Correct Answer: E
Explanation/Reference:
Explanation:
Passive monitoring metrics include the following:
Delay: Cisco PfR measures the average delay of TCP flows for a given prefix or traffic class. Delay is the measurement of the round-trip response time (RTT) between the transmission of a TCP synchronization message and receipt of the TCP acknowledgement.
Packet loss: Cisco PfR measures packet loss by tracking TCP sequence numbers for each TCP flow; it tracks the highest TCP sequence number. If it receives a subsequent packet with a lower sequence number, PfR increments the packet-loss counter. Packet loss is measured in packets per million.
Reachability: Cisco PfR measures reachability by tracking TCP synchronization messages that have been sent repeatedly without receiving a TCP acknowledgement.
Throughput: Cisco PfR measures TCP throughput by measuring the total number of bytes and packets for each interesting traffic class or prefix for a given interval of time.
Reference: http://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/performance- routing-pfr/ product_data_sheet0900aecd806c4ee4.html