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DNA-C Wireless Sensor Deployment - Conditional Option 43 return with VCI present on Option 60

Hello Community,


Hopefully, I am not the only one that has run into this. I am trying to initialize our AP1800S wireless sensors to find DNA Center. I am following Cisco's 1800S Deployment Guide and not having any luck. For certain reasons, we cannot make use of either the DNS option for discovery nor the regular DHCP option 43 listed in the guide. That leaves us with the conditional option 43 in response to the Sensor sending DHCP Option 60 up with VCI string "Sensor-Client-1800S". The deployment guide does not go into detail on this but provides an older link to a document showing how to do this on a Windows DHCP Server for Access Points. 


That older guide lists two different sub-option TLV blocks depending on the AP series. I am familiar with configuring Type 241 for certain AP models to find their wireless controller. (The other Type of 102 was for a specific AP series). I tried using this Type 241 with a length of IP address and value set to the DNAC IP address, but it does not work. I am wondering if I need to input the string listed in the guide for a regular Option 43, but not sure how to configure the sub-option TLV block to accommodate this correctly. 


TL:DR - Has anyone successfully deployed the 1800S wireless sensors using conditional DHCP option 43 in response to the VCI sent in Option 60 with a Windows DHCP server? If so, how?




Here is what I have configured which does not work.

DHCP VendorClasses.JPGPreDefined Options.JPGScopeOptionSet.JPG

VIP Advisor

Can you share how you attempted to utilize option 43? It should look something like this:
"5A1N;B2;I<dnac IP>;J80"

ASCII info:
5A1N - specifies PnP
B2 - ipv4
I (dnac ip) - What ip to connect to
J = port to use
Make sure your SVI has your helper pointing to DHCP.

Hello Mike,


Unfortunately, I already have DHCP option 43 configured for something else on our network, so I cannot use that method. Instead, I need to use the conditional DHCP option 43 which is triggered when the wireless sensor sends DHCP option 60 with a specific VCI string set by Cisco. Unconditional Option 43 is the response sent regardless of the clients' transmission of option 60 and is limited to one per DHCP scope.


The screenshots I included earlier show how I set our conditional option 43 in the method used for an Access Point which is the only example given from Cisco on the deployment guide. Unfortunately, it does not seem to work and I am wondering if the full Option 43 string needs sent back in response instead of just the DNA-C VIP. The examples Cisco gives for the APs does not allow for the full string if that is what is required. It only allows for an IP address.




Hi, Did you ever figure this one out?

You should really explore the DNS method. Make sure your certificate on DNAC is setup properly.