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Analyze connections between remote sites: Difference between revisions
Analyze connections between remote sites (view source)
Revision as of 12:04, 28 April 2020
, 28 April 2020→Evaluation
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The "Measurement" tab shows the results of the analysis of packet data | The "Measurement" tab shows the results of the analysis of packet data | ||
between the master and remote devices. | |||
At the bottom, the fourth graph shows the packet rate of all traffic | At the bottom, the fourth graph shows the packet rate of all traffic | ||
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To identify packet loss during a time interval, first select the | To identify packet loss during a time interval, first select the | ||
corresponding zoom level to see the | corresponding zoom level to see the entire time range. You can also | ||
select the time range by clicking into the graph. | select the time range by clicking into the graph. | ||
The second and third graph shows the number of packets lost | The second and third graph shows the number of packets lost | ||
separately for each direction. If packet loss | separately for each direction. If packet loss occurred, you will see a | ||
non-zero | non-zero value in the graph. | ||
Keep in mind that the analysis waits the configured maximum packet | Keep in mind that the analysis waits the configured maximum packet | ||
delay before deciding a packet is | delay before deciding if a packet is lost. This means that the | ||
time of the packet loss is actually before the data point in the | time of the packet loss is actually before the data point in the | ||
graph, up to the maximum number of packet delay | graph, up to the maximum number of packet delay seconds in the past. | ||
Example: In the graph above, a packet loss is indicated at | Example: In the graph above, a packet loss is indicated at | ||
17:45:34. For a configured maximum packet delay of 5 seconds, the | 17:45:34. For a configured maximum packet delay of 5 seconds, the | ||
original packet | original lost packet was sent 5 seconds earlier starting from | ||
17:45:29. | 17:45:29. | ||
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The "Two-way latency" graph shows the minimum, maximum and average | The "Two-way latency" graph shows the minimum, maximum and average | ||
delay of both | delay of both aggregated directions. Select the zoom level for the | ||
required time period and check if there are any unusual events in the graph. | |||
A high maximum but low average value means that there have been few | A high maximum but low average value means that there have been a few | ||
points in time where the delay was high but the | points in time where the delay was high but the majority of the traffic experienced a | ||
lower delay. | |||
A high maximum and high average indicates a general problem | A high maximum and high average indicates a general latency problem. | ||
A high latency does not necessarily mean | A high latency does not necessarily mean low bandwidth since network | ||
buffers can | buffers can handle latency and still provide high bandwidth. But | ||
real-time applications such as audio calls or video chats will | |||
exhibit poorer quality due to high latency. | |||
=== How to identify traffic happening during packet loss or high latency === | === How to identify traffic happening during packet loss or high latency === | ||
First select the | First, select the relevant time window when the packet loss or high | ||
latency | latency occurred. Consider the packet delay configuration value to | ||
select a time early enough to include the first arrival time of lost | select a time early enough to include the first arrival time of lost | ||
packets. | packets. | ||
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window. | window. | ||
Packet loss for TCP connections always | Packet loss for TCP connections always generate retransmission | ||
packets. Toggle the display of "TCP counters" on the top bar and sort | packets. Toggle the display of "TCP counters" on the top bar and sort | ||
the table for "TCP retransmissions" to see the IP addresses with the | the table for "TCP retransmissions" to see the IP addresses with the | ||
most retransmissions in that time period. | most retransmissions in that time period. | ||
Select an | Select an IP address which shows a high retransmission rate and check its peers or connections to | ||
identify the traffic | identify the traffic during the packet loss or high latency period. | ||