Path measurement: Difference between revisions

Path measurement (view source)

Revision as of 14:25, 7 May 2020

525 bytes added , 7 May 2020

→‎FAQ

Ralf

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 === FAQ ===
-.What does the note '''Network setup problem detected: Packet modification or complete loss''' means?
+# What does the note '''Network setup problem detected: Packet modification or complete loss''' means?
-:This message box appears if flows have been identified for which not a single packet could be seen on both sides. Usually this means that there is some device in between both measurement points that modifies the packet. This can be WAN optimizer which rewrite TCP connection for improved network performance. Such setup is not supported.
+#:This message box appears if flows have been identified for which not a single packet could be seen on both sides. Usually this means that there is some device in between both measurement points that modifies the packet. This can be WAN optimizer which rewrite TCP connection for improved network performance. Such setup is not supported.
+#: It can also mean that some other packet field is modified at some point in the network. One field that is known for modification is the IP identification field in the IPv4 header. For this case an additional option can be enabled to ignore this field.
+# What kind of packet information is used to determine latency and packet loss?
-.What kind of packet information is used to determine latency and packet loss?
+#:Both measurement devices calculate checksums starting from the layer 3 packet data to compare packet information on both sides.  This means for IPv4 and IPv6 traffic, the Ethernet header including possible VLAN tags is ignored. For non-IP traffic, the complete layer 2 packet is used so this traffic can only be analyzed in switched networks.
-:Both measurement devices calculate checksums starting from the layer 3 packet data to compare packet information on both sides.  This means for IPv4 and IPv6 traffic, the Ethernet header including possible VLAN tags is ignored. For non-IP traffic, the complete layer 2 packet is used so this traffic can only be analyzed in switched networks.
+# What can I do if I think the packet loss is wrong?
+#: You can contact [[Reaching Allegro Support|our support]] and if possible provide a small capture from both network sides that cover the same traffic. This will help us to find the reason for the shown packet loss.