MantisBT - Zandronum
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IDProjectCategoryView StatusDate SubmittedLast Update
0003069Zandronum[All Projects] Bugpublic2017-04-17 14:562018-09-30 21:43
ReporterBlews 
Assigned ToTorr Samaho 
PrioritynormalSeveritymajorReproducibilityalways
StatusclosedResolutionfixed 
PlatformMicrosoftOSWindowsOS VersionXP/Vista/7
Product Version3.0-beta 
Target Version3.0Fixed in Version3.0 
Summary0003069: Unable to connect -- Router disconnects.
DescriptionI am currently using a tablet connected to my computer via USB Tethering (Using PDANet) to use my Wifi connection. Turns out every time I try to enter any Zandronum 3.0 server, it gets stuck on "Requesting Snapshot . . . " and I get disconnected from PDAnet
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Issue History
Date ModifiedUsernameFieldChange
2017-04-17 14:56BlewsNew Issue
2017-04-17 19:16BlewsNote Added: 0017178
2017-04-17 19:16BlewsNote Edited: 0017178bug_revision_view_page.php?bugnote_id=17178#r10332
2017-04-18 00:17mifuNote Added: 0017184
2017-04-18 00:20mifuNote Edited: 0017184bug_revision_view_page.php?bugnote_id=17184#r10334
2017-04-18 00:54AlexMaxNote Added: 0017187
2017-04-18 01:11WaTaKiDNote Added: 0017188
2017-04-18 01:19WaTaKiDNote Edited: 0017188bug_revision_view_page.php?bugnote_id=17188#r10336
2017-04-18 12:18CutmanNote Added: 0017194
2017-04-18 12:18CutmanNote Edited: 0017194bug_revision_view_page.php?bugnote_id=17194#r10338
2017-04-18 17:53Torr SamahoNote Added: 0017196
2017-04-18 17:53Torr SamahoStatusnew => feedback
2017-06-24 15:35BlewsNote Added: 0017898
2017-06-24 15:35BlewsStatusfeedback => new
2017-06-25 13:29Torr SamahoNote Added: 0017906
2017-06-25 13:43Torr SamahoNote Edited: 0017906bug_revision_view_page.php?bugnote_id=17906#r10735
2017-06-25 13:43Torr SamahoAssigned To => Torr Samaho
2017-06-25 13:43Torr SamahoStatusnew => needs testing
2017-06-25 13:43Torr SamahoTarget Version => 3.0
2017-06-30 23:04Ru5tK1ngNote Added: 0017955
2017-06-30 23:04Ru5tK1ngStatusneeds testing => resolved
2017-06-30 23:04Ru5tK1ngResolutionopen => fixed
2017-06-30 23:04Ru5tK1ngFixed in Version => 3.0
2018-09-30 21:43Blzut3Statusresolved => closed

Notes
(0017178)
Blews   
2017-04-17 19:16   
Seems to be a problem only with TSPG's build
(0017184)
mifu   
2017-04-18 00:17   
(edited on: 2017-04-18 00:20)
Updating ticket as I was helping Blews out. It turns out that sv_maxpacketsize being set to 2048 by default is what has caused this.

It seems multiple people are having issues with connecting to any 3.0 server (stock build or the tspg modified build) if sv_maxpacketsize is set to 2048. I understand this is the default now but it seems to be causing issues.

It does not matter which mod it is either. It could be doom2.wad only and this issue occurs.

EDIT: Setting my servers to use sv_maxpacketsize 1024 has fixed this issue for these users.
(0017187)
AlexMax   
2017-04-18 00:54   
Is sv_maxpacketsize the maximum size of a server-transmitted UDP packet? If so, I think I know what's going on.

The UDP protocol allows you to send packets that are 65k large. However, Ethernet's maximum packet size is usually set to around 1500, and packets larger than that will be fragmented, sent in pieces, and reassembled on the other end. If any one of those fragmented packets is lost for any reason, the entire packet is discarded.

That is how things work under ideal circumstances. In reality, UDP is not treated very well by the wider internet, and sometimes fragmented UDP packets simply get blocked wholesale, or cause other undesirable behavior with poorly-programmed hardware. Fragmentation and reassembly also imposes additional latency, though I'm unsure if such latency is noticeable.

If that setting is what I think it is (and it might not be, so take my advice with a grain of salt), I think the proper solution is to bring down the maximum packet size to 1400 or so for now.

Ideally, Zandronum would have some sort of MTU negotiation, where the client and server would send each other packets of specific lengths to test how big of a packet the connection can handle, and how much latency each size introduces.
(0017188)
WaTaKiD   
2017-04-18 01:11   
(edited on: 2017-04-18 01:19)
i could be mistaken, but i believe sv_maxpacketsize was increased in 'https://bitbucket.org/Torr_Samaho/zandronum/commits/0de25ccf820e6235569403e429d738383eb123d6 [^]' for 'http://zandronum.com/tracker/view.php?id=1469 [^]'

EDIT: well i guess i am mistaken, i just tried a fresh ini and sv_maxpacketsize is 1024
(0017194)
Cutman   
2017-04-18 12:18   
Two other users are effected by this, but not on connection. They can join the game but they get stuck inside the end game results screen and have to quit the game and rejoin to get back in (making most modes unplayable).
(0017196)
Torr Samaho   
2017-04-18 17:53   
sv_maxpacketsize intentionally defaults to 1024. We did some experiments with higher values years ago and it only caused problems. Unless you know exactly what you are doing, you shouldn't touch sv_maxpacketsize.

Some time ago, I increased the internal parameter PACKET_BUFFER_SIZE from 1024 to 2048, but this is unrelated to sv_maxpacketsize. WaTaKiD, I think this is what you remembered.

So, are there still any issues if sv_maxpacketsize is kept at its default value 1024? From the notes above it sounds to me as if this fixes the problems.
(0017898)
Blews   
2017-06-24 15:35   
As of the v5b update of MM8BDM, I can't seem to join servers anymore, I'm presented with the same issue of repeating "Requesting Snapshot..."s , however my PDAnet doesn't disconnect anymore unlike the previous issue.

This has been tried on both zandronum 3.0 r170416-0710 and r170618-1927 alpha releases
(0017906)
Torr Samaho   
2017-06-25 13:29   
(edited on: 2017-06-25 13:43)
0003132:0017903 hopefully also takes care of this issue. Please check if this fixes the issue.
(0017955)
Ru5tK1ng   
2017-06-30 23:04   
Confirmed with ticket author that the issue is now resolved.