Create account / Log in

Losing connections to Vassal server

Issues with the Vassal engine.

Moderators: Tim M, uckelman

Losing connections to Vassal server

Postby palad0n » May 21st, 2020, 1:57 pm

As evinced by many posts over the years, many people have problems with frequent lost connections to the vassal server. In nearly all discussions, the most often cause cited is that the user has an issue, it is not a vassal server issue.

But could the server actually be the real issue?

What are the server's KeepAliveTime, KeepAliveInterval, TcpMaxDataRetransmissions and (possibly) the TcpTimedWaitDelay registry settings? The first may be set too low; sort of understandable given that we do not a lot of inactive connections clogging the server.

If these are not manually set, the default values should be adequate, although 2 hours for KeepAliveTime may be too long.

Just asking the question as I would be interested in the data output.
User avatar
palad0n
 
Posts: 42
Joined: August 4th, 2016, 12:09 pm
Location: Winmalee, NSW Australia

Re: Losing connections to Vassal server

Postby TsukudaJoe » May 21st, 2020, 3:16 pm

Yesterday I suddenly started getting a "lost connection to server" message. It was working fine the day before and I am not aware of any updates or changes to my system in the meantime.

Any ideas or fixes out there? I haven't been able to figure it out. I have spoken with other vassal users on the x-wing module and no one else appears to be having any trouble.
TsukudaJoe
 
Posts: 1
Joined: May 21st, 2020, 3:14 pm

Re: Losing connections to Vassal server

Postby uckelman » May 28th, 2020, 11:35 pm

Try one of the test builds named "VASSAL-3.3.0-svn9451-connection_test", available here:

http://www.vassalengine.org/~uckelman/tmp/

Do you still have connection problems with that?
User avatar
uckelman
Site Admin
 
Posts: 8369
Joined: December 10th, 2007, 9:48 am
Location: Durham, England

Re: Losing connections to Vassal server

Postby uckelman » May 28th, 2020, 11:51 pm

Thus spake palad0n:
> As evinced by many posts over the years, many people have problems with
> frequent lost connections to the vassal server. In nearly all
> discussions, the most often cause cited is that the user has an issue,
> it is not a vassal server issue.
>
> But could the server actually be the real issue?
>
> What are the server's KeepAliveTime, KeepAliveInterval,
> TcpMaxDataRetransmissions and (possibly) the TcpTimedWaitDelay registry
> settings? The first may be set too low; sort of understandable given
> that we do not a lot of inactive connections clogging the server.
>
> If these are not manually set, the default values should be adequate,
> although 2 hours for KeepAliveTime may be too long.

I'm not sure what you're talking about here---the fact that you mention
the registry makes me think you're referring to a Windows machine?

On Linux, in /proc/sys/net/ipv4 I see:

tcp_keepalive_time = 7200
tcp_keepalive_intvl = 75
tcp_keepalive_probes = 9

My understanding is that these are more for detection of dead connections
rather than for actually keeping connections alive.

The test build I mentioned above contains an application-level keep-alive:
It send out an empty message two minutes after the previous message has
gone out, to keep the connection open. (I'm not a networking expert by
any stretch, but this is similar to what ssh does for keeping idle
connections from being closed by hostile things like routers using NAT
and such.)

--
J.
User avatar
uckelman
Site Admin
 
Posts: 8369
Joined: December 10th, 2007, 9:48 am
Location: Durham, England

Re: Losing connections to Vassal server

Postby palad0n » May 29th, 2020, 2:38 am

7200 is 7.2 seconds, assuming it follows normal convention of being based on milliseconds. As vassal sever disconnects seem to occur around the 5 minute mark, I guess we can discount the server. Oh well, it was worth a thought.
User avatar
palad0n
 
Posts: 42
Joined: August 4th, 2016, 12:09 pm
Location: Winmalee, NSW Australia

Re: Losing connections to Vassal server

Postby palad0n » May 29th, 2020, 2:42 am

I will try the test build as well and advise. Thanks.

Being developmental software, may I assume that you would like any bug reports that I may encounter?
User avatar
palad0n
 
Posts: 42
Joined: August 4th, 2016, 12:09 pm
Location: Winmalee, NSW Australia

Re: Losing connections to Vassal server

Postby jrwatts » May 29th, 2020, 2:48 am

tcp_keepalive_time is in seconds, not milliseconds (according to this blog, at least).
jrwatts
 
Posts: 19
Joined: April 29th, 2020, 10:30 pm

Re: Losing connections to Vassal server

Postby uckelman » May 29th, 2020, 9:48 am

Thus spake palad0n:
> 7200 is 7.2 seconds, assuming it follows normal convention of being
> based on milliseconds. As vassal sever disconnects seem to occur around
> the 5 minute mark, I guess we can discount the server. Oh well, it was
> worth a thought.

No, both of those values are in _seconds_, so that's 2 hours.

--
J.
User avatar
uckelman
Site Admin
 
Posts: 8369
Joined: December 10th, 2007, 9:48 am
Location: Durham, England

Re: Losing connections to Vassal server

Postby uckelman » May 29th, 2020, 9:51 am

Thus spake palad0n:
> I will try the test build as well and advise. Thanks.
>
> Being developmental software, may I assume that you would like any bug
> reports that I may encounter?

Yes, that would be appreciated.

--
J.
User avatar
uckelman
Site Admin
 
Posts: 8369
Joined: December 10th, 2007, 9:48 am
Location: Durham, England


Return to Technical Support & Bugs

Who is online

Users browsing this forum: No registered users and 6 guests