What is Port Mirroring or SPAN? › What to Mirror in a Multi-tier Application

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What to Mirror in a Multi-tier Application

Use port mirroring to gain visibility into each tier of a multi-tier application. Place collection devices on individual switches to monitor server communications. You do not need to mirror all servers to obtain the appropriate metrics for monitoring. Mirroring all servers yields more duplicate packets and reduces monitor capacity.

For example, consider the following network:

Diagram of port mirroring for a multitier application

Because the mirroring configuration includes both transmitted and received packets, the number of ports required to be mirrored is reduced. When you mirror a tier, you see the traffic to that tier and to the next tier after it.

In this scenario, the ports to mirror are the Citrix Load Balancer, the NetReport, NetWeb, and NetApp servers. The data for the Oracle back-end server is obtained from the NetReport and NetApp server mirrors. Traffic mirrored from Citrix Load Balancer and NetReport provides visibility into the NetCitrix tier.