Cisco Cisco Prime Virtual Network Analysis Module (vNAM) 6.3 White Paper
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Cisco Virtualized Multiservice Data Center (VMDC) Virtual Services Architecture (VSA) 1.0
Design Guide
Chapter 1 VMDC VSA 1.0 Introduction
Overview
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.
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.
Problem Statement
The architecture described in this guide addresses the following customer challenges:
1.
Tenancy Scale: Previous VMDC systems releases leveraged various abstraction technologies, for
example, virtual LANs (VLANs) and virtual routing and forwarding (VRF), for tenant isolation,
including separated routing and forwarding. Each abstraction technology impacts logical scale and
control plane overhead. In a traditional hierarchical DC network model, the pressure point from a
scalability and control plane perspective is at the aggregation layer of the infrastructure, with the
number of route peers, VRFs, VLANs, and MAC capacity supported by aggregation nodes
presenting key multi-dimensional scalability factors. The virtual services architectural (VSA) model
introduced in this release presents an alternative, addressing tenancy scale using a centralized
provider edge (PE) and distributed, per-tenant virtual customer edge (vCE) routing model. Tenancy
scale is thus increased to the number of eBGP peers (or alternatively, static routes) supported by the
PE nodes. As of this writing, this is 5000 per pair of redundant ASR 9000 Series PE routers.
example, virtual LANs (VLANs) and virtual routing and forwarding (VRF), for tenant isolation,
including separated routing and forwarding. Each abstraction technology impacts logical scale and
control plane overhead. In a traditional hierarchical DC network model, the pressure point from a
scalability and control plane perspective is at the aggregation layer of the infrastructure, with the
number of route peers, VRFs, VLANs, and MAC capacity supported by aggregation nodes
presenting key multi-dimensional scalability factors. The virtual services architectural (VSA) model
introduced in this release presents an alternative, addressing tenancy scale using a centralized
provider edge (PE) and distributed, per-tenant virtual customer edge (vCE) routing model. Tenancy
scale is thus increased to the number of eBGP peers (or alternatively, static routes) supported by the
PE nodes. As of this writing, this is 5000 per pair of redundant ASR 9000 Series PE routers.
2.
Complexity: Current VMDC architecture models feature a relatively high degree of management
complexity because service appliances are shared across multiple tenants, and are allocated in
logical “slices” (contexts) by automation systems. The VSA model reduces service orchestration
complexity, removing cross-tenant dependencies for L4-L7 service allocation. The VSA model
represents a simpler logical topology compared to the back-to-back VRF-Lite method employed in
VMDC 2.X releases to create rigorous (VRF-based) tenant isolation.
complexity because service appliances are shared across multiple tenants, and are allocated in
logical “slices” (contexts) by automation systems. The VSA model reduces service orchestration
complexity, removing cross-tenant dependencies for L4-L7 service allocation. The VSA model
represents a simpler logical topology compared to the back-to-back VRF-Lite method employed in
VMDC 2.X releases to create rigorous (VRF-based) tenant isolation.
3.
Customer Evolution to NFV for IaaS: For years, customers have seen the transition from physical
to virtual services as a foundation for an evolution toward “next-gen” data center service-oriented
architectures, providing increased flexibility and agility through greater “software definability”.
to virtual services as a foundation for an evolution toward “next-gen” data center service-oriented
architectures, providing increased flexibility and agility through greater “software definability”.
4.
Need for virtual appliance-based multi-tenancy design guidance. VMDC VSA 1.0 is a starting point,
representing an opportunity to initially consider one specific deployment model (the vCE model)
out of several possible options for an “all-virtual” virtual private cloud instantiation, exploring
end-to-end service differentiation, performance and impact on future automation requirements.
representing an opportunity to initially consider one specific deployment model (the vCE model)
out of several possible options for an “all-virtual” virtual private cloud instantiation, exploring
end-to-end service differentiation, performance and impact on future automation requirements.
5.
Need to address logical segmentation constraints of traditional 802.1q VLAN L2 domains through
the application of virtual overlays. VMDC VSA 1.0 presents a first look at the use of VXLANs for
logical segmentation.
the application of virtual overlays. VMDC VSA 1.0 presents a first look at the use of VXLANs for
logical segmentation.
VMDC VSA 1.0 addresses the following use cases:
•
Data center and PoD design
•
Split N-tiered applications
•
Multi-tenancy (including Virtual Extensible LAN (VLXAN)-based logical segmentation)
•
Application-centric instrumentation (statistics collection, network analysis, WAN optimization,
Performance Agent)
Performance Agent)