Network Working Group L. Dunbar Internet Draft Futurewei Intended status: Informational A. Malis Expires: January 26, 2021 Malis Consulting C. Jacquenet Orange July 26, 2020 Networks Connecting to Hybrid Cloud DCs: Gap Analysis draft-ietf-rtgwg-net2cloud-gap-analysis-07 Abstract This document analyzes the IETF routing area technical gaps that may affect the dynamic connection to workloads and applications hosted in hybrid Cloud Data Centers from enterprise premises. Status of this Memo This Internet-Draft is submitted 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. 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 material or to cite them other than as "work in progress." 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 This Internet-Draft will expire on January 26, 2009. xxx, et al. Expires January 26, 2021 [Page 1] Internet-Draft Net2Cloud Gap Analysis July 2020 Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction...................................................3 2. Conventions used in this document..............................3 3. Gap Analysis for Accessing Cloud Resources.....................4 3.1. Multiple PEs connecting to virtual CPEs in Cloud DCs......6 3.2. Access Control for workloads in the Cloud DCs.............6 3.3. NAT Traversal.............................................7 3.4. BGP between PEs and remote CPEs via Internet..............7 3.5. Multicast traffic from/to the remote edges................8 4. Gap Analysis of Traffic over Multiple Underlay Networks........9 5. Aggregating VPN paths and Internet paths......................10 5.1. Control Plane for Cloud Access via Heterogeneous Networks11 5.2. Using BGP UPDATE Messages................................12 5.2.1. Lack ways to differentiate traffic in Cloud DCs.....12 5.2.2. Miss attributes in Tunnel-Encap.....................12 5.3. SECURE-EVPN/BGP-EDGE-DISCOVERY...........................12 5.4. SECURE-L3VPN.............................................13 5.5. Preventing attacks from Internet-facing ports............14 6. Gap Summary...................................................14 7. Manageability Considerations..................................15 8. Security Considerations.......................................16 9. IANA Considerations...........................................16 10. References...................................................16 10.1. Normative References....................................16 10.2. Informative References..................................16 11. Acknowledgments..............................................17 Dunbar, et al. Expires January 26, 2021 [Page 2] Internet-Draft Net2Cloud Gap Analysis July 2020 1. Introduction [Net2Cloud-Problem] describes the problems enterprises face today when interconnecting their branch offices with dynamic workloads hosted in third party data centers (a.k.a. Cloud DCs). In particular, this document analyzes the available routing protocols to identify whether there are any gaps that may impede such interconnection which may for example justify additional specification effort to define proper protocol extensions. For the sake of readability, an edge, C-PE, or CPE are used interchangeably throughout this document. More precisely: . Edge: may include multiple devices (virtual or physical); . C-PE: provider-owned edge, e.g. for SECURE-EVPN's PE-based BGP/MPLS VPN, where PE is the edge node; . CPE: device located in enterprise premises. 2. Conventions used in this document Cloud DC: Third party Data Centers that usually host applications and workload owned by different organizations or tenants. Controller: Used interchangeably with Overlay controller to manage overlay path creation/deletion and monitor the path conditions between sites. CPE-Based VPN: Virtual Private Network designed and deployed from CPEs. This is to differentiate from most commonly used PE-based VPNs a la RFC 4364. OnPrem: On Premises data centers and branch offices Dunbar, et al. Expires January 26, 2021 [Page 3] Internet-Draft Net2Cloud Gap Analysis July 2020 3. Gap Analysis for Accessing Cloud Resources Because of the ephemeral property of the selected Cloud DCs for specific workloads/Apps, an enterprise or its network service provider may not have direct physical connections to the Cloud DCs that are optimal for hosting the enterprise's specific workloads/Apps. Under those circumstances, an overlay network design can be an option to interconnect the enterprise's on-premises data centers & branch offices to its desired Cloud DCs. However, overlay paths established over the public Internet can have unpredictable performance, especially over long distances. Therefore, it is highly desirable to minimize the distance or the number of segments that traffic had to be forwarded over the public Internet. The Metro Ethernet Forum's Cloud Service Architecture [MEF-Cloud] also describes a use case of network operators using Overlay paths over an LTE network or the public Internet for the last mile access where the VPN service providers cannot always provide the required physical infrastructure. In some scenarios, some overlay edge nodes may not be directly attached to the PEs that participate to the delivery and the operation of the enterprise's VPN. When using an overlay network to connect the enterprise's sites to the workloads hosted in Cloud DCs, the existing C-PEs at enterprise's sites have to be upgraded to connect to the said overlay network. If the workloads hosted in Cloud DCs need to be connected to many sites, the upgrade process can be very expensive. [Net2Cloud-Problem] describes a hybrid network approach that extends the existing MPLS-based VPNs to the Cloud DC Workloads over the access paths that are not under the VPN provider's control. To make it work properly, a small number of the PEs of the BGP/MPLS VPN can be designated to connect to the remote workloads via secure IPsec tunnels. Those designated PEs are shown as fPE (floating PE or smart PE) in Figure 3. Once the secure IPsec tunnels are established, the workloads hosted in Cloud DCs can be reached by the enterprise's VPN without upgrading all of the enterprise's CPEs. The Dunbar, et al. Expires January 26, 2021 [Page 4] Internet-Draft Net2Cloud Gap Analysis July 2020 only CPE that needs to connect to the overlay network would be a virtualized CPE instantiated within the cloud DC. +--------+ +--------+ | Host-a +--+ +----| Host-b | | | | (') | | +--------+ | +-----------+ ( ) +--------+ | +-+--+ ++-+ ++-+ +--+-+ (_) | | CPE|--|PE| |PE+--+ CPE| | +--| | | | | | | |---+ +-+--+ ++-+ ++-+ +----+ / | | / | MPLS +-+---+ +--+-++--------+ +------+-+ | Network |fPE-1| |CPE || Host | | Host | | | |- --| || d | | c | +-----+ +-+---+ +--+-++--------+ +--------+ |fPE-2|-----+ +---+-+ (|) (|) (|) Overlay (|) (|) over any access +=\======+=========+ // \ | Cloud DC \\ // \ ++-----+ \\ + | | vCPE | +-+----+ ----+-------+-------+----- | | +---+----+ +---+----+ | Remote | | Remote | | App-1 | | App-2 | +--------+ +--------+ Figure 1: VPN Extension to Cloud DC In Figure 1, the optimal Cloud DC to host the workloads (as a function of the proximity, capacity, pricing, or any other criteria chosen by the enterprises) does not have a direct connection to the PEs of the NGP/MPLS VPN that interconnects the enterprise's sites. Dunbar, et al. Expires January 26, 2021 [Page 5] Internet-Draft Net2Cloud Gap Analysis July 2020 3.1. Multiple PEs connecting to virtual CPEs in Cloud DCs To extend BGP/MPLS VPNs to virtual CPEs in Cloud DCs, it is necessary to establish secure tunnels (such as IPsec tunnels) between the PEs and the vCPEs. Even though a set of PEs can be manually selected for a specific cloud data center, there are no standard protocols for those PEs to interact with the vCPEs instantiated in the third party cloud data centers over unsecure networks. The interaction includes exchanging performance, route information, etc.. When there is more than one PE available for use (as there should be for resiliency purposes or because of the need to support multiple cloud DCs geographically scattered), it is not straightforward to designate an egress PE to remote vCPEs based on applications. It might not be possible for PEs to recognize all applications because too much traffic traversing the PEs. When there are multiple floating PEs that have established IPsec tunnels with a remote CPE, the remove CPE can forward outbound traffic to the optimal PE, which in turn forwards traffic to egress PEs to reach the final destinations. However, it is not straightforward for the ingress PE to select which egress PEs to send traffic. For example, in Figure 1: - fPE-1 is the optimal PE for communication between App-1 <-> Host-a due to latency, pricing or other criteria. - fPE-2 is the optimal PE for communication between App-1 <-> Host-b. 3.2. Access Control for workloads in the Cloud DCs There is widespread diffusion of access policy for Cloud Resource, some of which is not easy for verification and validation. Because there are multiple parties involved in accessing Cloud Resources, policy enforcement points are not easily visible for policy refinement, monitoring, and testing. Dunbar, et al. Expires January 26, 2021 [Page 6] Internet-Draft Net2Cloud Gap Analysis July 2020 The current state of the art for specifying access policies for Cloud Resources could be improved by having automated and reliable tools to map the user-friendly (natural language) rules into machine readable policies and to provide interfaces for enterprises to self- manage policy enforcement points for their own workloads. 3.3. NAT Traversal Cloud DCs that only assign private IPv4 addresses to the instantiated workloads assume that traffic to/from the workload usually needs to traverse NATs. There is no automatic way for an enterprise's network controller to be informed of the NAT properties for its workloads in Cloud DCs One potential solution could be utilizing the messages sent during initialization of an IKE VPN when NAT Traversal option is enabled. There are some inherent problems while sending IPSec packets through NAT devices. One way to overcome these problems is to encapsulate IPSec packets in UDP. To do this effectively, there is a discovery phase in IKE (Phase1) that tries to determine if either of the IPSec gateways is behind a NAT device. If a NAT device is found, IPSec- over-UDP is proposed during IPSec (Phase 2) negotiation. If there is no NAT device detected, IPSec is used Another potential solution could be allowing the virtual CPE in Cloud DCs to solicit a STUN (Session Traversal of UDP Through Network Address Translation, [RFC3489]) Server to get the information about the NAT property, the public IP addresses and port numbers so that such information can be communicated to the relevant peers. 3.4. BGP between PEs and remote CPEs via Internet Even though an EBGP (external BGP) Multi-Hop design can be used to connect peers that are not directly connected to each other, there are still some issues about extending BGP from MPLS VPN PEs to remote CPEs in cloud DCs via any access path (e.g., Internet). The path between the remote CPEs and VPN PEs that maintain VPN routes can traverse untrusted segments. Dunbar, et al. Expires January 26, 2021 [Page 7] Internet-Draft Net2Cloud Gap Analysis July 2020 EBGP Multi-hop design requires configuration on both peers, either manually or via NETCONF from a controller. To use EBGP between a PE and remote CPEs, the PE has to be manually configured with the "next-hop" set to the IP address of the CPEs. When remote CPEs, especially remote virtualized CPEs are dynamically instantiated or removed, the configuration of Multi-Hop EBGP on the PE has to be changed accordingly. Egress peering engineering (EPE) is not sufficient. Running BGP on virtualized CPEs in Cloud DCs requires GRE tunnels to be established first, which requires the remote CPEs to support address and key management capabilities. RFC 7024 (Virtual Hub & Spoke) and Hierarchical VPN do not support the required properties. Also, there is a need for a mechanism to automatically trigger configuration changes on PEs when remote CPEs' are instantiated or moved (leading to an IP address change) or deleted. EBGP Multi-hop design does not include a security mechanism by default. The PE and remote CPEs need secure communication channels when connecting via the public Internet. Remote CPEs, if instantiated in Cloud DCs might have to traverse NATs to reach PEs. It is not clear how BGP can be used between devices located beyond the NAT and the devices located behind the NAT. It is not clear how to configure the Next Hop on the PEs to reach private IPv4 addresses. 3.5. Multicast traffic from/to the remote edges Among the multiple floating PEs that are reachable from a remote CPE in a Cloud DC, multicast traffic sent by the remote CPE towards the MPLS VPN can be forwarded back to the remote CPE due to the PE receiving the multicast packets forwarding the multicast/broadcast frame to other PEs that in turn send to all attached CPEs. This process may cause traffic loops. Dunbar, et al. Expires January 26, 2021 [Page 8] Internet-Draft Net2Cloud Gap Analysis July 2020 This problem can be solved by selecting one floating PE as the CPE's Designated Forwarder, similar to TRILL's Appointed Forwarders [RFC6325]. BGP/MPLS VPNs do not have features like TRILL's Appointed Forwarders. 4. Gap Analysis of Traffic over Multiple Underlay Networks Very often the Hybrid Cloud DCs are interconnected by multiple types of underlay networks, such as VPN, public Internet, wireless and wired infrastructures, etc. Sometimes the enterprises' VPN providers do not have direct access to the Cloud DCs that host some specific applications or workloads operated by the enterprise. When reached by an untrusted network, all sensitive data to/from this virtual CPE have to be encrypted, usually by means of IPsec tunnels. When reached by a trusted direct connect paths, sensitive data can be forwarded without encryption for better performance. If a virtual CPE in Cloud DC can be reached by both trusted and untrusted paths, better performance can be achieved to have a mixed encrypted and unencrypted traffic depending which paths the traffic is forwarded. However, there is no appropriate control plane protocol to achieve this automatically. Some networks achieve the IPsec tunnel automation by using the modified NHRP protocol [RFC2332] to register network facing ports of the edge nodes with their Controller (or NHRP server), which then maps a private VPN address to a public IP address of the destination node/port. DSVPN [DSVPN] or DMVPN [DMVPN] are used to establish tunnels between WAN ports of SDWAN edge nodes. NHRP was originally intended for ATM address resolution, and as a result, it misses many attributes that are necessary for dynamic virtual C-PE registration to the controller, such as: - Interworking with the MPLS VPN control plane. An overlay edge can have some ports facing the MPLS VPN network over which packets can be forwarded without any encryption and some ports facing the Dunbar, et al. Expires January 26, 2021 [Page 9] Internet-Draft Net2Cloud Gap Analysis July 2020 public Internet over which sensitive traffic needs to be encrypted. - Scalability: NHRP/DSVPN/DMVPN work fine with small numbers of edge nodes. When a network has more than 100 nodes, these protocols do not scale well. - NHRP does not have the IPsec attributes, which are needed for peers to build Security Associations over the public Internet. - NHRP messages do not have any field to encode the C-PE supported encapsulation types, such as IPsec-GRE or IPsec-VxLAN. - NHRP messages do not have any field to encode C-PE Location identifiers, such as Site Identifier, System ID, and/or Port ID. - NHRP messages do not have any field to describe the gateway(s) to which the C-PE is attached. When a C-PE is instantiated in a Cloud DC, it is desirable for the C-PE's owner to be informed about how and where the C-PE is attached. - NHRP messages do not have any field to describe C-PE's NAT properties if the C-PE is using private IPv4 addresses, such as the NAT type, Private address, Public address, Private port, Public port, etc. 5. Aggregating VPN paths and Internet paths Most likely, enterprises (especially the largest ones) already have their C-PEs interconnected by VPNs, based upon VPN techniques like EVPN, L2VPN, or L3VPN. Their VPN providers might have direct paths/links to the Cloud DCs that host their workloads and applications. When there is short term high traffic volume that can't justify increasing the VPNs capacity, enterprises can utilize public internet to reach their Cloud vCPEs. Then it is necessary for the vCPEs to communicate with the controller on how traffic is distributed among multiple heterogeneous underlay networks and to manage secure tunnels over untrusted networks. Dunbar, et al. Expires January 26, 2021 [Page 10] Internet-Draft Net2Cloud Gap Analysis July 2020 +---+ +--------------|RR |----------+ / Untrusted +-+-+ \ / +---------------------- / | \ Cloud DC +----+ +---------+ packets encrypted over | +------+ +----+ | TN3|--| A1-----+ Untrusted +-------+ |--| TN1| +----+ | C-PE A2-\ | | vCPE | +----+ +----+ | A A3--+--+ +---+ | | B | +----+ | TN2|--| | |PE+--------------+PE |---+ |--| TN3| +----+ +---------+ +--+ trusted +---+ | +------+ +----+ | WAN | | +----+ +---------+ +--+ packets +---+ | +------+ +----+ | TN1|--| C1--|PE| go natively |PE |---+ |--| TN1| +----+ | C-PE C2--+--+ without encry+---+ | | vCPE | +----+ | C | +--------------+ | | D | | | | | | +----+ | C3--| without encrypt over | | | +----+ | TN2|--| C4--+---- Untrusted --+------+ |--| TN2| +----+ +---------+ | +------+ +----+ | +------------------------ Figure 2: vCPEs reached by Hybrid Paths 5.1. Control Plane for Cloud Access via Heterogeneous Networks The Control Plane for managing applications and workloads in cloud DCs reachable by heterogeneous networks need to include the following properties: - vCPE in a cloud DCs needs to communicate with its controller of the properties of the directly connected underlay networks. - Need Controller-facilitated IPsec SA attributes and NAT information distribution o The controller facilitates and manages the peer authentication for all IPsec tunnels terminated at the vCPEs. - Establishing and Managing the topology and reachability for services attached to the vCPEs in Cloud DCs. o This is for the overlay layer's route distribution, so that a vCPE can populate its overlay routing table with Dunbar, et al. Expires January 26, 2021 [Page 11] Internet-Draft Net2Cloud Gap Analysis July 2020 entries that identify the next hop for reaching a specific route/service attached to the vCPEs. 5.2. Using BGP UPDATE Messages 5.2.1. Lack ways to differentiate traffic in Cloud DCs One enterprise can have different types of applications in one Cloud DC. Some can be production applications, some can be testing applications, and some can belong to one specific departments. The traffic to/from different applications might need to traverse different network paths or need to be differentiated by Control plane and data plane. BGP already has built-in mechanisms, like Route Target, to differentiate different VPNs. But Route Target (RT) is for MPLS based VPNs, therefore RT is not appropriate to directly apply to virtual paths laid over mixed VPNs, IPsec or public underlay networks. 5.2.2. Miss attributes in Tunnel-Encap [Tunnel-Encap] describes the BGP UPDATE Tunnel Path Attribute that advertises endpoints' tunnel encapsulation capabilities for the respective attached client routes encoded in the MP-NLRI Path Attribute. The receivers of the BGP UPDATE can use any of the supported encapsulations encoded in the Tunnel Path Attribute for the routes encoded in the MP-NLRI Path Attribute. Here are some of the issues raised by using [Tunnel-Encap] to distribute the property of client routes be carried by mixed of hybrid networks: - [Tunnel-Encap] doesn't have encoding methods to advertise that a route can be carried by mixed of IPsec tunnels and other already supported tunnels. - The mechanism defined in [Tunnel-Encap] does not facilitate the exchange of IPsec SA-specific attributes. 5.3. SECURE-EVPN/BGP-EDGE-DISCOVERY [SECURE-EVPN] describes a solution that utilize BGP as control plane for the Scenario #1 described in [BGP-SDWAN-Usage]. It relies upon a Dunbar, et al. Expires January 26, 2021 [Page 12] Internet-Draft Net2Cloud Gap Analysis July 2020 BGP cluster design to facilitate the key and policy exchange among PE devices to create private pair-wise IPsec Security Associations. [Secure-EVPN] attaches all the IPsec SA information to the actual client routes. [BGP-Edge-DISCOVERY] proposes BGP UPDATEs from client routers only include the IPsec SA identifiers (ID) to reference the IPsec SA attributes being advertised by separate Underlay Property BGP UPDATE messages. If a client route can be encrypted by multiple IPsec SAs, then multiple IPsec SA IDs are included in the Tunnel-Encap Path attribute for the client route. [BGP-Edge-DISCOVERY] proposes detailed IPsec SA attributes are advertised in a separate BGP UPDATE for the underlay networks. [Secure-EVPN] and [BGP-Edge-Discovery] differs in the information included in the client routes. [Secure-EVPN] attaches all the IPsec SA information to the actual client routes, whereas the [BGP-Edge- Discovery] only includes the IPsec SA IDs for the client routes. The IPsec SA IDs used by [BGP-Edge-Discovery] is pointing to the SA- Information which are advertised separately, with all the SA- Information attached to routes which describe the SDWAN underlay, such as WAN Ports or Node address. 5.4. SECURE-L3VPN [SECURE-L3VPN] describes a method to enrich BGP/MPLS VPN [RFC4364] capabilities to allow some PEs to connect to other PEs via public networks. [SECURE-L3VPN] introduces the concept of Red Interface & Black Interface used by PEs, where the RED interfaces are used to forward traffic into the VPN, and the Black Interfaces are used between WAN ports through which only IPsec-formatted packets are forwarded to the Internet or to any other backbone network, thereby eliminating the need for MPLS transport in the backbone. [SECURE-L3VPN] assumes PEs use MPLS over IPsec when sending traffic through the Black Interfaces. [SECURE-L3VPN] is useful, but it misses the aspects of aggregating VPN and Internet underlays. In addition: - The [SECURE-L3VPN] assumes that a CPE "registers" with the RR. However, it does not say how. It assumes that the remote CPEs are pre-configured with the IPsec SA manually. For overlay networks to connect Hybrid Cloud DCs, Zero Touch Provisioning is expected. Manual configuration is not an option. Dunbar, et al. Expires January 26, 2021 [Page 13] Internet-Draft Net2Cloud Gap Analysis July 2020 - The [SECURE-L3VPN] assumes that C-PEs and RRs are connected via an IPsec tunnel. For management channel, TLS/DTLS is more economical than IPsec. The following assumption made by [SECURE-L3VPN] can be difficult to meet in the environment where zero touch provisioning is expected: A CPE must also be provisioned with whatever additional information is needed in order to set up an IPsec SA with each of the red RRs - IPsec requires periodic refreshment of the keys. The [SECURE- L3VPN] does not provide any information about how to synchronize the refreshment among multiple nodes. - IPsec usually sends configuration parameters to two endpoints only and lets these endpoints negotiate the key. The [SECURE-L3VPN] assumes that the RR is responsible for creating/managing the key for all endpoints. When one endpoint is compromised, all other connections may be impacted. 5.5. Preventing attacks from Internet-facing ports When C-PEs have Internet-facing ports, additional security risks are raised. To mitigate security risks, in addition to requiring Anti-DDoS features on C-PEs, it is necessary for C-PEs to support means to determine whether traffic sent by remote peers is legitimate to prevent spoofing attacks, in particular. 6. Gap Summary Here is the summary of the technical gaps discussed in this document: - For Accessing Cloud Resources a) Traffic Path Management: when a remote vCPE can be reached by multiple PEs of one provider VPN network, it is not Dunbar, et al. Expires January 26, 2021 [Page 14] Internet-Draft Net2Cloud Gap Analysis July 2020 straightforward to designate which egress PE to the remote vCPE based on applications or performance. b) NAT Traversal: There is no automatic way for an enterprise's network controller to be informed of the NAT properties for its workloads in Cloud DCs. c) There is no loop prevention for the multicast traffic to/from remote vCPE in Cloud DCs. Needs a feature like Appointed Forwarder specified by TRILL to prevent multicast data frames from looping around. d) BGP between PEs and remote CPEs via untrusted networks. - Missing control plane to manage the propagation of the property of networks connected to the virtual nodes in Cloud DCs. BGP UPDATE propagate client's routes information, but don't distinguish underlay networks. - Issues of aggregating traffic over private paths and Internet paths a) Control plane messages for different overlay segmentations needs to be differentiated. User traffic belonging to different segmentations need to be differentiated. b) BGP Tunnel Encap doesn't have ways to indicate a route or prefix that can be carried by both IPsec tunnels and VPN tunnels c) Missing clear methods in preventing attacks from Internet- facing ports 7. Manageability Considerations Zero touch provisioning of overlay networks to interconnect Hybrid Clouds is highly desired. It is necessary for a newly powered up edge node to establish a secure connection (by means of TLS, DTLS, etc.) with its controller. Dunbar, et al. Expires January 26, 2021 [Page 15] Internet-Draft Net2Cloud Gap Analysis July 2020 8. Security Considerations Cloud Services are built upon shared infrastructures, therefore not secure by nature. Secure user identity management, authentication, and access control mechanisms are important. Developing appropriate security measurements can enhance the confidence needed by enterprises to fully take advantage of Cloud Services. 9. IANA Considerations This document requires no IANA actions. RFC Editor: Please remove this section before publication. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 10.2. Informative References [RFC8192] S. Hares, et al, "Interface to Network Security Functions (I2NSF) Problem Statement and Use Cases", July 2017 [RFC5521] P. Mohapatra, E. Rosen, "The BGP Encapsulation Subsequent Address Family Identifier (SAFI) and the BGP Tunnel Encapsulation Attribute", April 2009. [BGP-EDGE-DISCOVERY] L. Dunbar, et al, "BGP UPDATE for SDWAN Edge Discovery ", draft-dunbar-idr-sdwan-edge-discovery-00, Work-in-progress, July 2020. [BGP-SDWAN-Usage] L. Dunbar, et al, "BGP Usage for SDWAN Overlay Networks ", draft-dunbar-bess-bgp-sdwan-usage-08, work-in- progress, July 2020. Dunbar, et al. Expires January 26, 2021 [Page 16] Internet-Draft Net2Cloud Gap Analysis July 2020 [Tunnel-Encap] K. Patel, et al, "The BGP Tunnel Encapsulation Attribute", draft-ietf-idr-tunnel-encaps-17, July 2020. [SECURE-EVPN] A. Sajassi, et al, draft-sajassi-bess-secure-evpn-01, work in progress, March 2019. [SECURE-L3VPN] E. Rosen, "Provide Secure Layer L3VPNs over Public Infrastructure", draft-rosen-bess-secure-l3vpn-00, work- in-progress, July 2018 [DMVPN] Dynamic Multi-point VPN: https://www.cisco.com/c/en/us/products/security/dynamic- multipoint-vpn-dmvpn/index.html [DSVPN] Dynamic Smart VPN: http://forum.huawei.com/enterprise/en/thread-390771-1- 1.html [ITU-T-X1036] ITU-T Recommendation X.1036, "Framework for creation, storage, distribution and enforcement of policies for network security", Nov 2007. [Net2Cloud-Problem] L. Dunbar and A. Malis, "Seamless Interconnect Underlay to Cloud Overlay Problem Statement", draft-dm- net2cloud-problem-statement-02, June 2018 11. Acknowledgments Acknowledgements to John Drake for his review and contributions. Many thanks to John Scudder for stimulating the clarification discussion on the Tunnel-Encap draft so that our gap analysis can be more accurate. This document was prepared using 2-Word-v2.0.template.dot. Dunbar, et al. Expires January 26, 2021 [Page 17] Internet-Draft Net2Cloud Gap Analysis July 2020 Authors' Addresses Linda Dunbar Futurewei Email: ldunbar@futurewei.com Andrew G. Malis Malis Consulting Email: agmalis@gmail.com Christian Jacquenet Orange Rennes, 35000 France Email: Christian.jacquenet@orange.com Dunbar, et al. Expires January 26, 2021 [Page 18]