{"id":53,"date":"2023-12-15T09:34:07","date_gmt":"2023-12-15T09:34:07","guid":{"rendered":"http:\/\/192.168.0.177\/wordpress\/?p=53"},"modified":"2024-01-19T02:22:39","modified_gmt":"2024-01-19T02:22:39","slug":"rpi-nas-part-3-network-connections","status":"publish","type":"post","link":"https:\/\/mpr-projects.com\/index.php\/2023\/12\/15\/rpi-nas-part-3-network-connections\/","title":{"rendered":"RPi NAS: Part 3 Network Connections"},"content":{"rendered":"\n

In the previous post we decided on booting from an SD card. Now we’ll have a look at the speed of different types of network connections.<\/p>\n\n\n

This post is part of a series about building a Network-Attached Storage (NAS) with redundancy using a Raspberry Pi (RPi). See here<\/a> for a list of all posts in this series.<\/p>\n\n\n\n

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When we want to copy data to our NAS we first have to send it via a network from our computer to the Raspberry Pi. The speed of the network will be an upper limit for the overall transfer speed we can expect.<\/p>\n\n\n\n

I’m not considering a direct connection via USB for a few reasons. One is that I know from experience that I’m lazy when it comes to saving data. If I have to get up to grab hard drives from somewhere then I’ll usually postpone it1<\/a><\/sup>. I also don’t want to have potentially noisy hard drives sitting on my desk. Moreover, multiple users in my household should be able to access the drives so a USB-cable-bound storage solution would be inconvenient.<\/p>\n\n\n\n

So let’s have a look at our options for network connections!<\/p>\n\n\n\n

Ethernet<\/h2>\n\n\n\n

There are different Ethernet standards. As I’m writing this 1G Ethernet is widely available. It’s also the fastest standard that’s (natively) supported by the RPi 4b and 5. So let’s connect both the RPi and a computer the a router via Ethernet and test the speed of our connection. For this test we’ll use iperf3<\/em>, which allows us to estimate the maximum achievable bandwidth of a network. On the RPi we run<\/p>\n\n\n\n

iperf3 -s<\/code><\/pre>\n\n\n\n
and on the computer sending the data we run<\/p>\n\n\n\n
iperf3 -c rpi.ip.add.ress<\/code><\/pre>\n\n\n\n
You may have to install iperf3<\/em> first with sudo apt install iperf3<\/em>. The table below shows the results:<\/p>\n\n\n\n
Type of Connection<\/th>Connection Speed
 in bits<\/th>		Connection Speed
 in bytes<\/th><\/tr><\/thead>
Ethernet 1Gb\/s<\/td>941Mb\/s<\/td>~117.5MB\/s<\/td><\/tr><\/tbody><\/table>
Both the RPi and my computer are connected via Ethernet. The results are the average over five separate runs of iperf3<\/em>.<\/figcaption><\/figure>\n\n\n\n
So when it says Gigabit Ethernet then that really means that the physical connection supports transfers of up to 1Gb per second. However, not all of that bandwidth can be used for data transfer. To be able to communicate you need some sort of protocol that establishes and manages the communication (typically that’s TCP). This admin work uses some of the bandwidth. According to this article<\/a> there’s an overhead of approximately 5%, which is roughly what we’re seeing here ((1000-941)\/1000 = 0.059<\/code>).<\/p>\n\n\n\n
\"\"\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button><\/figure>\n\n\n\n
Are you getting slower transfer speeds? The connection is only as fast as the slowest link. So your computer, the cable from your computer to the router, your router and the cable from your router to the RPi (and all other components that you might have in-between) must all support Gigabit Ethernet. For example, it should say at least Cat5e or Cat6 on your Ethernet cable, anything lower and you won’t get the full speed (larger numbers are fine but not necessary).<\/p>\n\n\n\n
WiFi<\/h2>\n\n\n\n
WiFi is messy. There are many different standards and the speeds we will get depend on many factors.<\/p>\n\n\n\n
WiFi 5 Physical Speed<\/h3>\n\n\n\n
The latest and fastest WiFi standard that the RPi 4b (and the RPi 5) supports is WiFi 5 (standard 802.11ac<\/a>). What speeds can we expect to get from WiFi 5 under ideal circumstances?<\/p>\n\n\n\n
The answer is a little involved because it depends on<\/p>\n\n\n\n