Confused about LAN IP range

[smcgrath12]

Hi, I am currently using the 192.168.5.1 as my router IP and 255.255.255.0 as the subnet mask (SM). So the router converts this settings to the CIDR of 192.168.5.0/24. I get this part.

Now, I want to assign Class A address (10.0.0.0) as the IP range. For discussion sake, I need around 500 usable IPs and use IP addresses that start with "10" (more easier to remember and type instead of Class B). And I want to have the first 2 octets as "10.75". This is where I am confused a bit.

Question 1: If I put the router IP (in router web gui) as 10.75.4.1 and a SM of 255.255.254.0, is the range in CIDR format be "10.75.4.0/23"? If so, converting this CIDR to usable IPs using bitwise calculation gives a valid range of IPs from 10.75.4.1 - 10.75.5.255. And is so, the router IP is the first usable IP in this range, correct?

Question 2: But, if I put the router IP as 10.75.5.1 (3rd octet changed from 4 to 5) and the same SM of 255.255.254.0, is the range in CIDR format still "10.75.4.0/23"? If that is so, in this case, isn't the router IP NOT not the starting IP of this range, but somewhere in the middle of this range? Is that a problem?

 

[sfx2000]

http://www.ipaddressguide.com/cidr

 

[L&LD]

Now, I want to assign Class A address (10.0.0.0) as the IP range. For discussion sake, I need around 500 usable IPs and use IP addresses that start with "10" (more easier to remember and type instead of Class B).

Is that a problem?

Yes, it is a problem. Asus routers' firmware cannot handle anything bigger than /24 (effectively 253 clients).

 

[System Error Message]

LAN IP addresses are only important if you plan to have that network connect to the internet otherwise feel free to use 0.0.0.0/0. I bought a used asus router and it wasnt reset, apparently someone had tried to use the 10.0.0.0 ip range. Technically asus routers can work with bigger subnets. Try the 10.63.192.0/20 for example if you need more.

 

[sfx2000]

OP's concern - if I understand correctly - when working with VPN, overlapping IP ranges can be a problem...

 

[smcgrath12]

OP's concern - if I understand correctly - when working with VPN, overlapping IP ranges can be a problem...

Yes, that was one concern, though not immediately.

So, reading all the replies, ASUS (I have RT-AC68R) can ONLY handle 256 (or 254) clients on any one subnet, assuming they will be NATed through the router to the outside internet? Is this hard limit programmed into the firmware (Merlin) due to hardware constraints or because it is just the standard way the home routers are set up?

I have no way to test this, but what happens if I go with an IP pool of "10.x.x.x/23" and actually 254 clients are already connected and active, and a new request comes to the router for IP assignment?

Thanks for all the replies.

 

[sfx2000]

If you're just routing and not NAT'ing, AsusWRT could possibly handle things - concern here is that of resources - compute, switch bandwidth, and memory - getting beyond 254 clients is well beyond the scope of the underlying platform from Broadcom (it's meant as a SOHO/SMB class router in this regard) - so the software might be willing, but sooner or later, the resource constraints will not work in your favor...

Might consider something more focused on the small/medium enterprise market - Microtik and Ubiquity have some compelling options here, as do other players like Zyxel, Edimax, etc... and of course there's the pfSense option, and small enterprise class devices from Cisco and the like...

 

[L&LD]

Yes, that was one concern, though not immediately.

So, reading all the replies, ASUS (I have RT-AC68R) can ONLY handle 256 (or 254) clients on any one subnet, assuming they will be NATed through the router to the outside internet? Is this hard limit programmed into the firmware (Merlin) due to hardware constraints or because it is just the standard way the home routers are set up?

I have no way to test this, but what happens if I go with an IP pool of "10.x.x.x/23" and actually 254 clients are already connected and active, and a new request comes to the router for IP assignment?

Thanks for all the replies.

As RMerlin has stated previously, this is a hard limit that Asus' firmware has. RMerlin doesn't touch that part of the code (if I recall, it is closed source anyways).

 

[smcgrath12]

As RMerlin has stated previously, this is a hard limit that Asus' firmware has. RMerlin doesn't touch that part of the code (if I recall, it is closed source anyways).

Cool. Got it. Thanks.

If you're just routing and not NAT'ing, AsusWRT could possibly handle things - concern here is that of resources - compute, switch bandwidth, and memory - getting beyond 254 clients is well beyond the scope of the underlying platform from Broadcom (it's meant as a SOHO/SMB class router in this regard) - so the software might be willing, but sooner or later, the resource constraints will not work in your favor...

Might consider something more focused on the small/medium enterprise market - Microtik and Ubiquity have some compelling options here, as do other players like Zyxel, Edimax, etc... and of course there's the pfSense option, and small enterprise class devices from Cisco and the like...

Ok, Thanks for the options you listed, wasn't even aware of couple of names.