General Best Practices › Use a Port with the Largest Buffer Size

Use a Port with the Largest Buffer Size

CA Application Delivery Analysis, CA Multi-Port Monitor, and CA UC Monitor perform passive monitoring of network traffic. Data is typically sourced from multiple Gigabit interfaces and then sent out of a single Gigabit interface. This many-to-one relationship means that it is easily possible to overrun the buffer on the destination interface of the switch. The resulting congestion causes the switch to discard packets. The monitoring application assumes the presence of packet loss and reports inaccurate volumes and rates.

We recommend exporting mirrored data to a port on the Ethernet module with the largest buffer size per port. You can obtain a list of Cisco 6500 modules and the buffer depth per port on each module from the Cisco website. Use this list and the show module command to determine the best locations from which to export traffic. The increased buffer depth decreases the likelihood of packet loss at each switch port, which helps ensure that each packet is counted.