< draft-ietf-rtgwg-net2cloud-problem-statement-02.txt   draft-ietf-rtgwg-net2cloud-problem-statement-03.txt >
Network Working Group L. Dunbar Network Working Group L. Dunbar
Internet Draft A. Malis Internet Draft A. Malis
Intended status: Informational Futurewei Intended status: Informational Futurewei
Expires: Dec 2019 C. Jacquenet Expires: Dec 2019 C. Jacquenet
Orange Orange
M. Toy M. Toy
Verizon Verizon
June 17, 2019 July 3, 2019
Dynamic Networks to Hybrid Cloud DCs Problem Statement Dynamic Networks to Hybrid Cloud DCs Problem Statement
draft-ietf-rtgwg-net2cloud-problem-statement-02 draft-ietf-rtgwg-net2cloud-problem-statement-03
Abstract Abstract
This document describes the problems that enterprises face today This document describes the problems that enterprises face today
when connecting their branch offices to dynamic workloads in third when connecting their branch offices to dynamic workloads in third
party data centers (a.k.a. Cloud DCs). party data centers (a.k.a. Cloud DCs).
It examines some of the approaches interconnecting cloud DCs with It examines some of the approaches interconnecting cloud DCs with
enterprises' on-premises DCs & branch offices. This document also enterprises' on-premises DCs & branch offices. This document also
describes some of the network problems that many enterprises face describes some of the network problems that many enterprises face
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months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as at any time. It is inappropriate to use Internet-Drafts as
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This Internet-Draft will expire on December 17, 2019. This Internet-Draft will expire on January 3, 2009.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction...................................................3 1. Introduction...................................................3
1.1. On the evolution of Cloud DC connectivity.................3 1.1. On the evolution of Cloud DC connectivity.................3
1.2. The role of SD-WAN techniques in Cloud DC connectivity....4 1.2. The role of SD-WAN techniques in Cloud DC connectivity....4
2. Definition of terms............................................4 2. Definition of terms............................................4
3. Current Practices in Interconnecting Enterprise Sites with Cloud 3. Current Practices in Interconnecting Enterprise Sites with Cloud
DCs...............................................................5 DCs...............................................................5
3.1. Multiple connection to workloads in a Cloud DC............5 3.1. Multiple connection to workloads in a Cloud DC............5
3.2. Interconnect to Hybrid Cloud DCs..........................7 3.2. Interconnect to Hybrid Cloud DCs..........................7
3.3. Connecting workloads among hybrid Cloud DCs...............8 3.3. Connecting workloads among hybrid Cloud DCs...............8
4. Desired Properties for Networks that interconnect Hybrid Clouds9 4. Desired Properties for Networks that interconnect Hybrid Clouds9
5. Problems with MPLS-based VPNs extending to Hybrid Cloud DCs....9 5. Problems with MPLS-based VPNs extending to Hybrid Cloud DCs...10
6. Problem with using IPsec tunnels to Cloud DCs.................11 6. Problem with using IPsec tunnels to Cloud DCs.................11
6.1. Complexity of multi-point any-to-any interconnection.....11 6.1. Complexity of multi-point any-to-any interconnection.....12
6.2. Poor performance over long distance......................12 6.2. Poor performance over long distance......................12
6.3. Scaling Issues with IPsec Tunnels........................12 6.3. Scaling Issues with IPsec Tunnels........................13
7. Problems of Using SD-WAN to connect to Cloud DCs..............13 7. Problems of Using SD-WAN to connect to Cloud DCs..............13
7.1. SD-WAN among branch offices vs. interconnect to Cloud DCs13 7.1. SD-WAN among branch offices vs. interconnect to Cloud DCs14
8. End-to-End Security Concerns for Data Flows...................16 8. End-to-End Security Concerns for Data Flows...................16
9. Requirements for Dynamic Cloud Data Center VPNs...............16 9. Requirements for Dynamic Cloud Data Center VPNs...............16
10. Security Considerations......................................17 10. Security Considerations......................................17
11. IANA Considerations..........................................17 11. IANA Considerations..........................................17
12. References...................................................17 12. References...................................................17
12.1. Normative References....................................17 12.1. Normative References....................................17
12.2. Informative References..................................17 12.2. Informative References..................................17
13. Acknowledgments..............................................18 13. Acknowledgments..............................................18
1. Introduction 1. Introduction
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SD-WAN: Software Defined Wide Area Network. In this document, SD-WAN: Software Defined Wide Area Network. In this document,
"SD-WAN" refers to the solutions of pooling WAN "SD-WAN" refers to the solutions of pooling WAN
bandwidth from multiple underlay networks to get better bandwidth from multiple underlay networks to get better
WAN bandwidth management, visibility & control. When the WAN bandwidth management, visibility & control. When the
underlay networks are private networks, traffic can underlay networks are private networks, traffic can
traverse without additional encryption; when the traverse without additional encryption; when the
underlay networks are public, such as Internet, some underlay networks are public, such as Internet, some
traffic needs to be encrypted when traversing through traffic needs to be encrypted when traversing through
(depending on user provided policies). (depending on user provided policies).
VPC: Virtual Private Cloud. A service offered by Cloud DC VPC: Virtual Private Cloud is a virtual network dedicated to
operators to allocate logically-isolated cloud one client account. It is logically isolated from other
resources, including compute, networking and storage. virtual networks in a Cloud DC. Each client can launch
his/her desired resources, such as compute, storage, or
network functions into his/her VPC. Most Cloud
operators' VPCs only support private addresses, some
support IPv4 only, others support IPv4/IPv6 dual stack.
3. Current Practices in Interconnecting Enterprise Sites with Cloud DCs 3. Current Practices in Interconnecting Enterprise Sites with Cloud DCs
3.1. Multiple connection to workloads in a Cloud DC 3.1. Multiple connection to workloads in a Cloud DC
Most Cloud operators offer some type of network gateway through Most Cloud operators offer some type of network gateway through
which an enterprise can reach their workloads hosted in the Cloud which an enterprise can reach their workloads hosted in the Cloud
DCs. For example, AWS (Amazon Web Services) offers the following DCs. For example, AWS (Amazon Web Services) offers the following
options to reach workloads in AWS Cloud DCs: options to reach workloads in AWS Cloud DCs:
- AWS Internet gateway allows communication between instances in - AWS Internet gateway allows communication between instances in
AWS VPC and the internet. AWS VPC and the internet.
- AWS Virtual gateway (vGW) where IPsec tunnels [RFC6071] are - AWS Virtual gateway (vGW) where IPsec tunnels [RFC6071] are
established between an enterprise's own gateway and AWS vGW, so established between an enterprise's own gateway and AWS vGW, so
that the communications between those gateways can be secured that the communications between those gateways can be secured
from the underlay (which might be the public Internet). from the underlay (which might be the public Internet).
- AWS Direct Connect, which allows enterprises to purchase direct - AWS Direct Connect, which allows enterprises to purchase direct
connect from network service providers to get a private leased connect from network service providers to get a private leased
line interconnecting the enterprises gateway(s) and the AWS line interconnecting the enterprises gateway(s) and the AWS
Direct Connect routers. In addition, an AWS Transit Gateway can Direct Connect routers. In addition, an AWS Transit Gateway
be used to interconnect multiple VPCs in different Availability (https://aws.amazon.com/transit -gateway/) can be used to interconnect
Zones. multiple VPCs in different Availability Zones. AWS Transit
Gateway acts as a hub that controls how traffic is forwarded
among all the connected networks which act like spokes.
As an example, some branch offices of an enterprise can connect to As an example, some branch offices of an enterprise can connect to
over the Internet to reach AWS's vGW via IPsec tunnels. Other branch over the Internet to reach AWS's vGW via IPsec tunnels. Other branch
offices of the same enterprise can connect to AWS DirectConnect via offices of the same enterprise can connect to AWS DirectConnect via
a private network (without any encryption). ). It is important for a private network (without any encryption). ). It is important for
enterprises to be able to observe the specific behaviors when enterprises to be able to observe the specific behaviors when
connected by different connections. connected by different connections.
Figure below shows an example of some tenants' workloads are Figure below shows an example of some tenants' workloads are
accessible via a virtual router connected by AWS Internet Gateway; accessible via a virtual router connected by AWS Internet Gateway;
some are accessible via AWS vGW, and others are accessible via AWS some are accessible via AWS vGW, and others are accessible via AWS
Direct Connect. The vR1 can have its own IPsec capability for secure Direct Connect. vR1 uses IPsec to establish secure tunnels over the
tunnel over the internet to bypass paying additional price for the Internet to avoid paying extra fees for the IPsec features provided
IPsec features provided by AWS vGW. Some tenants can deploy separate by AWS vGW. Some tenants can deploy separate virtual routers to
virtual routers to connect to internet traffic and to traffic from connect to internet traffic and to traffic from the secure channels
the secure channels from vGW and DirectConnect, e.g. vR1 & vR2. from vGW and DirectConnect, e.g. vR1 & vR2. Others may have one
Others may have one virtual router connecting to both types of virtual router connecting to both types of traffic. Customer Gateway
traffic. Customer Gateway can be customer owned router or ports can be customer owned router or ports physically connected to AWS
physically connected to AWS Direct Connect GW. Direct Connect GW.
+------------------------+ +------------------------+
| ,---. ,---. | | ,---. ,---. |
| (TN-1 ) ( TN-2)| | (TN-1 ) ( TN-2)|
| `-+-' +---+ `-+-' | | `-+-' +---+ `-+-' |
| +----|vR1|----+ | | +----|vR1|----+ |
| ++--+ | | ++--+ |
| | +-+----+ | | +-+----+
| | /Internet\ For External | | /Internet\ For External
| +-------+ Gateway +---------------------- | +-------+ Gateway +----------------------
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| +-------+ Gateway +----------+ gateway | | +-------+ Gateway +----------+ gateway |
| \ / Connect \ / | \ / Connect \ /
| +-+----+ +------+ | +-+----+ +------+
| | | |
+------------------------+ +------------------------+
Figure 1: Examples of Multiple Cloud DC connections. Figure 1: Examples of Multiple Cloud DC connections.
3.2. Interconnect to Hybrid Cloud DCs 3.2. Interconnect to Hybrid Cloud DCs
Hybrid will be the most common usage of the cloud as more It is likely that hybrid designs will become the rule for cloud
enterprises see the benefits of integrating public and private cloud services, as more enterprises see the benefits of integrating public
infrastructures. However, enabling the growth of hybrid cloud and private cloud infrastructures. However, enabling the growth of
deployments in the enterprise requires fast and safe interconnection hybrid cloud deployments in the enterprise requires fast and safe
between public and private cloud services. interconnection between public and private cloud services.
For an enterprise to connect to applications & workloads hosted in For an enterprise to connect to applications & workloads hosted in
multiple Cloud DCs, the enterprise can use IPsec tunnels established multiple Cloud DCs, the enterprise can use IPsec tunnels established
over the Internet or a (virtualized) leased line service to connect over the Internet or a (virtualized) leased line service to connect
its on-premises gateways to each of the Cloud DC's gateways, virtual its on-premises gateways to each of the Cloud DC's gateways, virtual
routers instantiated in the Cloud DCs, or any other suitable design routers instantiated in the Cloud DCs, or any other suitable design
(including a combination thereof). (including a combination thereof).
Some enterprises prefer to instantiate their own virtual Some enterprises prefer to instantiate their own virtual
CPEs/routers inside the Cloud DC to connect the workloads within the CPEs/routers inside the Cloud DC to connect the workloads within the
Cloud DC. Then an overlay path is established between customer Cloud DC. Then an overlay path is established between customer
gateways to the virtual CPEs/routers for reaching the workloads gateways to the virtual CPEs/routers for reaching the workloads
inside the cloud DC. inside the cloud DC.
3.3. Connecting workloads among hybrid Cloud DCs 3.3. Connecting workloads among hybrid Cloud DCs
There are multiple approaches to interconnect workloads among There are multiple approaches to interconnect workloads among
different Cloud DCs: different Cloud DCs:
a) Utilize Cloud DC provided transit gateways. a) Utilize Cloud DC provided inter/intra-cloud connectivity
b) Hairpin all the traffic through the customer gateway, or services (e.g., AWS Transit Gateway) to connect workloads
instantiated in multiple VPCs. Such services are provided with
the cloud gateway to connect to external networks (e.g., AWS
DirectConnect Gateway).
b) Hairpin all traffic through the customer gateway, meaning all
workloads are directly connected to the customer gateway, so
that communications among workloads within one Cloud DC have to
traverse through the customer gateway.
c) Establish direct tunnels among different VPCs (Virtual Private c) Establish direct tunnels among different VPCs (Virtual Private
Clouds) via client's own virtual routers instantiated within Clouds) via client's own virtual routers instantiated within
Cloud DCs. DMVPN (Dynamic Multipoint Virtual Private Network) Cloud DCs. DMVPN (Dynamic Multipoint Virtual Private Network)
or DSVPN (Dynamic Smart VPN) techniques can be used to or DSVPN (Dynamic Smart VPN) techniques can be used to
establish direct Multi-point-to-Point or multi-point-to multi- establish direct Multi-point-to-Point or multi-point-to multi-
point tunnels among those client's own virtual routers. point tunnels among those client's own virtual routers.
Approach a) usually does not work if Cloud DCs are owned and managed Approach a) usually does not work if Cloud DCs are owned and managed
by different Cloud providers. by different Cloud providers.
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One of the main drivers for moving workloads into the cloud is One of the main drivers for moving workloads into the cloud is
the widely available cloud DCs at geographically diverse the widely available cloud DCs at geographically diverse
locations, where apps can be instantiated so that they can be locations, where apps can be instantiated so that they can be
as close to their end-users as possible. When the user base as close to their end-users as possible. When the user base
changes, the applications may be migrated to a new cloud DC changes, the applications may be migrated to a new cloud DC
location closest to the new user base. location closest to the new user base.
- Most of the cloud DCs do not expose their internal networks, so - Most of the cloud DCs do not expose their internal networks, so
the MPLS-based VPNs can only reach Cloud DC's Gateways, not to the MPLS-based VPNs can only reach Cloud DC's Gateways, not to
the workloads hosted inside. Even with AWS DirectConnect, the the workloads hosted inside. Even with AWS DirectConnect, the
connection only reaches the AWS DirectConnect Gateway. connection only reaches the AWS DirectConnect Gateway. AWS
DirectConnect Gateway uses BGP to exchange all routes with
devices located behind the gateway, even including routes of
applications that might be physically located in different
geographical locations. There is no visibility on how the
applications/workloads are interconnected within a Cloud DC or
across multiple Cloud DCs.
- Extensive usage of Overlay by Cloud DCs: - Extensive usage of Overlay by Cloud DCs:
Many cloud DCs use an overlay to connect their gateways to the Many cloud DCs use an overlay to connect their gateways to the
workloads located inside the DC. There is currently no standard workloads located inside the DC. There is currently no standard
that specifies the interworking between the Cloud Overlay and the that specifies the interworking between the Cloud Overlay and
enterprise' existing underlay networks. One of the the enterprise' existing underlay networks. One of the
characteristics of overlay networks is that some of the WAN ports rd of the edge nodes connect to 3 party networks. There is characteristics of overlay networks is that some of the WAN
therefore a need to propagate WAN port information to remote rd authorized peers in 3 party network domains in addition to route ports of the edge nodes connect to third party networks. There
propagation. Such an exchange cannot happen before communication is therefore a need to propagate WAN port information to remote
between peers is properly secured. authorized peers in third party network domains in addition to
route propagation. Such an exchange cannot happen before
communication between peers is properly secured.
Another roadblock is the lack of a standard way to express and Another roadblock is the lack of a standard way to express and
enforce consistent security policies for workloads that not only use enforce consistent security policies for workloads that not only use
virtual addresses, but in which are also very likely hosted in virtual addresses, but in which are also very likely hosted in
different locations within the Cloud DC [RFC8192]. The current VPN different locations within the Cloud DC [RFC8192]. The current VPN
path computation and bandwidth allocation schemes may not be path computation and bandwidth allocation schemes may not be
flexible enough to address the need for enterprises to rapidly flexible enough to address the need for enterprises to rapidly
connect to dynamically instantiated (or removed) workloads and connect to dynamically instantiated (or removed) workloads and
applications regardless of their location/nature (i.e., third party applications regardless of their location/nature (i.e., third party
cloud DCs). cloud DCs).
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| | +-+----+ | | +-+----+
| | /Internet\ One path via | | /Internet\ One path via
| +-------+ Gateway +---------------------+ | +-------+ Gateway +---------------------+
| \ / Internet \ | \ / Internet \
| +-+----+ \ | +-+----+ \
+------------------------+ \ +------------------------+ \
\ \
+------------------------+ native traffic \ +------------------------+ native traffic \
| ,---. ,---. | without encryption| | ,---. ,---. | without encryption|
| (TN-3 ) ( TN-4)| | | (TN-3 ) ( TN-4)| |
| `-+-' +--+ `-+-' | | +------+ | `-+-' +--+ `-+-' | | +------+
| +----|vR|-----+ | +--+ CPE | | +----|vR|-----+ | +----+ CPE |
| ++-+ | | +------+ | ++-+ | | +------+
| | +-+----+ | | | +-+----+ |
| | / virtual\ One path via IPsec Tunnel | | | / virtual\ One path via IPsec Tunnel |
| +-------+ Gateway +-------------------------- + | +-------+ Gateway +-------------------------- +
| \ / Encrypted traffic over| | \ / Encrypted traffic over|
| +-+----+ public network | | +-+----+ public network |
+------------------------+ | +------------------------+ |
| |
+------------------------+ | +------------------------+ |
| ,---. ,---. | Native traffic | | ,---. ,---. | Native traffic |
| (TN-5 ) ( TN-6)| without encryption | | (TN-5 ) ( TN-6)| without encryption |
| `-+-' +--+ `-+-' | over secure network| | `-+-' +--+ `-+-' | over secure network|
| +----|vR|-----+ | | | +----|vR|-----+ | |
| ++-+ | | | ++-+ | |
| | +-+----+ +------+ | | | +-+----+ +------+ |
| | / \ Via Direct /customer\ | | | / \ Via Direct /customer\ |
| +-------+ Gateway +----------+ gateway |-----+ | +-------+ Gateway +----------+ gateway |-----+
| \ / Connect \ / | \ / Connect \ /
| +-+----+ +------+ | +-+----+ +------+
+------------------------+ Customer GW has physical connection to AWS GW. +------------------------+Customer GW has physical connection to AWS GW
Figure 2: Different Underlays to Reach Cloud DC Figure 2: Different Underlays to Reach Cloud DC
8. End-to-End Security Concerns for Data Flows 8. End-to-End Security Concerns for Data Flows
When IPsec tunnels established from enterprise on-premises CPEs When IPsec tunnels established from enterprise on-premises CPEs
are terminated at the Cloud DC gateway where the workloads or are terminated at the Cloud DC gateway where the workloads or
applications are hosted, some enterprises have concerns regarding applications are hosted, some enterprises have concerns regarding
traffic to/from their workload being exposed to others behind the traffic to/from their workload being exposed to others behind the
data center gateway (e.g., exposed to other organizations that data center gateway (e.g., exposed to other organizations that
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