Slow network

[MattDLEA]

Does anyone have a dummies guide to trouble shooting a slow network?

 

I have ran Speedtest from a few pcs and the server and am getting ping 72 Download 1.93mbps Upload 1.65mbps we are on a 8mb Connection.

 

Is there a way to test internal speed between pc and server? LANSpeedTest?

 

Or could it just be the amount of stuff we now have hanging off the network.

1 Server

12 wifi AP

70+Pc

250 ipads

plus printers, photocopiers etc.

[witch]

Have you run the test from the point at which it enters the building? That'll rule out your PCs and server if it is still very slow

[MattDLEA]

BT wire it up to a cisco router this has 4 output ports but only one is active. This plugs into our switch then we go from there.

How would you test this, is it a case of unplugging the cable from the switch and then plugging directly into a laptop, or is there a way of doing it with out taking out the network?

[win]

I use this for testing local network speeds. Free and easy:

 

totusoft

 

Install it on your local PC and it will send a file to your server and measure the speed.

Edited September 24, 2014 by win

[Arcath]

BT wire it up to a cisco router this has 4 output ports but only one is active. This plugs into our switch then we go from there.

How would you test this, is it a case of unplugging the cable from the switch and then plugging directly into a laptop, or is there a way of doing it with out taking out the network?

 

Is this BT Lancashire Services? Because Ports 1-9 on the cisco are curriculum, 10 is for the Cachepilot (redundant now) and 11-14 is Admin with 24 for uplink to county

[MattDLEA]

Nope Northern Grid For Learning

[MattDLEA]

Just tested Lan with that software

My Pc not on ranger or domain 88.91 mbps to server both up and download and 91mbps to our NAS both up and download

PC in It suite on domain 79mbps upload 91mbps download to server 419mbps to NAS upload and 598mbps download.

 

What that mean

[witch]

I think you do need to take out the network and check what is coming in. Even checking after the switch and before the server would help

[MattDLEA]

Ok with just the server plugged straight into the router i get ping 8ms download 9.65 upload 8.32

Just plugged everything back in and pings of around 58ms download 3.07 uploads 1.53

[hallb15]

Just tested Lan with that software

My Pc not on ranger or domain 88.91 mbps to server both up and download and 91mbps to our NAS both up and download

PC in It suite on domain 79mbps upload 91mbps download to server 419mbps to NAS upload and 598mbps download.

 

What that mean

 

That means your PC is only on a 100Mbit connection to the server and NAS, whereas the PC in the ICT Suite has a 100MBit connection to the server, but a GBit connection to the NAS box. That sounds like a strange setup to me so I think you need to start checking your switches to see what spec they are.

In a small school you can still get away with 100MBit but realistically GBit should be the minimum these days.

 

Perhaps you could draw a simple network map to help identify where you might be getting bottlenecks.

[abillybob]

I just open task manager and go to the networking tab, if it says you have 1gbps ethernet connection for example by the side of it it will tell you real time how much of that 1gbps is being used and then you can work out how fast it is going but obviously remember to make the computer perform a task requesting the server, so put flash player offline installer on your server and open and install it on this machine. It will give an indication of how fast it's actually working at.

 

It sounds as if you're using a CAT5 cable rather than a CAT5E or 6. Some CAT 5 cables are only 100mbps where as the other too are normally standard 1gbps!

[IrritableTech]

If speed is slower on your network than when you're directly connected it probably will be one of two things. Contention - ie. more devices all trying to use the net at the same time, or noise. If some of your devices are causing lots of broadcast traffic, this will result in the increase in ping and therefore slow down speeds.

 

Fire up wireshark. I'd guess you might see lots of 'where is xxx tell yyy'.

 

If you need help interpreting the results of a wireshark scan - post some of the data here.

 

Have you spoken with Northern Grid? Their router may already be showing signs of your issue if you can get them to have a look.

[MattDLEA]

@abillybob Just looked at network connection tab on both the server and my pc they were both 100mbps.

In this rack I have 2 switches one a procurve 2810-24G (J9021A) that all ports are running at 1000mbps according to the lights.

The second switch is a HPprocurve 2650 j4899b which only has a few connections which included the server and my pc, moving server and pc to the other switch turned them in to 1Gbps connections.

Looking at the 2650 switch the lights are flashing to indicate its only running at 100mbps. So need to see how to get that to change to 1000mbps if possible and also check other connections.

@IrritableTech I emailed northerngrid they said contact BT who would do a test on the line.

Where would you install wireshark, pc or server? how long should i run it for and can i pm you the logs?

 

Cheers

[IrritableTech]

Wireshark can go on either really - I'd tend to use it on a client personally. I can take a quick look at the logs if you PM me.

 

I'd put the potential network configuration issues to one side for a while until you work out why your internet only runs at 25% when your devices are connected.

[MattRVBC]

Slightly confused here, speedtest.net will show you internet speeds from the gateway and the selected speed test server. IF it is your network generally that is running slow then i suggest performing some test internally to see where the issues are. Test your ping repose times from various places and see what response times you are getting back, if these are quite high then investigate using a packet sniffer (https://www.wireshark.org/download.html) to see what traffic is present.

 

If your running on a single subnet then there is a possibility of allot of broadcast traffic or even a broadcast storm, again use the above packet sniffer will tell you what traffic is is in transport.

 

Hope this helps

 

Matt

[MattDLEA]

Im getting confused now. @MattRVBC how do you mean ping different areas? like log on differnt computers around school and ping the server or ping bbc.co.uk etc?

 

Why would the speedtest be fast when its just the run from the server connected to the router 9mbps but when everything is connected it drops to 1-2mbps

[MattDLEA]

Ok pinged from various pcs around school all on different switches

 

PC1 -> Server <1ms TTL128 ->gateway >1ms TTL255 ->bbc.co.uk 13ms TTL48

PC2 -> Server <1ms TTL128 ->gateway <1ms TTL255 ->bbc.co.uk 13ms TTL48 first ping to server and gateway all 4 packets were lost but on all other pings reported fine

PC3 -> Server <1ms TTL128 ->gateway <1ms TTL255 ->bbc.co.uk 13ms TTL49

 

Does that mean anything to anyone

[MattRVBC]

OK, for example ping from a host to a server in a certain area (via a switch or router) to determine what response times you are getting from the ICMP request. Do the same test on another host passing traffic via a different switch\router and compare the response times. If one is higher than the other then this would suggest an issue with a switch or router. If both repose times are pretty high and your certain our are passing traffic through different switches\routers then I will look into performing some packet sniffing using wire shark to identify what tyope of traffic is swamping your network. IF you are a VLAN site then perform the same test on the various VLANS and compare the results.

 

You can ping external sites (BBC - Homepage) although is suspect that there will be some proxy server, filtering system or load balancing in place which may have an effect on the results.

 

Other possible causes could be a high amount of broadcast traffic or even a broadcast storm which is putting heavy load on your network. Wireshark will identify this for you if this is the case.

[njc235]

The 2650 is only a 10/100 switch.