RV325: Trying to set up class-B LAN addresses. Is that possible?

[KeeterJohnson]

I'm trying to replace a dead router from another vendor by using a new RV325 (firmware 1.2.1.14).  I thought this would be a simple drop-in swap but I'm struggling to configure it in a way that minimizes my installation work.  This is my first Cisco product and I must say I'm a bit confused about the RV325.  It seems to assume that I'm using only class-C addresses on each LAN subnet.  That's fine if you're using simple non-routable addresses like 192.168.0.1/24 with a 255.255.255.0 24-bit mask.  But I need to support non-routable class-C addresses in the 172.21.0.1 to 172.21.15.255 range.

Is there a way to force a 20-bit subnet mask (255.255.240.0)?  The web interface does not seem to support that, but perhaps it can be done with CLI commands

About of 1/3 of my IP devices use dynamic DHCP assignment, about 1/3 use static DHCP addresses bound to a specific MAC address, and about 1/3 are hard-coded at the client.  I really don't want to visit those to have to change them over to a new subnet scheme.

I have more questions about setting up DCHP for each VLAN ID.  This box seems to have some quirky restrictions that aren't well documented, but before I get into those questions I'd like to understand if I can use 172.21.1.0/20 LAN addresses.  If not, I will have to come up with an alternate plan.

[Arnaud BOULOGNE]

Hello, have you solved your problem? If yes, please let me know how you did it?

[KeeterJohnson]

Sorry, no, I never found a way to use larger subnets than /24.  The firmware is just not designed for that.

I spent a great deal of time messing around with it before I gave up.  After my box sat unused for months, I finally gave in and converted everything on my LAN to use /24.  It was a huge pain except for those few devices that need only DHCP assigned IP addresses.  Sadly, I have a lot of hard-coded IP addresses and MAC reservations and it was very time consuming to change them all. 

I needed /20 addressing. For a while I tried setting up several distinct /24 VLAN's to accommodate my network, then I told the RV325 to route traffic between the ports.  It worked, mostly, but there were too many side effects in doing that so I gave up and put everything all on one 8-bit subnet.

Of course, I had to change my DNS configuration, too.  The DNS service built into the RV325 is not a full-featured piece of DNS code, but it works in a crude way as long as you hand enter all the entries to match your IP assignments.

Another hold up for me was that I had to wait several months for Cisco to release firmware that could handle more than 30 pre-assigned MAC/IP addresses.  It now handles 80 of them, which covers my needs.

This was a big nuisance, but now that I have reconfigured my network to meet the limitations of this router everything is working okay for me.

Good luck.

[Arnaud BOULOGNE]

Thanks for your help KeeterJohnson