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DHCP Address Conflict : Decline conflict and PING_Conflict issue

Hello Guys,

I have Two routers are configured with HSRP and have DHCP POOL configured on Both Rotuer1 and Router2 .

All the user clients are getting ip from DHCP  from same network.

Rotuer1:

ip dhcp excluded-address 10.120.101.141 10.120.101.254

ip dhcp excluded-address 10.120.102.141 10.120.102.254

ip dhcp excluded-address 10.120.201.141 10.120.201.254

ip dhcp excluded-address 10.120.251.141 10.120.251.254

ip dhcp excluded-address 10.120.101.1 10.120.101.10

ip dhcp excluded-address 10.120.102.1 10.120.102.10

ip dhcp excluded-address 10.120.201.1 10.120.201.10

!

ip dhcp pool voice
   network 10.120.201.0 255.255.255.0
   default-router 10.120.201.1 255.255.255.0
   dns-server 10.1.200.22 10.1.200.23
   option 150 ip 10.120.201.2
   domain-name wr
!        
ip dhcp pool data
   network 10.120.101.0 255.255.255.0
   default-router 10.120.101.1
   dns-server 10.1.200.22 10.1.200.23
   netbios-name-server 10.1.200.22 10.1.200.23
   domain-name ***
   netbios-node-type h-node
   lease 10

ip dhcp pool data-vlan102
   network 10.120.102.0 255.255.255.0
   default-router 10.120.102.1 255.255.255.0
   dns-server 10.1.200.22 10.1.200.23
   netbios-name-server 10.1.200.22 10.1.200.23
   domain-name ***
   netbios-node-type h-node
   lease 7
!

Router2:-

ip dhcp excluded-address 10.120.101.1 10.120.101.140
ip dhcp excluded-address 10.120.102.1 10.120.102.140
ip dhcp excluded-address 10.120.201.1 10.120.201.140
ip dhcp excluded-address 10.120.251.1 10.120.251.140
!
ip dhcp pool voice
   network 10.120.201.0 255.255.255.0
   default-router 10.120.201.1 255.255.255.0
   option 150 ip 10.120.201.2
  dns-server 10.1.200.22 10.1.200.23
   domain-name wr
!        
ip dhcp pool data
   network 10.120.101.0 255.255.255.0
   default-router 10.120.101.1 255.255.255.0
   dns-server 10.1.200.22 10.1.200.23
   netbios-name-server 10.1.200.22 10.1.200.23
   domain-name ***
   netbios-node-type h-node
   lease 7

ip dhcp pool data-vlan102
   network 10.120.102.0 255.255.255.0
   default-router 10.120.102.1 255.255.255.0
   dns-server 10.1.200.22 10.1.200.23
   netbios-name-server 10.1.200.22 10.1.200.23
   domain-name ***
   netbios-node-type h-node
   lease 7

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Router1 DHCP error messages:-

Mar 12 06:07:58.494: %DHCPD-4-DECLINE_CONFLICT: DHCP address conflict:  client 0100.1e90.3718.55 declined 10.120.101.72.

Mar 15 03:48:38.191: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.74.
Mar 15 04:11:27.029: %DHCPD-4-DECLINE_CONFLICT: DHCP address conflict:  client 0100.123f.ab84.dc declined 10.120.101.59.
Mar 15 04:48:04.047: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.101.
Mar 15 04:48:05.047: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.105.
Mar 15 04:48:06.083: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.115.
Mar 15 04:48:07.083: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.116.
Mar 15 04:48:08.083: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.117.
Mar 16 03:20:48.220: %DHCPD-4-DECLINE_CONFLICT: DHCP address conflict:  client 0100.2197.3b50.e4 declined 10.120.101.37.
Mar 16 04:20:08.907: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.123.
Mar 16 04:20:09.907: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.126.
Mar 16 04:44:36.990: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.101.134.
Mar 16 21:37:46.021: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.201.69.
Mar 16 21:37:47.021: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.201.70.

Router1 -DHCP BINDINGS:-

sh ip dhc binding
Bindings from all pools not associated with VRF:
IP address          Client-ID/              Lease expiration        Type
                    Hardware address/
                    User name
10.120.101.11       0100.1e68.5fe9.50       Mar 27 2010 10:59 AM    Automatic
10.120.101.13       0100.1e90.3718.55       Mar 24 2010 09:54 AM    Automatic
10.120.101.14       0100.1f3b.4c28.5f       Mar 27 2010 10:59 AM    Automatic
10.120.101.16       0100.1bd4.0c34.de       Mar 27 2010 06:42 AM    Automatic
10.120.101.21       0100.1372.d191.a4       Mar 27 2010 06:42 AM    Automatic
10.120.101.36       0100.2163.2570.c1       Mar 27 2010 10:49 AM    Automatic
10.120.101.40       0100.16ea.dc12.06       Mar 25 2010 08:12 AM    Automatic
10.120.101.43       0100.13e8.ef6a.a9       Mar 27 2010 07:32 AM    Automatic
10.120.101.46       0100.1e68.bfb5.34       Mar 25 2010 06:33 PM    Automatic
10.120.101.59       0100.1de0.0f91.1b       Mar 27 2010 09:54 AM    Automatic
10.120.101.76       0100.16ea.dc27.1a       Mar 27 2010 10:09 AM    Automatic
10.120.101.81       0100.123f.ab84.dc       Mar 26 2010 11:46 AM    Automatic
10.120.101.98       0100.1302.cd03.22       Mar 27 2010 10:14 AM    Automatic
10.120.101.121      0100.1921.3c3b.c4       Mar 26 2010 03:07 AM    Automatic
10.120.101.122      0100.2197.3b50.e4       Mar 26 2010 07:21 AM    Automatic
10.120.101.133      0100.2197.3b50.d2       Mar 26 2010 08:20 AM    Automatic
10.120.101.140      0100.123f.abad.ff       Mar 27 2010 07:15 AM    Automatic
10.120.102.71       0100.1185.ef5b.b8       Mar 22 2010 05:32 AM    Automatic
10.120.201.27       0100.1bd4.0c3a.93       Mar 18 2010 09:58 AM    Automatic
10.120.201.67       0100.1c58.5758.61       Mar 18 2010 05:28 AM    Automatic
10.120.201.91       0100.1bd4.329e.20       Mar 18 2010 02:32 AM    Automatic
10.120.201.101      0100.1bd4.0c41.e3       Mar 18 2010 04:10 AM    Automatic
10.120.201.106      0100.1ebe.90e6.74       Mar 18 2010 04:14 AM    Automatic
10.120.201.107      0100.1bd4.0c40.7d       Mar 18 2010 04:14 AM    Automatic
10.120.201.111      0100.1bd4.329e.dd       Mar 18 2010 04:18 AM    Automatic
10.120.201.127      0100.1c58.5758.e9       Mar 18 2010 09:40 AM    Automatic
10.120.201.132      0100.1bd4.32ab.1a       Mar 18 2010 02:02 AM    Automatic
10.120.201.133      0100.1bd4.0c41.09       Mar 18 2010 02:02 AM    Automatic
10.120.201.134      0100.1bd4.0c40.b4       Mar 18 2010 09:42 AM    Automatic

Router 2 DHCP Error message:-

Feb 24 08:12:14.825 UAE: %DHCPD-4-PING_CONFLICT: DHCP address conflict:  server pinged 10.120.102.56.
Feb 28 06:53:46.795 UAE: %DHCPD-4-DECLINE_CONFLICT: DHCP address conflict:  client 0100.1185.ef5b.b8 declined 10.120.102.171.
Feb 28 07:13:27.999 UAE: %DHCPD-4-DECLINE_CONFLICT: DHCP address conflict:  client 0100.a0d1.2025.74 declined 10.120.101.33.
Mar 11 12:41:29.390 UAE: %DHCPD-4-DECLINE_CONFLICT: DHCP address conflict:  client 0100.123f.cc8d.ab declined 10.120.102.173.
Mar 12 09:57:53.889 UAE: %DHCPD-4-DECLINE_CONFLICT: DHCP address conflict:  client 0100.123f.ab84.dc declined 10.120.101.209.
Mar 13 12:18:38.204 UAE: %DHCPD-4-DECLINE_CONFLICT: DHCP address conflict:  client 0100.1921.3c33.0e declined 10.120.102.176.

Router2 IP DHCP Bindings:

h ip dhcp binding
Bindings from all pools not associated with VRF:
IP address          Client-ID/              Lease expiration        Type
                    Hardware address/
                    User name
10.120.101.5        0100.1279.6875.2e       Mar 23 2010 08:35 AM    Automatic
10.120.101.38       0100.1372.d61c.33       Mar 23 2010 08:28 AM    Automatic
10.120.101.62       0100.1e90.3719.0d       Mar 22 2010 02:47 PM    Automatic
10.120.101.67       0100.1921.3c37.bb       Mar 22 2010 07:32 AM    Automatic
10.120.101.145      0100.1921.3c78.fe       Mar 24 2010 07:26 AM    Automatic
10.120.101.150      0100.1e90.3a90.11       Mar 22 2010 04:17 PM    Automatic
10.120.101.176      0100.1c7e.936d.23       Mar 21 2010 07:25 AM    Automatic
10.120.101.190      0100.1c7e.eb40.20       Mar 24 2010 07:32 AM    Automatic
10.120.101.192      0100.1921.3c74.d9       Mar 21 2010 07:26 AM    Automatic
10.120.101.193      0100.1c7e.e840.20       Mar 24 2010 07:05 AM    Automatic
10.120.101.199      0100.1921.3c37.4d       Mar 23 2010 01:51 PM    Automatic
10.120.101.200      0100.1921.3c00.28       Mar 21 2010 02:59 PM    Automatic
10.120.101.201      0100.1921.3c3c.1a       Mar 24 2010 06:54 AM    Automatic
10.120.101.210      0100.1279.6878.fe       Mar 21 2010 07:38 AM    Automatic
10.120.101.219      0100.2197.253a.70       Mar 22 2010 09:51 AM    Automatic
10.120.101.226      0100.1921.3c35.a5       Mar 21 2010 02:05 AM    Automatic
10.120.101.230      0100.15b7.f515.54       Mar 22 2010 06:17 AM    Automatic
10.120.101.235      0100.2197.224e.f7       Mar 24 2010 07:17 AM    Automatic
10.120.101.237      0100.1c7e.8c2b.20       Mar 24 2010 09:54 AM    Automatic
10.120.102.89       0100.1195.e259.46       Mar 22 2010 01:22 PM    Automatic
10.120.102.177      0100.123f.cc8d.ab       Mar 22 2010 12:41 AM    Automatic
10.120.102.178      0100.1921.3c33.0e       Mar 24 2010 12:18 AM    Automatic
10.120.102.181      0100.0fb0.ddd7.35       Mar 23 2010 01:30 PM    Automatic
10.120.201.4        0100.1d45.2c80.9a       Mar 17 2010 01:32 PM    Automatic
10.120.201.39       0100.1bd4.32b5.77       Mar 17 2010 11:31 AM    Automatic
10.120.201.43       0100.1e7a.c4e0.df       Mar 17 2010 11:33 AM    Automatic
10.120.201.45       0100.1c58.1c8d.d3       Mar 17 2010 11:31 AM    Automatic
10.120.201.51       0100.1bd4.330d.fd       Mar 17 2010 12:20 PM    Automatic
10.120.201.52       0100.1bd4.0c41.96       Mar 17 2010 11:35 AM    Automatic
10.120.201.55       0100.1bd4.0c37.2e       Mar 17 2010 11:31 AM    Automatic
10.120.201.62       0100.1bd4.0c3a.d0       Mar 17 2010 11:32 AM    Automatic
10.120.201.63       0100.1bd4.32bb.a5       Mar 17 2010 11:32 AM    Automatic
10.120.201.64       0100.1bd4.0c4d.23       Mar 17 2010 11:32 AM    Automatic
10.120.201.73       0100.1c58.5752.1d       Mar 17 2010 01:15 PM    Automatic
10.120.201.86       0100.1bd4.0c4b.33       Mar 17 2010 11:35 AM    Automatic
10.120.201.87       0100.1c58.575d.b8       Mar 17 2010 11:31 AM    Automatic
10.120.201.92       0100.1bd4.0c4f.28       Mar 17 2010 11:33 AM    Automatic
10.120.201.94       0100.1bd4.0c4f.0a       Mar 17 2010 11:32 AM    Automatic
10.120.201.144      0100.1bd4.329b.f3       Mar 18 2010 03:34 AM    Automatic

If you look at Router 2 IP DHCP bindings it is releasing ip address even of the excluse list of R2 DHCP Scope.


R1 - EXCLUDE  SCOPE :- 10.120.101.141 - 10.120.101.254


R2 EXCLUDE SCOPE :- 10.120.101.1-140 .....but still R2 is giving ip's from excluse list.


Also I am not sure why these DHCP Conflicts and PING Conflict are keeping popping up, due to these my SCOPE is gettign fulled and my few client failed get IP address.


IS this some thing to  do with this command   no ip dhcp conflict logging  needeedto resolve this issue?

Apprecaite all your efforts!

Regards,

KA.

5 REPLIES
Hall of Fame Super Silver

Re: DHCP Address Conflict : Decline conflict and PING_Conflict i

Hello KA,

the following can be of help :

clear ip dhcp conflict ?
  *        Clear all address conflicts
  A.B.C.D  Clear a specific conflict

Hope to help

Giuseppe

New Member

Re: DHCP Address Conflict : Decline conflict and PING_Conflict i

Hello Giuslar,

Thanks for your posts!

I had tried the clear IP dhcp conflict ..command ..but its not resolving my issue permanantly.

Regards,

KA.

Try to divide pool on two

Try to divide pool on two parts /25. One part is one one router, second on the second router. The pool will be two times smaller but you can try to avoid conflicts between routers.

New Member

Hi what is best practice to

Hi what is best practice to have dhcp in core switch? are we just configure in 1 core? or we like you say this have to be make both core hold smaller segment of pool.

HelloTry decreasing your 

Hello

Try decreasing your  DHCP lease values for voice and Data

res

Paul

 

Please don't forget to rate any posts that have been helpful. Thanks.
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