I could have swore I had a

mike.stapf · ‎12-19-2014

Using a UC520 as DHCP server. We have about 50 wired and wireless clients. Problem started to occur that certain clients couldn't get IP. I'd reset the IP binding, and all would be good again for a few days and the same thing would start happening. Reset IP binding...good for 3 days...problems...reset IP binding...good for 3 days...problems. So I ran a DHCP conflict command, and got this:

192.168.10.100 Ping Aug 19 2014 10:23 PM
192.168.10.101 Gratuitous ARP Dec 01 2014 11:08 AM
192.168.10.102 Ping Aug 19 2014 10:44 PM
192.168.10.104 Gratuitous ARP Dec 01 2014 01:01 PM
192.168.10.106 Ping Dec 16 2014 08:09 AM
192.168.10.107 Gratuitous ARP Oct 17 2014 10:00 AM
192.168.10.109 Ping Dec 11 2014 08:30 AM
192.168.10.110 Ping Dec 11 2014 08:30 AM
192.168.10.111 Ping Aug 20 2014 08:12 AM
192.168.10.112 Ping Aug 20 2014 08:12 AM
192.168.10.115 Ping Aug 20 2014 08:31 AM
192.168.10.116 Ping Dec 11 2014 08:31 AM
192.168.10.117 Gratuitous ARP Dec 17 2014 08:29 PM
192.168.10.118 Gratuitous ARP Aug 29 2014 02:15 PM
192.168.10.119 Ping Dec 17 2014 11:36 PM
192.168.10.120 Gratuitous ARP Dec 16 2014 09:00 AM
192.168.10.121 Ping Dec 17 2014 11:36 PM
192.168.10.122 Ping Dec 11 2014 08:35 AM
192.168.10.123 Ping Dec 11 2014 08:35 AM
192.168.10.126 Ping Dec 16 2014 08:38 AM
192.168.10.127 Gratuitous ARP Aug 26 2014 11:11 AM
192.168.10.128 Gratuitous ARP Oct 01 2014 10:13 AM
192.168.10.130 Ping Dec 16 2014 08:38 AM
192.168.10.131 Gratuitous ARP Aug 26 2014 11:11 AM
192.168.10.132 Gratuitous ARP Nov 03 2014 02:05 PM
192.168.10.134 Gratuitous ARP Nov 03 2014 03:06 PM
192.168.10.135 Ping Aug 20 2014 10:19 AM
192.168.10.137 Gratuitous ARP Nov 03 2014 02:05 PM
192.168.10.138 Gratuitous ARP Nov 03 2014 02:06 PM
192.168.10.139 Ping Dec 18 2014 08:07 AM
192.168.10.140 Ping Dec 18 2014 08:07 AM
192.168.10.141 Ping Dec 16 2014 08:38 AM
192.168.10.142 Gratuitous ARP Oct 24 2014 02:52 PM
192.168.10.143 Ping Dec 16 2014 08:38 AM
192.168.10.145 Ping Dec 16 2014 08:39 AM
192.168.10.147 Ping Aug 20 2014 11:26 AM
192.168.10.148 Ping Dec 11 2014 09:11 AM
192.168.10.149 Gratuitous ARP Sep 17 2014 09:13 AM
192.168.10.150 Ping Dec 11 2014 09:11 AM
192.168.10.151 Ping Dec 16 2014 08:41 AM
192.168.10.152 Gratuitous ARP Dec 18 2014 11:12 AM
192.168.10.155 Gratuitous ARP Nov 21 2014 01:17 PM
192.168.10.157 Gratuitous ARP Dec 08 2014 01:56 PM
192.168.10.158 Gratuitous ARP Nov 18 2014 01:49 PM
192.168.10.161 Ping Aug 20 2014 11:48 AM
192.168.10.163 Gratuitous ARP Dec 18 2014 11:08 AM
192.168.10.164 Ping Aug 20 2014 11:50 AM
192.168.10.165 Ping Aug 20 2014 11:50 AM
192.168.10.166 Ping Dec 16 2014 09:00 AM
192.168.10.167 Ping Aug 20 2014 11:50 AM
192.168.10.168 Ping Dec 11 2014 09:46 AM
192.168.10.170 Ping Dec 16 2014 09:00 AM
192.168.10.171 Ping Dec 16 2014 09:00 AM
192.168.10.173 Gratuitous ARP Oct 24 2014 12:59 PM
192.168.10.174 Gratuitous ARP Dec 16 2014 09:00 AM
192.168.10.175 Ping Dec 11 2014 09:48 AM
192.168.10.176 Ping Dec 18 2014 08:38 AM
192.168.10.177 Ping Aug 20 2014 02:33 PM
192.168.10.178 Ping Aug 20 2014 02:33 PM
192.168.10.179 Ping Aug 20 2014 02:33 PM
192.168.10.180 Gratuitous ARP Oct 27 2014 01:38 PM
192.168.10.182 Gratuitous ARP Oct 27 2014 01:32 PM
192.168.10.183 Gratuitous ARP Nov 13 2014 08:45 AM
192.168.10.184 Ping Aug 20 2014 04:00 PM
192.168.10.185 Gratuitous ARP Nov 03 2014 01:48 PM
192.168.10.186 Ping Aug 20 2014 04:02 PM
192.168.10.187 Gratuitous ARP Nov 21 2014 01:18 PM
192.168.10.188 Ping Dec 18 2014 08:38 AM
192.168.10.193 Gratuitous ARP Oct 27 2014 01:33 PM
192.168.10.194 Gratuitous ARP Nov 13 2014 01:52 PM
192.168.10.195 Gratuitous ARP Sep 08 2014 08:52 AM
192.168.10.196 Gratuitous ARP Sep 08 2014 12:34 PM
192.168.10.197 Gratuitous ARP Sep 22 2014 04:45 PM
192.168.10.200 Ping Dec 18 2014 08:51 AM
192.168.10.201 Gratuitous ARP Oct 27 2014 01:42 PM
192.168.10.204 Gratuitous ARP Aug 26 2014 11:12 AM
192.168.10.205 Gratuitous ARP Sep 08 2014 08:54 AM
192.168.10.206 Ping Dec 18 2014 09:00 AM
192.168.10.208 Ping Dec 16 2014 09:30 AM
192.168.10.209 Ping Dec 18 2014 09:00 AM
192.168.10.212 Gratuitous ARP Oct 24 2014 01:02 PM
192.168.10.213 Gratuitous ARP Dec 02 2014 03:36 PM
192.168.10.214 Ping Dec 16 2014 09:38 AM
192.168.10.215 Ping Dec 18 2014 09:00 AM
192.168.10.217 Ping Dec 16 2014 10:58 AM
192.168.10.218 Ping Dec 18 2014 09:00 AM
192.168.10.219 Gratuitous ARP Nov 19 2014 01:42 PM
192.168.10.220 Ping Dec 16 2014 11:30 AM
192.168.10.221 Ping Dec 16 2014 11:30 AM
192.168.10.224 Gratuitous ARP Nov 18 2014 01:55 PM
192.168.10.225 Gratuitous ARP Oct 06 2014 01:55 PM
192.168.10.226 Ping Dec 16 2014 11:33 AM
192.168.10.227 Gratuitous ARP Dec 01 2014 01:35 PM
192.168.10.228 Ping Dec 16 2014 11:33 AM
192.168.10.229 Ping Dec 11 2014 12:52 PM
192.168.10.233 Gratuitous ARP Oct 24 2014 12:59 PM
192.168.10.234 Ping Dec 18 2014 09:01 AM
192.168.10.235 Gratuitous ARP Dec 02 2014 08:55 AM
192.168.10.236 Ping Dec 18 2014 09:01 AM
192.168.10.237 Ping Dec 18 2014 09:01 AM
192.168.10.239 Gratuitous ARP Oct 27 2014 01:40 PM
192.168.10.240 Gratuitous ARP Nov 19 2014 01:41 PM
192.168.10.70 Gratuitous ARP Oct 27 2014 01:39 PM
192.168.10.71 Gratuitous ARP Nov 13 2014 08:43 AM
192.168.10.72 Gratuitous ARP Nov 05 2014 02:11 PM
192.168.10.73 Ping Dec 10 2014 10:37 PM
192.168.10.74 Ping Dec 10 2014 10:37 PM
192.168.10.75 Gratuitous ARP Nov 19 2014 01:41 PM
192.168.10.76 Ping Dec 10 2014 10:37 PM
192.168.10.77 Gratuitous ARP Nov 10 2014 07:45 AM
192.168.10.78 Gratuitous ARP Nov 10 2014 07:45 AM
192.168.10.79 Ping Dec 17 2014 08:22 PM
192.168.10.80 Gratuitous ARP Oct 28 2014 01:04 PM
192.168.10.81 Ping Dec 17 2014 08:22 PM
192.168.10.82 Ping Dec 10 2014 10:38 PM
192.168.10.83 Gratuitous ARP Sep 30 2014 08:40 AM
192.168.10.84 Gratuitous ARP Dec 11 2014 09:46 AM
192.168.10.85 Gratuitous ARP Sep 11 2014 01:57 PM
192.168.10.86 Ping Dec 17 2014 08:22 PM
192.168.10.88 Gratuitous ARP Nov 19 2014 01:41 PM
192.168.10.89 Ping Dec 17 2014 08:23 PM
192.168.10.90 Gratuitous ARP Oct 24 2014 01:07 PM
192.168.10.91 Ping Dec 16 2014 08:02 AM
192.168.10.92 Ping Dec 16 2014 08:02 AM
192.168.10.93 Gratuitous ARP Dec 04 2014 08:50 AM
192.168.10.94 Ping Dec 11 2014 07:52 AM
192.168.10.95 Gratuitous ARP Dec 01 2014 01:35 PM
192.168.10.96 Ping Dec 16 2014 08:02 AM
192.168.10.98 Gratuitous ARP Nov 05 2014 02:10 PM
192.168.10.99 Gratuitous ARP Dec 18 2014 08:29 AM

My DHCP pool is 192.168.10.70 to 192.168.10.240. It looks like 120 of my 170 DHCP IPs have conflicts of some kind, and thus they aren't being assigned to client's anymore, essentially reducing my pool to about 50 addresses. Why did this happen, and how can I fix it? Any ideas?

michael o'nan · ‎12-19-2014

Post your DHCP configuration...

sh run | s dhcp

mike.stapf · ‎12-19-2014

ip dhcp relay information trust-all
ip dhcp use vrf connected
ip dhcp excluded-address 10.1.1.1 10.1.1.10
ip dhcp excluded-address 192.168.10.1 192.168.10.69
ip dhcp excluded-address 192.168.10.241 192.168.10.254
ip dhcp pool phone
   network 10.1.1.0 255.255.255.0
   default-router 10.1.1.1 
   option 150 ip 10.1.1.1 
ip dhcp pool data
   import all
   network 192.168.10.0 255.255.255.0
   default-router 192.168.10.1 
   dns-server 192.168.10.60 
   netbios-name-server 192.168.10.60 
   domain-name 
 ip address dhcp client-id FastEthernet0/0

michael o'nan · ‎12-19-2014

You might consider putting a lease timer on the DHCP pool. Since it seems 3 days is the magic number I would set for either 1 or 2 days.

ip dhcp pool data

lease 2

You can then monitor how many available addresses there are with show ip dhcp pool

mike.stapf · ‎12-19-2014

I could have swore I had a lease timer for 1 day - but I guess I didn't. I just set it at 2 days like you suggested...I guess we'll see if that helps.

Thanks.

DHCP conflicts with UC520