Please help with some suggestions with this topology. this topology will be installed in one room (the lab of the computer) with 2 different networks (2 networks), each of network there is provided Rachel, each network will provide 20 users. Do you any ideas?
If you have no issue with power you could consider a synology server. Any model with a + on the end should do.
Hi @inamusu.martins – with this setup, it’s probably not necessary to have a second RACHEL, at least right away. The user limitation on RACHEL-Plus is mostly around the WiFi signal. Since many of your devices are wired, and only some are WiFi, I think one unit would be fine.
At some point, if you have heavy usage, you may want to add a second RACHEL or you can build RACHEL on a more powerful machine. For the most part though, I think one RACHEL would be fine with ~20 devices accessing over the LAN and 15-20 devices accessing over WiFi.
This was my response to an email I received regarding this configuration.
Yes. The configuration you’re proposing will work brilliantly, provided you make the following configurations to the router & to your RACHELs.
Configure RACHEL on the right to use the wireless IP address of 192.168.88.1, which is the default. Configure its Ethernet interface to use a static IP address of 192.168.1.2.
Configure RACHEL on the left to use the wireless IP address of 192.168.89.1. Configure its Ethernet interface to use a static IP address of 192.168.1.3.
Configure the router to use 192.168.1.1 as the address. Set DHCP to start addressing at 192.168.1.11 (this allows you to create 10 static IP addresses in case you grow in the future). Create two static routes in the router (see the directions I provided previously). To reach 192.168.88.0/24 use 192.168.1.2. To reach 192.168.89.0/24 use 192.168.1.3.
When you log in from a wired station on the right you will need to point your browser at 192.168.1.2. When you log in from a wireless station on the right you will need to point your browser at 192.168.88.1.
When you log in from a wired station on the left you will need to point your browser at 192.168.1.3. When you log in from a wireless station on the left you will need to point your browser at 192.168.89.1.
Two questions in regards to your answer.
How many simultaneous users do you feel RACHEL Plus V3 can support via both wired & wireless?
What do you recommend someone to use to “build RACHEL on a more powerful machine”? It was my understanding that RACHEL does not work on a Windows Server (other than in stand-alone mode) & I didn’t think there was a “supported” Linux Server version of RACHEL either.
Hi @LarryY –
In response to your questions.
- It truly still depends on the use case. If you are not using this to have simultaneous users running Kolibri or KA-Lite, I think 20 users over ether and 15 users over WiFi is a good maximum.
If you are using this in a setting where you say “go” and have 10-12 users hit play all at the exact same time on some videos, you’re going to push the system too hard.
For most settings, where this is used as a research resource, the access is short and minimal requests for a wikipedia page, and then a user reads that page for a while, before requesting the server again.
- Correct, RACHEL does not work on a Windows Server. If someone is technical enough, they can install RACHEL on other operating systems like Ubuntu and Raspbian or Synology. In fact, volunteers here do a wonderful job of keeping up installation advice on those operating systems.
We (the two person World Possible team) can’t possibly support them all. We limit our support to doing as good a job we can on the one or two platforms we support while leaving us enough time to run a field staff of 10 and ship out products / fundraise. In theory, even Windows is possible, it’s just that someone has to develop a process to install all the components.
thank you dear Larry for great material.
Dear Jeremy, this topology for 40 users, that the reason i use 2 Rachel.
Yes, that would be a good topology @inamusu.martins
Thanks for this @LarryY – why would the second RACHEL need to change its WiFi IP address to 192.168.89.1?
Hi Jeremy. I thought someone might ask. Of course you don’t have to change the IP address, but if you want to balance the Wi-Fi load manually (which I thought they wanted to do) you can balance it by providing 2 different IP addresses. You might also want to change the SSID while you’re at it to RACHEL1 & RACHEL2, which I think would do the same thing, but I don’t like duplicate IP addresses. They can be problematic, especially if they overlap in coverage.
Thanks, I guess if you didn’t change the SSID I think you would have lots of potential issues. A user would never know which RACHEL they are connected to. If you connect to the RACHEL signal of RACHEL A, but browse to 192.168.89.1 I don’t think you would reach the homepage of RACHEL B. (I’m just speculating and asking for my own knowledge on all of this).
If you connected to the RACHEL signal and were in fact on RACHEL B’s signal, I don’t think you could browse to 192.168.88.1 and access RACHEL A.
I also think that even if you could, you wouldn’t necessarily be balancing the WiFi throughput at all. All 30 devices may connect to RACHEL A’s RACHEL signal even if you browse to the different homepages, I don’t think you would be doing anything the lessen the WiFi throughput of RACHEL A.
I think the only way to do this is to have the SSID changed on the two devices and at that point, I don’t know if there is any benefit to changing the 192.168.88.1 or not.
Would you agree with any of my speculation?
I agree that the SSIDs should be changed to ensure you’re load balancing. You probably can get away without changing the RACHEL IP addresses, but I would still prefer to change them just to keep everything clean.
Since I don’t know how to create a static route on RACHEL, I suspect you are correct when you say that RACHEL B would not know how to reach 192.168.88.1.
I’m not entirely sure about with RACHEL-Plus devices but you will probably want to change the wifi channel for each RACHEL device as well if they’re both using the same 2.4ghz range and not one with 5GHZ. If you set one to channel 1 and the other to 6 or 11 it should avoid interference from each other.
Another setting to look at is adding max_num_sta=20 in /etc/hostapd/hostapd.conf. This limits the connected devices to the hotspot so in this case 20. If you set this you can also add ap_max_inactivity=300 which will check if the devices connected are inactive and disconnect/deauthenticate them after 300 seconds which is 5 minutes. With that enabled you won’t have those 20 users used up and associated for too long while they may not be using the connection anymore. You can adjust that higher to something like 30 minutes.
Something I thought would be useful but couldn’t find an answer for is a way to tell users when a hotspot is full other than restarting the hotspot after changing the SSID to RACHEL-FULL or something with a script. I have tried to change the SSID without restarting using “sudo hostapd_cli --reload” after changing the SSID in hostapd.conf and it doesn’t seem to work with the Raspberry Pi. If anyone does want to experiment with this, you have to add “ctrl_interface=/var/run/hostapd” and “ctrl_interface_group=0” to hotapd.conf for hostapd_cli commands to work ( at least on the pi ).
On the topic of installers for Linux/Windows, it can be done but it takes a lot to maintain and a Windows installer would take a lot of time as it would be a completely different process. I recently made an Ubuntu Local installer for users on here and it’s on the FTP. It’s meant for offline use installed to each laptop, so it doesn’t create a wifi hotspot or provide IP addresses but does provide RACHEL so if you install it to a PC and connect it to a network users can access it by going to it’s IP address. I will get around to a better full Ubuntu installer but I ran into issues with configuring hostapd with my USB wifi device and driver settings. I suspect that is hard to plan around for an installer. I work on installers when people ask, but I focus on other things if it’s not immediately needed.
Hi James, @jamesk, have I read this right, you have setup RACHEL on a laptop? That is something I would be very interested in. Could you point me in the right direction please.
I posted it here for the people at the Austin Housing Authority who wanted to install RACHEL to laptops without making a hotspot or having other users connect to it. It should install on anything running that version of Ubuntu unless something has changed since then. Since it’s running a server with apache, if this is installed and connected to a network RACHEL will be available by accessing the IP address assigned to the device.
Thanks James. Thanks I’ll give this a try.