BGP UPDATE for SDWAN Edge Discovery
draft-ietf-idr-sdwan-edge-discovery-04
The information below is for an old version of the document.
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| Authors | Linda Dunbar , Susan Hares , Robert Raszuk , Kausik Majumdar , Gyan Mishra | ||
| Last updated | 2022-08-13 | ||
| Replaces | draft-dunbar-idr-sdwan-edge-discovery | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-idr-sdwan-edge-discovery-04
Network Working Group L. Dunbar
Internet Draft Futurewei
Intended status: Standard S. Hares
Expires: February 13, 2023 Hickory Hill Consulting
R. Raszuk
NTT Network Innovations
K. Majumdar
Microsoft
Gyan Mishra
Verizon
August 13, 2022
BGP UPDATE for SDWAN Edge Discovery
draft-ietf-idr-sdwan-edge-discovery-04
Abstract
The document describes the encoding of BGP UPDATE messages for the
SDWAN edge node property discovery.
In the context of this document, BGP Route Reflector (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-
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Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress."
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The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on Dec 11, 2020.
Copyright Notice
Copyright (c) 2022 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
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Table of Contents
1. Introduction...................................................3
2. Conventions used in this document..............................3
3. Framework of SDWAN Edge Discovery..............................5
3.1. The Objectives of SDWAN Edge Discovery....................5
3.2. Comparing with Pure IPsec VPN.............................5
3.3. Client Route UPDATE and SDWAN Tunnel UPDATE...............7
3.4. Edge Node Discovery.......................................9
4. Constrained propagation of BGP UPDATE.........................10
4.1. SDWAN Segmentation, SDWAN Virtual Topology and Client VPN10
4.2. Constrained Propagation of Edge Capability...............11
5. Client Route UPDATE...........................................12
5.1. SDWAN VPN ID in Client Route Update......................13
5.2. SDWAN VPN ID in Data Plane...............................13
6. SDWAN Underlay UPDATE.........................................13
6.1. NLRI for SDWAN Underlay Tunnel Update....................13
6.2. SDWAN-Hybrid Tunnel Encoding.............................14
6.3. IPsec-SA-ID Sub-TLV......................................15
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6.4. Extended Port Attribute Sub-TLV..........................15
6.5. Underlay Network Properties Sub-TLV......................17
7. IPsec SA Property Sub-TLVs....................................18
7.1. IPsec SA Nonce Sub-TLV...................................18
7.2. IPsec Public Key Sub-TLV.................................19
7.3. IPsec SA Proposal Sub-TLV................................20
7.4. Simplified IPsec SA sub-TLV..............................20
8. Error & Mismatch Handling.....................................22
9. SDWAN BGP UPDATE Encoding Examples............................23
9.1. Encoding example of WAN Port properties..................23
9.2. Encoding example of IPsec SA terminated at the C-PE2.....24
9.3. Encoding example #1 of using IPsec-SA-ID Sub-TLV.........24
10. Manageability Considerations.................................25
11. Security Considerations......................................26
12. IANA Considerations..........................................26
12.1. Hybrid (SDWAN) Overlay SAFI.............................26
12.2. Tunnel Encapsulation Attribute Type.....................26
12.3. Tunnel Encapsulation Attribute Sub-TLV Types............26
13. References...................................................27
13.1. Normative References....................................27
13.2. Informative References..................................27
14. Acknowledgments..............................................29
1. Introduction
[SDWAN-BGP-USAGE] illustrates how BGP [RFC4271] is used as a control
plane for a SDWAN network. SDWAN network refers to a policy-driven
network over multiple heterogeneous underlay networks to get better
WAN bandwidth management, visibility, and control.
The document describes BGP UPDATE messages for an SDWAN edge node to
advertise its properties to its RR which then propagates that
information to the authorized peers.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The following acronyms and terms are used in this document:
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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: Customer (Edge) Premises Equipment.
CPE-Based VPN: Virtual Private Secure network formed among CPEs.
This is to differentiate such VPNs from most commonly
used PE-based VPNs discussed in [RFC4364].
MP-NLRI: Multi-Protocol Network Layer Reachability Information
[MP_REACH_NLRI] Path Attribute defined in RFC4760.
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.
RR Route Reflector.
SDWAN: Software Defined Wide Area Network. In this document,
"SDWAN" refers to policy-driven transporting IP packets
over multiple different underlay networks to get better
WAN bandwidth management, visibility and control.
SDWAN Segmentation: Segmentation is the process of dividing the
network into logical sub-networks.
SDWAN VPN: refers to the Client's VPN, which is like the VRF on the
PEs of a MPLS VPN. One SDWAN client VPN can be mapped
one or multiple SD-WAN virtual topologies. How Client
VPN is mapped to a SDWAN virtual topology is governed by
policies.
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SDWAN Virtual Topology: Since SDWAN can connect any nodes, whereas
MPLS VPN connects a fixed number of PEs, one SDWAN
Virtual Topology refers to a set of edge nodes and the
tunnels (including both IPsec tunnels and/or MPLS
tunnels) interconnecting those edge nodes.
VPN Virtual Private Network.
VRF VPN Routing and Forwarding instance.
WAN Wide Area Network.
3. Framework of SDWAN Edge Discovery
3.1. The Objectives of SDWAN Edge Discovery
The objectives of SDWAN edge discovery are for an SDWAN edge node to
discover its authorized peers and their associated properties to
establish secure overlay tunnels. The attributes to be propagated
includes:
- the SDWAN (client) VPNs information,
- the attached routes under the SDWAN VPNs,
- the properties of the underlay networks over which the client
routes can be carried, and potentially more.
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 traffic over untrusted networks, IPsec
Security Associations (IPsec SA) must be established and maintained.
If an edge node has network ports behind a NAT, the NAT properties
need to be discovered by the authorized SDWAN peers.
Like any VPN networks, the attached client's routes belonging to
specific SDWAN VPNs can only be exchanged with the SDWAN peer nodes
authorized to communicate.
3.2. Comparing with Pure IPsec VPN
A pure IPsec VPN has IPsec tunnels connecting all edge nodes over
public networks. Therefore, it requires stringent authentication and
authorization (i.e., IKE Phase 1) before other properties of IPsec
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SA can be exchanged. The IPsec Security Association (SA) between two
untrusted nodes typically requires the following configurations and
message exchanges:
- IPsec IKEv2 to authenticate with each other
- Establish IPsec SA
o Local key configuration
o Remote Peer address (192.10.0.10<->172.0.01)
o IKEv2 Proposal directly sent to peer
o Encryption method, Integrity sha512
o Transform set
- Attached client prefixes discovery
o By running routing protocol within each IPsec SA
o If multiple IPsec SAs between two peer nodes are
established to achieve load sharing, each IPsec tunnel
needs to run its own routing protocol to exchange client
routes attached to the edges.
- Access List or Traffic Selector)
o Permit Local-IP1, Remote-IP2
In a BGP-controlled SDWAN network over hybrid MPLS VPN and public
internet underlay networks, all edge nodes and RRs are already
connected by private secure paths. The RRs have the policies to
manage the authentication of all peer nodes. More importantly, when
an edge node needs to establish multiple IPsec tunnels to many edge
nodes, all the management information can be multiplexed into the
secure management tunnel between RR and the edge node. Therefore,
the amount of authentication in a BGP-Controlled SDWAN network can
be significantly reduced.
Client VPNs are configured via VRFs, just like the configuration of
the existing MPLS VPN. The IPsec equivalent traffic selectors for
local and remote routes are achieved by importing/exporting VPN
Route Targets. The binding of client routes to IPsec SA is dictated
by policies. As a result, the IPsec configuration for a BGP
controlled SDWAN (with mixed MPLS VPN) can be simplified:
- The SDWAN controller has the authority to authenticate edges
and peers. Remote Peer association is controlled by the SDWAN
Controller (RR)
- The IKEv2 proposals, including the IPsec Transform set, can
be sent directly to peers, or incorporated in a BGP UPDATE.
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- BGP UPDATE: Announces the client route reachability for all
permitted parallel tunnels/paths.
o There is no need to run multiple routing protocols in
each IPsec tunnel.
- Importing/exporting Route Targets under each client VPN (VRF)
achieves the traffic selection (or permission) among clients'
routes attached to multiple edge nodes.
3.3. Client Route UPDATE and SDWAN Tunnel UPDATE
As described in [SDWAN-BGP-USAGE], two separate BGP UPDATE messages
are used for SDWAN Edge Discovery:
- Client routes BGP UPDATE:
This UPDATE is precisely the same as the BGP VPN client route
UPDATE. It uses the Encapsulation Extended Community and the
Color Extended Community to link with the SDWAN Tunnels UPDATE
Message as specified in section 8 of [RFC9012].
A new Tunnel Type (SDWAN-Hybrid) is added and used by the
Encapsulation Extended Community or the Tunnel-Encap Path
Attribute [RFC9012] to indicate mixed underlay networks.
- SDWAN UPDATE.
This UPDATE is for an edge node to advertise the properties of
directly attached underlay networks, including the NAT
information, pre-configured IPsec SA identifiers, and/or the
underlay network ISP information. This UPDATE can also include
the detailed IPsec SA attributes, such as keys, nonce,
encryption algorithms, etc.
In the following figure, there are potentially four underlay paths
between C-PE1 and C-PE2, even though C-PE1/C-PE2 might not use all
four underlay paths:
a) MPLS-in-GRE path.
b) node-based IPsec tunnel [2.2.2.2<->1.1.1.1]. As C-PE2 has two
public internet facing WAN ports, either of those two WAN port IP
addresses can be the outer destination address of the IPsec
encapsulated data packets.
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].
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+---+
+--------------|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
C-PE2 advertises the attached client routes as below:
Client Route UDPATE:
Extended community: RT for SDWAN VPN 1
NLRI: AFI=IPv4/IPv6 & SAFI = VPN
Prefix: 10.1.1.x; 20.1.1.x
NextHop: 2.2.2.2 (C-PE2)
Encapsulation Extended Community: tunnel-type=SDWAN-Hybrid
Color Extended Community: Site-identifier
The Client Route UPDATE is recursively resolved to the SDWAN UPDATE
which specifies the detailed properties including IPsec properties
of hybrid WAN underlay tunnels terminated at the C-PE2:
SDWAN UPDATE:
C-PE2 can use the following Update messages to advertise the
properties of Internet facing ports 192.0.0.1 & 170.0.0.1, and
their associated IPsec SA related parameters.
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Update #1 for the properties associated with the WAN port
192.0.0.1, such as the NAT properties, the underlay network
properties, etc. [Details in Section 9.1]
Update #2 for the properties associated with the WAN port
170.0.0.1 associated properties. [Details in Section 9.1]
Update #3 for IPsec parameters associated with IPsec tunnel
terminated at the Node level (2.2.2.2), such as the supported
encryption methods, public keys, etc. [Details in Section 9.2].
3.4. Edge Node Discovery
The basic scheme of SDWAN edge node discovery using BGP consists of
the following:
- Secure connection to a SDWAN controller (i.e., RR in this
context):
For an SDWAN edge with both MPLS and IPsec paths, the edge node
should already have a secure connection to its controller,
i.e., RR in this context. For an SDWAN edge that is only
accessible via Internet, the SDWAN edge, upon power-up,
establishes a secure tunnel (such as TLS or SSL) with the SDWAN
central controller whose address is preconfigured on the edge
node. The central controller informs the edge node of its local
RR. The edge node then establishes a transport layer secure
session with the RR (such as TLS or SSL).
- The Edge node will advertise its own properties to its
designated RR via the secure connection.
- The RR propagates the received information to the authorized
peers.
- The authorized peers can establish the secure data channels
(IPsec) and exchange more information among each other.
For an SDWAN deployment with multiple RRs, it is assumed that there
are secure connections among those RRs. How secure connections are
established among those RRs is out of the scope of this document.
The existing BGP UPDATE propagation mechanisms control the edge
properties propagation among the RRs.
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For some environments where the communication to RR is highly
secured, [RFC9016] IKE-less can be deployed to simplify IPsec SA
establishment among edge nodes.
4. Constrained propagation of BGP UPDATE
4.1. SDWAN Segmentation, SDWAN Virtual Topology and Client VPN
In SDWAN deployment, "SDWAN Segmentation" is a frequently used term,
referring to partitioning a network into multiple sub-networks, just
like MPLS VPNs. "SDWAN Segmentation" is achieved by creating SDWAN
virtual topologies and SDWAN VPNs. An SDWAN virtual topology
consists of a set of edge nodes and the tunnels (a.k.a. underlay
paths), including both IPsec tunnels and/or MPLS VPN tunnels,
interconnecting those edge nodes.
An SDWAN VPN is configured in the same way as the VRFs of an MPLS
VPN. One SDWAN client VPN can be mapped to multiple SD-WAN virtual
topologies. SDWAN Controller governs the policies of mapping a
client VPN to SDWAN virtual topologies.
Each SDWAN edge node may need to support multiple VPNs. Route Target
is used to differentiate the SDWAN VPNs. For example, in the picture
below, the "Payment-Flow" on C-PE2 is only mapped to the virtual
topology of C-PEs to/from Payment Gateway, whereas other flows can
be mapped to a multipoint-to-multipoint virtual topology.
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+---+
+--------------|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 Virtual Topology & VPN
4.2. Constrained Propagation of Edge Capability
BGP has a built-in mechanism [RFC4684] to dynamically achieve the
constrained distribution of edge information. In a nutshell, an
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:
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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 VPN #1 SDWAN VPN #1
SDWAN VPN #2 SDWAN VPN #3
Figure 3: Constraint propagation of Edge Property
However, a SDWAN overlay network can span across untrusted
networks, RR can't trust the RT Constraint (RTC) NLRI BGP UPDATE
from any nodes. RR can only process the RTC NLRI from authorized
peers for a SDWAN VPN.
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 VPNs.
When the RR receives 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 VPN.
5. Client Route UPDATE
The SDWAN network's Client Route UPDATE message is the same as the
MPLS VPN client route UDPATE message. The SDWAN Client Route UPDATE
message uses the Encapsulation Extended Community and the Color
Extended Community to link with the SDWAN Underlay UPDATE Message.
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5.1. SDWAN VPN ID in Client Route Update
An SDWAN VPN is same as a client VPN in a BGP controlled SDWAN
network. The Route Target Extended Community should be included in a
Client Route UPDATE message to differentiate the client routes from
routes belonging to other VPNs.
5.2. SDWAN VPN ID in Data Plane
For an SDWAN edge node which can be reached by both MPLS and IPsec
paths, 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 an IPsec tunnel, the GRE key field can
be used to carry the SDWAN VPN ID. For network virtual overlay
(VxLAN, GENEVE, etc.) encapsulation within the IPsec tunnel, the
Virtual Network Identifier (VNI) field is used to carry the SDWAN
VPN ID.
6. SDWAN Underlay UPDATE
The hybrid underlay tunnel UPDATE is to advertise the detailed
properties associated with the public facing WAN ports and IPsec
tunnels.
6.1. NLRI for SDWAN Underlay Tunnel Update
A new NLRI (SDWAN-SAFI=74) is introduced within the MP_REACH_NLRI
Path Attribute of RFC4760, for advertising the detailed properties
of the SDWAN tunnels terminated at the edge node:
+------------------+
| NLRI Length | 1 octet
+------------------+
| Topology-Type | 2 Octet
+------------------+
| Port-Local-ID | 4 octets
+------------------+
|SDWAN-Site-Color | 4 octets
+------------------+
| SDWAN-Node-ID | 4 or 16 octets
+------------------+
where:
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- NLRI Length: 1 octet of length expressed in bits as defined in
[RFC4760].
- Topology Type: 2 octet value. The SDWAN Site Type defines the
different types of Site IDs to be used in the deployment. This
document defines the following types:
Topology-Type = 1: For a simple deployment, such as all edge
nodes under one SDWAN management system, the node ID is
enough for the SDWAN management to map the site to its
precise geolocation.
Topology-Type = 2: For large SDWAN heterogeneous deployment
where a Geo-Loc Sub-TLV [LISP-GEOLoc]is needed to fully
describe the accurate location of the node.
- Port local ID: SDWAN edge node Port identifier, which is locally
significant. If the SDWAN NLRI applies to multiple WAN ports,
this field is NULL.
- SDWAN-Site-Color: to correlate with the Color-Extended-community
included in the client routes UPDATE. When a client route can be
reached by multiple SDWAN edges co-located at one site, the
SDWAN-Site-Color can indicate the site identifier.
- SDWAN Edge Node ID: The node's IPv4 or IPv6 address.
6.2. SDWAN-Hybrid Tunnel Encoding
A new BGP Tunnel-Type=SDWAN-Hybrid (code point TBD1) is to indicate
hybrid underlay tunnels.
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-Hybrid ) | Length (2 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SDWAN Hybrid Underlay network Sub-TLV Value Field
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6.3. IPsec-SA-ID Sub-TLV
IPsec-SA-ID Sub-TLV within the Hybrid Underlay Tunnel UPDATE
indicates one or more preestablished IPsec SAs by using their
identifiers, instead of listing all the detailed attributes of the
IPsec SAs.
Using an IPsec-SA-ID Sub-TLV not only greatly reduces the size of
BGP UPDATE messages, but also allows the pairwise IPsec rekeying
process to be performed independently.
The following is the structure of the IPsec-SA-ID sub-TLV:
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= IPsec-SA-ID subTLV (TBD2)| Length (2 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPsec SA Identifier #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPsec SA Identifier #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
If the client traffic needs to be encapsulated in a specific way
within the IPsec ESP Tunnel, such as GRE or VxLAN, etc., the
corresponding Tunnel-Encap Sub-TLV needs to be prepended right
before the IPsec-SA-ID Sub-TLV.
6.4. Extended Port Attribute Sub-TLV
Extended Port Attribute Sub-TLV is to advertise the properties
associated with a public internet facing WAN port which might be
behind NAT. An SDWAN edge node can query a STUN Server (Session
Traversal of UDP through Network address translation [RFC3489]) to
get the NAT properties, including the public IP address and the
Public Port number, to pass to its peers.
The location of a NAT device can be:
- 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.
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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.
As one SDWAN edge can connect to multiple peers, the pair-wise NAT
exchange as IPsec's IKE is not efficient. In the BGP Controlled
SDWAN, NAT properties for a WAN port are encoded in the Extended
Port Attribute sub-TLV, which the following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ISP-Sub-TLV |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o Port Ext Type (TBD3): indicating it is the Extended Port
Attribute 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.
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- 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.the NAT type can be: without NAT; 1:1 static NAT; Full
Cone; Restricted Cone; Port Restricted Cone; Symmetric; or
Unknown (i.e. no response from the STUN server).
o Encap Type.the encapsulation types supported 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 WAN 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. Underlay Network Properties Sub-TLV
The Underlay Network Sub-TLV is an optional Sub-TLV to carry the WAN
port connection types and bandwidth, such as LTE, DSL, Ethernet,
etc..
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=TBD4 | Length | Flag | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Connection Type| Port Type | Port Speed |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
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Type: TBD4.
Length: always 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: are listed below as:
Wired - 1
WIFI - 2
LTE - 3
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.
7. IPsec SA Property Sub-TLVs
This section describes the detailed IPsec SA properties sub-TLVs.
When the IPsec SA properties are associated with the node, any of
the node's WAN ports can be the outer destination address of the
IPsec encapsulated data packets.
7.1. 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]. The following fields are removed
because:
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- the Originator ID is same as the Node-ID in the SDWAN NLRI,
- the Tenant ID & Subnet ID are represented by the SDWAN VPN
ID in the Client UPDATE.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ID Length | Nonce Length |I| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rekey |
| Counter |
+---------------------------------------------------------------+
| IPsec SA Identifier |
+---------------------------------------------------------------+
| |
~ Nonce Data ~
| |
+---------------------------------------------------------------+
IPsec SA ID - The 4 bytes IPSec SA ID is to differentiate multiple
IPsec SAs terminated at the edge. The IPsec SA ID can be used in the
IPsec-SA-ID subTLV of a different BGP UPDATE message to refer to all
the values carried in the IPsec Public Key SubTLV and the IPsec SA
Proposal Sub-TLV that are in the same BGP UPDATE message as the
IPsec SA Nonce sub-TLV.
7.2. 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 advertised by the peers.
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.3. 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.
7.4. Simplified IPsec SA 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:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transform | Mode | AH algorithms |ESP algorithms |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ReKey Counter (SPI) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| key1 length | Key 1 ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| key2 length | Key 2 ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| key-i length | Nonce ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o IPsec-SimType: indicate the simplified IPsec SA attributes.
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 Transform (1 Byte):
Transform = 1 means AH,
Transform = 2 means ESP, or
Transform = 3 means AH+ESP.
o IPsec Mode (1 byte):
Mode = 1 indicates that the Tunnel Mode is used
Mode = 2 indicates that the Transport mode is used.
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 algorithms (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.
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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 (Security Parameter Index)): 4 bytes
o Public Key: IPsec public key
o Nonce.IPsec Nonce
o Duration: SA life span.
8. Error & Mismatch Handling
Each C-PE device advertises a SDWAN SAFI Underlay NLRI to the other
C-PE devices via a 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 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 is 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
SDWAN-Site-ID
Tunnel Encap Attr (Type=SDWAN)
ISP Sub-TLV for information about the ISP3
IPsec SA Nonce Sub-TLV,
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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.
9. SDWAN BGP UPDATE Encoding Examples
9.1. Encoding example of WAN Port properties
The C-PE2 of the Figure 1 can send the following SDWAN UPDATE
messages to advertise the properties associated with WAN Port
192.0.0.1 and WAN Port 170.0.0.1 respectively:
SDWAN NLRI: AFI=IPv4/IPv6 & SAFI = SDWAN;
Color match with the Client route UPDATE's Color
Extended Community
local port id for WAN port 192.0.0.1
Node-ID= 2.2.2.2 (C-PE2)
Tunnel-Type = Hybrid-SDWAN
Extended-Port-SubTLV for 192.0.0.1
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SDWAN NLRI: AFI=IPv4/IPv6 & SAFI = SDWAN;
Color match with the Client route UPDATE's Color
Extended Community
local port id for WAN port 170.0.0.1
Node-ID= 2.2.2.2 (C-PE2)
Tunnel-Type = Hybrid-SDWAN
Extended-Port-SubTLV for 170.0.0.1
9.2. Encoding example of IPsec SA terminated at the C-PE2
The C-PE2 of the Figure 1 can send the following SDWAN UPDATE
messages to advertise node level IPsec SA:
SDWAN NLRI: AFI=IPv4/IPv6 & SAFI = SDWAN;
Color match with the Client route UPDATE's Color
Extended Community
Port-ID=0
Node-ID= 2.2.2.2 (C-PE2)
Tunnel-Type = Hybrid-SDWAN
IPsec-SA-ID Sub-TLV or IPsec SA Property Sub-TLVs
9.3. Encoding example #1 of using IPsec-SA-ID Sub-TLV
This section provides an encoding example for the following
scenario:
- There are four IPsec SAs terminated at the same node.
- Two of the IPsec SAs use GRE (value =2) as Inner Encapsulation
within the IPsec Tunnel
- Two of the IPsec SA uses VxLAN (value = 8) as the Inner
Encapsulation within its IPsec Tunnel.
Here is the encoding for the scenario:
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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-Hybrid | Length = |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ GRE Sub-TLV ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| subTLV-Type = IPsec-SA-ID | Length = |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPsec SA Identifier = 1 |
+---------------------------------------------------------------+
| IPsec SA Identifier = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ VxLAN Sub-TLV ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|subTLV-Type = IPsec-SA-ID | Length= |
+-------------------------------+-------------------------------+
| IPsec SA Identifier = 3 |
+-------------------------------+-------------------------------+
| IPsec SA Identifier = 4 |
+---------------------------------------------------------------+
The Length of the Tunnel-Type = SDDWAN-Hybrid is the sum of the
following:
- Tunnel-end-point sub-TLV total length
- The GRE Sub-TLV total length,
- The IPsec-SA-ID Sub-TLV length,
- The VxLAN sub-TLV total length, and
- The IPsec-SA-ID Sub-TLV length.
10. Manageability Considerations
Unlike MPLS VPN whose PE nodes are all controlled by the network
operators, SDWAN edge nodes can be installed anywhere, in shopping
malls, in 3rd party Cloud DCs, etc.
It is very important to ensure that client routes advertisement
from an SDWAN edge node are legitimate. The RR needs to drop all
the BGP Update messages from an SDWAN edge nodes that have invalid
Route Targets.
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11. 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.
SDWAN edge nodes might not have secure channels with the RR. In
this case, BGP connection has be established over IPsec or TLS.
12. IANA Considerations
12.1. Hybrid (SDWAN) Overlay SAFI
IANA has assigned SAFI = 74 as the Hybrid (SDWAN)SAFI.
12.2. Tunnel Encapsulation Attribute Type
IANA is requested to assign a type from the BGP Tunnel Encapsulation
Attribute Tunnel Types as follows:
Value Description Reference
----- ------------ ---------
TBD1 SDWAN-Hybrid [this document]
12.3. Tunnel Encapsulation Attribute Sub-TLV Types
IANA is requested to assign three Types, as follows, in the BGP
Tunnel Encapsulation Attribute Sub-TLVs registry:
Value Type Description Reference
----- ----------------------- ---------------
TBD2 IPSEC-SA-ID Sub-TLV [Section 6.3]
TBD3 Extended Port Property Sub-TLV [Section 6.4]
TBD4 Underlay ISP Properties Sub-TLV [Section 6.5]
TBD5 IPsec SA Nonce Sub-TLV [Section 7.1]
TBD6 IPsec Public Key Sub-TLV [Section 7.2]
TBD7 IPsec SA Proposal Sub-TLV [Section 7.3]
TBD8 Simplified IPsec SA sub-TLV [Section 7.4]
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13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI
10.17487/RFC4271, January 2006, <https://www.rfc-
editor.org/info/rfc4271>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, DOI
10.17487/RFC4760, January 2007, <https://www.rfc-
editor.org/info/rfc4760>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9012] Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", RFC 9012, DOI
10.17487/RFC9012, April 2021, <https://www.rfc-
editor.org/info/rfc9012>.
13.2. Informative References
[RFC8192] S. Hares, et al, "Interface to Network Security Functions
(I2NSF) Problem Statement and Use Cases", July 2017
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[RFC5521] P. Mohapatra, E. Rosen, "The BGP Encapsulation Subsequent
Address Family Identifier (SAFI) and the BGP Tunnel
Encapsulation Attribute", April 2009.
[RFC9061] Marin-Lopez, R., Lopez-Millan, G., and F. Pereniguez-
Garcia, "A YANG Data Model for IPsec Flow Protection Based
on Software-Defined Networking (SDN)", RFC 9061, DOI
10.17487/RFC9061, July 2021, <https://www.rfc-
editor.org/info/rfc9061>.
[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.
[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.
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[Net2Cloud-Problem] L. Dunbar and A. Malis, "Dynamic Networks to
Hybrid Cloud DCs Problem Statement", draft-ietf-rtgwg-
net2cloud-problem-statement-12, March 7, 2022.
[Net2Cloud-gap] L. Dunbar, A. Malis, and C. Jacquenet, "Networks
Connecting to Hybrid Cloud DCs: Gap Analysis", draft-ietf-
rtgwg-net2cloud-gap-analysis-07, July, 2020.
[RFC9012] K. Patel, et al "The BGP Tunnel Encapsulation Attribute",
RFC9012, April 2021.
14. Acknowledgments
Acknowledgements to Wang Haibo, Hao Weiguo, and ShengCheng for
implementation contribution; Many thanks to Yoav Nir, Graham
Bartlett, Jim Guichard, John Scudder, and Donald Eastlake for their
review and suggestions.
This document was prepared using 2-Word-v2.0.template.dot.
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Authors' Addresses
Linda Dunbar
Futurewei
Email: ldunbar@futurewei.com
Sue Hares
Hickory Hill Consulting
Email: shares@ndzh.com
Robert Raszuk
NTT Network Innovations
Email: robert@raszuk.net
Kausik Majumdar
Microsoft
Email: kmajumdar@microsoft.com
Gyan Mishra
Verizon Inc.
Email: gyan.s.mishra@verizon.com
Contributors' Addresses
Donald Eastlake
Futurewei
Email: d3e3e3@gmail.com
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