OSA/OFC/NFOEC 2011
OMW1.pdf OMW1.pdf
Cloud Computing over Telecom Network Dominique Verchere Alcatel-Lucent Bell Labs, Route de Villejust, 91620 Nozay, France e-mail:
[email protected]
Abstract: Telecom operators should configure networks with end-to-end bandwidth and latency guarantees for Cloud infrastructure as services. IT and connectivity services require to be associated in workflows handled at edge routers of wavelength switched Optical Networks. OCIS codes: (060.4510) Optical communications, (060.4256) Networks, network optimization
1. Introduction Companies are outsourcing their demands on IT towards datacenters stressing for explicit bandwidth and low latency connectivity services. Telecom operators are looking forward to delivering these services for their customers for interests. First is the rapid set-up of Virtual Organizations (VO) with the related IT service access. Enterprises come together to share their competencies consequently a fast reconfigurable network is key for implementing a VO. Secondly collaborations are to better execute projects attached to business opportunities. The third motivation is to split costs of OAM by outsourcing datacenter managements. However current «Cloud computing» model is not mature because between network and datacenter infrastructures, it is still required to specify interfaces including for network service management [2]. Telecom operator advantage is the central role in interconnecting datacenters and companies with the opportunity to managing more precisely the delivery of network services to Generalized Service Provider (GSP): Fig.1. By designing the connectivity services according to their position in the application workflows, wavelength connections are managed to fill end-to-end QoS connectivity requirements. Cloud computing applications require explicit reservation of network resources with other types of IT resources (e.g. computational, storage). The enterprises express to GSP their QoS requirements including the maximum cost they are willing to sustain and a time window within which the workflow has to be completed. The calendar positions the timing constraints of the application workflow and it enables to orchestrate the service elements from different Infrastructure as Service Providers. The iteration starts with selection of Infrastructure as Service Providers The binding of customer applications’ workflows over connectivity services triggering automatically wavelength connection reconfigurations is a capability that Telecom operators are now looking for with the supports of Generalized Multi-Protocol Label Switching protocols. This binding requires vertical service interactions allowing the negotiation of connectivity services between a network infrastructure provider and Service Providers. On Fig.1 the Service orders are issued by the Execution Management System (EMS) with parameters including IT + network service type, the class of end devices used to deliver the services, the duration of the service and its accounting. The connectivity services must be activated according to the execution of workflows handled at the EMS. The challenge of Cloud Computing service is to provide control and management to support timed based connectivity service activations. Scheduler is fundamental for advanced reservations of wavelength used by connectivity services. Section 2 outlines the extensions of optical networks delivering Cloud Computing services. Scheduling connectivity services are presented in section 3 with Cloud Networking Service Manager (CNSM). Section 4 presents a scenario with a sequence diagram of the functions involved. Conclusion is drawn with the challenges of standardizing the service management interfaces and the scheduler parameters. 2. Optical Network Architecture delivering Cloud Computing services Optical networks enhanced with Generalized Multi-Protocol Label Switching (GMPLS) based protocols and Path Computation Element (PCE) offer the opportunity to control, provision and operate automatically wavelength switched optical network (WSON) connections [5]. The WSON network is able to match the dynamic and ultra-high bandwidth requirements of stringent distributed applications delivered from the clouds. The control of high-level connectivity service provisioning is decoupled from the basic connection control. Connectivity service control can therefore be provided at the edges or at the region boundaries where service admission control is performed. Call admission control is a policy function invoked by an ingress node and may involve cooperation with several egress nodes. The acceptance of a connectivity service order only indicates that it has the permission to request one or more WSON connections to be provisioned. It does not imply that any of those WSON connections to be allocated to the connectivity service. Ingress node hosting connectivity service admission control as represented on Fig.2 is responsible for checking that valid service order is issued by user including authentication, authorization, accounting as well as QoS
OSA/OFC/NFOEC 2011
OMW1.pdf OMW1.pdf
explicitly provided e.g. bandwidth, end-to-end transmission delays, availability. These connectivity parameters are checked against a Service Level Specification (SLS), a set of values previously agreed between Telecom network service provider and user for wavelength connectivity service. These parameters indicate duration and range of connectivity service. If any available wavelengths can fulfill the SLS of the connectivity service order, these parameters can be renegotiated with the Enterprise user. The range of this connectivity service negotiation is determined by rules derived from the Service Order, which itself is derived from the policies embedded in the EMS. The egress nodes selected by the connectivity service admission control functions as represented on Fig.2 are responsible for checking that the called datacenters are entitled to accept the connectivity services based on the contract between Enterprise user and the datacenter service provider. CNSM enables connectivity service provisioning to be decoupled from implementation of the wavelength connections. This functional separation facilitates the development and deployment of new Cloud Computing services independently of the IT and network infrastructures and further multi-vendor scenarios. CNSM needs to standardize the service management interfaces to allow on one hand to receive service orders from the EMS of GSP and on the other hand to trigger commands towards Network Resource Management agent (NRMA). These two interfaces are based on MTOSI [3]. MTOSI specifications are produced by the Tele-Management Forum in multiTechnology Operation system support Program (mTOP). MTOSI is a unified open interface to be used among heterogeneous types of network management systems to provide connectivity services and to request wavelength connections. MTOSI standard encompasses all switching capability technologies from layer 1 (e.g., SONET/SDH, wavelength) through higher switching capable layer technologies such as layer 2 (e.g. Ethernet, T-MPLS) and layer 3 (e.g. MPLS, IP). 3.
Scheduling Carrier Grade Connectivity services
Telecom network can offer Cloud computing services with guaranteed delivery time intervals if connectivity service management are enhanced to associate the scheduling functions. To enable guaranteed delivery time intervals, it is also required to standardize the parameters associated to connectivity services and especially the scheduling parameters. The time constraints have to be associated with network resource space constraints meaning that an association of the connectivity services with explicit network resource reservations is done by triggering WSON connections provisioned by NRMA agent and controlled by GMPLS controllers. The service-scheduler function allows activating/de-activating the connectivity services when required according to the workflow execution of the cloud computing based applications [1]. Furthermore the service scheduler is designed to allow the composition of scheduled connectivity services such as carrier grade Ethernet VPN with other types of carrier grade IT services. Different scheduler algorithms can be plugged enabling to take into account different management policies of the Telecom operators. Further optimization strategies are defined to allocate the amounts of resources from the networking and datacenter infrastructures interconnected. The connectivity service scheduling function takes into account the constraints expressed in the service orders issued from the EMS. The Connectivity service activation commands are part of the CNSM South Bound Interface. The commands are sent towards the NRMA following the data and information model of Service Component Activation Interface [3]. The commands issued follow a sequence diagram considering the states of the connectivity services: Feasibility Check, Reservation, Provisioning, Activation, Deactivation, and Termination (Fig. 4). CNSM manages the status of the connectivity services (Reserved, Provisioned or Activated) and stores this information in the service Inventory Data-Base. The optimization of scheduled connectivity services consider the transmission capacity of the optical network only or the joint capacity of the optical network associated with the computing and storage as services. Optimization algorithms are processed in Super Path Computation Element (PCE) capable of computing optimal shortest paths for single or set of connectivity service requests with guaranteed delivery time constraints. The Super PCE, extension of the PCE [4], is essential for the NMRA, it is associated to a Network Planning tool for using the wavelength provisioning policies and to the Network Resource Scheduler which is aware of the wavelength connection availability stored in the Traffic Engineering database. 4. Industrial application Scenario with Datacenter access A R&D project can require ultra-high-performance computing (HPC) capability generating very large amounts of data for a defined time interval. These conditions push enterprises to access remotely storage services and computational services supported with reconfigurable wavelength connections instead of owning these complex IT infrastructures. The scheduler of the CNSM allows reserving in advance connectivity services with negotiated QoS and then each service is allocated on a wavelength connection between two or more IT service end-points. When scheduled connectivity service is instantiated then a wavelength connection may require to be provisioned by NRS. The sequence diagram of a switched connection differs slightly. The background process is monitoring the states
OSA/OFC/NFOEC 2011
OMW1.pdf OMW1.pdf
(available or used) of the wavelength connections and logs their states in Inventory Database. When the connectivity service is bound to the wavelength delivered by the NRS (i.e. after the connectivity binding stage illustrated on Fig. 3), the NRS returns a connectivity service ID to CNSM that can be used to reference the connectivity service order from GSP. Before the application workflow starts (i.e. T1-ε) the provisioned wavelength is activated by the NRS. Similarly after the time T2, the NRS deactivates the connection provisioned by the NMS. The connection state is changed to available. Application Workflow
Initialization
Cloud Networking Service Manager Service Scheduler
Calendar
Service Orders
Service Orchestration
Connectivity Services
(1)
Service Inventory Management
(2)
Infrastructure Provider Selection
IaaS Provider Negotiation
Generalized Service Provider (GSP) Failed Passed
(3)
Network Resource Management System agent Planning Tool Super-PCE N.R.Scheduler
Enterprises
☺ Service Orders
Complete
(4) GMPLS
controlled Telecom Network
Execution Management System (EMS)
(5)
Fig.1: GSP issues Service Orders Generalized Service Provider
Cloud NRSNetworking Service Manager Scheduler Negotiation Inventory
Orders for IaaS (A-B;T1-T2)
Fig.2: Cloud Networking Service Manager
Network Resource Manager agent (NRS)
NMS PCE GMPLS
FeasibiltyChecked checkFeasibility
Query for status
Query
design Read Inventory-DB
Proposition (+price)
Response
Decision (accepted)
Contract
Check network state
Designed
Status update response Service Reservation
Background process
(T1-T2)
reserve
Confirmed
Path Selection response
TE-DB(t) updates
Reserved
Path ComputationSelection config. ERO
Ack. + Selection status
provision
remove
unprovision remove
Reserving Resources
Provisioned
Res. Reservation resp.
remove
Ack. + Connection ID
Ack.+ IaaS ID
Connectivity – Connection binding
Contract - Service binding t=T1- ε
Scheduled Connection
Connectivity activation req. ε
LSP Reserved
Res. Allocation resp.
deactivate terminate
allocations
A-B LSP Connection Allocated used Connectivity deactivation req. Resource de-allocation ε
Provisioned Inactive
activate
Res. allocation (GMPLS)
Service Activated t=T2 + ε
remove
Path req. (PCE) Connection Requested
Provisioned Inactive
unreserve
design
Connectivity Reservation req. (T1-T2)
Service Provisioning (T1-T2)
Ack.+ Service ID
Datacenters
Res. Reservation resp.
de-allocations
Active terminate terminate
remove
TE-DB updates
Ack. + Connection ID Connection unbinding
Fig.3: Service Provisioning & Activation sequence diag.
Terminated
Fig.4: Connectivity service State Machine
5. Conclusion With the introduction of a Cloud Networking Service manager, reconfigurable wavelength switched optical network is suitable to deliver Infrastructure as Services to enterprises. However some fundamental challenges still remains to be solved such the standard specifications of services scheduler architecture for Telecom Networks. Furthermore, the CNSM should maintain the confidentiality of the provisioning rules for Telecom service providers. 6.
References
[1] P. Vicat-Blanc Primet et al, “Virtualizing and scheduling optical network infrastructure for emerging IT services”, Journal of Optical Communications and Networking, 2009 [2] G.Koslovski et al, “VXDL: Virtual Resources and Interconnection Networks Description Language”, Gridnets ICST Conf. 2008 [3] “Multi-Technology Operations Systems Interface (MTOSI) 2.0” TMF Forum, May 2008. [4] A. Farrel et al. “A Path Computation Element (PCE)-Based Architecture”, IETF RFC4665, August 2006. [5] Y. Lee et al. “Framework for GMPLS and PCE Control of Wavelength Switched Optical Networks (WSON)” IETF Internet draft, work in progress, draft-ietf-ccamp-rwa-wson-framework-07.txt
