Non-24 bit subnet mask - any downsides?

[Zbig]

Hi everyone

I'm about to setup the home network from scratch in my new apartment. I'm pretty much set on getting a new Asus router and put my tired old Linksys WRT320N out to pasture. Still not decided on the exact model yet, though. I'm trying to take this opportunity and get rid of one of the minor nuisances I have with my current setup which is the IPv4 addressing within my LAN. I often have a need to recall an IP address of a particular device or system quickly and find them hard to memorize. And I can't always rely on the name resolution. I've tried to devise some simple "sub-addressing" scheme where I divided the fourth octet of the /24 mask to ranges like "10-20: Laptops; 30-40: virtual machines", etc. but found it awkward, inconvenient and hard to follow. So I figured I'll just use non-default subnet mask of 255.255.192.0(/18) which will allow me to use the 192.168.0.1 - 192.168.63.254 range on my LAN side enabling me to employ some more sensible addressing scheme of 192.168.xxx.yyy where xxx=001Cs, xxx=002:Android devices, and so on, and so forth. Don't get me wrong - I'm not some basement-dwelling freak surrounded by tens of PCs, but not having any kind of addressing scheme whatsoever I find messy, even for two PCs, some mobile devices and few VMs.

So my question is, has anyone encountered any kind of problems on the router side of things by not using the default 192.168.0.0/24 netmask? Few words of explanation as of why I'm asking such general question in the Asus AC-class routers section specifically: I've learned of the CTF acceleration feature found in some of the Asus devices and I'm wondering if the "non-standard" network mask could somehow impair this mechanism (e.g. they could be looking at the last octet of the address field only or something like that).

Thanks in advance and best regards,
Zbig

 

[RMerlin]

Asuswrt's networkmap cannot properly handle subnets larger than /24.

 

[Zbig]

Asuswrt's networkmap cannot properly handle subnets larger than /24.

Oh, bummer. Do you know if they consider it a bug (I know I would) pending fixing or they're fine with that? Thank you for your information, it has probably saved me some frustration.

 

[RMerlin]

Oh, bummer. Do you know if they consider it a bug (I know I would) pending fixing or they're fine with that? Thank you for your information, it has probably saved me some frustration.

No idea. The code was specifically designed that way - it will only scan the 254 IPs from a /24. That code dates back from years ago, back when a /24 was the norm for any home network.

That does not mean that you cannot use a larger subnet tho, just that the networkmap client list might not be accurate.

 

[Ronv42]

I played around in Tomato with a smaller netmask and it worked for the router but I did find bugs in some software packages and devices. For example one of my older Roku's could no longer discover my media servers. After about 3 days of headaches I abandoned the project. But that was about 3 years ago, things may have changed.

 

[Zbig]

Thanks for your input, guys. Based on that, I've abandoned the idea and just revived my simple "bunch the devices into subranges of 10" scheme with dynamic DHCP pool at the top. I definitely don't want to solve, what essentially is a non-issue, by breaking service auto-discovery and who knows what else. After all, I still hope we'll switch to native IPv6 during my lifetime - good luck memorizing these addresses