[CentOS] Weird bandwith behaviour (download throughput) on CentOS based gateway

Tue Oct 10 01:57:56 UTC 2017
Jobst Schmalenbach <jobst at barrett.com.au>

On Mon, Oct 09, 2017 at 03:05:51PM +0200, hw (hw at adminart.net) wrote:
> Jobst Schmalenbach <jobst at barrett.com.au> writes:
> > On Thu, Oct 05, 2017 at 02:57:18PM +1300, Clint Dilks (clintd at scms.waikato.ac.nz) wrote:
> >> On Thu, Oct 5, 2017 at 2:41 PM, Jobst Schmalenbach <jobst at barrett.com.au>
> Is there a dependency on which machine you test first?  Perhaps the file
> has been stored in some cache along the way and for the second test, it
> can be delivered from the cache instead of from the source, which might
> yield higher speeds.

Very good question, answer is no for the following reasons:

 - it happens for all downloads - yum, wget etc
 - I have looked at the interfaces using ngrep, all traffic goes straight out through the closest (as in hops) interface
 - As you raised this I have disabled caching on the command line using wget, still happens
 - As you raised this I have checked whether there are any (environment) options set, none
   I, too, use the same bash scripts on all machines I have

I though about the interfaces, but can't be. The last two interfaces are on the problem machine, but when downloading on the LAN I get a throughput of ~28mbs, only when downloading on the gateway I only get <10mbs.

So still baffled.


Computing power increases as the square of the cost. If you want to do it twice as cheaply, you have to do it four times as fast.

  | |0| |   Jobst Schmalenbach, General Manager
  | | |0|   Barrett & Sales Essentials
  |0|0|0|   +61 3 9533 0000, POBox 277, Caulfield South, 3162, Australia