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Path measurement: Difference between revisions
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* Description of this master device: This field is only used for informational purposes to identify the master device. It can be freely chosen, for example to the location the device is installed. This field can also be left empty to use the default name '''master'''. | * Description of this master device: This field is only used for informational purposes to identify the master device. It can be freely chosen, for example to the location the device is installed. This field can also be left empty to use the default name '''master'''. | ||
The following '''Remote device''' configuration section configures the access to the remote device: | The following '''Remote device''' configuration section configures the access to the remote device: | ||
* Device to use: To use a remote device for path measurement, you first need to add that device as a remote device the list of [[Multi-device settings]]. It does not matter if the device is active or not. | * Device to use: To use a remote device for path measurement, you first need to add that device as a remote device the list of [[Multi-device settings]]. It does not matter if the device is active or not. You can select the device from the list of known multi-devices. | ||
* Device description: Similar to the description of the master device, this field is for informational purpose only and has no other effect than helping identifying the remote device in the statistics. Usually the location of the remote device is entered. | * Device description: Similar to the description of the master device, this field is for informational purpose only and has no other effect than helping identifying the remote device in the statistics. Usually the location of the remote device is entered. | ||
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* '''Maximum packet delay''': This field describes the maximum amount of seconds to wait for packet information from the remote device. | * '''Maximum packet delay''': This field describes the maximum amount of seconds to wait for packet information from the remote device. | ||
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: It basically means that the master devices waits for this number of seconds before deciding if a packet has been lost or not. If the data from the remote device arrives before those number of seconds, the path measurement can account the packet loss, if any and the two-way latency. This value must be at least as large as the worst-case latency between both measurement sites. | : It basically means that the master devices waits for this number of seconds before deciding if a packet has been lost or not. If the data from the remote device arrives before those number of seconds, the path measurement can account the packet loss, if any and the two-way latency. This value must be at least as large as the worst-case latency between both measurement sites. | ||
: Usually 3 seconds are more than enough but when the network in between can have a very long delay, you can increase the value. This will, however, use more main memory for the packet buffer. | : Usually 3 seconds are more than enough but when the network in between can have a very long delay, you can increase the value. This will, however, use more main memory for the packet buffer. | ||
* '''Ignore IP identification field''': This option can be enabled if the IP identification field in the IPv4 header is modified by some component in the network. Often it remains constant for a single packet so this option should be left disabled as it will also increase the chance of reporting duplicate packets. But if you notice symmetrical packet loss you can enable this option to see if this helps. | * '''Ignore IP identification field''': This option can be enabled if the IP identification field in the IPv4 header is modified by some component in the network. Often it remains constant for a single packet so this option should be left disabled as it will also increase the chance of reporting duplicate packets. But if you notice symmetrical packet loss you can enable this option to see if this helps. | ||
* '''Ignore VLAN tags for connection matching''': The path measurement only calculate loss and latency for connections seen on both devices. Usually the connection ID takes the IP pairs, port ports and possible VLAN tags into account. If a VLAN is different on both machines for the some connection, then this option must be enabled to be able to correlate the connection and calculate correct statistics. | |||
The settings must be saved but to actually take effect, a restart of the packet processing is necessary. If this step is required will tell so at the bottom of the page under '''Required actions'''. | The settings must be saved but to actually take effect, a restart of the packet processing is necessary. If this step is required will tell so at the bottom of the page under '''Required actions'''. | ||