NAD 3020 manual Aggregation Layer, Access Layer

Design Guide

Figure 7. Data Center Front-End Network

Aggregation Layer

The aggregation layer is a point of convergence for network traffic that provides connectivity between server farms and the rest of the enterprise. The aggregation layer supports Layer 2 and Layer 3 functions and presents an ideal location for deploying centralized application, security, and management services. Shared across the access layer server farms, these data center services provide an efficient, scalable, predictable, and deterministic behavior common to server-farm needs.

The aggregation layer provides a comprehensive set of features for the data center. The following devices support these features:

●Multilayer aggregation switches

●Load-balancing devices

●Firewalls

●IDSs

●Content engines

●Secure Sockets Layer (SSL) offloaders

●Network-analysis devices

Access Layer

The primary role of the access layer is to provide the server farms with port density. In addition, it must be a flexible, efficient, and predictable environment supporting client-to-server and server-to- server traffic. A Layer 2 domain meets these requirements by providing the following:

●Adjacency between servers and service devices

●A deterministic, fast-converging, loop-free topology

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