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DHCP issue on Cisco IOS router

Difan Zhao
Contributor
Contributor

Hi experts,

I recently got complaints that some clients can't get IP address through the DHCP server configured on a Cisco IOS router. I turned on debugging on DHCP events and packets and I see the following logs.

Mar 22 15:33:41: DHCPD: DHCPREQUEST received from client 0100.1b63.f246.8c.
Mar 22 15:33:41: DHCPD: Finding a relay for client 0100.1b63.f246.8c on interface FastEthernet1/0.10.
Mar 22 15:33:41: DHCPD: Seeing if there is an internally specified pool class:
Mar 22 15:33:41:   DHCPD: htype 1 chaddr 001b.63f2.468c
Mar 22 15:33:41:   DHCPD: remote id 020a0000cf6050011000000a
Mar 22 15:33:41:   DHCPD: circuit id 00000000

...

Mar 22 15:34:02: DHCPD: DHCPREQUEST received from client 0100.1b63.f246.8c.
Mar 22 15:34:02: DHCPD: Finding a relay for client 0100.1b63.f246.8c on interface FastEthernet1/0.10.
Mar 22 15:34:02: DHCPD: Seeing if there is an internally specified pool class:
Mar 22 15:34:02:   DHCPD: htype 1 chaddr 001b.63f2.468c
Mar 22 15:34:02:   DHCPD: remote id 020a0000cf6050011000000a
Mar 22 15:34:02:   DHCPD: circuit id 00000000

Then it will repeat and repeat for this MAC. Any reason why the router is not assigning an IP to it? It actually happens to some other MACs as well... They are from different vendors and located on different switches... I can't really find a pattern for this problem... The DHCP pool hasn't run out and it still has available IPs in it.

Thanks

6 Replies 6

cadet alain
Mentor
Mentor

Hi,

Can you post following:

- sh ip dhcp pool

-sh ip dhcp binding

-sh run int f1/0.10

Regards.

Alain.

Don't forget to rate helpful posts.

Hi Alain, thanks for quick reply. The followings contain the output that you required. I hided the prefix of the IP with a.b.c. Thanks!

interface FastEthernet1/0.10
description : DHCP for EXHIBITION VLAN
encapsulation dot1Q 10
ip address a.b.c.1 255.255.255.128
no ip redirects
no ip unreachables
no ip proxy-arp
end
!

r#sh ip dhcp pool

Pool EXHIBIT :
Utilization mark (high/low)    : 100 / 0
Subnet size (first/next)       : 0 / 0
Total addresses                : 126
Leased addresses               : 47
Pending event                  : none
1 subnet is currently in the pool :
Current index        IP address range                    Leased addresses
a.b.c.118        a.b.c.1      - a.b.c.126     47
!

#sh run | in/be dhcp
no ip dhcp use vrf connected
ip dhcp excluded-address a.b.c.1 a.b.c.11
ip dhcp excluded-address a.b.c.126
ip dhcp excluded-address a.b.c.100 a.b.c.101
ip dhcp excluded-address a.b.c.51
ip dhcp pool EXHIBIT

   network a.b.c.0 255.255.255.128
   default-router a.b.c.1
   dns-server 207.172.3.8 207.172.3.9
   domain-name xyz.com

!

#sh ip dhcp binding
Bindings from all pools not associated with VRF:
IP address          Client-ID/              Lease expiration        Type
                    Hardware address/
                    User name
a.b.c.19        0168.7f74.6260.9b       Mar 23 2011 01:56 PM    Automatic
a.b.c.52        0100.4854.897d.17       Mar 23 2011 12:53 PM    Automatic
a.b.c.56        0100.4063.e7b5.b2       Mar 23 2011 03:33 PM    Automatic
a.b.c.57        0100.1b63.f246.8c       Mar 23 2011 03:34 PM    Automatic
a.b.c.68        015c.5948.0b97.d6       Mar 22 2011 05:59 PM    Automatic
a.b.c.69        0168.7f74.626d.67       Mar 23 2011 07:07 AM    Automatic
a.b.c.70        0198.fc11.5027.1d       Mar 22 2011 07:04 PM    Automatic
a.b.c.71        01dc.2b61.04ba.af       Mar 22 2011 10:26 PM    Automatic
a.b.c.72        017c.c537.58e6.64       Mar 22 2011 08:37 PM    Automatic
a.b.c.73        017c.6d62.3303.57       Mar 23 2011 03:54 AM    Automatic
a.b.c.74        0124.ab81.cda4.68       Mar 23 2011 05:01 AM    Automatic
a.b.c.75        0100.1e52.8f11.a5       Mar 23 2011 02:47 PM    Automatic
a.b.c.76        0100.264a.5fc8.e3       Mar 23 2011 07:13 AM    Automatic
a.b.c.77        017c.6d62.38cd.40       Mar 23 2011 02:06 PM    Automatic
a.b.c.78        0100.1d4f.f647.79       Mar 23 2011 02:37 PM    Automatic
a.b.c.79        0100.26b0.8637.3d       Mar 23 2011 01:16 PM    Automatic
a.b.c.81        0130.694b.e9de.82       Mar 23 2011 03:19 PM    Automatic
a.b.c.82        0100.21e9.6864.80       Mar 23 2011 12:04 PM    Automatic
a.b.c.83        0124.ab81.63e6.b5       Mar 23 2011 09:38 AM    Automatic
a.b.c.84        0100.16b6.0455.c2       Mar 23 2011 09:42 AM    Automatic
a.b.c.85        0100.1302.4c96.9e       Mar 23 2011 09:49 AM    Automatic
a.b.c.86        0140.a6d9.741c.e0       Mar 23 2011 12:12 PM    Automatic
a.b.c.87        0100.264a.b8e9.50       Mar 23 2011 10:16 AM    Automatic
a.b.c.88        0140.a6d9.4911.67       Mar 23 2011 03:19 PM    Automatic
a.b.c.89        013c.7437.1e32.96       Mar 23 2011 10:27 AM    Automatic
a.b.c.90        01d8.3062.689c.4b       Mar 23 2011 11:55 AM    Automatic
a.b.c.91        0158.946b.4df8.bc       Mar 23 2011 10:49 AM    Automatic
a.b.c.92        0100.2215.7368.26       Mar 23 2011 10:23 AM    Automatic
a.b.c.93        0100.23df.76ea.90       Mar 23 2011 02:33 PM    Automatic
a.b.c.94        0124.ab81.708d.83       Mar 23 2011 03:58 PM    Automatic
a.b.c.95        0100.1cb3.163d.5a       Mar 23 2011 03:13 PM    Automatic
a.b.c.96        01cc.08e0.2aeb.96       Mar 23 2011 01:27 PM    Automatic
a.b.c.97        0188.c663.d0d0.55       Mar 23 2011 01:57 PM    Automatic
a.b.c.98        0100.1b77.08bb.89       Mar 23 2011 01:15 PM    Automatic
a.b.c.99        0100.1ec2.47d7.19       Mar 23 2011 12:43 PM    Automatic
a.b.c.102       0100.1310.8e74.78       Mar 23 2011 12:41 PM    Automatic
a.b.c.103       0100.24d6.58b0.82       Mar 23 2011 01:44 PM    Automatic
a.b.c.104       0100.2608.7df2.68       Mar 23 2011 03:23 PM    Automatic
a.b.c.106       01c8.bcc8.1a86.41       Mar 23 2011 03:56 PM    Automatic
a.b.c.107       01a4.6706.1e54.94       Mar 23 2011 04:08 PM    Automatic
a.b.c.108       017c.c537.46ac.0e       Mar 23 2011 02:41 PM    Automatic
a.b.c.111       0100.037f.0ea2.19       Mar 23 2011 02:47 PM    Automatic
a.b.c.112       01d8.3062.75c5.9c       Mar 23 2011 03:33 PM    Automatic
a.b.c.113       0021.9116.449e          Mar 23 2011 03:36 PM    Automatic
a.b.c.114       0100.1ff3.46d9.a9       Mar 23 2011 03:40 PM    Automatic
a.b.c.116       0104.1e64.4a0d.a3       Mar 23 2011 04:21 PM    Automatic
a.b.c.117       0190.27e4.4ae8.94       Mar 23 2011 04:24 PM    Automatic


Thanks!

Hi,

The router gave an IP to this client

a.b.c.57        0100.1b63.f246.8c       Mar 23 2011 03:34 PM    Automatic

Regards.

Alain

Don't forget to rate helpful posts.

hi,

try adding this and test again.

interface FastEthernet1/0.10

ip helper-address a.b.c.1

add "ip helper-address a.b.c.1" will cause loop

and repeat more

also trager new error message

  • %IP-3-LOOPPAK: Looping packet detected and dropped -
  •   DHCPD: too many hops.

Sounds like some compability issue. As when 1 single client have this issue, other client getting ip normal at same time.

the error MAC address for my case is.

DHCPD: DHCPREQUEST received from client 01ec.55f9.c4cb.f4.

DHCPD: Finding a relay for client 01ec.55f9.c4cb.f4 on interface FastEthernet0/0/0.

DHCPD: Seeing if there is an internally specified pool class:

  DHCPD: htype 1 chaddr ec55.f9c4.cbf4

  DHCPD: remote id 020a0000c0a8010100000000

  DHCPD: circuit id 00000000


MAC addressEC55F9
CompanyHon Hai Precision Ind. Co.,Ltd.

Not sure what OS running on the client side.

tried change few DHCP attributes not help

ip dhcp ping packets 3 (default 2)

ip dhcp ping timeout 100 (default 500ms)

ip dhcp-server query lease retries 3 (default 2

ip dhcp-server query lease timeout 2

Router IOS sh ver

Cisco IOS Software, 2800 Software (C2800NM-ADVENTERPRISEK9-M), Version 12.4(24)T6, RELEASE SOFTWARE (fc2)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2011 by Cisco Systems, Inc.

Compiled Tue 23-Aug-11 01:30 by prod_rel_team

ROM: System Bootstrap, Version 12.3(8r)T7, RELEASE SOFTWARE (fc1)

DAICATAI18
Beginner
Beginner

I have the same error, how to fix it, please help me

So many dhcp request

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