[EdLUG] Diagnosing a slow Internet problem

[Edinburgh Linux Users Group]

Christian,

On 06/24/16 02:01:19, Edinburgh Linux Users Group wrote:
> Hi,
> 
> Here are my questions:
> 
>    1. Why did my speed tests fail in this situation?
>    2. Are the ping speeds normal for this situation?
>    3. What diagnostic tests can I run to isolate the slowness on this
>    system?

[snip]

> Since I couldn't run speedtest, I pinged google instead.  Here are the
> results from the lobby:
> 
> cje at cje-ultralap440:~$ ping www.google.com
> 
> PING www.google.com (216.58.192.4) 56(84) bytes of data.
> 
> 64 bytes from nuq04s29-in-f4.1e100.net (216.58.192.4): icmp_seq=1
> ttl=52
> time=8.24 ms
> 
> 64 bytes from nuq04s29-in-f4.1e100.net (216.58.192.4): icmp_seq=2
> ttl=52
> time=7.31 ms
> <snip>
> 
> --- www.google.com ping statistics ---
> 
> 16 packets transmitted, 12 received, 25% packet loss, time 15037ms
> 
> rtt min/avg/max/mdev = 6.962/7.497/8.198/0.366 ms
> 

The round trip times show your network latency but say nothing about speed.
They are good going on excellent.

25% packet loss is a very bad thing.  It means that 25% of your network traffic
is being transmitted twice to fix errors.

ifconfig or iwconfig, if wireless is involved may point to a source os the errors.

ifconfig shows
        RX packets 272685  bytes 338439675 (322.7 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 167065  bytes 17145073 (16.3 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

I don't have iwtools installed to show an example of that.

> Here is the test from the basement:
> 
> cje at cje-ultralap440:~$ ping www.google.com
> 
> PING www.google.com (216.58.192.4) 56(84) bytes of data.
> 
> 64 bytes from nuq04s29-in-f4.1e100.net (216.58.192.4): icmp_seq=1
> ttl=52
> time=8.24 ms
> 
> 64 bytes from nuq04s29-in-f4.1e100.net (216.58.192.4): icmp_seq=2
> ttl=52
> time=7.31 ms
> <snip>
> 
> --- www.google.com ping statistics ---
> 
> 11 packets transmitted, 11 received, 0% packet loss, time 10015ms
> 
> rtt min/avg/max/mdev = 7.022/7.816/8.519/0.451 ms

No dropped packets, so this looks OK.

You don't need a speed test site to test your dowmload speed.
A wget of a large file from a good server will do nicely.

e.g. wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.6.2.tar.xz
linux-4.6.2.tar.xz   60%[===========>        ]  51.68M  1.14MB/s    eta 26s

There is no need to wget the entire file.
Press Ctl-C when the speed stabises.  Here 1.14MB/s
Thats bytes/sec, multiply by 10 to get bits/sec to factor in the TCP overhead.
Thus your 2Mbit/sec downlink should get you about 200kB/sec, 
provided nobody else is using it.


> 
> cje at cje-ultralap440:~$
> 
> *My second question*: Are these ping speeds normal?
> 
> My third question: What can I do to find the problem with the system?
> 
> Thanks!
> 
> 
> 
> 
> -- 
> Christian Einfeldt
> 

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