Which of the following statements are true regarding Cisco PfR? (Select 2 choices.)
A. Active mode generates probes for all exit paths.
B. Passive mode generates probes for all exit paths.
C. Active mode monitors delay, packet loss, throughput, and reachability.
D. Both active mode and passive mode monitor reachability and delay.
E. Active mode uses NetFlow to monitor performance metrics.
F. Passive mode uses NetFlow to monitor performance metrics.
Explanation:
Passive mode uses NetFlow to monitor performance metrics, and both active mode and passive mode monitor reachability and delay. Cisco Performance Routing (PfR) enhances traditional routing methods by dynamically selecting the best path for applications based on network performance. The path selection procedure can be influenced by several factors, including delay, packet loss, reachability, throughput, jitter, and mean opinion score (MOS). The following three monitoring modes are used by PfR:
– Passive mode
– Active mode
– Fast mode
Passive mode relies on NetFlow to capture performance metrics, including delay, packet loss, reachability, and throughput. Throughput can be measured for all traffic flows. Delay, packet loss, and reachability can be measured only for Transmission Control Protocol (TCP) flows. Passive mode does not use IP Service Level Agreement (SLA) probes to monitor exit paths.
Active mode does not use NetFlow to monitor performance metrics. Instead, active mode relies on IP SLA probes that generate traffic to capture performance metrics. Metrics used by active mode include delay, jitter, MOS, and reachability. Short-term monitoring uses the last five probe results; Long-term monitoring uses the last 60 probe results.
Fast mode is similar to active mode. Active mode generates IP SLA probes only for the active exit path. By contrast, fast mode continuously generates IP SLA probes for all possible exit paths, not just the active exit path. Fast mode allows route changes to be made within three seconds. However, the performance benefits of fast mode require significant processor overhead? therefore, Cisco recommends that you use fast mode only for performance-sensitive traffic, such as Voice over IP (VoIP) or video traffic.
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