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How does an IAP 103/104/105 decide to assign a 169.x.x.x address?

We have IAP 103/104/105. All are on OS release 6.4.2.6-4.1.1.6_50009

 

We have two VLANS - #1 and #4.  #1 is the Main wifi and #4 is the Guest wifi. The VLANs are on separate subnets with separate DHCP/DNS servers.  The IAPs do not assign addresses.

 

Under the Network setings page the VLAN settings are IP assignment as VC managed and VLAN assignment as for example Guest (vlan:4).

 

Under More>DHCP Server both wifi names are set under Centralized DHCP Scope. Both are set the Centralized, L2 with the correct VLANs.

 

Yet we still get clients with 169 addresses.

 

Hints, suggestions, and questions welcome.  What should we look at please?

 

Thanks!

 

 

Re: How does an IAP 103/104/105 decide to assign a 169.x.x.x address?

169.254.x.x addresses are self-assigned by the clients when they fail to receive an IP address after a DHCP request. Microsoft calls it APIPA, or Automatic Private IP Addresses, but most all IP-based clients support this functionality. 

 

https://en.wikipedia.org/wiki/Link-local_address

 

If you are seeing clients getting this often, but others are working fine, you would want to look at how well your DHCP server scales (most people don't give enough hardware resources to their DHCP servers, esp for large deployments), or your DHCP server are either not getting or are missing the DHCP requests as they come in.

Jerrod Howard
Sr. Techical Marketing Engineer
MVP

Re: How does an IAP 103/104/105 decide to assign a 169.x.x.x address?

You should set your Client IP as Network assigned (since you're getting the DHCP from the network, and not from the VC):

iAP-SSID-IP-settings.png

--Matthew

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Re: How does an IAP 103/104/105 decide to assign a 169.x.x.x address?

Thanks jhoward. We do know about the self assigned IP addresses. Some brain fart said we read that there was an Aruba part in that - not.  So much for what is left of our collective brains. See us go Doh! about that piece.

 

What is interesting and this pertains to the post by msabin also - we had set the DHCP Servers up for the two networks, but that appears to block the VLAN setup as Network Assigned via the Edit Network pages.  Every time I tried to select the Network Assigned radio button and saved the setting was reverted to VC Assigned.  Not sure the why there.

 

So last night I removed the two DHCP Server items - we now have no server definitions under the More>DHCP Servers page.  I then went back into the Edit pages for the networks I was able to select Network Assigned on the VLAN page.  We are running under that mode today.

 

Also per your comments about DHCP and resources.  We are not that big a shop - the DHCP server is a Win2012 instance without much else going on.  But I remembered after reading your note that Win2012 server has a wizard for split scoping DHCP.  I walked through that last night (a 5 minute effort) and we are running under splilt scope today. 

 

So far so good as the morning ramps up and users jump on wifi. 

 

My thanks to both you and msabin for your comments and thoughts.

 

 

 

Re: How does an IAP 103/104/105 decide to assign a 169.x.x.x address?

That makes sense, the VC wouldn't let you point to external servers if it sees internal DHCP servers configured on the VC, though chances are the network DHCP servers were seeing the same L2 requests, which might have confused clients getting two offers from two different sources.

 

Glad it's working better fo far, let us know if that changes!

Jerrod Howard
Sr. Techical Marketing Engineer
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