This document is targeted at providing a reference topology relevant to today's common enterprise data center environment that has been extended to reflect some of the new products and features that are available to the network designer. Best practices in the area of network device configuration for Layer-3 and Layer-2 features are also provided.
The main sections of this design document cover the following:
Data Center Network Topologies–This section discusses the hierarchical network design reference model, insertion of data center services, designs using Nexus 7000 Virtual Device Contexts (VDCs), and the use of logical networking constructs to control the flow of traffic across the topology.
Layer 3 Design and Features–This section discusses IP routing topology design decisions and features. These guidelines pertain primarily to configuration of and interaction between the core and aggregation layers of the network with additional implications on insertion of data center services—such as firewall and server load balancing.
Layer 2 Design and Features–This section discusses Ethernet forwarding within a broadcast domain, with a particular emphasis on Spanning Tree Protocol (STP) and alternative features for forwarding loop prevention such as Virtual Port Channels (vPC) in NX-OS and the Cisco Catalyst 6500 Virtual Switching System (VSS). These guidelines pertain primarily to configuration of and interaction between the aggregation and access layers of the network, but also affect design decisions for service insertion.
