The answer in a nutshell is: We can as well turn off these chat messages, I've put that on the todo list for the next patch pack.
A slightly more detailed answer is this:
I think there's a major design flaw in the IL2 net code causing this issue.
It's basically caused by the way IL2 tries to fight cheaters.
This is done by comparing the sequence numbers of the packets sent by each player to the sequence number of the last packet received, and if there's a number of packets missing, by comparing the client time to the server time.
The idea behind comparing sequence numbers is: Whe a player uses some means to skip packets for a period of time (e.g. by issueing some activity that occupies all bandwidth on his internet connection), a couple of packets will not get through anymore, giving the player the ability to "warp" to some distant place once the next packet arrives at the server again.
This would get noticed by the server using the sequence number comparison and the server would issue a warning and increase an internal counter that will kick the user if this happens repeatedly.
That much, that good.
The idea behind comparing client time to server time is basically the same, since the client could manipulate his local time and cause warping by this as well, however this idea falls short:
When the server time is adjusted (*), all clients times will be out of sync immediately and they won't come back to sync anymore.
Unfortunately IL2 is lacking any code to check such type of server sided time changes.
Any packet coming from a client with invalid timestamp (read: offset to server time exceeds limits) will not be counted as a "valid" good packet anymore.
It will by computed as usual, but after a certain time the server will notice that he didn't receive a "valid" good packet from the client for a period of time and will start issueing lag warnings.
That's what we see here.
And to make matters worse, there's no way out of this, since even if client and server times would sync somehow again, the server will not even consider asking the client for it's time once the client reached a certain threshold of failed packet timestamps.
The bottom line is that most probably this is caused by server-sided time adjustments (*) and has nothing to do with real lag, client issues, cheating or the like.
It's definitely safe to ignore these messages, at least on our server, since it's configured not to kick players for lag warnings.
(*) Synchronizing a local PCs time frequently (e.g. with some external high precision time source via NTP) is nothing special.
On a virtualized system (like our game server) however depending on the CPU load the local clock will run out of sync quite soon and rather massive, that's why NTP sync is essential and that's also why such system step into this trap quite frequently.
Best regards - Mike
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Topic: Lag messages (Read 1303 times)
