Internet Access - Buggy

[bodminman]

Good morning all,

 

since the beginning of last week we have had an issue with browsing the web. Basically, if I open IE, Chrome or Firefox and try going to the BBC weather peage, firstly nothing happens for approx 3 seconds and then it can take another 3-5 seconds to finish loading. This used to be as quick as clicking your fingers!

 

Performance of other things across the LAN appear to be fine. ie access to shared resourses and the Terminal Server are all working sweet without any delays or errors etc.

 

We have a 20mb leased line and looking at the stats on both the Lightspeed box and those that we receive from BT, we're pretty much cruising at 19mb on the download side of things. To be honest we have been cruising at 19mb during term time for about 18 months since the number of boarders etc has increased but it has never caused us any issues.

 

We use Lightspeed that in turn goes through a Sonicwall NSA240. Simple ping tests around the network are all <1ms but when pinging out to say google.co.uk this tends to be between 10ms - 110ms which I know is very silly indeed!

 

I have done a walk around the site which included all the boarders rooms to look for any physical problems but all was well.

 

I have contacted our ISP who have run sone diags and said that all is ok.

 

Anyone got any quick ideas on where to look next?

 

Thanks in anticipation!

 

PS: I have a migraine so please be gentle.

[ReBoot]

Maybe worth checking your DNS performance. My School seemed to suffer a slowdown last week with similar symptoms. I use Google public DNS at my school. If you have access to squid you can get DNS stats for your site. I don't know if you can do this on Smoothwall.

[bodminman]

Thanks @ReBoot. We also use Google's public DNS here. I did swap it over to BT's DNS for a few days to see if anything improved but it didn't.

[ReBoot]

Mine seems back to normal now. A reminder that the internet is a best effort network and performance is not always as predictable as we would like.

 

I run this utility on my proxy server https://pypi.python.org/pypi/speedtest-cli at 2 hour intervals to show the raw internet speed before Squid and Dansguardian. Quite useful if a teacher reports a slow connection at a particular time of day.

[free780]

I thought be practice was to use root hints rather than forwarders.

[jamesfed]

When you run nslookup against a domain do you ever get it timing out? Try some domains that your users might not normally visit (say cheese.com).

 

If they are timing out now and again then its DNS, was recently helping out another school with a similar issue - something weird in their Watchguard firewall was making it such that the response from the DNS server was being dropped as an invalid packet (most odd!). Never managed to fix it but replacing the Watchguard with a Smoothwall Express appliance worked

[slancaster]

When you run nslookup against a domain do you ever get it timing out? Try some domains that your users might not normally visit (say cheese.com).

 

If they are timing out now and again then its DNS, was recently helping out another school with a similar issue - something weird in their Watchguard firewall was making it such that the response from the DNS server was being dropped as an invalid packet (most odd!). Never managed to fix it but replacing the Watchguard with a Smoothwall Express appliance worked

 

Do you have any more info on this post? We may be having the same issue with Watchguard and Smoothwall...

[jamesfed]

Do you have any more info on this post? We may be having the same issue with Watchguard and Smoothwall...

 

I'm afraid I never investigated the issue any further than noticing that the Watchguard was frequently dropping DNS requests; given the school I was doing the work for just needed a basic Firewall that 'just worked' a Smoothwall Express box seemed to do the trick.

[slancaster]

no problem, thanks for getting back to me though.