Optimizing Packet Mirroring Performance

Packet mirroring operations require some system resources. As a general rule, to avoid performance degradation, limit the amount of mirrored traffic to a maximum of five percent of the E Series router’s total traffic.

For many packet mirroring environments, using the 5-percent guideline is sufficient. However, if you want to more closely manage packet mirroring’s use of your router’s resources, this section provides guidelines and equations to help you determine your packet mirroring requirements.

The guidelines for packet mirroring requirements use the following assumptions for a specific line module:

Determine Traffic Loads

Using the previous assumptions, you can determine traffic loads for a given line module:

Establish Resource Guidelines

Next, using the traffic loads that you determined for the line module, you can establish guidelines for the amount of packet mirroring traffic for your router.

If you exceed these guidelines, regular (non-packet mirroring) packets from all subscribers, including nonmirrored subscribers, will be dropped. If the fabric bandwidth is not exceeded, then the performance penalties are contained within the slot where the packet mirroring activity occurs. However, if the fabric bandwidth is exceeded, traffic from other line modules might also be dropped.

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