How can I calculate network send lose rate?

[Kation]

I try to get QUIC_STATISTICS_V2 from connection.
But I'm confused with statistics result.

SendTotalPackets is much large than what I saw in WireShark. Is that not the same meaning?

SendSuspectedLostPackets is smaller than SendSpuriousLostPackets, but source code comment Actual lost is (SuspectedLostPackets - SpuriousLostPackets)
https://github.com/microsoft/msquic/blob/af6bb2b51a1ad7ece794fc66ff5d5176f4a908df/src/inc/msquic.h#L613C48-L613C107

Is send lose rate could be SendSpuriousLostPackets / SendTotalPackets?

[guhetier]

Hi,

For each connection:
SendSpuriousLostPackets represents the number of packets that have been considered lost, but were eventually acknowledged (so not lost for real, although we might have already retransmitted their content).
SendSuspectedLostPackets represents the number of packets that have been considered lost.
SendTotalPackets is the number of QUIC packets sent (in some situations, multiple packets can share a single UDP datagram).

SendSuspectedLostPackets is smaller than SendSpuriousLostPackets

This is curious and should normally not be the case. Looking for logs like "Spurious loss detected" and "Lost:" could help you understand why you see it (the packet number will be printed in the logs).

I hope it helps.

[Kation]

Is there a way to get UDP datagram sent /lost packets count?

[guhetier]

No. QUIC doesn't track UDP datagrams, but QUIC packets, and there is no 1 to 1 mapping between datagrams and packets (a datagram can sometimes contain multiple packets for a single connection).