What exactly is different about steam TCP mode?

[iSnack2.0]

So, with the current login issues that seem to be affecting some people but not others, I can now only login when I launch steam in TCP mode. I never had to do this before.

So I was wondering what exactly is different about TCP mode? I know that it is a different internet protocal to UDP, but other than that I have no idea. Are any features disabled? Does it run slower or something?

[aiusepsi]

There aren't any really significant differences from an end-user perspective. Steam usually defaults to UDP mostly for kinda historical reasons; games use UDP because the TCP protocol adds latency, and Steam ended up using the same protocol as Valve's games.

The only real difference technically is that UDP is connectionless and TCP has connections, so in UDP mode Steam implements connections itself on top of UDP, and with TCP they're built-in. If there's a difference in your ability to login it implies some sort of networking problem between you and Steam that's treating TCP and UDP traffic differently, which is not too unlikely; TCP is a lot more common (HTTP is over TCP, for instance) so you might not ordinarily notice bad handling of UDP datagrams.

[Straws]

....so -tcp makes my ping higher?

[iSnack2.0]

So wait, are you suggesting the current problems are my ISP's fault?

[Lotsa]

Originally posted by Strategy Gamer:

So wait, are you suggesting the current problems are my ISP's fault?

It can't be your ISP, I am having the exact same issues even after trying 3 modems and 2 PC's and checking 2 seperate internet connection, we both live on opposite sides of the world also

It has something to do with Steam and a few other people have had problems also.

[aiusepsi]

Could be a problem really close to Valve's end, or a weird routing problem on any one of the networks in between. I wouldn't really want to speculate as to what's going on.

And no, -tcp doesn't make your ping higher in games because they still use UDP. There's no real technical reason why Steam has to use UDP, they're not really latency sensitive, so using TCP is totally fine. Indeed Steam does use TCP for plenty of things, like downloading app metadata, the store and community pages, game downloads...

[GnomePuncher]

I'm having the same issue, re-installed steam and it only works in -tcp mode. The problem is when I try to play Day of Defeat no servers will respond.

[RulerBrendan]

Originally posted by SirGnomePuncher:

I'm having the same issue, re-installed steam and it only works in -tcp mode. The problem is when I try to play Day of Defeat no servers will respond.

You have that problem too? I can't play any multiplayer games because the servers don't respond. I tried going into the game launch settings and typing -tcp but it didn't help, yet it did let steam run when I used it.

[aiusepsi]

Sounds like your UDP connectivity is screwed up. You'll want to fix that, for lots of very good reasons (chiefly minimising latency) games can't be reconfigured to use TCP instead.

[RulerBrendan]

And how might one do that?

[iSnack2.0]

Originally posted by rulerbrendan:

And how might one do that?

Try waiting a week or so and hoping your ISP will fix it by itself. When I couldn't connect via UDP it was only a temporary issue that only lasted a day or two.

[76561198203293679]

lol

[PUPILUPI]

v

[Seven7]

check router, firewall, restart router, type in command prompt: ipconfig /flushdns
if not helped
https://support.steampowered.com/kb_article.php?ref=8571-GLVN-8711
and testing open ports

-tcp mode is self-testing, self-repair and update mode, you can't play online or buy in this mode - this difference

[RulerBrendan]

Originally posted by Strategy Gamer:

Originally posted by rulerbrendan:

And how might one do that?

Try waiting a week or so and hoping your ISP will fix it by itself. When I couldn't connect via UDP it was only a temporary issue that only lasted a day or two.

Wait a week? TRY 6 MONTHS!!!

Originally posted by Seven7:

check router, firewall, restart router, type in command prompt: ipconfig /flushdns
if not helped
https://support.steampowered.com/kb_article.php?ref=8571-GLVN-8711
and testing open ports

-tcp mode is self-testing, self-repair and update mode, you can't play online or buy in this mode - this difference

I've done a few of those (router, firewall restart router) but the command prompt and the web address I can do! thanks!

[RulerBrendan]

Originally posted by Seven7:

check router, firewall, restart router, type in command prompt: ipconfig /flushdns
if not helped
https://support.steampowered.com/kb_article.php?ref=8571-GLVN-8711
and testing open ports

-tcp mode is self-testing, self-repair and update mode, you can't play online or buy in this mode - this difference

Tried it....didn't work...but thanks for trying! btw, my ip is static, not dynamic. I know that makes a difference.