Network Working Group L. Dunbar Internet Draft Futurewei Intended status: Standard S. Hares Expires: January 2, 2021 Hickory Hill Consulting R. Raszuk Bloomberg LP K. Majumdar CommScope July 2, 2020 BGP UPDATE for SDWAN Edge Discovery draft-dunbar-idr-sdwan-edge-discovery-00 Abstract The document describes encoding of BGP UPDATE messages for the SDWAN edge node discovery. In the context of this document, BGP Route Reflectors (RR) is the component of the SDWAN Controller that receives the BGP UPDATE from SDWAN edges and in turns propagates the information to the intended peers that are authorized to communicate via the SDWAN overlay network. 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 xxx, et al. Expires January 2, 2021 [Page 1] Internet-Draft BGP for SDWAN Edge Discovery July 2020 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on Dec 2, 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. Framework of SDWAN Edge Discovery..............................4 3.1. The Objectives of SDWAN Edge Discovery....................4 3.2. Basic Schemes.............................................4 3.3. Edge Node Discovery using BGP.............................7 4. BGP UPDATE to Support SDWAN Segmentation.......................8 4.1. Constrained Propagation of Edge Capability................9 4.2. SDWAN Segmentation for Control Plane.....................10 4.3. SDWAN Instance Identifier in Data Plane..................12 5. IPsec Tunnel Type for client's routes in Tunnel-Encap.........12 5.1. Encoding.................................................12 5.2. Encoding Example.........................................14 5.2.1. Multiple IPsec SAs Sharing One Tunnel End Point.....14 5.2.2. Multiple IPsec SAs Having different Tunnel End Points16 6. Underlay Network Properties Advertisement using MP-NLRI.......16 6.1. Controller Facilitated IPsec Tunnels for SDWAN Networks..17 6.2. NLRI encoding for Underlay Network Properties............19 6.3. Underlay Properties encoding in the Tunnel Path Attribute22 6.4. Extended Sub-TLV for NAT.................................23 Dunbar, et al. Expires Dec 2, 2021 [Page 2] Internet-Draft BGP for SDWAN Edge Discovery July 2020 6.5. IPsec Security Association Property Sub-TLVs.............25 6.6. IPsec SA Nonce Sub-TLV...................................26 6.7. IPsec Public Key Sub-TLV.................................27 6.8. IPsec SA Proposal Sub-TLV................................28 6.9. ISP of the Underlay network Sub-TLV .....................28 6.10. Simplified IPsec Security Association sub-TLV...........29 6.11. Remote Endpoint.........................................30 7. Error & Mismatch Handling.....................................31 8. Manageability Considerations..................................32 9. Security Considerations.......................................32 10. IANA Considerations..........................................33 11. References...................................................33 11.1. Normative References....................................33 11.2. Informative References..................................33 12. Acknowledgments..............................................34 1. Introduction [SDWAN-BGP-USAGE] illustrates how BGP is used as control plane for a SDWAN network. SDWAN network is an overlay network with some special properties. The document describes a BGP UPDATE for SDWAN edge nodes to announce its properties to its RR which then propagates to the authorized peers. 2. Conventions used in this document Cloud DC: Off-Premise Data Centers that usually host applications and workload owned by different organizations or tenants. Controller: Used interchangeably with SDWAN controller to manage SDWAN overlay path creation/deletion and monitor the path conditions between sites. CPE-Based VPN: Virtual Private Secure network formed among CPEs. This is to differentiate from most commonly used PE- based VPNs a la RFC 4364. MP-NLRI: The MP_REACH_NLRI Path Attribute defined in RFC4760. Dunbar, et al. Expires Dec 2, 2021 [Page 3] Internet-Draft BGP for SDWAN Edge Discovery July 2020 SDWAN End-point: can be the SDWAN edge node address, a WAN port address (logical or physical) of a SDWAN edge node, or a client port address. OnPrem: On Premises data centers and branch offices SDWAN: Software Defined Wide Area Network. In this document, "SDWAN" refers to the solutions of pooling WAN bandwidth from multiple underlay networks to get better WAN bandwidth management, visibility.control and application ID based forwarding for some applications. 3. Framework of SDWAN Edge Discovery 3.1. The Objectives of SDWAN Edge Discovery The objectives of SDWAN edge discovery is for a SDWAN edge node to discover its authorized peers to which its attached clients traffic need to communicate. The attributes to be propagated includes the SDWAN instances supported, the attached routes under specific SDWAN instances, and the properties of the underlay networks over which the client routes can be carried. Some SDWAN peers are connected by both trusted VPNs and untrusted public networks. Some SDWAN peers are connected only by untrusted public networks. For the portion over untrusted networks, IPsec secure tunnels have to be established. If an edge node has network ports behind the NAT, the NAT properties needs to be discovered by authorized SDWAN peers. Just like any VPN networks, the attached client's routes belonging to specific SDWAN instances have to be segmented and only exchanged to the SDWAN peer nodes that are authorized to communicate. 3.2. Basic Schemes There are two types of BGP UPDATE for SDWAN Edge Discovery: - UPDATE for the attached client routes: This is the traditional BGP UPDATEs, i.e. for a SDWAN node to advertise the attached client routes to remote peers. This UPDATE will continue using all the existing BGP attributes, Dunbar, et al. Expires Dec 2, 2021 [Page 4] Internet-Draft BGP for SDWAN Edge Discovery July 2020 such as using the existing AFI/SAFI for IP or VPN. A new IPsec Tunnel Type needs to be added to the Tunnel-Encap Path Attribute [Tunnel-encap]. See Section 5 for the detailed encoding. - UPDATEs for underlay network properties: This UPDATE is for an edge node to advertise the properties of directly attached underlay networks, including the underlay network ISP information, NAT information, the supported IPsec keys, nonce, encryption algorithms, etc. This UPDATE is for peers to discover remote node's properties to establish IPsec tunnels and to traverse NAT. Each established IPsec tunnel has a unique identifier which can be referenced by the Tunnel-Encap Path Attribute to indicate the routes in the NLRI can be carried by the tunnel. In the following figure: there are four types tunnels between C-PE1 and C-PE2: a) MPLS-in-GRE path; b) node-based IPsec tunnel [2.2.2.2<->1.1.1.1]. c) port-based IPsec tunnel [192.0.0.1 <-> 192.10.0.10]; and d) port-based IPsec tunnel [172.0.0.1 <-> 160.0.0.1]; The regular BGP Route UPDATE messages indicate which tunnels the client routes can be carried in the Tunnel-Encap Path Attribute. For example, in the figure below, the client routes 10.1.1.1 and 20.1.1.1 can be carried by IPSec SA terminated at 192.0.0.1, IPSec SA terminated at 170.0.0.1, or MPLS-in-GRE tunnel. Some routes can be carried by the IPsec SA terminated at the node's Loopback address. Dunbar, et al. Expires Dec 2, 2021 [Page 5] Internet-Draft BGP for SDWAN Edge Discovery July 2020 +---+ +--------------|RR |----------+ / Untrusted +-+-+ \ / \ / \ +---------+ MPLS Path +-------+ 11.1.1.x| C-PE1 A1-------------------------------B1 C-PE2 |10.1.1.x | | | | 21.1.1.x| A2(192.10.0.10)------( 192.0.0.1)B2 |20.1.1.x | | | | | Addr A3(160.0.0.1) --------(170.0.0.1)B3 Addr | | 1.1.1.1 | |2.2.2.2| +---------+ +-------+ Figure 1: Hybrid SDWAN BGP UPDATE from C-PE2 for the attached client routes is like: Extended community: RT for SDWAN Instance 1 Prefix: 10.1.1.x; 20.1.1.x NH: C-PE 2 Tunnel Encap Attr [AFI/SAFI = 1/1) MPLS-in-GRE [tunnel type=11] Sub-TLV for MPLS-in-GRE [Section 3.2.6 of Tunnel-encap] IPSec SA for 192.0.0.1 [tunnel type=4] Tunnel-End-Point Sub-TLV [Section 3.1 of Tunnel-encap] IPsec SA sub-TLV [See the Section 5] Tunnel Encap Attr [AFI/SAFI = 1/1) IPSec SA for 170.0.0.1 Tunnel-End-Point Sub-TLV /*the address*/ IPsec SA sub-TLV Note: [Tunnel-Encap] Section 11 specifies that each Tunnel Encap Attribute can only have one Tunnel-End-Point sub-TLV. Therefore, two separate Tunnel Encap Attributes are needed to indicate that the prefix can be carried by either one. BGP UPDATE from C-PE1 for the attached client routes is like: Prefix 11.1.1.x NH: C-PE 1 Dunbar, et al. Expires Dec 2, 2021 [Page 6] Internet-Draft BGP for SDWAN Edge Discovery July 2020 Tunnel Encap Attr [AFI/SAFI = 1/1) MPLS-in-GRE /*11.1.1.x can only be reached by MPLS network*/ Sub-TLV for MPLS-in-GRE [Section 3.2.6 of Tunnel-encap] Extended community: RT for SDWAN Instance 1, 2 Prefix 21.1.1.x NH: C-PE 1 Tunnel Encap Attr (AFI/SAFI = 1/1) MPLS-in-GRE Sub-TLV for MPLS-in-GRE IPSec SA for 192.10.0.10 Tunnel-End-Point Sub-TLV IPsec SA sub-TLV Tunnel Encap Attr (AFI/SAFI = 1/1) IPSec SA for 160.0.0.1 Tunnel-End-Point Sub-TLV IPsec SA sub-TLV 3.3. Edge Node Discovery using BGP The basic scheme of SDWAN Edge node discovery using BGP consists of: - Upon powering up, a SDWAN edge node establish a secure tunnel (such as TLS, SSL) with the SDWAN central controller whose address is preconfigured on the edge node. The central controller will inform the edge node of its local RR. The edge node will establish a transport layer secure session with the RR (such as TLS, SSL). - The Edge node will advertise its own properties to its designated RR via the secure transport layer tunnel. This is different from traditional BGP, where each node sends its properties (BGP UPDATE) to its neighbors, which in turn propagate to all the nodes in the network. - The RR propagates the received information to the authorized peers. Dunbar, et al. Expires Dec 2, 2021 [Page 7] Internet-Draft BGP for SDWAN Edge Discovery July 2020 - The authorized peers can establish the secure data channels (IPsec) and exchange more information among each other. For a SDWAN deployment with multiple RRs, it is assumed that there are secure connections among those RRs. How secure connections being established among those RRs is the out of the scope of the current draft. The existing BGP UPDATE propagation mechanisms control the edge properties propagation among the RRs. For some special environment where the RR and communication to RR are highly secured, [SDN-IPsec] IKE-less can be deployed to simplify IPsec tunnel establishment among edge nodes. 4. BGP UPDATE to Support SDWAN Segmentation One SDWAN network can be segmented to multiple instances. Each SDWAN edge node may need to support multiple SDWAN instances. One client's traffic may need to be mapped to different SDWAN segmentations based on client's policy. Therefore, we need encoding to differentiate SDWAN instances. For example, in the picture below, the "PaymentFlow" (payment applications) can only be propagated to "Payment GW". Other flows can be propagated to all other nodes. This is very similar to VPNs. But need to differentiate from traditional MPLS VPNs because a SDWAN edge may also support traditional MPLS VPNs. [Note: SDWAN Instance ID is configured the same way as VRF, or EVI as in EVPN. For node with both MPLS and IPsec ports, the label for MPLS can be used for SDWAN Instance ID] Dunbar, et al. Expires Dec 2, 2021 [Page 8] Internet-Draft BGP for SDWAN Edge Discovery July 2020 +---+ +--------------|RR |----------+ / Untrusted +-+-+ \ / \ / \ +---------+ MPLS Path +-------+ 11.1.1.x| C-PE1 A1-------------------------------B1 C-PE2 |10.1.1.x | | | | 21.1.1.x| A2(192.10.0.10)------( 192.0.0.1)B2 |20.1.1.x | | | | | Addr A3(160.0.0.1) --------(170.0.0.1)B3 Addr |11.2.2.x | 1.1.1.1 | / |2.2.2.2| +---------+ / +-------+ / /PaymentFlow / +----+----+ | payment | | Gateway | +---------+ Figure 2: SDWAN Segmentation 4.1. Constrained Propagation of Edge Capability BGP has built-in mechanism to dynamically achieve the constrained distribution of edge information. RFC4684 describes the BGP RT constrained distribution. In a nutshell, a SDWAN edge sends RT Constraint (RTC) NLRI to the RR for the RR to install an outbound route filter, as shown in the figure below: Dunbar, et al. Expires Dec 2, 2021 [Page 9] Internet-Draft BGP for SDWAN Edge Discovery July 2020 RT Constraint RT constraint NLRI={SDWAN#1, SDWAN#2} NLRI={SDWAN#1, SDWAN#3} -----> +---+ <----------- +--------------------|RR1|------------------+ | Outbound Filter +---+ Outbound Filter | | Permit SDWAN#1,#2 Permit SDWAN#1,#3| | Deny all Deny all | | <------- ---------> | | | +-----+---+ MPLS Path +-----+-+ 11.1.1.x| C-PE1 A1-------------------------------B1 C-PE2 |10.1.1.x | | | | 21.1.1.x| A2(192.10.0.10)------( 192.0.0.1)B2 |20.1.1.x | | | | | Addr A3(160.0.0.1) --------(170.0.0.1)B3 Addr | | 1.1.1.1 | |2.2.2.2| +---------+ +-------+ SDWAN Instance #1 SDWAN Instance #1 SDWAN Instance #2 SDWAN Instance #3 Figure 3: Constraint propagation of Edge Property However, as SDWAN overlay network span across untrusted networks, RR can't trust the RT Constraint (RTC) NLRI BGP UPDATE from any nodes. Polices must be configured on RR to filter out unauthorized nodes to be registered as interested in certain SDWAN instances. RR can only process the RTC NLRI from authorized peers for a SDWAN instance. It is out of the scope of this document on how RR is configured with the policies to filter out unauthorized nodes for specific SDWAN instances. The policy configuration could be by manual commands or by management systems. When the RR receives edge node property BGP UPDATE from an edge node, it propagates the received UPDATE message to the nodes that are in the Outbound Route filter for the specific SDWAN instance. 4.2. SDWAN Segmentation for Control Plane SDWAN Instances is represented by the SDWAN Target ID in the BGP Extended Community. Dunbar, et al. Expires Dec 2, 2021 [Page 10] Internet-Draft BGP for SDWAN Edge Discovery July 2020 Same as Route Target for VPN, a different Type is used to differentiate SDWAN Instances from MPLS VPN instances. This is especially useful when a CPE supports both MPLS VPN and SDWAN Segmentation (instances). Encoding: RFC4360: Extended Community for SDWAN Route Target 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type high | Type low(*) | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |I|T| 6-bit val | +-+-+-+-+-+-+-+-+ The high-order octet of the Type Field T bit =0 (transitive) when SDWAN edge sends to its RR which then propagates to remote peers based on outbound filters. RFC4760 states that Route Target community is transitive For SDWAN, an edge receiving the SDWAN Update shouldn't forward it to other nodes. T bit =1 (non-transitive) when RR propagates the UPDATE to SDWAN EDGE [IANA Consideration: Following the encoding scheme specified by RFC7153, need IANA to assign the following values for the "Type High" Octet: - Transitive (when edge announce the advertisement to its RR): Ox0A, which is the number after 0x08 for Flow Spec Redirect. - Non Transitive (when RR send to remote edges): Ox4A Dunbar, et al. Expires Dec 2, 2021 [Page 11] Internet-Draft BGP for SDWAN Edge Discovery July 2020 Request a new value of the low- order octet of the Type field for this community (different from the VPN Route Target 0x02)? ] 4.3. SDWAN Instance Identifier in Data Plane From data plane perspective, packets from different SDWAN network instances (or segmentations) need to have their corresponding SDWAN instance identifier encoded in the header. For a SDWAN edge node which can be reached by both MPLS and IPsec path, the client packets reached by MPLS network will be encoded with the MPLS Labels based on the scheme specified by RFC8277. For GRE Encapsulation within IPsec tunnel, the GRE key field can be used to carry the SDWAN Instance ID. For NVO (VxLAN, GENEVE, etc.) encapsulation within the IPsec tunnel, Virtual Network Identifier (VNI) field is used to carry the SDWAN Instance ID. [Note: the SDWAN Instance ID is same as EVI in EVPN, or VNI if VxLAN is used]. 5. IPsec Tunnel Type for client's routes in Tunnel-Encap 5.1. Encoding This document introduces the following extension to the tunnel encapsulation attribute specified in [Tunnel-Encaps]: . Support for the following IPsec tunnel types: IPsec in Tunnel [value 4] using two new SUB-TLVs: IPsec-SA-ID, and IPsec-SA- Group. Editor's note: The IPSEC-SA-Group was designed to provide better scaling for multiple SA terminated at one endpoint. One end point can have multiple SAs, one SA can encrypt client data to or from CPE1 and another one for CPE2. Dunbar, et al. Expires Dec 2, 2021 [Page 12] Internet-Draft BGP for SDWAN Edge Discovery July 2020 IPsec-SA-ID Sub-TLV 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPsec SA Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The IPsec SA identifier (2 Octet) is for cross reference the IPsec SA attributes being advertised by the Underlay Network Properties Advertisement UPDATE [Section 6]. If the client traffic needs to be encapsulated in a specific type within the IPsec ESP Tunnel, such as GRE or VxLAN, etc., the corresponding Tunnel-Encap Sub-TLV needs to be appended right after the IPsec-SA-ID Sub-TLV. Editor Note: 4 octets can be considered as well for IPsec-SA-ID. IPsec-SA-Group Sub-TLV: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | InnerEncapType | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPsec SA Identifier #1 | IPsec SA Identifier #2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ |IPsec SA Identifier #n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IPsec-SA-Group Sub-TLV IPsec-SA-Group Sub-TLV is for the scenario that the client prefix can be carried by multiple IPsec SAs with the same inner encapsulation. Multiple IPsec SA IDs are included in the IPsec-ID- Group Sub-TLV. If different inner encapsulation is desired within IPsec tunnels, then multiple IPsec-SA-Group Sub-TLVs can be included within one Tunnel Encap Path Attribute. InnerEncapType (2 octet) indicates the encapsulation type for the payload within the IPsec ESP Tunnel. The Inner Encap Type value will take the value specified by the IANA Consideration Section (12.5) of [Tunnel-Encap]: Dunbar, et al. Expires Dec 2, 2021 [Page 13] Internet-Draft BGP for SDWAN Edge Discovery July 2020 - types 8 (VXLAN), 9 (NVGRE), 11 (MPLS-in-GRE), and 12 (VXLAN- GPE) in the "BGP Tunnel Encapsulation Tunnel Types" registry. - types 1 (L2TPv3), 2 (GRE), and 7 (IP in IP) in the "BGP Tunnel Encapsulation Tunnel Types" registry. For each of the Tunnel Types specified, the detailed encapsulation value field as specified by Section 3.2 of [Tunnel-Encap] is appended right after the IPsec Sub-TLV. Since IPsec SA has a lot of attributes, such as public keys, nonce, encryption algorithms etc., the IPsec Tunnel Identifier [ID] is used instead of listing all those attributes in the client routes update. Using IPsec Tunnel ID greatly reduces the size of BGP client UPDATE messages, especially when the client routes can be carried by multiple IPsec tunnels. Another added benefit of using IPsec Tunnel ID is that the client routes can be advertised independently from the IPsec SA rekeying process. The Tunnel Ending Point Sub-TLV specified by the Section 3.1 of [Tunnel-Encap] has to be attached to identify the IPsec Tunnel terminating address. There can be multiple IPsec tunnels terminating at one WAN port or at one node, e.g. one tunnel for going to destination "A", another one for going to destination "B". Use SDWAN for retail industry as an example, it is necessary for all shops at any location to only exchange Payment System traffic with the Payment Gateway, while other traffic can be exchanged with any nodes. Therefore, there could be multiple IPsec Sub-TLVs bound with one Tunnel Ending Point Sub-TLV. However, it is quite common in SDWAN deployment that all IPsec attributes from one node or one port are the same for all destinations. In that case, IPsec SA ID is set to 0 and the terminating address can be used to cross reference the IPsec SA attributes which are advertised by the Underlay Network Property advertisement UPDATE. 5.2. Encoding Example 5.2.1. Multiple IPsec SAs Sharing One Tunnel End Point The encoding example is for the following scenario: Dunbar, et al. Expires Dec 2, 2021 [Page 14] Internet-Draft BGP for SDWAN Edge Discovery July 2020 - there are three IPsec SAs terminating at the same WAN Port address (or the same node address) - Two of the IPsec SAs use GRE (value =2) as Inner Encapsulation within the IPsec Tunnel - One of the IPsec SA uses VxLAN (value = 8) as the Inner Encapsulation within its IPsec Tunnel. Here is the encoding for the scenario: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel-Type =4 (IPsec) | Length = | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel-end-Point Sub-TLV | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |IPsec-SA-group:InnerEncapType=2| Length = 4 | +-------------------------------+-------------------------------+ | IPsec SA Identifier = 1 | IPsec SA Identifier = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | GRE-KEY (4 Octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |IPsec-SA-ID: =3 | Reserved | +-------------------------------+-------------------------------+ ~ VxLAN Sub-TLV ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Length of the Tunnel-Type = 4 (IPsec) is the sum of the following: - Tunnel-end-point sub-TLV total length - the IPsec-SA-Group Sub-TLV length + 4 (the two octets for InnerEncapType + the two octets for the Length field) - GRE-Key Length (4) - The IPsec-SA-ID Sub-TLV length: 4 - The VxLAN sub-TLV total length Dunbar, et al. Expires Dec 2, 2021 [Page 15] Internet-Draft BGP for SDWAN Edge Discovery July 2020 5.2.2. Multiple IPsec SAs Having different Tunnel End Points If IPsec SAs are terminating at different addresses, which can be different WAN ports or Node lookback address, then multiple Tunnel Encap Attributes have to be included in the client UPDATE. The encoding example for the Figure 1: - there is one IPsec SA terminating at the WAN Port address 192.0.0.1; and another IPsec SA terminating at WAN Port 170.0.0.1; - Both IPsec SAs use GRE (value =2) as Inner Encapsulation within the IPsec Tunnel 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel-Type =4 (IPsec) | Length = | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel-end-Point Sub-TLV | ~ for 192.0.0.1 ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPsec SA Identifier = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ GRE Sub-TLV ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel-Type =4 (IPsec) | Length = | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel-end-Point Sub-TLV | ~ for 170.0.0.1 ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPsec SA Identifier = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ GRE sub-TLV ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 6. Underlay Network Properties Advertisement using MP-NLRI For the Figure 1 in Section 3, C-PE2 needs to advertise its IPsec SA associated attributes, such as the public keys, the nonce, the Dunbar, et al. Expires Dec 2, 2021 [Page 16] Internet-Draft BGP for SDWAN Edge Discovery July 2020 supported encryption algorithms for the IPsec tunnels terminated at 192.0.0.1, 170.1.1.1 and 2.2.2.2 respectively. Using the IPsec Tunnel [ISP4: 160.0.0.1 <-> ISP2:170.0.0.1] as an example: C-PE1 needs to advertise the following attributes for establishing the IPsec SA: NH: 160.0.0.1 SDWAN Node ID SDWAN-Site-ID Tunnel Encap Attr (Type=SDWAN) ISP Sub-TLV for information about the ISP4 IPsec SA Nonce Sub-TLV, IPsec SA Public Key Sub-TLV, IPsec SA Sub-TLV for the supported transforms {Transforms Sub-TLV - Trans 2, Transforms Sub-TLV - Trans 3} C-PE2 needs to advertise the following attributes for establishing IPsec SA: NH: 170.1.1.1 SDWAN Node ID SDWAN-Site-ID Tunnel Encap Attr (Type=SDWAN) ISP Sub-TLV for information about the ISP2 IPsec SA Nonce Sub-TLV, IPsec SA Public Key Sub-TLV, IPsec SA Sub-TLV for the supported transforms {Transforms Sub-TLV - Trans 2, Transforms Sub-TLV - Trans 4} As both end points support Transform #2, the Transform #2 will be used for the IPsec Tunnel [ISP4: 160.0.0.1 <-> ISP2:170.0.0.1]. 6.1. Controller Facilitated IPsec Tunnels for SDWAN Networks IPsec is a common technique used to encrypt traffic traversing untrusted networks. IPSec operation between two peer nodes need to perform Internet Key Exchange (IKEv2), which can be broken down into the following steps: Dunbar, et al. Expires Dec 2, 2021 [Page 17] Internet-Draft BGP for SDWAN Edge Discovery July 2020 - IKE_SA_INIT exchanges: This pair of messages negotiate cryptographic algorithms, exchange nonces, and do a Diffie- Hellman exchange. - IKE_AUTH: this pair of messages authenticate the previous messages, exchange identities and certificates, and establish the first Child SA. Based on the authentication used: Pre- Shared Key, RSA certificates or EAP the number of messages exchanged in IKE_AUTH can grow. - CREATE_CHILD_SA - This is simply used to create additional CHILD-SAs as needed - INFORMATIONAL- During an IKEv2 SA lifetime, peers may desire to exchange some control messages related to errors or have notifications of certain events. This function is accomplished by INFORMATIONAL exchange. In SDWAN environment, each SDWAN edge node might need to establish IPsec tunnels to multiple peers, and there can be multiple IPsec tunnels for different client traffic between any two peers. In addition, SDWAN edge nodes can be far apart. Upon powering up, a SDWAN edge might not know their authorized communication peers and might not have the policies configured for aligning traffic with their specific IPsec Tunnels. Therefore, the IPsec operation in SDWAN environment are usually facilitated by its SDWAN Controller. [SDN-IPsec] describes two different mechanisms to achieve controller facilitated IPsec configuration: IKE case vs. IKE-less case. Under the IKE case, the Controller is in charge of provisioning the required information to IKE, the Security Policy Database (SPD) and the Security Association Database (PAD). The SDWAN peers exchange the Internet Key Exchange (IKE) protocol and manage SPD and SAD. Under the IKE-less case, the Controller will provide the required parameters to create valid entries in the SPD and the SAD into the edge nodes. Therefore, the edge node will only need to implementation IPsec encryption while automated key management functionality is moved to the Controller. For BGP controlled SDWAN networks, there is already a secure management tunnel established between RR and the edge nodes, all the negotiations exchanged in IKEv2 can be carried by BGP UPDATE messages to/from the Route Reflector (RR), which will propagate the information to the intended destinations. More importantly, when an edge node needs to establish multiple IPsec tunnels to many different SDWAN edge nodes, all the management information can be multiplexed into the secure management tunnel between RR and the Dunbar, et al. Expires Dec 2, 2021 [Page 18] Internet-Draft BGP for SDWAN Edge Discovery July 2020 edge node. Therefore, there is reduced amount of work on authentication in processing in BGP Controlled SDWAN networks. In addition, BGP has a built-in mechanism to constrain SDWAN UPDATE messages only to the authorized peers that an SDWAN edge node can communicate [RFC4364]. 6.2. NLRI encoding for Underlay Network Properties For the MPLS VPN, the underlay network is controlled by the VPN service provider, therefore, there is no need for nodes to advertise any underlay properties to remote peers. For the untrusted underlay network to which a SDWAN edge is connected, many attributes need to be advertised to remote nodes, such as: - ISP information of the underlay network, - NAT property - the geolocation of the SDWAN edge - IPsec SA attributes, such as public keys, nonce, supported encryption algorithms, etc. - the IPsec tunnel termination address Here is the encoding for those attributes in the NLRI field within the MP_REACH_NLRI Path Attribute of RFC4760, under a SDWAN SAFI (code = 74): Dunbar, et al. Expires Dec 2, 2021 [Page 19] Internet-Draft BGP for SDWAN Edge Discovery July 2020 +------------------+ | NLRI Length | 1 octet +------------------+ | Site-Type | 1 Octet +------------------+ | IPSec-SA-Type | 1 Octet +------------------+ | Port-Local-ID | 4 octets +------------------+ | SDWAN-Site-ID | 4 octets +------------------+ | SDWAN-Node-ID | 4 or 16 octets +------------------+ where: - NLRI Length: 1 octet of length expressed in bits as defined in [RFC4760]. - Site Type: 1 octet value. The SDWAN Site Type defines the different types of Site IDs to be used in the deployment. The draft defines the following types: Site-Type = 1: For simple deployment, such as all edge nodes under one SDWAN management system, a simple identifier is enough for the SDWAN management to map the site to its precise geolocation. Site-Type = 2: to indicate that the value in the site-ID is locally significant, therefore, need a Geo-Loc Sub-TLV to fully describe the accurate location of the node. This is for large SDWAN heterogeneous deployment where Site IDs has to be described by proper Geo-location of the Edge Nodes [LISP- GEOLoc]. - IPSec-SA-Type: 1 octet value. The IPSec SA Type represents two different types of IPSec SA Sub-TLV encoding to be carried with the NLRI. IPSec-SA-Type = 1 : Simple IPSec Security Association properties defined in IPSec SA Sub-TLV. Dunbar, et al. Expires Dec 2, 2021 [Page 20] Internet-Draft BGP for SDWAN Edge Discovery July 2020 IPSec-SA-Type = 2: The full set of IPSec Sub-TLVs including Nonce, Public Key, Proposal and Transform Sub-TLVs. - Port local ID: SDWAN edge node Port identifier, which can be locally significant. The detailed properties about the network connected to the port are further encoded in the Tunnel Path Attribute. - SDWAN-Site-ID: used to identify a common property shared by a set of SDWAN edge nodes, such as the property of a specific geographic location shared by a group of SDWAN edge nodes. The property is used to steer an overlay route to traverse specific geographic locations for various reasons, such as to comply regulatory rules, to utilize specific value-added services, or others. - SDWAN Edge Node ID: a routable address (IPv4 or IPv6) within the WAN to reach this node or port. [Editor's note on using SDWAN SAFI for the underlay network property advertisement: SDWAN SAFI [IANA assigned =74] is used instead of IP SAFI in the MP-NLRI [RFC4760] Path Attribute to advertise the underlay network properties to emphasize that the address in the NLRI is NOT client addresses. If the same IP SAFI used, receiver needs to add extra logic to differentiate regular BGP MP-NLRI client routes advertisement from the SDWAN underlay network properties advertisement. The benefit of using the same IP SAFI is that the UPDATE can traverse existing routers without being dropped. Since the SDWAN underlay network UPDATE is only between SDWAN edge and its corresponding RR, there won't be any intermediated routers. Therefore, this benefit becomes not applicable. ] The underlay network property encoding structure is as follows: SDWAN SAFI NLRI: Dunbar, et al. Expires Dec 2, 2021 [Page 21] Internet-Draft BGP for SDWAN Edge Discovery July 2020 Encoding for Site-Type = 1, IPSec-SA-Type = 1 is defined below: Attributes: Tunnel Encaps Attribute (23) Tunnel Type: SDWAN-Underlay (to be assigned by IANA) NAT Sub-TLV (Optional) IPsec-SA Attribute Sub-TLV (Mandatory Base Sub-TLV) ISP of the Underlay network Sub-TLV (Optional) Encoding for Site-Type = 2, IPSec-SA-Type = 1 is defined below: Geo-Prefix and Geo-Point Sub-TLV (Mandatory) Attributes: Tunnel Encaps Attribute (23) Tunnel Type: SDWAN-Underlay (to be assigned by IANA) NAT Sub-TLV (Optional) IPsec-SA Attribute Sub-TLV (Mandatory Base Sub-TLV) ISP of the Underlay network Sub-TLV (Optional) The Geo-Prefix and Geo-Point Sub-TLV is defined in [LISP-GEOLOC]. 6.3. Underlay Properties encoding in the Tunnel Path Attribute The underlay properties are encoded in the Tunnel Encapsulation Attribute defined in [Tunnel-Encap] using a new Tunnel-Type TLV (code point to be assigned by IANA). The Tunnel Encaps Attribute are defined as follows: Dunbar, et al. Expires Dec 2, 2021 [Page 22] Internet-Draft BGP for SDWAN Edge Discovery July 2020 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel-Type(=SDWAN-Underlay )| Length (2 Octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ SDWAN Underlay network Sub-TLV Value Field Where: Tunnel Type is SDWAN-Underlay (to be assigned by IANA). 6.4. Extended Sub-TLV for NAT When a SDWAN edge node is connected to an underlay network via a port behind NAT devices, traditional IPsec uses IKE for NAT negotiation. The location of a NAT device can be such that: - Only the initiator is behind a NAT device. Multiple initiators can be behind separate NAT devices. Initiators can also connect to the responder through multiple NAT devices. - Only the responder is behind a NAT device. - Both the initiator and the responder are behind a NAT device. The initiator's address and/or responder's address can be dynamically assigned by an ISP or when their connection crosses a dynamic NAT device that allocates addresses from a dynamic address pool. Because one SDWAN edge can connect to multiple peers via one underlay network, the pair-wise NAT exchange as IPsec's IKE is not efficient. In BGP Controlled SDWAN, NAT information of a WAN port is advertised to its RR in the BGP UPDATE message. It is encoded as an Extended sub-TLV that describes the NAT property if the port is behind a NAT device. A SDWAN edge node can inquire STUN (Session Traversal of UDP Through Network Address Translation RFC 3489) Server to get the NAT property, the public IP address and the Public Port number to pass to peers. Dunbar, et al. Expires Dec 2, 2021 [Page 23] Internet-Draft BGP for SDWAN Edge Discovery July 2020 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Port Ext Type | EncapExt subTLV Length |I|O|R|R|R|R|R|R| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | NAT Type | Encap-Type |Trans networkID| RD ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local IP Address | 32-bits for IPv4, 128-bits for Ipv6 ~~~~~~~~~~~~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local Port | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Public IP | 32-bits for IPv4, 128-bits for Ipv6 ~~~~~~~~~~~~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Public Port | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Where: o Port Ext Type: indicate it is the Port Ext SubTLV. o PortExt subTLV Length: the length of the subTLV. o Flags: - I bit (CPE port address or Inner address scheme) If set to 0, indicate the inner (private) address is IPv4. If set to 1, it indicates the inner address is IPv6. - O bit (Outer address scheme): If set to 0, indicate the public (outer) address is IPv4. If set to 1, it indicates the public (outer) address is IPv6. - R bits: reserved for future use. Must be set to 0 now. o NAT Type.without NAT; 1:1 static NAT; Full Cone; Restricted Cone; Port Restricted Cone; Symmetric; or Unknown (i.e. no response from the STUN server). Dunbar, et al. Expires Dec 2, 2021 [Page 24] Internet-Draft BGP for SDWAN Edge Discovery July 2020 o Encap Type.the supported encapsulation types for the port facing public network, such as IPsec+GRE, IPsec+VxLAN, IPsec without GRE, GRE (when packets don't need encryption) o Transport Network ID.Central Controller assign a global unique ID to each transport network. o RD ID.Routing Domain ID.need to be global unique. o Local IP.The local (or private) IP address of the port. o Local Port.used by Remote SDWAN edge node for establishing IPsec to this specific port. o Public IP.The IP address after the NAT. If NAT is not used, this field is set to NULL. o Public Port.The Port after the NAT. If NAT is not used, this field is set to NULL. 6.5. IPsec Security Association Property Sub-TLVs Editor's Note: RFC7296 specifies the IPsec SA attributes exchange among two peers to establish peer-wise IPsec SA. [Controller-IKE] specifies the structure for a controller to facilitate the exchange of the RFC7296 specified IPsec SA attributes among many nodes. [CONTROLLER-IKE] specifies the Device Information Message (DIM) for the edge node to advertise to its controller, which includes DH public number, nonce, peer identity, an indication whether this is the initial distributed policy, and rekey counter. The originating edge node distributes the DH public value along with the other values in the DIM (using IPsec Tunnel TLV in Tunnel Encapsulation Attribute) to other remote C-PEs via the RR. Each receiving C-PE uses this DH public number and the corresponding nonce in creation of IPsec SA pair to the originating C-PE - i.e., an outbound SA and an inbound SA. The detail procedures are described in section 5.2 of [CONTROLLER-IKE]. [SECURE-VPN] proposes the BGP UPDATE Sub-TLV structure to carry the information specified by [Controller-IKE] to be propagated among peers via BGP. Dunbar, et al. Expires Dec 2, 2021 [Page 25] Internet-Draft BGP for SDWAN Edge Discovery July 2020 To expedite the standardization process, this draft aligns with the IPsec Sub-TLVs described in the Section 6.1, 6.2 and 6.3 of [SECURE-EVPN], with some optimization. For scalability reason, this draft advertises the IPSec SA related attributes at a different pace than client routes UPDATEs. Client Routes UPDATE only references the identifier for the prior established IPsec SAs. The optimized IPsec SA attributes are represented by a set of Sub- TLVs: - IPsec SA Nonce Sub-TLV - IPsec SA Public Key Sub- TLV - IPsec SA Proposal Sub-TLV: to indicate the number of Transform Sub-TLVs o Transforms Substructure Sub-TLV For BGP controlled SDWAN network, very often an edge node doesn't know its peer identity. Then the peer identity field can be null. 6.6. IPsec SA Nonce Sub-TLV The Nonce Sub-TLV is based on the Base DIM sub-TLV as described the Section 6.1 of [SECURE-EVPN]. IPsec SA ID is added to the sub-TLV, which is to be referenced by the client route NLRI Tunnel Encap Path Attribute for the IPsec SA. The following fields are removed because: - the Originator ID is carried by the NLRI, - the Tenant ID is represented by the Route Target Extended Community, and - the Subnet ID are carried by the BGP route UPDATE. The format of this Sub-TLV is as follows: Dunbar, et al. Expires Dec 2, 2021 [Page 26] Internet-Draft BGP for SDWAN Edge Discovery July 2020 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ID Length | Nonce Length |I| Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Rekey | | Counter | +---------------------------------------------------------------+ | IPsec SA ID | Reserved | +---------------------------------------------------------------+ | | ~ Nonce Data ~ | | +---------------------------------------------------------------+ IPsec SA ID - The 2 bytes IPSec SA ID could 0 or non-zero values. It is cross referenced by client route's IPSec Tunnel Encap IPSec-SA-ID or IPSec-SA-Group Sub-TLV in Section 5. When there are multiple IPsec SAs terminated at one address, such as WAN port address or the node address, they are differentiated by the different IPsec SA IDs. 6.7. IPsec Public Key Sub-TLV The IPsec Public Key Sub-TLV is derived from the Key Exchange Sub- TLV described in [SECURE-EVPN] with an addition of Duration filed to define the IPSec SA life span. The edge nodes would pick the shortest duration value between the SDWAN SAFI pairs. The format of this Sub-TLV is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Diffie-Hellman Group Num | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Key Exchange Data ~ | | +---------------------------------------------------------------+ | Duration | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Dunbar, et al. Expires Dec 2, 2021 [Page 27] Internet-Draft BGP for SDWAN Edge Discovery July 2020 6.8. IPsec SA Proposal Sub-TLV The IPsec SA Proposal Sub-TLV is to indicate the number of Transform Sub-TLVs. This Sub-TLV aligns with the sub-TLV structure from [SECURE-VPN] The Transform Sub-sub-TLV will following the section 3.3.2 of RFC7296. 6.9. ISP of the Underlay network Sub-TLV The purpose of the Underlay network Sub-TLV is to carry the ISP WAN port properties with SDWAN SAFI NLRI. It would be treated as optional Sub-TLV. The BGP originator decides whether to include this Sub-TLV along with the SDWAN NLRI. If this Sub-TLV is present, it would be processed by the BGP receiver and to determine what local policies to apply for the remote end point of the Underlay tunnel. The format of this Sub-TLV is as follows: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Flag | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Connection Type| Port Type | Port Speed | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Where: Type: To be assigned by IANA Length: 6 bytes. Flag: a 1 octet value. Reserved: 1 octet of reserved bits. It SHOULD be set to zero on transmission and MUST be ignored on receipt. Connection Type: There are two different types of WAN Connectivity. They are listed below as: Wired - 1 WIFI - 2 LTE - 3 Dunbar, et al. Expires Dec 2, 2021 [Page 28] Internet-Draft BGP for SDWAN Edge Discovery July 2020 5G - 4 Port Type: There are different types of ports. They are listed Below as: Ethernet - 1 Fiber Cable - 2 Coax Cable - 3 Cellular - 4 Port Speed: The port seed is defined as 2 octet value. The values are defined as Gigabit speed. 6.10. Simplified IPsec Security Association sub-TLV For a simple SDWAN network with edge nodes supporting only a few pre-defined encryption algorithms, a simple IPsec sub-TLV can be used to encode the pre-defined algorithms, as below: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |IPsec-simType |IPsecSA Length | Flag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Protocol Type | IPsec Mode | AH algorithms |ESP algorithms | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ReKey Counter | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | key1 length | Public Key ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | key2 length | Nonce ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPsec SA ID | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Duration | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Where: Dunbar, et al. Expires Dec 2, 2021 [Page 29] Internet-Draft BGP for SDWAN Edge Discovery July 2020 o IPsec-SimType: The type value has to be between 128~255 because IPsec-SA subTLV needs 2 bytes for length to carry the needed information. o IPsec-SA subTLV Length (2 Byte): 25 (or more) o Flags: 1 octet of flags. None are defined at this stage. Flags SHOULD be set to zero on transmission and MUST be ignored on receipt. o IPsec Protocol Types (1 Byte): the value can be AH, ESP, or AH+ESP. o IPsec Mode (1 byte): the value can be Tunnel Mode or Transport mode o AH algorithms (1 byte): AH authentication algorithms supported, which can be md5 | sha1 | sha2-256 | sha2-384 | sha2-512 | sm3. Each SDWAN edge node can have multiple authentication. algorithms; send to its peers to negotiate the strongest one. o ESP (1 byte): ESP authentication algorithms supported, which can be md5 | sha1 | sha2-256 | sha2-384 | sha2-512 | sm3. Each SDWAN edge node can have multiple authentication algorithms; send to its peers to negotiate the strongest one. Default algorithm is AES-256. o When node supports multiple authentication algorithms, the initial UPDATE needs to include the "Transform Sub-TLV" described by [SECURE-EVPN] to describe all of the algorithms supported by the node. o Rekey Counter: 4 bytes o Public Key: IPsec public key o Nonce.IPsec Nonce o IPsec SA ID: The 2 bytes IPSec SA ID could 0 or non-zero values. It is cross referenced by client route's IPSec Tunnel Encap IPSec-SA-ID or IPSec-SA-Group Sub-TLV in Section 5. When there are multiple IPsec SAs terminated at one address, such as WAN port address or the node address, they are differentiated by the different IPsec SA IDs. o Duration: SA life span. 6.11. Remote Endpoint The Remote Endpoint sub-TLV is not used for SDWAN NLRI because Dunbar, et al. Expires Dec 2, 2021 [Page 30] Internet-Draft BGP for SDWAN Edge Discovery July 2020 o Tunnel end point address is already included in the Tunnel-end- point Sub-TLV. o The underlay networks to which an SDWAN edge node are connected might have different identifiers than their corresponding AS numbers on the SDWAN controller. The SDWAN controller might use its own specific identifiers for the underlay networks. o The Transport-Network-ID in the EncapExt sub-TLV represents the SDWAN unique network identifier. If the Remote Endpoint Sub-TLV is present, it is ignored by the RR and other SDWAN edge nodes. 7. Error & Mismatch Handling Each C-PE device advertises SDWAN SAFI Underlay NLRI to the other C- PE devices via BGP Route Reflector to establish pairwise SAs between itself and every other remote C-PEs. During the SAFI NLRI advertisement, the BGP originator would include either simple IPSec Security Association properties defined in IPSec SA Sub-TLV based on IPSec-SA-Type = 1 or full-set of IPSec Sub-TLVs including Nonce, Public Key, Proposal and number of Transform Sub-TLVs based on IPSec-SA-Type = 2. The C-PE devices would compare the IPSec SA attributes between the local and remote WAN ports. If there is a match on the SA Attributes between the two ports, the IPSec Tunnel would be established. The C-PE devices would not try to negotiate the base IPSec-SA parameters between the local and the remote ports in the case of simple IPSec SA exchange or the Transform sets between local and remote ports if there is a mismatch on the Transform sets in the case of full-set of IPSec SA Sub-TLVs. As an example, using the Figure 1 in Section 3, to establish IPsec Tunnel between C-PE1 and C-PE2 WAN Ports A2 and B2 [A2: 192.10.0.10 <-> B2:192.0.0.1]: C-PE1 needs to advertise the following attributes for establishing the IPsec SA: NH: 192.10.0.10 SDWAN Node ID Dunbar, et al. Expires Dec 2, 2021 [Page 31] Internet-Draft BGP for SDWAN Edge Discovery July 2020 SDWAN-Site-ID Tunnel Encap Attr (Type=SDWAN) ISP Sub-TLV for information about the ISP3 IPsec SA Nonce Sub-TLV, IPsec SA Public Key Sub-TLV, Proposal Sub-TLV with Num Transforms = 1 {Transforms Sub-TLV - Trans 1} C-PE2 needs to advertise the following attributes for establishing IPsec SA: NH: 192.0.0.1 SDWAN Node ID SDWAN-Site-ID Tunnel Encap Attr (Type=SDWAN) ISP Sub-TLV for information about the ISP1 IPsec SA Nonce Sub-TLV, IPsec SA Public Key Sub-TLV, Proposal Sub-TLV with Num Transforms = 1 {Transforms Sub-TLV - Trans 2} As there is no matching transform between the WAN ports A2 and B2 in C-PE1 and C-PE2 respectively, there will be no IPsec Tunnel be established. 8. Manageability Considerations TBD - this needs to be filled out before publishing 9. Security Considerations The document describes the encoding for SDWAN edge nodes to advertise its properties to their peers to its RR, which propagates to the intended peers via untrusted networks. The secure propagation is achieved by secure channels, such as TLS, SSL, or IPsec, between the SDWAN edge nodes and the local controller RR. [More details need to be filled in here] Dunbar, et al. Expires Dec 2, 2021 [Page 32] Internet-Draft BGP for SDWAN Edge Discovery July 2020 10. IANA Considerations This document requires the following IANA actions. o SDWAN Overlay SAFI = 74 assigned by IANA o SDWAN Route Type 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 11.2. 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. [CONTROLLER-IKE] D. Carrel, et al, "IPsec Key Exchange using a Controller", draft-carrel-ipsecme-controller-ike-01, work- in-progress. [LISP-GEOLOC] D. Farinacci, "LISP Geo-Coordinate Use-Case", draft- farinacci-lisp-geo-09, April 2020. [SDN-IPSEC] R. Lopez, G. Millan, "SDN-based IPsec Flow Protection", draft-ietf-i2nsf-sdn-ipsec-flow-protection-07, Aug 2019. [SECURE-EVPN] A. Sajassi, et al, "Secure EVPN", draft-sajassi-bess- secure-evpn-02, July 2019. [Tunnel-Encap]E. Rosen, et al, "The BGP Tunnel Encapsulation Attribute", draft-ietf-idr-tunnel-encaps-09, Feb 2018. Dunbar, et al. Expires Dec 2, 2021 [Page 33] Internet-Draft BGP for SDWAN Edge Discovery July 2020 [VPN-over-Internet] 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 [Net2Cloud-gap] L. Dunbar, A. Malis, and C. Jacquenet, "Gap Analysis of Interconnecting Underlay with Cloud Overlay", draft-dm- net2cloud-gap-analysis-02, work-in-progress, Aug 2018. [Tunnel-Encap] E. Rosen, et al "The BGP Tunnel Encapsulation Attribute", draft-ietf-idr-tunnel-encaps-10, Aug 2018. 12. Acknowledgments Acknowledgements to Wang Haibo, Hao Weiguo, and ShengCheng for implementation contribution; Many thanks to Jim Guichard, John Scudder, and Donald Eastlake for their review and contributions. This document was prepared using 2-Word-v2.0.template.dot. Dunbar, et al. Expires Dec 2, 2021 [Page 34] Internet-Draft BGP for SDWAN Edge Discovery July 2020 Dunbar, et al. Expires Dec 2, 2021 [Page 35] Internet-Draft BGP for SDWAN Edge Discovery July 2020 Authors' Addresses Linda Dunbar Futurewei Email: ldunbar@futurewei.com Sue Hares Hickory Hill Consulting Email: shares@ndzh.com Robert Raszuk Email: robert@raszuk.net Kausik Majumdar CommScope Email: Kausik.Majumdar@commscope.com Dunbar, et al. Expires Dec 2, 2021 [Page 36]