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Experimenting with network topology and throughput.


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#1
I am running a new router in my home now. A Celeron 3865U mini PC with 6 ports. I'm not sure if a Celeron is capable of switching gigabit speeds, so tested it out with the iPerf benchmark tool.

So what iperf is doing is really testing the maximum transfer speed (upload or download) of your network. You need a computer running iPerf in server mode (in my case the router), and then run clients at various computers to test the speed.

This is the results of running iPerf in one of the development machines.
Code:
Client connecting to 10.x.x.x, TCP port 5001
TCP window size:  325 KByte (default)
------------------------------------------------------------
[  3] local 10.x.x.x port 42884 connected with 10.x.x.x port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  1.15 GBytes   987 Mbits/sec

987 Mbits, not too bad. Good to know I'm wrong. Celeron is capable of maxing out a gigabit network.

Next, I try this from my NAS.
Code:
[  3] local 10.x.x.x port 33607 connected with 10.x.x.x port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  1014 MBytes   851 Mbits/sec

Not as quick, but still acceptable. Kind of expected because this NAS is running on HP N54L, and I believe it's using Marvel  NIC. This network card is slower than Intel (and consume more power).

And this is the throughput from my primary music player (running Snakeoil of course):
Code:
[  3] local 10.x.x.x port 58196 connected with 10.x.x.x port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   625 MBytes   524 Mbits/sec

524 Mbit/s. This is expected because I am using a PCI network card, PCI maxes out at 533 Mbit/s. So I'm already very close to the limit. Besides USB is 480 Mbits/s so this is OK.

Finally, I run this on the Raspberry Pi 3... And what an appaling result!!
Code:
[  3] local 10.x.x.x port 35116 connected with 10.x.x.x port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   338 MBytes   284 Mbits/sec

284 Mbits/s! Did I got that right?

A quick google couldn't tell me anything conclusive. But it does appear network is a bottle neck with these Pis. As good as they are, there are restrictions when it's a SoC.

USB 2.0 max out at 480 Mbits/s  anyway, so I reckon even at this speed the Pi should be able to handle high res or DSD relatively well. But there's not much room for error here.

ODroids, Banana Pis can sustain higher throughputs. They are also more expensive.

Anyway, why the new router? I am finally going to bite the bullet and seggerate everything in my network into it's own VLAN. Not entirely sure what that'd do, so watch this space.
Snakeoil Operating System - Music, your way!
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#2
So before we begin, let's introduce the hardware:

This is the new router:
   
Purchased off Aliexpress. It took about a month to deliver to Perth.

Here's the unit, plus:
  • 2x 8GB of 2133 MHz RAM puchased locally
  • Reused an old 500 GB HDD I have lying around somewhere
   

Here's a look of the insides. This is the base of the unit. Behind this board sits the CPU, and that's attached to the top of the case, where all the heat sink fins are. The picture doesn't give you a scale of how small and compact this unit is. The machining is done to millimeter perfection! There is no gap for me to pry the bottom cover off. I have to remove one of the sides so I can remove the top.
   

And here it is with RAM and HDD fitted. This should give you a scale of how compact this unit unit is.
   

Last but not least, my network is now broken up into:
   

So what is a VLAN? It stands for Virtual Local Area Network. In a network switch, all computers have the capability to talk to any other computer on this same switch. A virtual LAN is like inception, it creates another switch inside this switch (hence the word virtual), and computers can only talk to another computer if they are on the same virtual switch.

So in the above example, computers in "DEV" can only see other computers in "DEV". If there is a need to talk to computers outside the virtual switch, they need to go through the router.

In this setup, I have broken down the network communications logically, this in turn prevents a lot of unnecessary suprious network traffic on the network. The theory is, the overheads of VLAN will outweigh the constant traffic noise that is bombaring all the ports on the network. 

So if I design this right, the "Music" VLAN will be where my music server and players are. It can still communicate with any computer on the other VLAN, but it will no longer see the unnecessary broadcast messages (This is the noise I am referring to).

For this to work, the router has to be extrememly fast, and be capable of receiving and forwardinig packets at a moment's notice. Hence the choice of the Minisys router. It has 6 network ports. 1 is connected to the Internet, 4 goes back to the switch (This is called LAGG).

Don't worry if you don't understand any of the above. Big Grin

The unit is powered off a 12 V SMPS. Not ideal for sound quality, so it'd be something I'd look at addressing in the future.

For folks who are interested in specs, here's the router specifications:
   

There are faster versions - fanless i5 and even an i7 in a different case. But a router is designed to run 24x7. Figures a Celeron will be better for the environment.

My only worry was it is incapable of switching at the maximum speed. For now that seems to be OK. I doubt the Celeron can do full 6 ports at 1 gbps, but that is not a requirement for me.

My quick tests have showed me, not all network chips are built the same. Some chips are just faster than the others. The fastest chips so far are still made from Intel.

I don't  use any audiophile network cables in my setup at all. But in the future if I get a chance to try them out, will be interested to see the iPerf results Big Grin .. My guess is they'd be the same in terms of throughput.
Snakeoil Operating System - Music, your way!
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#3
Been busy lately so havn't had the time to sit down for a proper audition.. But did managed to sneak in a couple hours last night and on Sunday...

I havn't totally isolated the NAS with my CAP yet, but removed enough of the other machines off to their own VLANs and thought that should make a good difference.

So what's my first impressions? Not so good unfortuantely..

[Image: bad_atmosphere.gif]

Not entirely sure what is happening, just do not feel that engaged with the music with this new setup now. The music is boring and lifeless...

This is weird because technically the packets are transferred local to the switch, and not to the router. So everything should be the same as before - with the exception of less spurious network traffic and more VLANs..

More VLANs. Maybe I should stick to just 2 VLANs - one for music, and one for everything else, instead of trying to be too clever and seperate out everything. :shrug: D'oh.

Will continue to try different things over the next few days and see how it goes.
Snakeoil Operating System - Music, your way!
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