Cisco’s Virtual Multiservice Data Center (VMDC), is Cisco’s reference architecture for cloud deployment and has been widely adopted by numerous Solution Providers and enterprises worldwide.
Cisco’s Virtual Multiservice Data Center (VMDC), is Cisco’s reference architecture for cloud deployment and has been widely adopted by numerous Solution Providers and enterprises worldwide. In this and previous releases, VMDC has provided design guidance for scalable, secure, resilient, public and private cloud infrastructures serving multiple consumers or tenants:
VMDC VSA 1.0 is the first VMDC release dealing specifically with the transition to NFV (Network Function Virtualization) of IaaS network services in the data center. Such services comprise virtual routers, virtual firewalls, load balancers, network analysis and WAN optimization virtual appliances.
In this release, we focus mainly on public provider use cases, building a new logical topology model around the creation of virtual private cloud tenant containers in the shared data center infrastructure. Future releases will incorporate additional cloud consumer models specific to enterprise and private cloud use cases. In particular, future releases will address hybrid consumer models, comprising physical and virtual service appliances, used together as part of a per-consumer or per-tenant service set. These can be implemented on either a 2.X (classical Ethernet) or 3.X (FabricPath) VMDC infrastructure.
However, in this release we focus on fundamental implications of an all-virtual approach, and have opted to do so over a simple FabricPath data center topology previously validated in VMDC 3.0.
Previous VMDC releases incorporated physical appliance-based and DSN module-based services, and virtual service appliance form factors. From VMDC 2.2 forward, two tiers of security policy enforcement points are featured in the enterprise-grade Expanded Gold container: the first perimeter firewall implemented on a physical form factor, and the second (VSG) implemented as a virtual appliance. The premise was that this hybrid model would best satisfy rigorous security requirements. As is traditional, with the exception of the VMDC 3.0 “Switched Data Center” FabricPath topology model, all physical form factors were attached at the aggregation or aggregation-edge nodes.
VMDC VSA 1.0 departs from tradition in that all IaaS network service functions are virtualized. In this model, services are attached via VLAN stitching at the virtual access edge in the compute layer of the infrastructure. The list of virtual service appliances includes: CSR; Citrix ADC, formerly NetScaler VPX, or Cisco Citrix ADC 1000v for SLB; ASA 1000V; VSG; Virtual Network Analysis Module (vNAM); and the Virtual WAN Acceleration Service Module (vWAAS). Running on general-purpose server hardware, these software-based form factors are ideal for cloud data centers in that they are software-defined and provide flexibility and agility through enhanced programmability.
Server Load Balancer
The Citrix ADC VPX and Cisco’s OEM product, Citrix ADC 1000v, are virtual appliances that perform SLB and SSL offload services in the VMDC VSA 1.0 architecture. As of this writing, the VPX is available in four models, ranging from 200 Mbps to 3 Gbps maximum throughput, suiting a broad range of performance requirements and use cases. This release leverages the 200 Mbps (VPX-200) model. Supported hypervisors as of this writing are: vSphere ESXi, Microsoft Hyper-V, and Citrix Hypervisor, formerly XenServer. This release is based on the vSphere ESXi hypervisor. The number of logical network interfaces supported by the VPX is determined by hypervisor limits. Currently, for vSphere 5.1 and ESXi hardware version VMX-09, this is a maximum of 10. The VPX supports IPv4 and IPv6 packets, and can operate in transparent or routed mode. Required VPX-200 resources are two vCPUs, 2 GB RAM, and 20 GB HD.
In this release we focus mainly on load balancing and resilience capabilities, however this virtual SLB (vSLB) implementation is quite feature-rich, supporting a broad range of use cases and functionality. The Citrix ADC may be installed from an OVF and configured via CLI, however further enhancing usability and ease of configuration is the browser-based VPX GUI. More detailed information about the Citrix ADC is available online.
To address the identified requirements, we modified the Unified Computing component of the VMDC architecture, shifting virtualized service functions from the Unified Fabric/Data Center Networking portions of the infrastructure.
In general, the solution comprises three modular layers:
The solution is complemented by Cloud Service Management components that enable end to end provisioning and orchestration, along with monitoring and assurance.
The architecture described in this guide addresses the following customer challenges:
VMDC VSA 1.0 addresses the following use cases: