Clients hit and miss when questing DHCP addresses

[X2Logic]

Morning everyone!

I would like to reach into this community for support on a DHCP issue at one of my sites.

We have chromebooks, Windows laptops, tablets, etc. on our wireless network. Our 4500X is handling our DHCP pool. This pool has a total of 4094 available address and about 800 are leased, so there is plenty of addresses to give out. I am experiencing that certain devices fail to receive DHCP information. For example, a chromebook will fail to get DHCP, but after 3-5 times of continuous requesting, it receives its IP address. It is a hit and miss. Other times it might not get any IP and fail.

I've cleared bindings, conflicts and released all leases with no success to find the issue. IP leases are set to default time, which I believe is 1 day. Can you recommend where I can start with troubleshooting? Thank you in advance!

[balaji.bandi]

So is this issue on Wireless devices ? also wired devices ?

as you mentioned default is 1 days, you can also reduce due to nature of use.

we also need to understand how your network topology looks like, where the users connection failing to get DHCP clear demarcation to identify the issue, also post DHCP config,

worth check - Cat 4500 CPU,. Interface usase, run debug on WLC what is the reason for the user not getting lease ?

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-9300-series-switches/217429-troubleshoot-slow-or-intermittent-dhcp-o.html

Try cleanups as menttioned in the thread:

https://community.cisco.com/t5/switching/dhcp-how-to-use-quot-ip-dhcp-binding-cleanup-interval-quot/td-p/1616988

[X2Logic]

Hey Balaji,

Only wireless devices are displaying this problem. Wired devices are not part of this DHCP pool, as they have statically assigned IP's. DHCP is served locally at this site. We use 3702I-A-K9 AP's connected to 2960X switches that route back to the 4500X. No config changes have been made for several years. We've never had these issues until now.

I will go ahead an review the links you have provided so I may further troubleshoot.

Here is our pool config:

Pool Wireless_Clients :
Utilization mark (high/low) : 100 / 0
Subnet size (first/next) : 0 / 0
Total addresses : 4094
Leased addresses : 861
Excluded addresses : 1
Pending event : none
1 subnet is currently in the pool :
Current index IP address range Leased/Excluded/Total
10.122.46.250 10.122.32.1 - 10.122.47.254 861 / 1 / 4094

sh ip dhcp server statistics
Memory usage 252107
Address pools 3
Database agents 0
Automatic bindings 986
Manual bindings 0
Expired bindings 31888
Malformed messages 25
Secure arp entries 0
Renew messages 54368
Relay bindings 0
Relay bindings active 10
Relay bindings terminated 0
Relay bindings selecting 10

Message Received
BOOTREQUEST 212
DHCPDISCOVER 988560
DHCPREQUEST 664703
DHCPDECLINE 6
DHCPRELEASE 96351
DHCPINFORM 16469
DHCPVENDOR 0
BOOTREPLY 0
DHCPOFFER 0
DHCPACK 0
DHCPNAK 0

Message Sent
BOOTREPLY 0
DHCPOFFER 276160
DHCPACK 651156
DHCPNAK 5052

Message Forwarded
BOOTREQUEST 0
DHCPDISCOVER 0
DHCPREQUEST 0
DHCPDECLINE 0
DHCPRELEASE 0
DHCPINFORM 0
DHCPVENDOR 0
BOOTREPLY 0
DHCPOFFER 0
DHCPACK 0
DHCPNAK 0

[MHM Cisco World]

ip dhcp bootp ignore <<- try add this. why?
I see 

BOOTREQUEST 212
BUT 
BOOTREPLY 0

keep monitor your DHCP local server

[balaji.bandi]

Check any device which does not have a static assignment and see if that DHCP work as expected.

(Wireless I do not suggest having static assignment for all clients - I understand some requirement but not all)