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Occasional Contributor II

DHCP scope are all oversubsribed

Hi,

 

Always surprises with new ARUBA codes now a days, I am in a bad shape with the new issue i am facing with 6000, now the box is with 6.3.0.2, we have DHCP with scopes enabled for 4000 ips, however during morning DHCP lease out all ips even though the number of users are not more than 1600, vlan-assignment count and dhcp lease count are not matching at all, also noted that DHCP report shows that users getting multiple ip for same device, contacted ARUBA support, they suggested to change the hash algorithm to even, no luck, then fast age enabled, removed vlan pool name and added vlans manually, now waiting for the next day, realy a nightmare situation evry morning, could someone come up with an advise.

 

Thank you

 

 

27 REPLIES
MVP

Re: DHCP scope are all oversubsribed

I don't have experience with Aruba's internal DHCP server, but can you decrease the lease time to something aggressive like 10 minutes?
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Ryan Holland, ACDX #1 ACMX #1
The Ohio State University

Re: DHCP scope are all oversubsribed

Edit: Unrelated

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Occasional Contributor II

Re: DHCP scope are all oversubsribed

We use microsoft DHCP, we tried all different settings with leasetime, the issue doesnt point to the lease time. vlan assignement table show a figure which is compeltely lower figure that the total dhcp addresses leased out, also what triggered to lease multiple ips for same device in DHCP.

Frequent Contributor II

Re: DHCP scope are all oversubsribed

What model of controller do your have? Controllers older that the 7200 series have a maximun of 512 leases and are not designed for Production use.

I notice the limit on the 7210 is 5000 leases.


Bruce Osborne - Wireless Engineer
ACCP, ACMP
Occasional Contributor II

Re: DHCP scope are all oversubsribed

We use IPAM appliances for our DHCP. Due to class change times (overlap of users in the building - those leaving class and those awaiting to walk into a class), we have our lease times set for 15 min minimum lease time, 20 min default lease time, and 21 min maximum lease time. We had to keep the maximum close to the default because Apple devices (at one time) tended to ignore the default time and went for the maximum time.

Contributor II

Re: DHCP scope are all oversubsribed


nointerference wrote:

We use microsoft DHCP, we tried all different settings with leasetime, the issue doesnt point to the lease time. vlan assignement table show a figure which is compeltely lower figure that the total dhcp addresses leased out, also what triggered to lease multiple ips for same device in DHCP.


Wireshark at the DHCP server.  With an external (to the controller) DHCP server that would be my first step in figuring out "also what triggered to lease multiple ips for same device in DHCP."    Are the multiple leases per device offered at the same time? 

Kevin Schoenfeld

Frequent Contributor II

Re: DHCP scope are all oversubsribed

Oops. I missed the detail that you are using a Microsoft DHCP server

 

:(


Bruce Osborne - Wireless Engineer
ACCP, ACMP
Occasional Contributor II

Re: DHCP scope are all oversubsribed

it looks like not a DHCP server or a lease issue, how same device can have different ip, also we do have enogh ips in dhcp scope to handle the number of devices. It's all happening in first 40 mins, but controller outputs shows not that many devices is assigned in those scopes. Show vlan-assign.

 

 

Contributor II

Re: DHCP scope are all oversubsribed


nointerference wrote:

it looks like not a DHCP server or a lease issue, how same device can have different ip, also we do have enogh ips in dhcp scope to handle the number of devices. It's all happening in first 40 mins, but controller outputs shows not that many devices is assigned in those scopes. Show vlan-assign.

 

 


Well, it sounds like your DHCP server disagrees.  Sounds like controller shows n number of clients; but your dhcp server believes it has dished out more (n+something) IPs than that.  My advice stands - I'd start with a packet capture (and/or a detailed analysis of the DHCP log) at the DHCP server.

 

Are you seeing lots of DHCP NAKs from clients?  Are you seeing multiple Discover/Requests per device?

Kevin Schoenfeld

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