< draft-ietf-rtgwg-net2cloud-problem-statement-03.txt   draft-ietf-rtgwg-net2cloud-problem-statement-04.txt >
Network Working Group L. Dunbar Network Working Group L. Dunbar
Internet Draft A. Malis Internet Draft Futurewei
Intended status: Informational Futurewei Intended status: Informational Andy Malis
Expires: Dec 2019 C. Jacquenet Expires: Dec 2019 Independent
C. Jacquenet
Orange Orange
M. Toy M. Toy
Verizon Verizon
July 3, 2019 September 23, 2019
Dynamic Networks to Hybrid Cloud DCs Problem Statement Dynamic Networks to Hybrid Cloud DCs Problem Statement
draft-ietf-rtgwg-net2cloud-problem-statement-03 draft-ietf-rtgwg-net2cloud-problem-statement-04
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 interconnecting their branch offices with dynamic workloads in
party data centers (a.k.a. Cloud DCs). third 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
when they have workloads & applications & data split among hybrid when they have workloads & applications & data split among different
data centers, especially for those enterprises with multiple sites data centers, especially for those enterprises with multiple sites
that are already interconnected by VPNs (e.g., MPLS L2VPN/L3VPN). that are already interconnected by VPNs (e.g., MPLS L2VPN/L3VPN).
Current operational problems are examined to determine whether there Current operational problems are examined to determine whether there
is a need to improve existing protocols or whether a new protocol is is a need to improve existing protocols or whether a new protocol is
necessary to solve them. necessary to solve them.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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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
reference material or to cite them other than as "work in progress." reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
This Internet-Draft will expire on January 3, 2009. This Internet-Draft will expire on March 23, 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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document must include Simplified BSD License text as described in document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License. warranty as described in the Simplified BSD License.
Table of Contents Table of Contents
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. Interconnecting Enterprise Sites with Cloud DCs................5
DCs...............................................................5 3.1. Multiple connections to workloads in a Cloud DC...........5
3.1. Multiple connection to workloads in a Cloud DC............5 3.2. Interconnect Private and Public Cloud DCs.................7
3.2. Interconnect to Hybrid Cloud DCs..........................7 3.3. Desired Properties for Networks that interconnect Hybrid
3.3. Connecting workloads among hybrid Cloud DCs...............8 Clouds.........................................................8
4. Desired Properties for Networks that interconnect Hybrid Clouds9 4. Multiple Clouds Interconnection................................9
5. Problems with MPLS-based VPNs extending to Hybrid Cloud DCs...10 4.1. Multi-Cloud Interconnection...............................9
6. Problem with using IPsec tunnels to Cloud DCs.................11 4.2. Desired Properties for Multi-Cloud Interconnection.......11
6.1. Complexity of multi-point any-to-any interconnection.....12
6.2. Poor performance over long distance......................12
6.3. Scaling Issues with IPsec Tunnels........................13
7. Problems of Using SD-WAN to connect to Cloud DCs..............13 5. Problems with MPLS-based VPNs extending to Hybrid Cloud DCs...11
7.1. SD-WAN among branch offices vs. interconnect to Cloud DCs14 6. Problem with using IPsec tunnels to Cloud DCs.................13
8. End-to-End Security Concerns for Data Flows...................16 6.1. Complexity of multi-point any-to-any interconnection.....13
9. Requirements for Dynamic Cloud Data Center VPNs...............16 6.2. Poor performance over long distance......................14
10. Security Considerations......................................17 6.3. Scaling Issues with IPsec Tunnels........................14
11. IANA Considerations..........................................17 7. Problems of Using SD-WAN to connect to Cloud DCs..............15
12. References...................................................17 7.1. SD-WAN among branch offices vs. interconnect to Cloud DCs15
12.1. Normative References....................................17 8. End-to-End Security Concerns for Data Flows...................18
12.2. Informative References..................................17 9. Requirements for Dynamic Cloud Data Center VPNs...............18
13. Acknowledgments..............................................18 10. Security Considerations......................................19
11. IANA Considerations..........................................19
12. References...................................................19
12.1. Normative References....................................19
12.2. Informative References..................................19
13. Acknowledgments..............................................20
1. Introduction 1. Introduction
1.1. On the evolution of Cloud DC connectivity 1.1. On the evolution of Cloud DC connectivity
The ever-increasing use of cloud applications for communication The ever-increasing use of cloud applications for communication
services change the way corporate business works and shares services change the way corporate business works and shares
information. Such cloud applications use resources hosted in third information. Such cloud applications use resources hosted in third
party DCs that also host services for other customers. party DCs that also host services for other customers.
With the advent of widely available third party cloud DCs in diverse With the advent of widely available third-party cloud DCs in diverse
geographic locations and the advancement of tools for monitoring and geographic locations and the advancement of tools for monitoring and
predicting application behaviors, it is technically feasible for predicting application behaviors, it is technically feasible for
enterprises to instantiate applications and workloads in locations enterprises to instantiate applications and workloads in locations
that are geographically closest to their end-users. Such proximity that are geographically closest to their end-users. Such proximity
improves end-to-end latency and overall user experience. Conversely, improves end-to-end latency and overall user experience. Conversely,
an enterprise can easily shutdown applications and workloads an enterprise can easily shutdown applications and workloads
whenever end-users are in motion (thereby modifying the networking whenever end-users are in motion (thereby modifying the networking
connection of subsequently relocated applications and workloads). In connection of subsequently relocated applications and workloads). In
addition, an enterprise may wish to take advantage of more and more addition, an enterprise may wish to take advantage of more and more
business applications offered by third party private cloud DCs. business applications offered by third party private cloud DCs.
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resources (without any assistance from the VPN service provider), or resources (without any assistance from the VPN service provider), or
wait for their VPN service provider to make new agreements with data wait for their VPN service provider to make new agreements with data
center providers to connect to the cloud resources. Either way has center providers to connect to the cloud resources. Either way has
additional infrastructure and operational costs. additional infrastructure and operational costs.
In addition, more enterprises are moving towards hybrid cloud DCs, In addition, more enterprises are moving towards hybrid cloud DCs,
i.e. owned or operated by different Cloud operators, to maximize the i.e. owned or operated by different Cloud operators, to maximize the
benefits of geographical proximity, elasticity and special features benefits of geographical proximity, elasticity and special features
offered by different cloud DCs. offered by different cloud DCs.
1.2. The role of SD-WAN techniques in Cloud DC connectivity 1.2. The role of SD-WAN techniques in Cloud DC connectivity
This document discusses the issues associated with connecting This document discusses the issues associated with connecting
enterprise to their workloads/applications instantiated in multiple enterprise's workloads/applications instantiated in multiple third-
third-party data centers (a.k.a. Cloud DCs). Very often, the actual party data centers (a.k.a. Cloud DCs) and its on-prem data centers.
Cloud DCs that host the workloads/applications can be transient. . Very often, the actual Cloud DCs that host the
workloads/applications can be transient.
SD-WAN, initially launched to maximize bandwidths between locations SD-WAN, initially launched to maximize bandwidths between locations
by aggregating multiple paths managed by different service by aggregating multiple paths managed by different service
providers, has expanded to include flexible, on-demand, application- providers, has expanded to include flexible, on-demand, application-
based connections established over any networks to access dynamic based connections established over any networks to access dynamic
workloads in Cloud DCs. workloads in Cloud DCs.
As a consequence, this document discusses the use of SD-WAN Therefore, this document discusses the use of SD-WAN techniques to
techniques as a means to improve enterprise-to-cloud DC improve enterprise-to-cloud DC and cloud DC-to-cloud DC
connectivity. connectivity.
2. Definition of terms 2. Definition of terms
Cloud DC: Third party Data Centers that usually host applications Cloud DC: Third party Data Centers that usually host applications
and workload owned by different organizations or and workload owned by different organizations or
tenants. tenants.
Controller: Used interchangeably with SD-WAN controller to manage Controller: Used interchangeably with SD-WAN controller to manage
SD-WAN overlay path creation/deletion and monitoring the SD-WAN overlay path creation/deletion and monitoring the
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(depending on user provided policies). (depending on user provided policies).
VPC: Virtual Private Cloud is a virtual network dedicated to VPC: Virtual Private Cloud is a virtual network dedicated to
one client account. It is logically isolated from other one client account. It is logically isolated from other
virtual networks in a Cloud DC. Each client can launch virtual networks in a Cloud DC. Each client can launch
his/her desired resources, such as compute, storage, or his/her desired resources, such as compute, storage, or
network functions into his/her VPC. Most Cloud network functions into his/her VPC. Most Cloud
operators' VPCs only support private addresses, some operators' VPCs only support private addresses, some
support IPv4 only, others support IPv4/IPv6 dual stack. support IPv4 only, others support IPv4/IPv6 dual stack.
3. Current Practices in Interconnecting Enterprise Sites with Cloud DCs 3. Interconnecting Enterprise Sites with Cloud DCs
3.1. Multiple connection to workloads in a Cloud DC 3.1. Multiple connections 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 Direct Connect routers. In addition, an AWS Transit Gateway can
(https://aws.amazon.com/transit -gateway/) can be used to interconnect be used to interconnect multiple VPCs in different Availability
multiple VPCs in different Availability Zones. AWS Transit Zones. AWS Transit Gateway acts as a hub that controls how
Gateway acts as a hub that controls how traffic is forwarded traffic is forwarded among all the connected networks which act
among all the connected networks which act like spokes. 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;
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| | +-+----+ +------+ | | +-+----+ +------+
| | / \ For Direct /customer\ | | / \ For Direct /customer\
| +-------+ 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 Private and Public Cloud DCs
It is likely that hybrid designs will become the rule for cloud It is likely that hybrid designs will become the rule for cloud
services, as more enterprises see the benefits of integrating public services, as more enterprises see the benefits of integrating public
and private cloud infrastructures. However, enabling the growth of and private cloud infrastructures. However, enabling the growth of
hybrid cloud deployments in the enterprise requires fast and safe hybrid cloud deployments in the enterprise requires fast and safe
interconnection 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. Desired Properties for Networks that interconnect Hybrid Clouds
There are multiple approaches to interconnect workloads among The networks that interconnect hybrid cloud DCs must address the
different Cloud DCs: following requirements:
- High availability to access all workloads in the desired cloud
DCs.
Many enterprises include cloud infrastructures in their
disaster recovery strategy, e.g., by enforcing periodic backup
policies within the cloud, or by running backup applications in
the Cloud, etc. Therefore, the connection to the cloud DCs may
not be permanent, but rather needs to be on-demand.
a) Utilize Cloud DC provided inter/intra-cloud connectivity - Global reachability from different geographical zones, thereby
facilitating the proximity of applications as a function of the
end users' location, to improve latency.
- Elasticity: prompt connection to newly instantiated
applications at Cloud DCs when usages increase and prompt
release of connection after applications at locations being
removed when demands change.
Some enterprises have front-end web portals running in cloud
DCs and database servers in their on-premises DCs. Those Front-
end web portals need to be reachable from the public Internet.
The backend connection to the sensitive data in database
servers hosted in the on-premises DCs might need secure
connections.
- Scalable security management. IPsec is commonly used to
interconnect cloud gateways with CPEs deployed in the
enterprise premises. For enterprises with a large number or
branch offices, managing the IPsec's Security Associations
among many nodes can be very difficult.
4. Multiple Clouds Interconnection
4.1. Multi-Cloud Interconnection
Enterprises today can instantiate their workloads or applications in
Cloud DCs owned by different Cloud providers, e.g. AWS, Azure,
GoogleCloud, Oracle, etc. Interconnecting those workloads involves
three parties: The Enterprise, its network service providers, and
the Cloud providers.
All Cloud Operators offer secure ways to connect enterprises' on-
prem sites/DCs with their Cloud DCs.
Some Cloud Operators allow enterprises to connect via private
networks. For example, AWS's DirectConnect allows enterprises to use rd 3 party provided private Layer 2 path from enterprises' GW to AWS
DirectConnect GW. Microsoft's ExpressRoute allows extension of a
private network to any of the Microsoft cloud services, including
Azure and Office365. ExpressRoute is configured using Layer 3
routing. Customers can opt for redundancy by provisioning dual links
from their location to two Microsoft Enterprise edge routers (MSEEs)
located within a third-party ExpressRoute peering location. The BGP
routing protocol is then setup over WAN links to provide redundancy
to the cloud. This redundancy is maintained from the peering data
center into Microsoft's cloud network.
Google's Cloud Dedicated Interconnect offers similar network
connectivity options as AWS and Microsoft. One distinct difference,
however, is that Google's service allows customers access to the
entire global cloud network by default. It does this by connecting
your on-premises network with the Google Cloud using BGP and Google
Cloud Routers to provide optimal paths to the different regions of
the global cloud infrastructure.
All those connectivity options are between Cloud providers' DCs and
the Enterprises, but not between cloud DCs. For example, to connect
applications in AWS Cloud to applications in Azure Cloud, there must
be a third-party gateway (physical or virtual) to interconnect the
AWS's Layer 2 DirectConnect path with Azure's Layer 3 ExpressRoute.
Enterprises can also instantiate their own virtual routers in
different Cloud DCs and administer IPsec tunnels among them, which
by itself is not a trivial task. Or by leveraging open source VPN
software such as strongSwan, you create an IPSec connection to the
Azure gateway using a shared key. The strong swan instance within
AWS not only can connect to Azure but can also be used to facilitate
traffic to other nodes within the AWS VPC by configuring forwarding
and using appropriate routing rules for the VPC. Most Cloud
operators, such as AWS VPC or Azure VNET, use non-globally routable
CIDR from private IPv4 address ranges as specified by RFC1918. To
establish IPsec tunnel between two Cloud DCs, it is necessary to
exchange Public routable addresses for applications in different
Cloud DCs. [BGP-SDWAN] describes one method. Other methods are worth
exploring.
In summary, here are some approaches, available now (which might
change in the future), to interconnect workloads among different
Cloud DCs:
a) Utilize Cloud DC provided inter/intra-cloud connectivity
services (e.g., AWS Transit Gateway) to connect workloads services (e.g., AWS Transit Gateway) to connect workloads
instantiated in multiple VPCs. Such services are provided with instantiated in multiple VPCs. Such services are provided with
the cloud gateway to connect to external networks (e.g., AWS the cloud gateway to connect to external networks (e.g., AWS
DirectConnect Gateway). DirectConnect Gateway).
b) Hairpin all traffic through the customer gateway, meaning all b) Hairpin all traffic through the customer gateway, meaning all
workloads are directly connected to the customer gateway, so workloads are directly connected to the customer gateway, so
that communications among workloads within one Cloud DC have to that communications among workloads within one Cloud DC must
traverse through the customer gateway. traverse through the customer gateway.
c) Establish direct tunnels among different VPCs (Virtual Private c) Establish direct tunnels among different VPCs (AWS' Virtual
Clouds) via client's own virtual routers instantiated within Private Clouds) and VNET (Azure's Virtual Networks) via
Cloud DCs. DMVPN (Dynamic Multipoint Virtual Private Network) client's own virtual routers instantiated within Cloud DCs.
or DSVPN (Dynamic Smart VPN) techniques can be used to DMVPN (Dynamic Multipoint Virtual Private Network) or DSVPN
establish direct Multi-point-to-Point or multi-point-to multi- (Dynamic Smart VPN) techniques can be used to establish direct
point tunnels among those client's own virtual routers. Multi-point-to-Point or multi-point-to multi-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.
Approach b) creates additional transmission delay plus incurring Approach b) creates additional transmission delay plus incurring
cost when exiting Cloud DCs. cost when exiting Cloud DCs.
For the Approach c), DMVPN or DSVPN use NHRP (Next Hop Resolution For the Approach c), DMVPN or DSVPN use NHRP (Next Hop Resolution
Protocol) [RFC2735] so that spoke nodes can register their IP Protocol) [RFC2735] so that spoke nodes can register their IP
addresses & WAN ports with the hub node. The IETF ION addresses & WAN ports with the hub node. The IETF ION
(Internetworking over NBMA (non-broadcast multiple access) WG (Internetworking over NBMA (non-broadcast multiple access) WG
standardized NHRP for connection-oriented NBMA network (such as ATM) standardized NHRP for connection-oriented NBMA network (such as ATM)
network address resolution more than two decades ago. network address resolution more than two decades ago.
There are many differences between virtual routers in Public Cloud There are many differences between virtual routers in Public Cloud
DCs and the nodes in an NBMA network. NHRP cannot be used for DCs and the nodes in an NBMA network. NHRP cannot be used for
registering virtual routers in Cloud DCs unless an extension of such registering virtual routers in Cloud DCs unless an extension of such
protocols is developed for that purpose. Therefore, DMVPN and/or protocols is developed for that purpose, e.g. taking NAT or dynamic
DSVPN cannot be used directly for connecting workloads in hybrid addresses into consideration. Therefore, DMVPN and/or DSVPN cannot
Cloud DCs. be used directly for connecting workloads in hybrid Cloud DCs.
Other protocols such as BGP can be used, as described in [BGP- Other protocols such as BGP can be used, as described in [BGP-
SDWAN]. SDWAN].
4. Desired Properties for Networks that interconnect Hybrid Clouds 4.2. Desired Properties for Multi-Cloud Interconnection
The networks that interconnect hybrid cloud DCs must address the
following requirements:
- High availability to access all workloads in the desired cloud
DCs.
Many enterprises include cloud infrastructures in their
disaster recovery strategy, e.g., by enforcing periodic backup
policies within the cloud, or by running backup applications in
the Cloud, etc. Therefore, the connection to the cloud DCs may
not be permanent, but rather needs to be on-demand.
- Global reachability from different geographical zones, thereby Different Cloud Operators have different APIs to access their Cloud
facilitating the proximity of applications as a function of the resources. It is difficult to move applications built by one Cloud
end users' location, to improve latency. operator's APIs to another. However, it is highly desirable to have
- Elasticity: prompt connection to newly instantiated a single and consistent way to manage the networks and respective
applications at Cloud DCs when end-users' usages increase and security policies for interconnecting applications hosted in
prompt release of connection after applications at locations different Cloud DCs.
being removed when demands change.
Some enterprises have front-end web portals running in cloud
DCs and database servers in their on-premises DCs. Those Front-
end web portals need to be reachable from the public Internet.
The backend connection to the sensitive data in database
servers hosted in the on-premises DCs might need secure
connections.
- Scalable security management. IPsec is commonly used to The desired property would be having a single network fabric to
interconnect cloud gateways with CPEs deployed in the which different Cloud DCs and enterprise's multiple sites can be
enterprise premises. For enterprises with a large number or attached or detached, with a common interface for setting desired
branch offices, managing the IPsec's Security Associations policies. SDWAN is positioned to become that network fabric enabling
among many nodes can be very difficult. Cloud DCs to be dynamically attached or detached. But the reality is
that different Cloud Operators have different access methods, and
Cloud DCs might be geographically far apart. More Cloud connectivity
problems are described in the subsequent sections.
The difficulty of connecting applications in different Clouds might
be stemmed from the fact that they are direct competitors. Usually
traffic flow out of Cloud DCs incur charges. Therefore, direct
communications between applications in different Cloud DCs can be
more expensive than intra Cloud communications.
5. Problems with MPLS-based VPNs extending to Hybrid Cloud DCs 5. Problems with MPLS-based VPNs extending to Hybrid Cloud DCs
Traditional MPLS-based VPNs have been widely deployed as an Traditional MPLS-based VPNs have been widely deployed as an
effective way to support businesses and organizations that require effective way to support businesses and organizations that require
network performance and reliability. MPLS shifted the burden of network performance and reliability. MPLS shifted the burden of
managing a VPN service from enterprises to service providers. The managing a VPN service from enterprises to service providers. The
CPEs attached to MPLS VPNs are also simpler and less expensive, CPEs attached to MPLS VPNs are also simpler and less expensive,
since they do not need to manage routes to remote sites; they simply since they do not need to manage routes to remote sites; they simply
pass all outbound traffic to the MPLS VPN PEs to which the CPEs are pass all outbound traffic to the MPLS VPN PEs to which the CPEs are
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DC, but the network service provider might not have PEs located DC, but the network service provider might not have PEs located
at the new location. at the new location.
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. An
the MPLS-based VPNs can only reach Cloud DC's Gateways, not to enterprise with a hybrid cloud deployment can use an MPLS-VPN
the workloads hosted inside. Even with AWS DirectConnect, the to connect to a Cloud provider at multiple locations. The
connection only reaches the AWS DirectConnect Gateway. AWS connection locations often correspond to gateways of different
DirectConnect Gateway uses BGP to exchange all routes with Cloud DC locations from the Cloud provider. The different
devices located behind the gateway, even including routes of Cloud DCs are interconnected by the Cloud provider's own
applications that might be physically located in different internal network. At each connection location (gateway), the
geographical locations. There is no visibility on how the Cloud provider uses BGP to advertise all of the prefixes in the
applications/workloads are interconnected within a Cloud DC or enterprise's VPC, regardless of which Cloud DC a given prefix
across multiple Cloud DCs. is actually in. This can result in inefficient routing for the
end-to-end data path.
- 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 that specifies the interworking between the Cloud Overlay and
the 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 characteristics of overlay networks is that some of the WAN
ports of the edge nodes connect to third party networks. There ports of the edge nodes connect to third party networks. There
is therefore a need to propagate WAN port information to remote is therefore a need to propagate WAN port information to remote
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[RFC4664] L. Andersson and E. Rosen, "Framework for Layer 2 Virtual [RFC4664] L. Andersson and E. Rosen, "Framework for Layer 2 Virtual
Private Networks (L2VPNs)", Sept 2006. Private Networks (L2VPNs)", Sept 2006.
[BGP-SDWAN] L. Dunbar, et al. "BGP Extension for SDWAN Overlay [BGP-SDWAN] L. Dunbar, et al. "BGP Extension for SDWAN Overlay
Networks", draft-dunbar-idr-bgp-sdwan-overlay-ext-03, Networks", draft-dunbar-idr-bgp-sdwan-overlay-ext-03,
work-in-progress, Nov 2018. work-in-progress, Nov 2018.
13. Acknowledgments 13. Acknowledgments
Many thanks to Chris Bowers, Ignas Bagdonas, Michael Huang, Liu Yuan Many thanks to Alia Atlas, Chris Bowers, Ignas Bagdonas, Michael
Jiao, Katherine Zhao, and Jim Guichard for the discussion and Huang, Liu Yuan Jiao, Katherine Zhao, and Jim Guichard for the
contributions. discussion and contributions.
Authors' Addresses Authors' Addresses
Linda Dunbar Linda Dunbar
Futurewei Futurewei
Email: Linda.Dunbar@futurewei.com Email: Linda.Dunbar@futurewei.com
Andrew G. Malis Andrew G. Malis
Futurewei Independent
Email: agmalis@gmail.com Email: agmalis@gmail.com
Christian Jacquenet Christian Jacquenet
Orange Orange
Rennes, 35000 Rennes, 35000
France France
Email: Christian.jacquenet@orange.com Email: Christian.jacquenet@orange.com
Mehmet Toy Mehmet Toy
Verizon Verizon
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