A data center, which is home to the computation power and storage, is central to cloud computing and contains thousands of devices like servers, switches, and routers.
Currently, a layered approach is the basic foundation of the network architecture design, which has been tested in some of the largest deployed data centers.
Architectural Design of Data Centers
- Core Layer
- Aggregation Layer Modules
- Access Layer
The basic layers of a data center consist of the core, aggregation, and access layers, as shown in the figure below:
- The access layer is where the servers in racks physically connect to the network. There are typically 20 to 40 servers per rack, each connected to an access switch with a 1 Gbps link.
- Access switches usually connect to two aggregation switches for redundancy with10 Gbps links.
- The aggregation layer usually provides important functions, such as domain service, location service, server load balancing, and more.
- The core layer provides connectivity to multiple aggregation switches and provides a resilient routed fabric with no single point of failure. The core routers manage traffic into and out of the data center.
1. Core Layer
Core layer—Provides the high-speed packet switching backplane for all flows going in and out of the data center.
The core layer provides connectivity to multiple aggregation modules and provides a resilient Layer 3 routed fabric with no single point of failure.
The core layer runs an interior routing protocol, such as OSPF or EIGRP, and load balances traffic between the campus core and aggregation layers using Cisco Express Forwarding-based hashing algorithms.
2. Aggregation Layer Modules
Provide important functions, such as service module integration, Layer 2 domain definitions, spanning tree processing, and default gateway redundancy.
Server-to-server multi-tier traffic flows through the aggregation layer and can use services, such as firewall and server load balancing, to optimize and secure applications.
The smaller icons within the aggregation layer switch in Figure represent the integrated service modules.
These modules provide services, such as content switching, firewall, SSL offload, intrusion detection, network analysis, and more.
3. Access Layer
Where the servers physically attach to the network.
The server components consist of 1RU servers, blade servers with integral switches, blade servers with pass-through cabling, clustered servers, and mainframes with OSA adapters.
The access layer network infrastructure consists of modular switches, fixed-configuration 1 or 2RU switches, and integral blade server switches.
Switches provide both Layer 2 and Layer 3 topologies, fulfilling the various server broadcast domain or administrative requirements.