Wireless Access

Contributor I

DHCP Master/Standby Redundancy


I have a quick query.  Firstly it is in the pipeline to move our DHCP to an external server but it isn't as easy given our current setup.  This will be planned for later this year.


I have two controllers, one master and one standby at present.  DHCP is currently handled by our controller.  I have the failover set up and working when the master dies the standby comes up and takes control of the APs - all come up but when I connect i cannot get an IP address as the DHCP scope have not been configured.  


1. Is it possible for me to create a DHCP scope identical to the one on the master controller? I know this is not best practice but given the two controllers will not be acting as the master at the same time (i.e. one will be master and the other standby) will it work? What problems might this cause?


2.  If this will cause problems can anyone advise on a workaround solution in the meantime? Can the backup controller be given an external DHCP server in the DHCP scope settings? What way would this work if on the first controller the DHCP is set to be handled by the controller itself?  


Guru Elite

Re: DHCP Master/Standby Redundancy

You should split the scope between the two controllers.  Regardless of the controller role on either controller (master, backup, local) configuring a dhcp server on a controller means that it will always answer dhcp requests.  Splitting the scope means that no duplicate addresses will be given out.

*Answers and views expressed by me on this forum are my own and not necessarily the position of Aruba Networks or Hewlett Packard Enterprise.*
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Contributor I

Re: DHCP Master/Standby Redundancy

Thank you for this!

I had thought about splitting the scope however we do not have enough IP addresses to split the scope on the controllers itself as there is a 2048 limit on DHCP leases and we have over 1000 connections already. 

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