Wireless Access

Greetings all,

Having a heck of a time trying to get DHCP servers setup on my 620 with ArubaOS 6.3.1.2.

Issue: I'm getting the following error after hitting Apply after adding a DHCP pool:

Error processing command:ip dhcp pool "Employee_DHCP" network 10.1.100.0 255.255.255.0 >> Failed to add pool Employee_DHCP which has 253 addresses. Maximum addresses configurable is 256. Currently configured are 253 addresses. You may want to exclude unused address ranges.

Here are the screenshots. Any help would be appreciated!

Reference: My VLANs:

Here is the DHCP pool I tried to create against the Employee VLAN, VLAN 20 (10.1.100.254):

Here it is added, after hitting "Done":

Now I hit "Apply" and I get the error and the Employee DHCP pool is removed:

This is because you already have a DHCP pool configured which contains 253 IP addresses.

You cannot have more than 256 in total.

Thanks! So this isn't all that clear in the window - is the maximum a total of 255 *potential* addresses or *actual* addresses?

I ask because let's say I have the two VLANs, both are 255.255.255.0, but even if I try to exclude the ranges to make 255 total, it still fails. Sounds like I need two subnets to *equal* 255, for example:

Employee_DHCP: 255.255.255.224 (30 potential hosts) - 10.1.100.1 to 10.1.100.30 (30 actual hosts)

Guest_DHCP: 255.255.255.128 (126 potential hosts) - 10.1.200.1 to 10.1.200.126 (126 actual hosts)

OR (what I wanted to do):

Employee_DCHP: 255.255.255.0 (255 potential hosts) - excluding 10.1.100.51 to 10.1.100.254 (50 actual hosts)

Guest_DHCP: 255.255.255.0 (255 potential hosts) - excluding 10.1.200.201 to 10.1.200.254 (200 actual hosts)

Thanks all!

These limitations to the internal DHCP server have been added in ArubaOS 6.3 (and they kinda suck). The limit is based on the number of potential addresses. If you create exclusions in your subnet this will lower this number.

Adding two /24's on a Aruba 620 (= max 256 potential addresses) can be a bit problematic, but it can be done:

1) Add first /24 DHCP scope

2) Exclude *all* addresses in this /24

3) Add second /24 DHCP scope

4) Now adjust the exlusions for both /24's - keeping in mind the total number cannot be more than 256

So I think I figured it out, but I think there is a bug in the GUI. I bet doing all this in the CLI works since others were able to do this in the CLI (see: http://tnotez.wordpress.com/2013/08/23/day-out-with-aruba-controller-620-initial-configuration-part-1/) and would be much better from a reliability standpoint, but regardless, I got it working in the GUI with a workaround.

Solution: Create the excluded ranges before adding the new DHCP pool

So you canspan VLANs, but as long as the total is below 255, this workaround works above.

So add the excluded range for the yet-to-be created DHCP Pool FIRST.

Success! I was bit under, did 249 IPs just to make sure.

If anyone from Aruba is watching, this probably warrants a defect report.

Ah, that works as well :) Thanks for sharing :)

For the record, I ended up downgrading from AOS 6.3.1.2 to 6.1.3.11 due to a number of reasons, one being 6.1.3.11 shows the resulting ranges after the exclusions hwere 6.3.1.2 does not.