Green. VNID 10 and VNID 20 are used to identify tenant1 and
   tenant2 respectively. PE1 assigned MPLS VPN Label 1000 and 2000 for
   the routes from CE1 and CE2 respectively.

4. Traditional Option-C [RFC4364] Recap

   In traditional Option-C defined in [RFC4364], an MP-EBGP session
   between the end PEs in source and destination ASs is used for the
   redistribution of VPN-IPv4 routes. Labeled IPv4 routes are
   redistributed by EBGP between neighboring autonomous systems to
   establish an end to end label-switched path, inter-AS Option-C uses
   BGP as the label distribution protocol. Through this solution, VPN
   connectivity is maintained while keeping VPN-IPv4 routes out of the
   ASBRs, an ASBR only need maintain labeled IPv4/32 routes to the PE
   routers within its AS. If the /32 routes for the PE routers are NOT
   made known to the P routers(other than the ASBRs), then a packet's
   ingress PE need to put a three-label stack on it. The bottom label
   is assigned by the egress PE, corresponding to the packet's
   destination address in a particular VRF.  The middle label is
   assigned by the ASBR, corresponding to the /32 route to the egress
   PE.  The top label is assigned by the ingress PE's IGP Next Hop,
   corresponding to the /32 route to the ASBR.

5. Inter-As Option-C Solution

   Each NVE operates as default layer 3 gateway for local connecting
   TS(s). VRFs are created on each NVE to isolate IP forwarding process
   between different tenants. At least a VNID(or VSID and MPLS Label)
   is used as identification for each tenant.

   Similar to traditional Option-C defined in [RFC4364], an end to end
   tunnel path from NVE to PE as transport layer should be established
   firstly through EBGPs (AS-AS) and IBGPs (AS-PE and AS-NVE), and then
   run MP-BGP over the tunnel so VPN-IPv4 routes can be exchanged
   between the NVE and PE without AS awareness. Unlike traditional
   Option-C BGP label switched path, the tunnel path has two segments,
   one segment from NVE to ASBR-d in NVO3 network is NVO3 tunnel,
   another segment from ASBR-d to PE in WAN network is traditional BGP
   LSP, the two segments should be stitched together, the stitching
   point is at ASBR-d. The behavior on ASBR-w and PEs in MPLS VPN
   network has no difference with the behavior of ASBR and PEs in
   traditional RFC4364 based MPLS VPN Option-C network.

5.1. EBGP process for transport layer stitching

   This section will describe the EBGP procedures for the transport
   layer forwarding path stitching.


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   In WAN to DC direction, when ASBR-d receives labeled IPv4/32 routes
   from ASBR-w, IP allocation method, UDP port allocation method and
   GRE key allocation method can be used for the stitching. Which
   method should be chosen by the operators depends on the data center
   network type and the network scale. For the UDP based network of
   VXLAN [RFC7348] and MPLS In UDP [RFC7510], either IP allocation
   method or UDP port allocation method can be used. UDP port
   allocation should be within UDP ephemeral port range. For NVGRE
   network, only IP allocation method can be used. For MPLS Over GRE
   network, either IP allocation method or GRE key allocation method
   can be used.

   In DC to WAN direction, the transport layer stitching solution is
   same for all kinds of NVO3 network. In this solution, ASBR-d
   announces labeled IPv4/32 routes to ASBR-w for each NVE where unique
   MPLS Label is allocated for each NVE. The allocated MPLS Label and
   NVE IP address mapping forms incoming forwarding table which is used
   to stitch BGP LSP and NVO3 tunnel for inbound traffic forwarding,
   i.e., from external DC to internal DC.



5.1.1. UDP based overlay network

   Both VXLAN and MPLS In UDP are UDP based encapsulations. For the
   outbound traffic from NVE to ASBR-d, there are two options at ASBR-d,
   i.e., the ASBR-d only accepts the traffic with standard destination
   UDP port(4789 for VXLAN [RFC7348], 6635 for MPLS In UDP [RFC7510])
   or non-standardized destination UDP port in outer UDP header
   encapsulation.

   In WAN to DC direction, if standard destination UDP port solution is
   used, when ASBR-d receives labeled IPv4/32 routes from ASBR-w, IP
   address allocation method should be used. The ASBR allocates an IP
   address per MPLS Label specified for a particular route defined in
   [RFC3107] to identify each remote PE, and then advertises the
   IPv4/32 route to all local NVEs with the VXLAN or MPLS In UDP tunnel
   attribute. [TUNNELENCAP] defines the relevant TLVs and sub-TLVs for
   the Tunnel Encapsulation Attribute. The local NVEs will encapsulate
   transport layer header using the Tunnel Encapsulation Attribute for
   the traffic from internal DC to external DC, the new allocated IP is
   the destination IP in NVO3 tunnel outer header, the UDP port is the
   standard well-known port for VXLAN and MPLS In UDP. The IP pool
   should be configured in beforehand on ASBR-d. The new allocated IP
   and MPLS Label correspondence forms outgoing forwarding table on
   ASBR-d which is used to stitch NVO3 tunnel and BGP LSP for outbound
   traffic forwarding. If non-standard destination UDP port is used,


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   ASBR-d can allocate the combination of IP and UDP port(or only UDP
   port) per MPLS Label to identify each remote PE, and then advertises
   the IPv4/32 route received from ASBR-w to all local NVEs with the
   Tunnel Encapsulation Attribute. For each NVE, the destination IP and
   the destination port in NVO3 tunnel outer header is the new
   allocated IP and the new allocated port respectively. The new
   allocated IP and UDP port combination (or only UDP port) and MPLS
   Label correspondence forms outgoing forwarding table on ASBR-d. This
   method is called UDP allocation method, the allocated UDP port range
   should be configured in beforehand on ASBR-d.

   In summary, IP allocation method has more IP address consumption
   than the UDP allocation method. If there is large number of remote
   PEs in WAN network, the UDP allocation method is suggested to be
   used to enhance network scalability.

5.1.2. GRE based overlay network

   Both NVGRE and MPLS Over GRE are GRE based encapsulations. The GRE
   key field can be used to convey application-specific key value. In
   NVGRE, the key field has been used to convey 24-bit Virtual Subnet
   Identifier (VSID) as tenant identification, so for NVGRE, the GRE
   key field can't be used for the stitching purpose and only IP
   allocation method can be used. In MPLS Over GRE, the GRE key field
   has not been used explicitly by an application and can be used for
   the transport layer stitching at ASBR-d, i.e., GRE key allocation
   method can be used to conserve IP address space.

   In WAN to DC direction, for MPLS Over GRE, when ASBR-d receives
   labeled IPv4/32 routes from ASBR-w, the ASBR can allocate a GRE key
   per MPLS Label to identify each remote PE, and then advertises the
   IPv4/32 route to all local NVEs with the Tunnel Encapsulation
   Attribute. The new allocated GRE key and MPLS Label correspondence
   forms outgoing forwarding table on ASBR-d. This method is called GRE
   key allocation method.



   If ASBR-d needs to change IP address, UDP port or GRE key for a
   particular /32 route, it should advertising a new route with the
   same NLRI and a new Tunnel Encapsulation Attribute to refresh all
   NVEs's local information.

5.2. VPN routes exchange

   Each NVE and remote PE should establish MP-EBGP session for the
   announcement of VPN-IPv4 routes through RFC4364. Route


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   distinguishers (RD) and RT are specified for each VRF on each NVE
   and PE.

   Each NVE advertises all local VPN route to remote PEs using tenant
   identification VNID (or VSID and MPLS Label) as MPLS VPN Label.
   These remote PEs deal with the NVE as regular PE, they match RT and
   populates these VPN route to local VRF. For the traffic from remote
   CE to local TS, ingress PE uses the VNID as bottom label in MPLS
   encapsulation. Because VNID field is 24 bits, to ensure these NVEs
   and PEs interworking, VNID length should not beyond 20 bits, i.e.,
   VNID value must not be larger than 1 Million. In NVO3 network, VNID
   space should be partitioned, only the VNIDs of lower 1 Million can
   be used for interconnection with outer MPLS VPN network, the rest 15
   Million VNIDs can only be used for intra DC.

   Each MPLS VPN PE also advertises all local VPN route to peer NVEs,
   these NVEs match RT and populates these VPN route to local VRF. For
   the traffic from local TS to remote CE, because ingress NVE doesn't
   support MPLS encapsulation, it encoded the MPLS VPN Label advertised
   from remote PE as VNID in NVO3 encapsulation.

5.3. Data forwarding process

   When VXLAN network and UDP port allocation method are used in data
   center, the procedures of data forwarding between TS1 and CE1 in
   figure 1 will be described step by step as follows.

5.3.1. Data flow from TS1 to CE1

   1. TS1 sends a packet to NVE1, destination IP is CE1's IP.

   2. NVE1 acquires local VRF relying on packet input interface, then
      looks up the VRF's routing table corresponding to tenant 1,
      performs NVO3 encapsulation, and then sends the encapsulation
      packet to ASBR-d. The MPLS VPN Label associated with the packet's
      destination address is encoded in VNID field. VXLAN tunnel
      destination IP and destination UDP port are the new IP address
      and UDP port allocated on ASBR-d associated with the /32 routes
      for the PE routers that the remote CE attached.

   3. ASBR-d decapsulates the VXLAN encapsulation and then performs
      MPLS encapsulation. Two Labels should be pushed for the MPLS
      encapsulation, BGP LSP Label as top Label and MPLS VPN Label as
      bottom Label. BGP LSP Label is acquired by looking up outgoing
      stitching table, MPLS VPN Label is copied from VNID.




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   4. ASBR-w swaps BGP MPLS Label, then push IGP Label and sends the
      packet to PE1. MPLS VPN Label remains unchanged.

   5. PE1 pops all MPLS Label, finds local VRF relying on bottom MPLS
      VPN Label, looks up local IP forwarding table in the VRF, and
      then sends the packet to CE1.

5.3.2. Data flow from CE1 to TS1

   1. CE1 sends a packet to PE1, destination IP is TS1's IP.

   2. PE1 acquires local VRF relying on packet input interface, then
      looks up the VRF's routing table. It puts a three-label stack on
      it. The bottom label is the tenant VNID corresponds to TS1, the
      VNID is 10. The middle label is assigned by the ASBR-w,
      associating with the /32 route for the egress NVE1. The top label
      is assigned by the ingress PE's IGP Next Hop, corresponding to
      the /32 route to ASBR-w.

   3. ASBR-w pops top IGP Label, swaps middle BGP Label, and then sends
      the packet to ASBR-d.

   4. ASBR-d decapsulates MPLS encapsulation, performs VXLAN
      encapsulation and then sends the packet to egress NVE1. The
      egress NVE's IP address is acquired relying on looking up
      incoming stitching table, VNID is copied from the bottom MPLS
      Label ,i.e., MPLS VPN Label.

   5. NVE1 decapsulates NVO3 encapsulation, finds local VRF relying on
      VNID, looks up routing table and then sends the packet to TS1.



6. NVE-NVA architecture

   In this architecture, the NVE control plane and forwarding
   functionality are decoupled. All NVEs in NVO3 network don't need to
   support BGP protocol, these NVEs have only data plane functionality
   and are controlled by centralized NVA using openflow, ovsdb, i2rs,
   etc. The NVA runs BGP with ASBR-d to exchange plain /32 IP route of
   each remote PE associated with the BGP tunnel encapsulation
   attribute. The NVA also runs MP-BGP protocol [RFC4364] with remote
   PE for all the NVEs to exchange VPNv4 route, VNID is used as MPLS
   VPN Label. ASBR-d can choose IP allocation, UDP allocation or GRE
   key allocation method for the transport stitching.




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   NVA maintains all tenant information, and originates BGP routes with
   the appropriate RD and RT.  The NVA tenant information includes
   VNID(or VSID and MPLS Label) to identify each tenant and the
   corresponding RD and RT. This information can be statically
   configured by operators or dynamically allocated. This information
   also includes all TS's MAC/IP address and its attached NVE
   information.

6.1. EBGP process for transport layer stitching

   DC to WAN direction:

   1. ASBR-d allocates BGP MPLS Label per NVE.

   2. ASBR-d advertises BGP Label routing information to peer ASBR-w.
      ASBR-d generates incoming stitching table <new allocated BGP MPLS
      Label, NVE IP>.

   WAN to DC direction:

   1. ASBR-d receives BGP Label routing information from peer ASBR-w.

   2. ASBR-d allocates NVO3 Tunnel IP, UDP port or GRE key for each
      MPLS Label received from ASBR-w, the ASBR-d announces the /32
      Route to NVA with the Tunnel Encapsulation Attribute.

   3. ASBR-d generates outgoing stitching table<new allocated Tunnel
      IP(or UDP port and GRE key), received MPLS Label>.

6.2. VPN route exchange

     NVA advertises all internal data center tenant routing information
     to remote PEs using RFC 4364, which includes RD, RT, IP prefix,
     and MPLS VPN Label, the tenant identification of VNID(or VSID and
     MPLS Label) is used as MPLS VPN Label.

     Each remote MPLS VPN PE also advertises local VPN routes to NVA.
     NVA acquires NVO3 Tunnel IP(or UDP port and GRE key) allocated by
     ASBR-d corresponding to the PE, matches RT attribute and populates
     the VPN routes to local VRF.

     Then the NVA downloads corresponding VPN forwarding table
     including <destination IP prefix/Mask, NVO3 Tunnel IP(or UDP port
     and GRE key), VNID>to each NVE.



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                               VPN route exchange
          -------------------------------------------------
          |                                               |
         ------ IBGP --------   EBGP   --------         -----
         |NVA | -----|ASBR-d |-------- |ASBR-w |--------|PE |
         ------      --------          --------         -----
           .
           . Southbound interface(Openflow,OVSDB,I2RS,etc)
      ............
      .          .
      .          .
      .          .
   ------     ------
   |NVE1|     |NVE2|
   ------     ------
                       Figure 2 NVE-NVA Architecture

7. Security Considerations

   Internal IP (Loopback IP for PE/NVE) addresses a network is
   advertised and visible in another network, which is a security risk.
   Most operators wants to prevent any external visibility and access
   into their internal devices IP. option C is suggested to be deployed
   within a single SP or enterprise with both MPLS and NVO3 networks.

8. IANA Considerations

   NA.

9. References

9.1. Normative References

[1]  [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate

      Requirement Levels", BCP 14, RFC 2119, March 1997.

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

[3]  [RFC3107] Y. Rekhter,E. Rosen, ''Carrying Label Information in
      BGP-4'', RFC 3107, May 2001






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9.2. Informative References

   [1]   [NVA] D.Black, etc, "An Architecture for Overlay Networks
         (NVO3)", draft-ietf-nvo3-arch-01, February 14, 2014

   [2]   [RFC7047]  B. Pfaff, B. Davie,''The Open vSwitch Database
         Management Protocol'', RFC 7047, December 2013

   [3]  [OpenFlow1.3]OpenFlow Switch Specification Version 1.3.0 (Wire
         Protocol 0x04). June 25, 2012.
         (https://www.opennetworking.org/images/stories/downloads/sdn-
         resources/onf-specifications/openflow/openflow-spec-v1.3.0.pdf)

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

   [5]  [NVGRE] P. Garg, etc, "NVGRE: Network Virtualization using
         Generic Routing Encapsulation", draft-sridharan-
         virtualization-nvgre-08, April 13, 2015.

   [6]  [TUNNELENCAP] E. Rosen, etc, "Using the BGP Tunnel
         Encapsulation Attribute without the BGP Encapsulation SAFI",
         draft-rosen-idr-tunnel-encaps-00, June, 2015.

10. Acknowledgments

   Authors like to thank Thomas Morin, Dacheng Zhang, Shunwan Zhuang,
   Haibo Wang, Jie Dong for their valuable inputs.

Authors' Addresses

   Weiguo Hao
   Huawei Technologies
   101 Software Avenue,
   Nanjing 210012
   China
   Phone: +86-25-56623144
   Email: haoweiguo@huawei.com


   Lucy Yong
   Huawei Technologies
   Phone: +1-918-808-1918
   Email: lucy.yong@huawei.com




Hao & et,al           Expires February 11, 2016              [Page 13]


Internet-Draft            Inter-As Option-C                   May 2015


   Susan Hares
   Huawei Technologies
   Phone: +1-734-604-0323
   Email: shares@ndzh.com.


   Osama Zia
   Microsoft
   Email: osamaz@microsoft.com


   Muhammad Durrani
   Cisco
   Phone: +1-408-527-6921
   Email: mdurrani@cisco.com

































Hao & et,al           Expires February 11, 2016              [Page 14]


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