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 TWGS and strange network latency problems: suggestions? 
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Gunnery Sergeant

Joined: Thu Feb 07, 2008 10:02 pm
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Unread post TWGS and strange network latency problems: suggestions?
I am trying to diagnose a network latency problem which seems to be giving (all) users all sorts of trouble, but no other application on the internal network exhibits similar problems. I hope someone here has seen something like this and can tell me where to look.

To sum it up: users experience 5-30 seconds of intermittent lag at a time. This lag may occur very frequently (several times a minute), and it may not occur for minutes or hours. An interesting feature of the lag is that it is per-session. If a user experiences this lag, he can open a new telnet window to the server and connect. Although his new session may be stalled in the process of logging in and getting through the daily logs, the connect() client call exhibits no latency issues. It looks like something somewhere the way is losing individual packets and it is taking that router (assuming it is a router and not twgs or the os) a *very* long time to find them, or it gives up.

Do any of the following sound like they could be causing the network lag *as described above* (please do not tell me if it causes something I am not experiencing, and please read the symptoms first, because they rule out quite a bit):
1) TWGS is running under vista.
2) The network connection is 802.11b from the TWGS server to the local router.
3) The ISP is cablevision.

Here are some other interesting puzzle pieces:
1) The ISP has icmp blocked at a point where the IPs go from, on the client side, a real IP address to 10.11 internal, then back to real IP addresses.
2) There are no problems when connected to TWGS from *inside* the local area network.
3) There are no transmission problems when connecting from the internal network to an external TWGS
4) There is no lag inside the local area network or on the TWGS machine when, say, browsing the web.

Please note, I have not been able to recreate the latency problems connecting via ssh (sshing with nagle off) *from* the twgs server *to* a player's host. This is a player host which *is* experiencing packet loss or transmission interruption to the twgs host. Granted, as of yet, I have not pushed the same order of magnitude of 1-character payload packets across the wire as a tradewars session. As a last ditch test to evaluate the machine on which TWGS runs, I suppose I could write a quick tcp connect client (no-nagle) which hits a player's echo port and spews data both in chunks and one character at a time as fast as it can just to test the twgs machine itself... but ssh from that machines exhibits no problems.

Is this an upstream's router problem, or very poorly implemented bandwidth throttling, or perhaps an interaction between twgs/vista/dropped packets? If we assume the packet loss on the internal network is negligible, that explains why there are no problems internally. Recall, there are no unrecoverable packet loss problems when connecting to an external twgs server.

Anyone got a clue? Cuz I need one.

-karl


Thu Feb 07, 2008 10:56 pm
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Joined: Tue Nov 28, 2006 4:04 pm
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Unread post Re: TWGS and strange network latency problems: suggestions?
Sounds like game data file corruption. This happens frequently in games with a lot of messages like alien fig hit messages and such. Each game has a file called TWMAIL.DAT file in that games folder. After you figure out which game(s) are the culprit, delete that file and see if it helps.


Fri Feb 08, 2008 3:31 am
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Gameop
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Unread post Re: TWGS and strange network latency problems: suggestions?
Respectfully, I have to disagree with you D. From the description of the problem, if a Mail.Dat file is corrupted, I have found that affects users connecting from inside the local network, as well as those connecting from the internet... not that I have any better ideas...

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Fri Feb 08, 2008 7:52 am
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Unread post Re: TWGS and strange network latency problems: suggestions?
I would first eliminate the wireless connection as a potential issue. The reason for this is that I ran a Netgear wireless and had all kinds of intermittent lag issues very similar to what you describe. I also tried the wireless in B, G, and N mode using various channels on the wireless and the problem never really went away. I connected my server to the wireless router by ethernet and have not experienced any issues since.

Using a Dlink wireless router I have no issues playing a game and the server connects as stated above. The Dlink wireless runs circles around the Netgear wireless in N mode (I know there will be people who have had the opposite experience).

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Fri Feb 08, 2008 5:56 pm
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Unread post Re: TWGS and strange network latency problems: suggestions?
TWmail.dat file would affect all users, including local connections. IIRC, it will either time out while reading your messages, or you can't enter the game at all.

I need to ask a couple questions:

1. Are you running any BBS software?
2. Are you running VMWare?
3. Router type? Wired or wireless?

The reason I ask is I've experienced a similar problem, though not as complex as yours. Just the lag issue. It would affect both the BBS software to the point that it would hang when users went into a door or exited a door. It would also do the same to my TWGS. I have narrowed my issues down to either our BBS software or my VMWare on Vista.

As far as your issue, it *could* be the interaction with Vista/TWGS/router. I am wondering if the Windows Defender or firewall is somehow blocking the application? Seen that happen before.

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Fri Feb 08, 2008 6:00 pm
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Gameop
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Unread post Re: TWGS and strange network latency problems: suggestions?
I have been having same problem at MTW and have not been able to pin it down.

Not a Vista Issue, I am running Windows Server 2003.

Not a wireless router issue, I am colocated at my ISP, no wireless router used.

I delete mail files daily, but have seen problem even then.

Not CPU maxing out, I have quad CPU's and even seen this happen with 20% CPU utilization.

My guess that when there is alot of activity going on in a game(s), it may be a disk access issue. The mail files can get backed up in the buffer to a point where the server seems to stop to give the server time to write al the files to the disk.

Possiably this can be changed somehow in the next release? Limiting the file somehow to not record hits on fighters when moving through a grid? This would also improve the time it takes to log into a game where a mail file is extremly long because of the long mail files.

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Sun Feb 17, 2008 7:42 am
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