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https://github.com/albrechtl/rpi-managed-switch-4-port

An open source 4 port Gigabit managed switch based on a Raspberry Pi
https://github.com/albrechtl/rpi-managed-switch-4-port

Last synced: 6 months ago
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An open source 4 port Gigabit managed switch based on a Raspberry Pi

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# 4-Port Managed Switch



An open-source 4-port gigabit managed switch HAT based on a Raspberry Pi with OpenWrt support.



**Disclaimer:** This is an ongoing project where some features are not working, and some hardware bugs may exist.



![4 Port Managed Switch Front](pictures/switch-front.jpg)



## Features

* 4 Gigabit Ethernet RJ45 ports  

* Supports Raspberry Pi 1–5 (including Raspberry Pi Zero 1–2)  

  - Tested with a Raspberry Pi Zero 1  

  - Raspberry Pi 5 is not working with OpenWrt due to this [issue](https://github.com/openwrt/openwrt/issues/18034)  

* Works with a [custom OpenWrt](https://github.com/AlbrechtL/rpi-managed-switch-openwrt/tree/rpi_managed_switch)  

* Two overlays:  

  1. For Linux [Distributed Switch Architecture (DSA)](https://www.kernel.org/doc/Documentation/networking/dsa/dsa.txt)  

  2. For OpenWrt [swconfig](https://openwrt.org/docs/techref/swconfig)  

* VLAN support

* Switching hardware offloading support 

* Hardware design in KiCad

* Ready for JLCPCB production

  - Using a much as possible basic parts to lower the assembling costs



## Software Status



The hardware works with a modified OpenWrt: https://github.com/AlbrechtL/openwrt/tree/rpi_managed_switch



I added the following to OpenWrt:  

* Two device tree overlays (for swconfig and DSA)  

* Enabled the ENC28J60 driver  

* Added a small patch to enable the ENC28J60 for DSA  

* Added detection of swconfig or DSA in the first boot scripts so that OpenWrt uses the switch  



See the differences:  

https://github.com/openwrt/openwrt/compare/main...AlbrechtL:openwrt:rpi_managed_switch  



To communicate with the RTL8367S switch chip, two different Linux drivers are available:  



**1. Distributed Switch Architecture (DSA)**



Driver: `drivers/net/dsa/realtek/rtl8365mb.c`

* Pros:  

  - Integrated into the Linux kernel  

  - Mainline RTL8367S support  

  - Works on Raspberry Pi OS with a custom Linux kernel

* Cons:

  - Hardware offloading and VLAN support only via patch (see https://github.com/AlbrechtL/openwrt/commit/a1c16e23b97d4cd1c184bd464960a6b93470e16a)

  - There was a discussion on the Linux kernel mailing list about the missing hardware offloading and VLAN support (https://lkml.iu.edu/hypermail/linux/kernel/2407.0/01589.html)

  - OpenWrt driver discussion (https://forum.openwrt.org/t/reduce-number-of-drivers-for-rtl8367s/237681)



Working DSA Example:

```

root@OpenWrt:~# ip addr

1: lo:  mtu 65536 qdisc noqueue state UNKNOWN qlen 1000

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

       valid_lft forever preferred_lft forever

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: eth0:  mtu 1508 qdisc fq_codel state UP qlen 1000

    link/ether b8:27:eb:8f:43:df brd ff:ff:ff:ff:ff:ff

    inet6 fe80::ba27:ebff:fe8f:43df/64 scope link 

       valid_lft forever preferred_lft forever

3: lan1@eth0:  mtu 1500 qdisc noqueue master switch state UP qlen 1000

    link/ether b8:27:eb:8f:43:df brd ff:ff:ff:ff:ff:ff

4: lan2@eth0:  mtu 1500 qdisc noqueue master switch state DOWN qlen 1000

    link/ether b8:27:eb:8f:43:e0 brd ff:ff:ff:ff:ff:ff

5: lan3@eth0:  mtu 1500 qdisc noqueue master switch state DOWN qlen 1000

    link/ether b8:27:eb:8f:43:e1 brd ff:ff:ff:ff:ff:ff

6: lan4@eth0:  mtu 1500 qdisc noqueue master switch state UP qlen 1000

    link/ether b8:27:eb:8f:43:e2 brd ff:ff:ff:ff:ff:ff

7: switch:  mtu 1500 qdisc noqueue state UP qlen 1000

    link/ether b8:27:eb:8f:43:df brd ff:ff:ff:ff:ff:ff

    inet6 fe80::ba27:ebff:fe8f:43df/64 scope link 

       valid_lft forever preferred_lft forever

8: switch.1@switch:  mtu 1500 qdisc noqueue state UP qlen 1000

    link/ether b8:27:eb:8f:43:df brd ff:ff:ff:ff:ff:ff

    inet 192.168.1.1/24 brd 192.168.1.255 scope global switch.1

       valid_lft forever preferred_lft forever

    inet6 fd8d:3fdb:486f::1/60 scope global noprefixroute 

       valid_lft forever preferred_lft forever

    inet6 fe80::ba27:ebff:fe8f:43df/64 scope link 

       valid_lft forever preferred_lft forever

```



OpenWrt DSA screenshot  

![OpenWrt dsa](pictures/openwrt-switch-screenshot-dsa.png)  



**1. OpenWrt swconfig**



Driver: `drivers/net/phy/rtl8367b.c`

* Pros:  

  - Full hardware offloading support  

  - VLAN support  

* Cons:  

  - OpenWrt-specific  

  - OpenWrt is transitioning from swconfig to DSA  



OpenWrt swconfig screenshot  

![OpenWrt swconfig](pictures/openwrt-switch-screenshot.png)  



## Hardware Status



I have two assembled PCBs that have basic functionality. See [issues](https://github.com/AlbrechtL/rpi-managed-switch-4-port/issues) for a list of hardware problems.



**Raspberry Pi Zero**

![4 Port Managed Switch Top](pictures/switch-top.jpg)



**Raspberry Pi 5**

![4 Port Managed Switch Top](pictures/switch-top-rpi5.jpg)



## Performance



I don't have detailed performance measurements yet, but here are some bandwidth indications:  

* **RJ45–RJ45 with DSA (rtl8365mb) and offloading patch:** ~1 Gbit/s (wire speed, full-duplex)   

* **RJ45–RJ45 with DSA (rtl8365mb):** ~2 Mbit/s  

  Currently, the RTL8367S DSA driver doesn't support hardware offloading. As a result, all traffic is routed through the Raspberry Pi and the very slow SPI interface. For a switch, this is not acceptable.  

* **RJ45–RJ45 with OpenWrt swconfig (rtl8367b):** ~1 Gbit/s (wire speed, full-duplex)  

* **Raspberry Pi to RJ45 (CPU port):** ~5 Mbit/s (half-duplex)  

  To support the inexpensive Raspberry Pi Zero, an external SPI Ethernet chip (ENC28J60) is used to connect to the main switch chip (RTL8367S). Due to the slow SPI interface, only ~5 Mbit/s can be achieved. However, for a managed web interface, that's sufficient.  



## Acknowledgements



I would like to thank the following open-source projects. Without these great works, this open-source switch would not be possible:  

* [OpenWrt](https://openwrt.org/)  

* RTL8367S Managed Switch  

  - Blog post: https://blog.brixit.nl/making-a-linux-managed-network-switch/  

  - KiCad: https://github.com/FOSDEM/video/tree/master/hardware/pcbs/switch_board  

* ENC28J60 on a Raspberry Pi Zero  

  - Hackster: https://www.hackster.io/lightside-instruments/the-ethernet4pizero-ethernet-for-raspberry-pi-zero-shield-dd4316  

  - KiCad: https://github.com/lightside-instruments/ethernet4pizero.git  

* [RPI5-CFE-Hat](https://github.com/will127534/RPI5-CFE-Hat)  

* [PCIe3_Hub](https://github.com/will127534/PCIe3_Hub)  

* [RouterPi](https://github.com/ZakKemble/RouterPi)