Slow Internet

[sippo]

We have a dedicated 100mb leased line, with in-house smoothwall.

 

I have been told that the internet has been really slow since September. No-one ever brought it up before.

 

I am going to restart our webfiltering, but is there anything that could 'slow' the web down? It's fine if the proxy is bypassed. The proxy is configured via log on script.

[speckytecky]

Your set up sounds far superior to our Fiber To The Cabinet here in Devizes @sippo but we went over to that in September as well and ever since (despite speedtests showing circa 10.00 mbps upload and download on our previous set up to just under 40.00 mbps download and a widely fluctuating upload of below 2.00 to just under 10.00 mbps) I have been having teaching staff complaining that such things as BBC Clips is now unreliable - playing ok sometimes then at others stalling. SWGfL are investigating with the Provider (TalkTalk) and tell me they think they have a solution that should give me happy teachers by the end of the week.

[sippo]

We're 'independent' on schools broadband but I think its more do with our smoothie...if it is bypassed the web is fine.

[jinnantonnixx]

Bufferbloat could be a cause. In a nutshell it's caused by large switch memory buffers allowing high speed, filling up, then throttling the network to zero. Rinse and repeat. It's normal behaviour for the TCP protocol (i.e. drop packets and slow down transmissions), but when you have several segments the buffer problem can be noticeable.

 

You'll see great download speeds, but terrible general browsing speeds.

 

The criminal mastermind: bufferbloat! | jg's Ramblings

 

As a check, are you able to bypass some network segments and plug in near the front of the firewall/cache?

 

http://www.squidworks.net/2013/04/buffer-bloat-a-minis-to-the-tcp-protocol/

Edited December 11, 2013 by jinnantonnixx

[sippo]

Is there anything I can do to reduce this or see if it is having an effect? We are all HP procurves.

[jinnantonnixx]

The simple test is to reduce the buffer size on the switches and see what happens. I'm assuming this is possible, it's been a while since I was involved in hardware support.

 

(More background)

HP Blogs - What you need to know about data center switching ... - The HP Blog Hub

Edited December 11, 2013 by jinnantonnixx

[jinnantonnixx]

Oh another thing - check your DNS is up to scratch. Busy pages cause tons of DNS lookups and a struggling DNS server will really hamper things.

Is Smoothwall configured to use the same DNS servers in the same order (if you have multiple DNS)

 

 

--

 

 

A good test is Firebug for Firefox. This is excellent in showing you where the bottlenecks are (from the workstation point of view) and if you have DNS timeouts.

https://getfirebug.com/network

Edited December 11, 2013 by jinnantonnixx

[cpjitservices]

MTU Size, by default I think its 1518 - change it to 2000 and see if that helps.

[sippo]

MTU size?

[cpjitservices]

The maximum packet size that can be passed onwards to other devices, We had a problem with a 100 Meg DIA, turned out it was flow control and MTU size, altered the MTU size to higher and got whopping speeds.

[sippo]

How do I check/change this?

 

Edit: Don't worry I have found it. Thanks!

Edited December 11, 2013 by sippo

[lmgtfy]

Do you have Smoothwall intercepting HTTPS traffic?

[cpjitservices]

@sippo - only change the MTU size on the interface of your fiber.

[sippo]

I changed it on the ports used in the smoothwall. Is that bad?!

[cpjitservices]

Has it made a difference ?

 

You only need to change it on the port where your fiber is connected... Ethernet doesn't support any MTU size over 1500. It may not help. Im sure some Smoothwall experts on here would advise you.

[sippo]

Yeah it has made a difference on testing, but have obviously asked the staff to test - probably won't hear anything as it took them 3 months to mention that the internet was slow in the first place!

 

Thanks for your help.

[john]

Would maybe suggest raising a case with Smoothwall to get it checked your load could be high on your box which will slow it down a bit if it was high etc...

[sippo]

I have called raised with them as well. I actually did that first but 'you lot' helped me quicker!