Limit of 64 Manually Assigned IP around the DHCP list - Workaround for RT-AX92U?

[pgershon]

I am converting my powerline light switches in my house (Insteon) to IP based switches by Shelly and TP-Link/KASA. For the software I use, I need static IP addresses so I can differentiate between lights in the house (I use one switch to dim on turn on/off another). My RT-AX92U has been working fine, but I am pushing the limit of 64. This is not a Merlin router so that workaround from YAZ does not apply. Are there ways I can do this with my existing routers (I like teh current Mesh setup). An inexpensive DHCP server perhaps external to the ASUS devices?

 

[OzarkEdge]

You'll also need a way to restore manually-assigned IP addresses after resetting or replacing the router. Seems like a major hassle by design.

OE

 

[ColinTaylor]

An inexpensive DHCP server perhaps external to the ASUS devices?

This would seem to be the best solution. But I don't know whether there would be issues interacting with AiMesh.

There are free DHCP servers for most platforms, and of course Linux. PiHole also has a DHCP server that allows for static DHCP leases. I've not used that so I don't know if there are any limitations with it.

 

[bbunge]

I am converting my powerline light switches in my house (Insteon) to IP based switches by Shelly and TP-Link/KASA. For the software I use, I need static IP addresses so I can differentiate between lights in the house (I use one switch to dim on turn on/off another). My RT-AX92U has been working fine, but I am pushing the limit of 64. This is not a Merlin router so that workaround from YAZ does not apply. Are there ways I can do this with my existing routers (I like teh current Mesh setup). An inexpensive DHCP server perhaps external to the ASUS devices?

Static IP addresses are assigned at the client. Narrow your DHCP pool and give each client its own address. Much easier than using Manually Assigned in the router GUI especially when you need to reset the router.

 

[pgershon]

Unfortunately, the TP Link/ KASA devices do not let you assign static IP addresses. Manually-assigned IP addresses can only be done by the router. The Shelly devices do seem to permit the user to assign a true static IP.

Unfortunately the Raspberry PI DHCP server idea seems like the best one, but it is not my preference. I wish I could do through ASUS scripting. Too bad Merlin does bot support this router.

 

[eibgrad]

This is precisely why having third-party firmware support is so important. Everything is great w/ the OEM firmware until it isn't. You wouldn't even need YazDHCP. A simple reconfiguration of DNSMasq using a postconf file containing your own statics leases using host-record directives would do the job.

So either you use a secondary DHCP server, or configure some of these devices manually, on the device itself. With the latter not a possibility, running a separare DHCP server would do the trick. In fact, most businesses would NOT be running it on their router anyway. It's only on the router w/ consumer-grade routers for convenience. So it's not really a big deal if you have to host it elsewhere.

 

[pgershon]

Thanks. This is kind of where I ended up. Is Raspberry PI the way to go or are their other alternatives. I am not a LINUX guy but have figured some things out with Terminal on my mac in the past. Dont have the hardware so its an investment in something new regardless.

 

[eibgrad]

I had one more thought here.

In most cases, DNSMasq (the DHCP server) defaults to assigning IPs based on a hash of the device's MAC address. That's why, even without static leases, you'll find your assignments do NOT change all that much, if ever. There always remains the remote possibility it might happen, esp. if the number of available IPs is low, and the number of clients is high. There's just a much better chance of a hash collision, thus the assigned IP might change for a given device.

So what I'm thinking is if you made the IP pool bigger (e.g., /23 instead of /24), you might find your assigned IPs won't change at all! Esp. if you make their expiration infinite. So once assigned, they are effectively permanent, even if you factory reset the router. Or maybe just making them infinite would be sufficient, just so long as you had enough IPs available for future expansion.

 

[pgershon]

I am limited to 255 IP addresses, right? Not sure what you mean "f you made the IP pool bigger (e.g., /23 instead of /24)"?

 

[eibgrad]

Any IPv4 address consists of a maximum 32 bits. The /24 notation is the same as 255.255.255.0 for the netmask. 24 in this case means the leftmost 24 bits represent the *network* portion of the IP address, w/ the remaining 8 bits available for host assignments. 2^8 bits means 256 possible hosts (although the first and last can't actually be assigned (x.x.x.0 and x.x.x.255)), so 256 - 2, or 254 hosts.

If you change the netmask to /23 (255.255.254.0), you *double* the number of hosts to 512 (less the first and last in that range, so actually 510). Reduce it to /22 (255.255.252.0), and it doubles again (1022). Etc.

The following chart might be useful.

Page Not Found

 

[pgershon]

Thanks. Never saw that before. So if I go to 255.255.254.0, do I get IP addresses like 192.168.x.345 permitted? Or are the expanded IP addresses shown in another way?

 

[eibgrad]

Thanks. Never saw that before. So if I go to 255.255.254.0, do I get IP addresses like 192.168.x.345 permitted? Or are the expanded IP addresses shown in another way?

NO. You can use the following link to see what range of hosts are available.

IP Subnet Calculator

This IP subnet calculator covers both IPv4 and IPv6 protocols, providing information such as IP address, network address, subnet mask, IP range, and more.

www.calculator.net

For 192.168.1.0/23 (or 192.168.0.0/23), the range of usable hosts would be from 192.168.0.1 thru 192.168.1.254.

IOW, that third octet can now be either 0 or 1, whereas before w/ /24, it never changed.

 

[pgershon]

got it - thanks