Specifications

DESIGN GUIDE - Data Center LAN Connectivity Design Guide

Aggregation Layer Design Considerations

Due to their location in the network, aggregation-layer switches must provide scalable, high-performance, high-

density, wire-rate ports, and HA hardware and software features that deliver carrier-class reliability and robustness.

The aggregation layer is also a location from which to deploy additional services, such threat containment. Layer 3

should be provided at the aggregation layer for route summarization, fast convergence, and load-sharing.

In some instances, based on port density, aggregation throughput, and oversubscription requirements, the

aggregation layer may be eliminated and collapsed into the core layer. For more detail on this configuration, please

view the Data Center Core Layer Design Recommendations section.

High Availability (HA)

It’s crucial that data center networks operate with maximum reliability and uptime. Device redundancy is required,

and all devices must have robust HA features such as redundant, load-sharing power supplies and cooling fans, and

in some cases, fully redundant hardware. Redundant GbE downlinks to the access layer and 10 GbE uplinks to the

core layer are also required.

Scalability

The aggregation layer must provide high-density port connectivity to the core layer and be able to easily handle peak

throughput while adding minimal latency.

Network Virtualization

Aggregation switches should also support generic routing encapsulation (GRE) tunneling for sending mirrored traffic

to monitoring devices in the network operations center for centralized troubleshooting and analysis, or to build

segregated overlay networks without the challenges associated with Spanning Tree.

Application Visibility

To successfully manage a network, it’s important to know how it’s being used so that application deliver may be

optimized and efficiency maximized. Real-time information and detailed reporting are needed to provide rapid access

into LAN wide application information that can help identify patterns or applications that are disrupting performance

or in need of QoS support.

Security and Threat Containment

It’s vital that the aggregation layer include integrated security features to guard against intruders or other external

threats such as distributed denial of service (DDoS) attacks. It should deliver an extra layer of security by first

authenticating users and performing virus checks, then enforcing precise, end-to-end security policies that

determine who can access what network resources, as well as quality of service (QoS) policies to ensure delivery of

business processes.

Data Center Aggregation Layer Design Recommendations

Traditional Layered Approach

For a traditional three-layer network design, Juniper Networks recommends the EX8200 line of switches for

aggregation layer deployment. All Juniper solutions at the aggregation layer offer the following features and benefits:

High Availability (HA)1.

The EX8200 line of switches offer fail-safe operations. Redundant links to each core layer device are provided in

the event of a device or link failure. The EX8200 line also offers a redundant control plane as well as redundant

power supplies and fans. All equipment runs JUNOS Software, providing HA features such as QoS and Graceful

Routing Engine Switchover, preserving forwarding and routing operations during device events with non-stop

forwarding and automatic load balancing.