CANOGA PERKINS 9145EMP NID Software Version 3.1 - Manual (Page 55)

Diagnostics 9145EMP NID Software User’s Manual
Latency/Jitter Test
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4.2 Latency/Jitter Test
The Latency/Jitter Test screen is used to initiate tests that measure network latency, inter-frame
jitter and frame loss from the local 9145EMP to a remote 9145EMP or other IP agent. At the
Diagnostics menu, type 2 and press Enter. The Latency/Jitter Test screen (Figure 4-3) opens.
Beneath the Maximum Latency and Maximum Jitter test results are the Far End P-Bit Sent/Rcvd,
Local P-Bit Sent/Rcvd, Far End DSCP Sent/Rcvd, and Local DSCP Sent/Rcvd. This data is used
to determine if the programmed Packet Priority or DSCP was changed during the Round Trip
between the local 9145EMP and the destination 9145EMP (far end). Only a 9145 or 9145EMP
destination can provide the Far End PBit/DSCP function.
The leg of the trip (Local to Far End or Far End to Local) on which the P-Bit remarking or DSCP
change is occurring will be identified. It is assumed that each Latency/Jitter test that is initiated
will take a particular path, so each round trip overwrites the previous round trip values.
The following values appear at the top of the screen (Figure 4-3):
Test IP Addr/VLAN The destination IP address and VLAN for the currently test or the last test
completed.
Round Trip Packets Number of completed round trips.
Test Duration The length of time the test has been running, or the length of the last test run.
Dropped Packets Number of packets sent which received no response.
Minimum Latency (ms) Time in ms for the shortest round trip.
Minimum Jitter (ms) Smallest absolute time difference between 2 round trips.
Average Latency (ms) Computed by adding all the round trip latencies and dividing by the num-
ber of completed round trips.
Average Jitter (ms) Computed by adding all the absolute time differences between successive
round trips and dividing by the number of completed round trips minus 1.
Maximum Latency (ms) The highest time interval for a successful round trip.
Maximum Jitter (ms) The highest absolute time difference between 2 successful round trips.
Far End PBit Sent The programmed priority value entered.
Far End PBit Rcvd The priority as it was received at the destination 9145EMP.
Local PBit Sent The programmed priority value is put back into the packet at the far end for the
return trip.
Local PBit Rcvd The priority as it was received at the end of the Round Trip.