Network Working Group L. Dunbar
Internet Draft Futurewei
Intended status: Informational A. Malis
Expires: October 20, 2023 Malis Consulting
C. Jacquenet
Orange
M. Toy
Verizon
K. Majumdar
Microsoft
April 24, 2023
Dynamic Networks to Hybrid Cloud DCs: Problem Statement and
Mitigation Practices
draft-ietf-rtgwg-net2cloud-problem-statement-26
Abstract
This document describes the network-related problems enterprises
face at the moment of writing this specification when
interconnecting their branch offices with dynamic workloads in
third-party data centers (a.k.a. Cloud DCs) and some mitigation
practices. There can be many problems associated with connecting to
or among Cloud DCs; the Net2Cloud problem statements are mainly for
enterprises that already have traditional VPN services and are
interested in leveraging those networks (instead of altogether
abandoning them). Other problems are out of the scope of this
document.
This document also describes the mitigation practices for getting
around the identified problems.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
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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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Table of Contents
1. Introduction...................................................3
2. Definition of terms............................................3
3. Issues and Mitigation Methods of Connecting to Cloud DCs.......4
3.1. Increased BGP errors and Mitigation Methods...............4
3.2. Site failures and Methods to Minimize Impacts.............5
3.3. Optimal Paths to Cloud DC locations.......................6
3.4. Network Issues for 5G Edge Clouds and Mitigation Methods..6
3.5. DNS Practices for Hybrid Workloads........................7
3.6. NAT Practice for Accessing Cloud Services.................8
3.7. Cloud Discovery Practices.................................8
4. Dynamic Interconnecting Enterprise Sites with Cloud DCs........9
4.1. Sites to Cloud DC.........................................9
4.2. Inter-Cloud Connection...................................11
4.3. Extending Private VPNs to Hybrid Cloud DCs...............13
5. Methods to Scale IPsec tunnels to Cloud DCs...................14
5.1. Scaling Issues with IPsec Tunnels........................14
5.2. Poor performance when overlay public internet............15
6. Requirements for Dynamic Cloud Data Center VPNs...............15
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7. Security Considerations.......................................16
8. IANA Considerations...........................................17
9. References....................................................17
9.1. Normative References.....................................17
9.2. Informative References...................................18
10. Acknowledgments..............................................19
1. Introduction
With the advent of widely available third-party cloud DCs and
services in diverse geographic locations and the advancement of
tools for monitoring and predicting application behaviors, it is
very attractive for enterprises to instantiate applications and
workloads in locations that are geographically closest to their end-
users. Such proximity can improve end-to-end latency and overall
user experience. Conversely, an enterprise can easily shutdown
applications and workloads whenever end-users are in motion (thereby
modifying the networking connection of subsequently relocated
applications and workloads).
Key characteristics of Cloud Services are on-demand, scalable,
highly available, and usage-based billing. Cloud Services, such as,
compute, storage, network functions (most likely virtual), third
party managed applications, etc. are usually hosted and managed by
third party Cloud Operators. Examples of Cloud network functions
are: Virtual Firewall services, Virtual private network services,
Virtual PBX services including voice and video conferencing systems,
etc. Cloud Data Center (DC) is shared infrastructure that hosts the
Cloud Services to many customers.
2. Definition of terms
Cloud DC: Third party Data Centers that usually host applications
and workload owned by different organizations or
tenants.
Controller: Used interchangeably with SD-WAN controller to manage
SD-WAN overlay path creation/deletion and monitoring the
path conditions between two or more sites.
Heterogeneous Cloud: applications and workloads split among Cloud
DCs owned or managed by different operators.
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Hybrid Clouds: Hybrid Clouds refers to an enterprise using its own
on-premises DCs in addition to Cloud services provided
by one or more cloud operators. (e.g. AWS, Azure,
Google, Salesforce, SAP, etc).
VPC: Virtual Private Cloud is a virtual network dedicated to
one client account. It is logically isolated from other
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. At the moment of of
writing this specification, most Cloud operators' VPCs
only support private addresses, some support IPv4 only,
others support IPv4/IPv6 dual stack.
3. Issues and Mitigation Methods of Connecting to Cloud DCs
There are many problems associated with connecting to Cloud DCs,
many of which are out of the IETF scope. This section is to identify
some of the high-level problems that can be addressed by IETF,
especially by Routing area. Other problems are out of the scope of
this document. By no means has this section covered all problems for
connecting to Hybrid Cloud Services, e.g., difficulty in managing
cloud spending is not discussed here.
3.1. Increased BGP errors and Mitigation Methods
Traditional network service providers usually have prior negotiated
peering policies with their BGP peers over fixed interfaces. Cloud
GWs need to peer with a larger variety of parties, via private
circuits or IPsec over public internet. Many of those peering
parties may not be traditional network service providers. Their BGP
configurations practices might not be consistent, and some are done
by less experienced personnel. All those can contribute to increased
BGP peering errors such as capability mismatch, unwanted route
leaks, missing Keepalives, and errors causing BGP ceases. Capability
mismatch can cause BGP sessions not established properly.
If a BGP speaker receives from its peer a capability that it does
not itself support or recognize, it must ignore that capability and
the BGP session must not be terminated per RFC5492. When receiving a
BGP UPDATE with a malformed attribute, the revised BGP error
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handling procedure [RFC7606] should be followed instead of session
resetting.
Many Cloud DCs don't support multi hop eBGP peering with external
devices. To get around this limitation, it is necessary for
enterprises GWs to establish IPsec tunnels to the Cloud GWs to form
IP adjacency.
Some Cloud DC eBGP peering only supports limited number of routes
from external entities. To get around this limitation, on-premises
DCs need to set up default routes to be exchanged with the Cloud DC
eBGP peers. When inbound routes exceed the maximum routes threshold
for a peer, the current common practice is generating out of band
alerts (e.g., Syslog) via management system to the peer, or
terminating the BGP session (with cease notification messages [RFC
4486] being sent).
3.2. Site failures and Methods to Minimize Impacts
Failures within a site include (but not limited to) a site capacity
degradation or entire site going down. The reasons for these
capacity degradations or failures can include: a) fiber cut for
links connecting to the site or among pods within the site, b)
cooling failures, c) insufficient backup power, d) cyber threat
attacks, e) too many changes outside of the maintenance window, or
other errors. Fiber-cut is not uncommon within a Cloud site or
between sites.
As described in RFC7938, Cloud DC BGP might not have an IGP to route
around link/node failures within its domain.
When a site failure happens, the Cloud DC GW visible to clients is
running fine; therefore, the site failure is not detectable by the
Clients using Bidirectional Forwarding Detection (BFD).
When a site capacity degrades or goes to zero, there are massive
numbers of routes needing to be changed.
The large number of routes switching over to another site can also
cause overloading that triggers more failures.
In addition, the routes (IP addresses) in a Cloud DC cannot be
aggregated nicely, triggering very large number of BGP UPDATE
messages when a failure occurs.
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It might be more effective to do mass reroute, similar to EVPN
[RFC7432] defined mass withdraw mechanism to signal a large number
of routes being changed to remote PE nodes as quickly as possible.
3.3. Optimal Paths to Cloud DC locations
Many applications have multiple instances instantiated in different
Cloud DCs. A commonly deployed solution has DNS server(s) responding
to an FQDN (Fully Qualified Domain Name) inquiry with an IP address
of the closest or lowest cost DC that can reach the instance. Here
are some problems associated with DNS-based solutions:
- Dependent on client behavior
- Misbehaving client can cache results indefinitely.
- Client may not receive service even though there are
servers available in other Cloud DCs because the failing
IP address is still cached in the DNS resolver and has not
expired yet.
- No inherent leverage of proximity information present in the
network (routing) layer, resulting in loss of performance.
- Inflexible traffic control:
The Local DNS resolver becomes the unit of traffic management.
This requires DNS to receive periodical update of the network
condition, which is difficult.
To address the problems listed above, ANYCAST addresses can be
utilized so that network proximity and conditions can be inherently
considered in optimal path selection.
3.4. Network Issues for 5G Edge Clouds and Mitigation Methods
The 5G edge clouds [3GPP-5G-Edge] may host edge computing servers
(virtual or physical) for Ultra-low latency services that must be
near the UEs (User equipment). Those edge computing applications
have low latency connections to the UEs and regular connections to
backend servers or databases in other locations.
The low latency services traffic to/from the edge Clouds are
transported through the 5G Local Data Networks (LDN) and 5G UPFs to
the UEs. The LDN's ingress routers, directly connected to the User
Plane Functions (UPF), might be co-located with 5G Core functions in
the edge Cloud data centers. The 5G Core functions include Radio
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Control Functions, Session Management Functions (SMF), Access
Mobility Functions (AMF), User Plane Functions (UPF), and others.
Here are some network problems with connecting the services in the
5G Edge Cloud DCs:
1) The difference in routing distances to multiple server
instances in different edge Clouds is relatively small.
Therefore, the edge Cloud with the shortest routing distance
might not be the best in providing the overall latency.
2) Capacity status at the Edge Cloud DC might play a bigger role
for E2E performance.
3) Source (UEs) can ingress from different LDN Ingress routers
due to mobility.
To get around those problems, the ingress routers can incorporate
the destination site's capabilities with the routing distance in
computing the optimal paths.
3.5. DNS Practices for Hybrid Workloads
DNS name resolution is essential for on-premises and cloud-based
resources. For customers with hybrid workloads, which include on-
premises and cloud-based resources, extra steps are necessary to
configure DNS to work seamlessly across both environments.
Cloud operators have their own DNS to resolve resources within their
Cloud DCs and to well-known public domains. Cloud's DNS can be
configured to forward queries to customer managed authoritative DNS
servers hosted on-premises and to respond to DNS queries forwarded
by on-premises DNS servers.
For enterprises utilizing Cloud services by different cloud
operators, it is necessary to establish policies and rules on
how/where to forward DNS queries. When applications in one Cloud
need to communicate with applications hosted in another Cloud, DNS
queries from one Cloud DC could be forwarded to the enterprises' on-
premises DNS, which in turn be forwarded to the DNS service in
another Cloud. Configuration can be complex depending on the
application communication patterns.
However, even with carefully managed policies and configurations,
collisions can still occur. If an organization uses an internal name
like .internal and then want your services to be available via or
within some other cloud provider which also uses .internal, then
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collisions might occur. Therefore, it is better to use the global
domain name even when an organization does not make all its
namespace globally resolvable. An organization's globally unique DNS
can include subdomains that cannot be resolved outside certain
restricted paths, zones that resolve differently based on the origin
of the query, and zones that resolve the same globally for all
queries from any source.
Globally unique names do not equate to globally resolvable names or
even global names that resolve the same way from every perspective.
Globally unique names can prevent any possibility of collisions at
present or in the future, and they make DNSSEC trust manageable.
Consider using a registered and fully qualified domain name (FQDN)
from global DNS as the root for enterprise and other internal
namespaces.
3.6. NAT Practice for Accessing Cloud Services
Cloud resources, such as VM instances, are usually assigned private
IP addresses. By configuration, some private subnets can have the
NAT function to reach out to external networks, and some private
subnets are internal to Cloud only.
Different Cloud operators support different levels of NAT functions.
For example, AWS NAT Gateway does not currently support connections
towards, or from VPC Endpoints, VPN, AWS Direct Connect, or VPC
Peering [AWS-NAT]. AWS Direct Connect/VPN/VPC Peering does not
currently support any NAT functionality.
Google's Cloud NAT [Google-NAT] allows Google Cloud virtual machine
(VM) instances without external IP addresses and private Google
Kubernetes Engine (GKE) clusters to connect to the Internet. Cloud
NAT implements outbound NAT in conjunction with a default route to
allow instances to reach the Internet. It does not implement inbound
NAT. Hosts outside the VPC network can only respond to established
connections initiated by instances inside the Google Cloud; they
cannot initiate new connections to Cloud instances via NAT.
For enterprises with applications running in different Cloud DCs,
proper configuration of NAT must be performed in Cloud DCs and their
on-premises DC.
3.7. Cloud Discovery Practices
One of the concerns of using Cloud services is not being aware of
where the resource is located, especially that Cloud operators can
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move application instances from one place to another. When
applications in Cloud communicate with on-premises applications, it
may not be clear where the Cloud applications are located or to
which VPCs they belong.
Being able to detect Cloud services location can help on-premises
gateways (routers) to switch the services to a more optimal site
when the current cloud site encounters failures or degradation. A
significant difference is that cloud discovery uses the cloud
vendor's API to extract data on your cloud services rather than the
direct access used in scanning your on-premises infrastructure.
For enterprises that instantiate virtual routers in Cloud DCs,
metadata can be attached (e.g., GENEVE header or IPv6 optional
header) to indicate Geo-location of the Cloud DCs.
4. Dynamic Interconnecting Enterprise Sites with Cloud DCs
For many enterprises with established provide VPNs (e.g., private
circuits, MPLS-based L2VPN/L3VPN) interconnecting branch offices &
on-premises data centers, connecting to Cloud services will be a mix
of different types of networks. When an enterprise's existing VPN
service providers do not have direct connections to the desired
cloud DCs that the enterprise prefers to use, the enterprise faces
additional infrastructure and operational costs to utilize the Cloud
services.
This section describes practices to connect to Cloud services.
4.1. Sites to Cloud DC
Most Cloud operators offer some type of network gateway through
which an enterprise can reach their workloads hosted in the Cloud
DCs. For example, AWS (Amazon Web Services) offers the following
options to reach workloads in AWS Cloud DCs [AWS-Cloud-WAN]:
- AWS Internet gateway allows communication between instances in
AWS VPC and the internet.
- AWS Virtual gateway (vGW) where IPsec tunnels [RFC6071] are
established between an enterprise's own gateway and AWS vGW, so
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that the communications between those gateways can be secured
from the underlay (which might be the public Internet).
- AWS Direct Connect, which allows enterprises to purchase direct
connect from network service providers to get a private leased
line interconnecting the enterprises gateway(s) and the AWS
Direct Connect routers. In addition, an AWS Transit Gateway can
be used to interconnect 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.
Microsoft Azure's Virtual WAN [Azure-SD-WAN] 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
the 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.
Figure 1 below shows an example of some of a tenant's workloads that
are accessible via a virtual router connected by AWS Internet
Gateway; some are accessible via AWS vGW, and others are accessible
via AWS Direct Connect.
Different types of access require different level of security
functions. Sometimes it is not visible to end customers which type
of network access is used for a specific application instance. To
get better visibility, separate virtual routers (e.g., vR1 & vR2)
can be deployed to differentiate traffic to/from different cloud
GWs. It is important for some enterprises to be able to observe the
specific behaviors when connected by different connections.
Customer Gateway can be customer owned router or ports physically
connected to AWS Direct Connect GW.
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+------------------------+
| ,---. ,---. |
| (TN-1 ) ( TN-2)|
| `-+-' +---+ `-+-' |
| +----|vR1|----+ |
| ++--+ |
| | +-+----+
| | /Internet\ For External
| +-------+ Gateway +----------------------
| \ / to reach via Internet
| +-+----+
| |
| ,---. ,---. |
| (TN-1 ) ( TN-2)|
| `-+-' +---+ `-+-' |
| +----|vR2|----+ |
| ++--+ |
| | +-+----+
| | / virtual\ For IPsec Tunnel
| +-------+ Gateway +----------------------
| | \ / termination
| | +-+----+
| | |
| | +-+----+ +------+
| | / \ For Direct /customer\
| +-------+ Gateway +----------+ gateway |
| \ / Connect \ /
| +-+----+ +------+
| |
+------------------------+
Figure 1: Examples of Multiple Cloud DC connections.
4.2. Inter-Cloud Connection
The connectivity options to Cloud DCs described in the previous
section are for reaching Cloud providers' DCs, but not between cloud
DCs. When applications in AWS Cloud need to communicate with
applications in Azure, today's practice requires 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. For example, open-source VPN
software such as strongSwan can be leveraged to create an IPSec
connection to the Azure gateway. The StrongSwan instance within AWS
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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.
In summary, here are some approaches, available 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
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 must
traverse through the customer gateway.
c) Establish direct tunnels among different VPCs (AWS' Virtual
Private Clouds) and VNET (Azure's Virtual Networks) via
client's own virtual routers instantiated within Cloud DCs.
NHRP (Next Hop Resolution Protocol) [RFC2735] based multi-point
techniques can be used to establish direct 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
by different Cloud providers.
Approach b) creates additional transmission delay plus incurring
cost when exiting Cloud DCs.
For the Approach c), NHRP [RFC2735] is used for spoke nodes to
register their IP addresses & WAN ports with the hub node. The IETF
ION (Internetworking over NBMA (non-broadcast multiple access)) WG
standardized NHRP for connection oriented NBMA network (such as ATM)
network address resolution more than two decades ago.
There are many differences between virtual routers in Public Cloud
DCs and the nodes in an NBMA network. NHRP cannot be used for
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registering virtual routers in Cloud DCs unless an extension of such
protocols is developed for that purpose, e.g., taking NAT or dynamic
addresses into consideration. Therefore, existing NHRP based VPN
technique cannot be used directly for connecting workloads in hybrid
Cloud DCs.
4.3. Extending Private VPNs to Hybrid Cloud DCs
Traditional private VPNs, including private circuits or MPLS based
L2/L3 VPNs, have been widely deployed as an effective way to support
businesses and organizations that require network performance and
reliability. L2/L3 VPN shifts the burden of managing a VPN service
from enterprises to service providers. The CPEs attached to a
private VPN are simpler and less expensive because they do not need
to manage routes to remote sites; they pass all outbound traffic to
the private VPN PEs to which the CPEs are attached (albeit multi-
homing scenarios require more processing logic on CPEs). Private
VPN has addressed the problems of scale, availability, and fast
recovery from network faults, and incorporated traffic-engineering
capabilities.
However, an enterprise's private VPN's PE (Provider Edge) nodes
might not have the direct connections to the third-party cloud DCs
needed by the enterprise to provide easy access to its end users.
When the user base changes, the enterprise might want to migrate its
workloads/applications to a new cloud DC location closest to the new
user base. The existing private VPN provider might not have circuits
at the new location. Deploying PEs routers at new locations takes a
long time (weeks if not months), which defeats one of the benefits
of Clouds' geographically diverse locations allowing workloads to be
as close to their end-users as possible.
When the private VPN network can't reach the desired Cloud DCs,
IPsec tunnels can be used to dynamically connect the private VPN PEs
with the desired Cloud DCs GWs. As the private VPNs provide more
secure and higher quality services, choosing a PE closest to the
Cloud GW for the IPsec tunnel is desirable to minimize the IPsec
tunnel distance over the public Internet.
In order to support Explicit Congestion Notification (ECN) [RFC3168]
usage by private VPN traffic, the PEs that establish the IPsec
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tunnels with the Cloud GW need to comply with the ECN behavior
specified by RFC6040 [RFC6040].
An enterprise can connect to multiple Cloud DC locations and
establish different BGP peers with Cloud GW routers at different
locations. As multiple Cloud DCs are interconnected by the Cloud
provider's own internal network, its topology and routing policies
are not transparent or even visible to the enterprise customer's on-
prem routers. One Cloud GW BGP session might advertise all of the
prefixes of the enterprise's VPC, regardless of which Cloud DC a
given prefix resides, which can cause improper optimal path
selection for on-prem routers. To get around this problem, virtual
routers in Cloud DCs can be used to attach metadata (e.g., in the
GENEVE header or IPv6 optional header) to indicate the Geo-location
of the Cloud DC, the delay measurement, or other relevant data.
5. Methods to Scale IPsec tunnels to Cloud DCs
As described in Section 4.3, IPsec tunnels can be used to
dynamically establish connection between private VPN PEs with Cloud
GW. Enterprises can also instantiate virtual routers within Cloud
DCs to connect to their on-premises devices via IPsec tunnels.
As described in [Int-tunnels], IPsec tunnels can introduce MTU
problems. This document assumes that endpoints manage the
appropriate MTU sizes, therefore, not requiring VPN PEs to perform
the fragmentation when encapsulating user payloads in the IPsec
packets.
5.1. Scaling Issues with IPsec Tunnels
IPsec tunnels are a very convenient solution for an enterprise with
limited locations to reach a Cloud DC.
However, for a medium-to-large enterprise with multiple sites and
data centers to connect to multiple cloud DCs, there are N*N number
of IPsec tunnels among Cloud DC gateways and all those sites. Each
of those IPsec Tunnels requires pair-wise periodic key refreshment.
For a company with hundreds or thousands of locations, managing
hundreds (or even thousands) of IPsec tunnels can be very processing
intensive. That is why many Cloud operators only allow a limited
number of (IPsec) tunnels & bandwidth to each customer.
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To scale the IPsec key management, a solution like group encryption
where a single IPsec SA is necessary at the GW can be considered.
But the drawback of the group encryption is higher security risk of
the key distribution and maintenance of a key server.
5.2. Poor performance when overlay public internet
IPsec encap & decap are very processing intensive, which can degrade
router performance. NAT also adds to the performance burden.
When enterprise CPEs or gateways are far away from cloud DC gateways
or across country/continent boundaries, performance of IPsec tunnels
over the public Internet can be problematic and unpredictable. Even
though there are many monitoring tools available to measure delay
and various performance characteristics of the network, the
measurement for paths over the Internet is passive and past
measurements may not represent future performance.
Many cloud providers can replicate workloads in different available
zones. An App instantiated in a cloud DC closest to clients may have
to cooperate with another App (or its mirror image) in another
region or database server(s) in the on-premises DC. This kind of
coordination requires predicable networking behavior/performance
among those locations.
6. Requirements for Dynamic Cloud Data Center VPNs
To address the aforementioned issues, any solution for enterprise
VPNs that includes connectivity to dynamic workloads or applications
in cloud data centers should satisfy a set of requirements:
- 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.
- Scalable policy management: apply the appropriate polices to
the newly instantiated application instances at any Cloud DC
locations.
- The solution should allow enterprises to take advantage of the
current state-of-the-art private VPN technologies, including
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the traditional circuit-based, MPLS-based VPNs, or IPsec-based
VPNs (or any combination thereof) that run over the public
Internet.
- The solution should not require an enterprise to upgrade all
their existing CPEs.
- The solution should support scalable IPsec key management among
all nodes involved in DC interconnect schemes.
- The solution needs to support easy and fast, on-the-fly, VPN
connections to dynamic workloads and applications in third
party data centers, and easily allow these workloads to migrate
both within a data center and between data centers.
- Allow VPNs to provide bandwidth and other performance
guarantees.
- Be a cost-effective solution for enterprises to incorporate
dynamic cloud-based applications and workloads into their
existing VPN environment.
7. Security Considerations
The security issues in terms of networking to clouds include:
- Service instances in Cloud DCs are connected to users
(enterprises) via Public IP ports which are exposed to the
following security risks:
a) Potential DDoS attack to the ports facing the untrusted
network (e.g., the public internet), which may propagate to the
cloud edge resources. To mitigate such security risk, it is
necessary for the ports facing internet to enable Anti-DDoS
features.
b) Potential risk of augmenting the attack surface with inter-
Cloud DC connection by means of identity spoofing, man-in-the-
middle, eavesdropping or DDoS attacks. One example of
mitigating such attacks is using DTLS to authenticate and
encrypt MPLS-in-UDP encapsulation (RFC 7510).
- Potential attacks from service instances within the cloud. For
example, data breaches, compromised credentials, and broken
authentication, hacked interfaces and APIs, account hijacking.
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- When IPsec tunnels established from enterprise on-premises CPEs
are terminated at the Cloud DC gateway where the workloads or
applications are hosted, traffic to/from an enterprise's
workload can be exposed to others behind the data center
gateway (e.g., exposed to other organizations that have
workloads in the same data center).
To ensure that traffic to/from workloads is not exposed to
unwanted entities, IPsec tunnels may go all the way to the
workload (servers, or VMs) within the DC.
Many Cloud operators offer monitoring services for data stored in
Clouds, such as AWS CloudTrail, Azure Monitor, and many third-party
monitoring tools to improve visibility to data stored in Clouds.
Solution drafts resulting from this work will address security
concerns inherent to the solution(s), including both protocol
aspects and the importance (for example) of securing workloads in
cloud DCs and the use of secure interconnection mechanisms.
8. IANA Considerations
This document requires no IANA actions. RFC Editor: Please remove
this section before publication.
9. References
9.1. Normative References
[RFC2735] B. Fox, et al "NHRP Support for Virtual Private networks".
Dec. 1999.
[RFC4271] Y. Rekhter, et al "BGP-4". Jan 2006
[RFC5492] J. Scudder, R. Chandra "Capabilities Advertisement with
BGP-4". Feb 2009
[RFC6040] B. Briscoe, "Tunnelling of Explicit Congestion
Notification", RFC6040, Nov 2010.
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Internet-Draft Net2Cloud Problem Statement
[RFC7606] E. Chen, et al "Revised Error Handling for BGP UPDATE
Messages". Aug 2015.
[RFC7938] P. Lapukkov, et al "Use of BGP for Routing in Large-
Scale Data Centers", Aug. 2016
9.2. Informative References
[RFC8192] S. Hares, et al "Interface to Network Security Functions
(I2NSF) Problem Statement and Use Cases", July 2017
[ITU-T-X1036] ITU-T Recommendation X.1036, "Framework for creation,
storage, distribution and enforcement of policies for
network security", Nov 2007.
[RFC6071] S. Frankel and S. Krishnan, "IP Security (IPsec) and
Internet Key Exchange (IKE) Document Roadmap", Feb 2011.
[RFC4364] E. Rosen and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", Feb 2006
[RFC4664] L. Andersson and E. Rosen, "Framework for Layer 2 Virtual
Private Networks (L2VPNs)", Sept 2006.
[3GPP-5G-Edge] 3GPP TS 23.548 v18.1.1, "5G System Enhancements for
Edge Computing", April 2023.
[AWS-NAT] NAT gateways - Amazon Virtual Private Cloud.
[AWS-Cloud-WAN] Introducing AWS Cloud WAN (Preview) | Networking &
Content Delivery (amazon.com).
[Azure-NAT] What is Azure Virtual Network NAT? | Microsoft Learn
[Azure-SD-WAN] Architecture: Virtual WAN and SD-WAN connectivity -
Azure Virtual WAN | Microsoft Learn.
[Google-NAT] Cloud NAT overview | Google Cloud.
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[Int-tunnels] J. Touch and W Townsley, "IP Tunnels in the Internet
Architecture", draft-ietf-intarea-tunnels-13.txt, March,
2023.
10. Acknowledgments
Many thanks to Adrian Farrel, Alia Atlas, Chris Bowers, Paul Vixie,
Paul Ebersman, Timothy Morizot, Ignas Bagdonas, Donald Eastlake,
Michael Huang, Liu Yuan Jiao, Katherine Zhao, and Jim Guichard for
the discussion and contributions.
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Authors' Addresses
Linda Dunbar
Futurewei
Email: Linda.Dunbar@futurewei.com
Andrew G. Malis
Malis Consulting
Email: agmalis@gmail.com
Christian Jacquenet
Orange
Rennes, 35000
France
Email: Christian.jacquenet@orange.com
Mehmet Toy
Verizon
One Verizon Way
Basking Ridge, NJ 07920
Email: mehmet.toy@verizon.com
Kausik Majumdar
Microsoft Azure
kmajumdar@microsoft.com
Dunbar, et al. [Page 20]
