The Cisco Virtualized Multiservice Data Center (VMDC) is the reference architecture for IaaS cloud deployments and has been widely adopted by a large number of service providers and enterprises worldwide. This architectural system provides design and implementation guidance for both enterprises deploying private cloud services, and for Service Providers (SPs) building public and virtual private cloud services. Cisco’s VMDC reference architectures, which are regularly updated, integrates Cisco and third-party products, such as the Citrix ADC, formerly NetScaler SDX appliance, across the cloud computing ecosystem into a validated end-to-end system that customers can deploy with confidence.

Data Center Interconnect (DCI) refers to underlying technologies used to connect geographically dispersed data  centers to support Business Critical operations. This VMDC DCI solution provides validated guidelines for cloud data center connectivity across metro distances (less than 200 km) and geo distances (more than 200 km). This VMDC DCI solution enables critical business operations including:

• Application business continuity across multiple data center sites
• Application disaster recovery and avoidance across multiple data center sites
• Application geo-clustering and load balancing across multiple data center sites
• Complete workload mobility across multiple data center sites
• Operations functions across multiple data center sites including workload rebalancing, Maintenance operations, and consolidation of workloads

Since VMDC DCI will use the “Typical Data Center” design, the Citrix SDX SLB appliance is configured in one-arm mode. This has several key benefits, especially in multi-site scenarios:

• One-arm mode limits the extension of FabricPath VLANs to the appliances
• One-arm mode keeps VLAN ARP entries off the SDX SLB
• The port-channel attachment method allows for a separation of failure domains.
• Source-NAT on the SDX SLB insures symmetric routing and a return path for moved workloads. This is especially important for DCI designs that span multiple sites.

Incorporating Citrix ADC SDX, this approach delivers increased tenancy scale and simplifies tenancy resource management.

Interconnecting Cloud Data Centers can be a complex undertaking for Enterprises and SP’s. Enabling business critical applications to operate across or migrate between metro/geo sites impacts each Tier of the Cloud Data Center. Customers require a validated end-to-end DCI solution that integrates Cisco’s best in class products at each tier, to address the most common Business Continuity and workload mobility functions. To support workloads that move between geographically diverse data centers, VMDC DCI provides Layer 2 extensions that preserve IP addressing, extended tenancy and network containers, a range of stateful L4-L7 services, extended hypervisor geo-clusters, geo-distributed virtual switches, distributed storage clusters, different forms of storage replication (synchronous and asynchronous), geo-extensions to service orchestration tools, IP path optimization to redirect users to moved VMs and workloads, and finally, support across multiple hypervisors. The cumulative impact of interconnecting data centers is significant and potentially costly for SPs and Enterprises. Lack of technical guidance and best practices for an “end-to-end” business continuity solution is a pain point for customers that are not staffed to sift through these technical issues on their own. In addition, multiple vendors and business disciplines are required to design and deploy a successful business continuity and workload mobility solution. VMDC DCI simplifies the design and deployment process by providing a validated reference design for each tier of the Cloud Data Center.

The VMDC DCI design uses the following definitions to assess the overall cost of a recovery time resulting from workload mobility or a recovery plan:

• Business Continuity - Processes to ensure that essential Business functions can continue during and after an outage. Business continuance seeks to prevent interruption of mission-critical services, and to re-establish full functioning as swiftly and smoothly as possible.
• Recovery Point Objective (RPO) - Amount of data loss that’s deemed acceptable, defined by application, in the event of an outage. RPO can range from zero (0) data loss to minutes or hours of data loss depending on the criticality of the application or data.
• Recovery Time Objective (RTO) - Amount of time to recover critical business processes to users, from initial outage, ranging from zero time to many minutes or hours.
• Recovery Capacity Objective (RCO) - Additional capacity at recovery sites required to achieve RPO/RTO targets across multi-site topologies. This may include many-to-one site recovery models and planned utilization of recovery capacity for other functions
• Metro Distance - Typically less than 200 km and less than 10 ms RTT
• Geo Distance - Typically greater than 200 km and less than 100 ms RTT

Features

The VMDC DCI solution incorporates a wide range of Cisco cloud innovations and Partner products. These products are integrated within the Cisco Validated Design (CVD). The DCI solution provides compelling benefits to Public and Private Cloud Providers:

• Simplify the DCI Design Process for Operations Teams - Interconnecting Cloud Data Centers involves many infrastructure elements and application components that provide critical business services. The VMDC DCI design provides a validated reference design that significantly reduces risk of implementation using Cisco’s latest product innovations and partner products. This VMDC DCI design builds upon previous VMDC releases that have been extensively validated and widely deployed by Enterprises and Service Providers worldwide. The validated VMDC DCI design enables Public and Private Cloud Providers to deploy DCI functions with confidence.
• End-to-end Validation of the Application Environment - The VMDC DCI solution delivers validated guidelines across the end-to-end layers of the cloud data center. The DCI design spans different sites and addresses each element of the Application environment including WAN connections, LAN extensions, tenancy, network containers, distributed virtual switching, and L4-L7 services; as well as traditional functions such as hypervisor vMotion and storage replication. This is a true DCI solution that directly addresses each element of the Application environment.
• Validates 2 of the most used DCI Design Options - VMDC DCI validates the most common design options to achieve 2 major Recovery Point Objective (RPO) and Recovery Time Objective (RTO) targets. The first design option enables the movement of applications, their date, their services, and network containers to support near zero RPO/RTO for the most business critical functions. Less business critical applications can be mapped to a second design option to achieve RPO/RTO targets of 15 minutes or more.
• Minimal Disruption to the Application - VMDC DCI allows operators to preserve IP addresses of moved applications, their services, and network container between sites.
• Reduction in CAPEX/OPEX for DCI Deployments - VMDC DCI helps customers align the correct DCI design to achieve the selected application RPO/RTO targets. The most stringent recovery targets typically require the highest CAPEX/OPEX. VMDC DCI provides a framework to map Applications to different Criticality Levels, and then select the most cost effective option that meets application requirements.
• Planned Usage of Recovery Capacity - Recovery capacity at remote sites can be used for other applications during “normal operations” and “reclaimed” as needed by Operations Teams during recovery events. This “Reuse-Reclaim” design strategy allows for planned utilization of extra capacity and many-to-one resource sharing, reducing CAPEX/OPEX.
• DCI Use Cases Validated with Business Applications - VMDC DCI utilized traditional business applications across each workload migration and business continuity use case. The test applications include Oracle database servers, Microsoft SharePoint and SQL, for single tier and multi-tier test applications.
• Multiple Hypervisors supported - Both VMware and Microsoft Hyper-V environments are supported. Microsoft Hyper-V design guidance is provided as a separate addendum.
• Product Performance Measured across DCI Use Cases - The performance of Cisco products and Partner Products used in VMDC DCI was measured and documented across metro/geo environments. Performance limitations, design recommendations, and configurations are provided for Cisco and Partner products.
• Operational Simplicity - This VMDC DCI release utilizes cloud service orchestration and resource provisioning products from Cisco and Cisco partners to support multi-site environments. Automated provisioning of cloud assets significantly simplifies operations, especially across multi-site designs.