# [Solved] Does anyone have trouble using Tumblr?

## ZHQ

Hehe, another question guys.

I've been trying to figure out why I can't make posts to my Tumblr. If I type in a text post with more than a paragraph or try to upload even a small picture (54 kb)/url, my post won't "go through".

It uploads to a certain percentage usually and then just sits there with the loading cursor. After a while, it'll display some sort of error message (I'm using chrome, so it'll default to a page not found or something.)

My wireless is working fine when I connect manually using iwconfig. I set the rate to be 54 Mb/s and as you can see, I can post here just fine. I can even watch youtube videos! Do you think this is a problem on Tumblr's end or does anyone else have this problem?

Thanks again!

EDIT: By the way, this problem affects not only Tumblr, but any other site that requires data heavy connections. These sites probably all transfer data in similar fashion (I haven't figured out what those characteristics are, but you should be able to tell by the fact it's not loading properly).Last edited by ZHQ on Tue Jun 28, 2011 8:39 am; edited 1 time in total

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## BradN

What web browser/version, any plugins in use?  Can you test from another machine on your connection?

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## ZHQ

Haha, oh yeah. Sorry...

I'm using Chromium. A recent build (I installed it about a week or two ago). I noticed on Windows, the internet speed seems to be faster (for the same network). I have to reboot into Windows to post, which is successful. I use Chrome. I'm sure this is the same for any network I use. I've tried it with my local library's wireless network [I get timeout in linux, but it works in windows] and at work, etc...

I don't know if it helps, but I noticed that when uploading text, it will say "Uploading: 0%" and then when it stalls, it says "waiting for http://www.tumblr.com..". The same thing happens for a photo upload but it will get to an arbitrary number (usually 20%) before stalling.

Thanks for the reply!

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## cach0rr0

check ifconfig -v

what does it show for your MTU?

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## BradN

Oooh, good call, hadn't thought about the MTU.  Also check the MTU in windows (not sure if it shows on ipconfig or not but there should be a way), and see if it's the same as linux has.  If needed, you can lower linux's MTU with ifconfig for testing - example:

ifconfig eth0 mtu 400

A MTU of 500 should work 100% on any connection I've ever seen, including dial-up, but it will increase overhead a lot.  You can always experiment and find what the largest value that works is.  1500 is a normal ethernet MTU but some routing systems have other limitations or overhead that subtract from that maximum size.  Some ethernet networks actually allow larger MTU's (usually up to 9000 or so) that can reduce overhead on large data transfers, but such "jumbo packets" usually can't traverse the internet in general.

Edit:  Did a little checking, and if you're going through PPPOE, you may need to set the MTU to 1492 to account for an 8 byte packet header that gets added.  I tried looking for ways to view the current MTU in windows and couldn't find anything, but there are various ways to change the MTU, varying per OS version.

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## Hu

Windows does not expose the MTU very readily, but there are a few ways to find it.  The most reliable way is to use ping -f -l $candidate_MTU for various candidates until you find the largest number that does not trigger fragmentation.  This number will be slightly smaller than the actual MTU, since ping adds some extra bytes beyond the value you specified.  In my testing, ping seemed to add 28 bytes of control information (IP headers, etc.).

Supposedly, some versions of Windows also store the MTU in the registry, but I did not find that to be the case for the system I checked.

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## ZHQ

Okay...

On linux, ifconfig -v shows my MTU for wlan0 as 1500. On windows, I found that the maximum packet size was 1464 before it started telling me the packets needed to be fragmented.

I'm going to try and change the MTU on gentoo to 1464 and see what happens. Also, one question: If this is an MTU problem, does this mean I have to calibrate my MTU if I use a different wireless network? For example, if I go to the library after I solve this issue (hypothetically), is it possible that I will have the same problem, because I need to change my MTU to yet another value specifically for the library network?

Thanks guys. I actually didn't expect anyone to reply to such a vague question, but you've really been helpful.  :Very Happy: 

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## BradN

From what you posted, 1492 is the correct setting.  1464 will work but it won't be quite as efficient.  This is apparently because their connection is through DSL using PPPOE - most other types of internet connections don't have a restriction like that, and maybe their router's DHCP server isn't reporting the max MTU in a normal way.  I would suspect that normally the MTU is configured over DHCP like the rest of the connection parameters.

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## ZHQ

Yep. I changed to 1460 and it works now. It is most likely as you guys say (makes sense to me!). Consequently, 1492 also works and is probably faster. I can't really tell without doing some measuring.

You guys are amazing! Thank you very much!

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