RV180 DHCP Server Question

[ncsucpe93]

Hello folks,

     I have tried to configure a VLAN on our RV180 with IP Addresses 192.168.0.1 -> 192.168.254.254 to make sure we have lots of IP addresses for our "guest" network.  This shsould be possible with a NetMask of 255.255.0.0 and DHCP end address of 192.168.254.254 but it always complains about the last IP address.  As I have tried different things, it appears it is ignoring the NetMask and assumes 255.255.255.0 and makes the first three octets be the same.  Anyone know why this is and if there are any work aronuds?

John

[vvijaysa]

Hello John,

What firmware are you running? Is it the latest? I think old fimware had similar issues.

Thanks,

Vijay

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[ncsucpe93]

I am using the latest March firmware.

John

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[vvijaysa]

Hello John,

The error is because of the class of the IP address that you assigned. 192.x.x.x is a class C address so you cannot have a mask of 255.255.255.0. You need a class B IP private address like 172.16.0.1. Then you can apply your desired mask. The class B private IP address range is 172.16.0.0 to 172.31.255.255.

Thanks,

Vijay

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[ncsucpe93]

I tried that and it didn't let me do that either. I tried all three private classes and they all behave the same.

John

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[mpyhala · Accepted solution]

John,

The RV180(W) and other SMB routers will only allow a Class C subnet. The workaround is to create muliple VLANs (and multiple guest SSIDs in your case).

- Marty

[ncsucpe93]

Any incites into why this is? It is very annoying!

John

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[mpyhala]

John,

I cannot tell you specifically why the decision was made but in general the SMB routers are designed for small businesses, which Cisco Small Business defines as less than 100 users. A class C subnet should be more than enough for a typical SMB environment. If you have more than 100 users we recommend that you consider Cisco Enterprise solutions.

- Marty

[ncsucpe93]

Ok. Churches are kind of weird animals. We don't really have the need for the rest of the enterprise features. However, 255 devices in a tech savvy congregation can be 150 or less people.

Thanks for the confirmation that this is intended but it should be documented in the specs somewhere.

John

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[ncsucpe93]

One more comment, even for small business, I think you should support 255.255.254.0 subnet mask networks.

John

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[TekMason0]

I am in the same situation where we have a public/guest wireless network for visitors and cell phones that peeks out to about 300 devices.

I am able to put a 255.255.254.0 mask on my device (10.10.2.1) and lets me set the DHCP Starting IP Address to 10.10.2.20 and the Ending IP Address 10.10.3.254 which makes a total of 481 available addresses in the DHCP pool.

However, the RV180 is responding with DHCP NAK responses to my devices' DHCP REQUESTs with a OPTION 56 message of "no leases left" long before the supply of available addresses is reached.  Today, when I looked at the DHCP Leased Clients under Networking > LAN (Local Network) is showed that there were only 306 DHCP Leased Clients yet the router was throwing NAKs

No where I can find a published limit of the size of the DCHP pool or number of devices that can be attached to the RV180.  Additionally, the fact that it allows one to enter a subnet mask greater than a C class is a solid indication that it is supported.

TekMason