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Path measurement: Difference between revisions
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==== FAQ ==== | ==== FAQ ==== | ||
1.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. | ||
2.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. | ||