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Network Working Group                                          YJ. Stein
Internet-Draft                                                 Y. Gittik
Intended status: Informational                   RAD Data Communications
Expires: January 05, 2014                                      D. Kofman
                                                             K. Katsaros
                                                               M. Morrow
                                                                 L. Fang
                                                           Cisco Systems
                                                           W. Henderickx
                                                           July 04, 2013

                        Accessing Cloud Services


   Cloud services are revolutionizing the way computational resources
   are provided, but at the expense of requiring an even more
   revolutionary overhaul of the networking infrastructure needed to
   deliver them.  Much recent work has focused on intra- and inter-
   datacenter connectivity requirements and architectures, while the
   "access segment" connecting the cloud services user to the datacenter
   still needs to be addressed.  In this draft we consider tighter
   integration between the network and the datacenter, in order to
   improve end-to-end Quality of Experience, while minimizing both
   networking and computational resource costs.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 05, 2014.

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Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Model of Existing Cloud Services  . . . . . . . . . . . . . .   4
   3.  Optimized Cloud Access  . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Cloud services replace computational power and storage resources
   traditionally located under the user's table or on the user's in-
   house servers, with resources located in remote datacenters.  The
   cloud resources may be raw computing power and storage
   (Infrastructure as a Service - IaaS), or computer systems along with
   supported operating systems and tools (Platform as a Service - PaaS),
   or even fully developed applications (Software as a Service - SaaS).
   Processing power required for the operation of network devices can
   also be provided (e.g., Routing as a Service - RaaS).  The inter- and
   intra-datacenter networking architectures needed to support cloud
   services are described in [I-D.bitar-datacenter-vpn-applicability].

   The advantages of cloud services over conventional IT services
   include elasticity (the ability to increase or decrease resources on
   demand rather than having to purchase enough resources for worst case
   scenarios), scalability (allocating multiple resources and load-
   balancing them), high-availability (resources may be backed up by
   similar resources at other datacenters), and offloading of IT tasks
   (such as applications upgrading, firewalling, load balancing, storage
   backup, and disaster recovery).  These translate to economic

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   efficiencies if actually delivered.  The disadvantages of cloud
   service are lack of direct control by the customer, insecurity
   regarding remote storage of sensitive data, and communications costs
   (both direct monetary and technical such as lack of availability and
   additional transaction latency).

   The cloud service user connects to cloud resources over a networking
   infrastructure.  Today this infrastructure is often the public
   Internet, but (for reasons to be explained below) is preferably a
   network maintained by a Network Service Provider (NSP).  The
   datacenter(s) may belong to the NSP (which is the case considered by
   [I-D.masum-chari-shc]), or may belong to a separate Cloud Service
   Provider (CSP), and accessible from the NSP's network.  In the latter
   case there may or not be a business relationship between the NSP and
   CSP, the strongest such relationship being when either the NSP or CSP
   offers a unified "bundled" service to the customer.

   In order to obtain the advantages of cloud service without many of
   the disadvantages, the cloud services customer enters into a Service
   Level Agreement (SLA) with the CSP.  However, such an SLA by itself
   will be unable to guarantee end-to-end service goals, since it does
   not cover degradations introduced by the intervening network.
   Indeed, if the datacenter is accessed over the public Internet, end-
   to-end service goals may be unattainable.  Thus an additional SLA
   with the NSP (that may already be in effect for pre-cloud services)
   is typically required.  When the CSP and the NSP are the same entity
   but not offering a bundled service, these SLAs may still be separate

   Cloud services require a fundamental rethinking of the Information
   Technology (IT) infrastructure, due to the requirement for dynamic
   changes in IT resource configuration.  Physical IT resources are
   replaced by virtualized ones packaged in Virtual Machines (VMs).  VMs
   can be created, relocated while running (VM migration), and destroyed
   on-demand.  Since VMs need to interconnect, connect to physical
   resources, and connect to the cloud services user, they need to be
   allocated appropriate IP and layer 2 addresses.  Since these
   addresses need to be allocated, moved, and destroyed on-the-fly, the
   cloud IT revolution directly impacts the networking infrastructure.
   Recent work, such as [I-D.bitar-datacenter-vpn-applicability], has
   focused on requirements and architectures for connectivity inside and
   between datacenters.  However, the "access segment", that is, the
   networking infrastructure connecting the cloud services user to the
   datacenter, has not been fully addressed.

   The allocation, management, manipulation, and release of cloud
   resources is called "orchestration" (see [I-D.dalela-orchestration]).
   Orchestrators need to respond to user demands and uphold user SLAs

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   (perhaps exploiting virtualization techniques such as VM migration)
   while taking into account the location and availability of IT
   resources, and optimizing the CSP's operational objectives.  These
   objectives include, for example, decreasing costs by consolidating
   resources, balancing use of resources by reallocating computational
   and storage resources, and enforcing engineering, business, and
   security policies.  Orchestrators of the present generation do not
   attempt optimization of CSP's networking resources, but this
   generalization is being studied [I-D.ietf-nvo3-framework].
   Furthermore, these orchestrators are completely oblivious to the
   NSP's resources and objectives.  Hence, there is no mechanism for
   maintaining end-to-end SLAs, or for optimizing end-to-end networking.

   This goal of this Internet Draft is to kick off discussions on
   requirements and possible mechanisms for improving end-to-end Quality
   of Experience while minimizing both networking and computational

2.  Model of Existing Cloud Services

                     /- - - - - - - - - - - - - - - - - -I O I
                   /                 -------               I
                                     I OSS I           ----------
                 /                   -------           I        I
                                        I              I  DC A  I
               /    --------       -----------        /I        I
              /     I      I       I         I       / ----------
         --------   I      I       I   NSP   I--->---
         I user I->-I  CE  I--->---I         I
         --------   I      I       I network I--->---
                    I      I       I         I       \ ----------
                    --------       -----------        \I        I
                                                       I  DC B  I
                                                       I        I

     Figure 1: Simplified model of cloud service provided over Service
       Provider network to an enterprise customer behind a CE device

   For concreteness, we will assume the scenario of Figure 1.  On the
   left we see a cloud services user attached to a customer site
   network.  This network connects to the outside world via a Customer
   Edge (CE), which may be a branch-site router or switch, a special
   purpose cloud demarcation device, or in degenerate cases the user's
   computer itself.  The NSP network is assumed to be a well-engineered

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   network providing VPN and other SLA-based services to the customer
   site.  The NSP network is managed from an Operations Support System
   (OSS), which may include a Business Support System (BSS), the latter
   being needed for interfacing with the customer for approval of
   service reconfiguration, billing issues, etc.  In some cases, the
   functionality needed here may be obtained by interfacing with a
   Looking Glass server or a Policy and Charging Rules Function (PCRF).
   Connected to this network are datacenters (two are shown - datacenter
   A and datacenter B), which may belong to the NSP, or to a separate
   CSP.  The orchestrator of datacenter A is depicted as "O".
   Additionally, Internet access may be available directly from the CE
   (not shown) or from the NSP network.

   In the usual cloud services orchestration model the user requests a
   well-defined resource, for example over the telephone, via a web-
   based portal, or via a function call.  The orchestrator, after
   checking correctness, availability, and updating the billing system,
   allocates the resource, e.g., a VM on a particular CPU located in a
   particular rack in datacenter A. In addition, the required networking
   resources are allocated to the VM, e.g., an IP address, an Ethernet
   MAC address, and a VLAN tag.  The VM is now started and consumes CPU
   power, memory, and disk space, as well as communications bandwidth
   between itself and other VMs on the same CPU, within the same rack,
   on other racks in the same datacenter, between datacenters, and
   between itself and the user.  If it becomes necessary to move the VM
   from its allocated position to somewhere else (VM migration), the
   orchestrator needs to reallocate the required computational and
   communications resources.  An example case is "cloudbursting" where a
   customer who finds himself temporarily with insufficient local
   resources reaches out to the cloud for supplementary ones
   [I-D.mcdysan-sdnp-cloudbursting-usecase].  A priori this requires
   allocating new addresses and rerouting all of the aforementioned
   traffic types, while maintaining continuous operation of the VM.
   When the user informs the CSP that it no longer requires the VM, the
   orchestrator needs to clear the routing entries, withdraw the
   communications resources, release storage and computational
   resources, and update the billing system.

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   The operations of the previous paragraph are all performed by the
   orchestrator, with possible cooperation with orchestrators from other
   datacenters.  The needed routing information is advertised to the NSP
   via standard routing protocols, without taking into account possible
   effects on the NSP network.  If, for example, the path in the NSP
   network to datacenter A degrades, while the path to datacenter B is
   performing well, this information is neither known by the
   orchestrator, nor is there a method for the orchestrator to take it
   into account.  Instead, the NSP must find a way to reach datacenter
   A, even if this path is expensive, or of high latency, or problematic
   in some other way.

   This predicament arises due to the orchestrator communicating
   (indirectly) with the user, but not with the NSP's OSS.  In addition,
   although the CE may be capable of OAM functionality, fault and
   performance monitoring of the communications path through the NSP
   network are not employed.  Finally, while the user can (indirectly)
   communicate with the orchestrator, there is no coordinated path to
   the NSP's OSS/BSS.

3.  Optimized Cloud Access

                                   /------/--------------I O I
                                  /      /               -----
                                 /   -------               I
                                -----I OSS I           ----------
                               /     -------          /I        I
                              /         I            / I  DC A  I
                    -------- /     -----------      / /I        I
                    I      I/      I         I--->-' / ----------
         --------   I      I--->---I   NSP   I--->---
         I user I->-I  CE  I       I         I
         --------   I      I--->---I network I--->---
                    I      I       I         I       \ ----------
                    --------       -----------        \I        I
                                                       I  DC B  I
                                                       I        I

   Figure 2: Cloud service with dual homing between a cloud-aware CE and
        NSP network, and coordination between CE, NSP OSS/BSS, and

   Figure 2. depicts two enhancements to the previous scenario.  The
   trivial enhancement is the providing of dual-homing between the CE
   and the NSP network.  This is a well-known and widely deployed

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   feature, which may be implemented regardless of the cloud services.
   We shall see that it acquires additional meaning in the context of
   the solution described below.

   More significantly, Figure 2 depicts three new control communications
   channels.  The CE device is now assumed to be cloud-aware, and may
   communicate directly with the NSP OSS/BSS, and with the CSP
   orchestrator.  In addition, the latter two may communicate with each
   other.  These control channels facilitate new capabilities, that may
   improve end-to-end QoE while optimizing operational cost.  An
   alternative to a combined cloud/network CE is a separate "cloud
   demarcation device" placed behind the network CE.

   Consider the provisioning of a new cloud service.  With this new
   architecture the user's request is proxied by the cloud-aware CE to
   both the OSS/BSS and to the orchestrator.  Before commissioning the
   service, the orchestrator initiates network testing between the
   datacenter and the CE, and with the NSP's assistance QoS parameters
   are determined for alternative paths to various relevant datacenters.
   The NSP and CSP (whether a single SP or two) can now jointly decide
   on placement of the VM in order to optimize the user's end-to-end
   Quality of Experience (QoE) while minimizing costs to both SPs.  The
   best placement will necessitate the solution of a joint CSP + NSP
   optimization problem, while the latter minimization may only be
   reliable when a single SP provides networking and cloud resources.
   The joint optimization calculation will input the status of
   computational and storage resources at all relevant datacenters; as
   well as network delay, throughput, and packet loss to each
   datacenter.  In some cases re-allocation of existing computational
   and networking resources may needed.

   Similarly, the NSP OSS may trigger VM migration if network conditions
   degrade to the point where user QoE is no longer at the desired
   level, or may veto a CSP initiated VM migration when its effect would
   be too onerous on the NSP network.

   The cloud-aware CE may be configured to periodically test path
   continuity and measure QoS parameters.  The CE can then report that
   the estimated QoE drops under that specified in the SLA (or
   dangerously approaches it), in order to promote SLA assurance even
   when neither OSS nor orchestrator would otherwise know of the
   problem.  Additionally, the cloud-aware CE may report workload
   changes detected by monitoring the number of active sessions (e.g.,
   the number of "flows" or n-tuple pairs).  The OSS and orchestrator
   can jointly perform root cause analysis and decide to trigger VM
   migration or network allocation changes or both.  Finally, over-
   extended network segments may be identified, and pro-active VM
   migration and/or rerouting performed to better distribute the load.

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   When the CE is dual homed to the NSP network, the secondary link may
   be utilized in the conventional manner when the primary link fails,
   or may be selected as part of the overall optimization of QoE vs.
   cost.  Load balancing over both links may also employed.  The
   datacenters may also be connected to the network with multiple links
   (as depicted for DC A in Figure 2), enabling further connectivity

   In addition, popular yet stationary content may be cached in the NSP
   network, and optimization may lead to the NSP network providing this
   content without the need to access the datacenter at all.  In certain
   cases (e.g., catastrophic failure in the NSP network or of the
   connectivity between that network and the datacenter), the cloud-
   aware CE may choose to bypass the NSP network altogether and reach
   the datacenter over the public Internet (with consequent QoE
   reduction).  In other cases, it may make sense to locally provide
   standalone resources at the cloud demarcation device itself.

4.  Security Considerations

   Perceived insecurity of the customer's data sent to the cloud or
   stored in a datacenter is perhaps the single most important factor
   impeding the wide adoption of cloud services.  At present, the only
   solutions have been end-to-end authentication and confidentiality,
   with the high cost these place on user equipment.  The cloud-aware CE
   may assume the responsibility for securing the cloud services from
   the edge of the customer's walled garden, all the way to the

   Isolation of CSP customers is addressed in [I-D.masum-chari-shc].
   Security measures such as hiding of network topology, as well as on-
   the-fly inspection and modification of transactions are listed as
   requirements in [I-D.dalela-orchestration], while [I-D.dalela-sop]
   specifies encryption and authentication of orchestration protocol

   A further extension to the model is to explicitly include security
   levels as parameters of the QoE optimization process.  This parameter
   may be relatively coarse-grained (for example, 1 for services which
   must be provided only over secure links, 0.5 for those for which
   access paths under direct control of the NSP is sufficient, 0 for
   general services that may run over out-of-footprint connections).
   Security may also take regulatory restrictions into account, such as
   limitations on database migration across national boundaries.  Thus,
   the placement and movement of a VM will be accomplished based on full
   optimization of computational and storage resources; network delay,
   throughput, and packet loss; and security levels.  For example, for
   an application for which the user can not afford denial of service

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   the joint optimizaton would need to find the needed resources as
   close as possible to the end user.

5.  IANA Considerations

   This document requires no IANA actions.

6.  Acknowledgements

   The work of Y(J)S, YG, DK, and KK was conducted under the aegis of
   ETICS (Economics and Technologies for Inter-Carrier Services), a
   European collaborative research project within the ICT theme of the
   7th Framework Programme of the European Union that contributes to the
   objective "Network of the Future".

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7.  References

              Bitar, N., Balus, F., Lasserre, M., Henderickx, W.,
              Sajassi, A., Fang, L., Ikejiri, Y., and M. Pisica, "Cloud
              Networking: Framework and VPN Applicability", draft-bitar-
              datacenter-vpn-applicability-02 (work in progress), May

              Bitar, N., Balus, F., Lasserre, M., Henderickx, W.,
              Sajassi, A., Fang, L., Ikejiri, Y., and M. Pisica, "Cloud
              Networking: Framework and VPN Applicability", draft-bitar-
              datacenter-vpn-applicability-02 (work in progress), May

              Dalela, A. and M. Hammer, "Service Orchestration Protocol
              (SOP) Requirements", draft-dalela-orchestration-00 (work
              in progress), January 2012.

              Dalela, A. and M. Hammer, "Service Orchestration
              Protocol", draft-dalela-sop-00 (work in progress), January

              Hasan, M., Chari, A., Fahed, D., Tucker, L., Morrow, M.,
              and M. Malyon, "A framework for controlling Multitenant
              Isolation, Connectivity and Reachability in a Hybrid Cloud
              Environment", draft-masum-chari-shc-00 (work in progress),
              February 2012.

              McDysan, D., "Cloud Bursting Use Case", draft-mcdysan-
              sdnp-cloudbursting-usecase-00 (work in progress), October

              Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
              Rekhter, "Framework for DC Network Virtualization", draft-
              ietf-nvo3-framework-02 (work in progress), February 2013.

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Authors' Addresses

   Yaakov (Jonathan) Stein
   RAD Data Communications
   24 Raoul Wallenberg St., Bldg C
   Tel Aviv  69719

   Email: yaakov_s@rad.com

   Yuri Gittik
   RAD Data Communications
   24 Raoul Wallenberg St., Bldg C
   Tel Aviv  69719

   Email: yuri_g@rad.com

   Daniel Kofman
   23 Avenue d'Italie
   Paris  75013

   Email: daniel.kofman@telecom-paristech.fr

   Konstantinos Katsaros
   23 Avenue d'Italie
   Paris  75013

   Email: katsaros@telecom-paristech.fr

   Monique Morrow
   Cisco Systems
   Richtistrase 7
   CH-8304 Wallisellen

   Email: mmorrow@cisco.com

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   Luyuan Fang
   Cisco Systems
   300 Beaver Brook Road
   Boxborough, MA  01719

   Email: lufang@cisco.com

   Wim Henderickx
   Copernicuslaan 50
   2018 Antwerp

   Email: wim.henderickx@alcatel-lucent.com

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