Summary

trouble shooting : Cisco router DHCP No option 125

Top:
Configure DHCP on cisco router 2811 to assign italkBB: Cisco SPA 1202 a static IP.
Step 1, start dhcp service by command:
service dhcp


Step 2, Start cisco debug tool to check DHCP request by commands:
debug ip dhcp server packet
terminal monitor
Debug info :
DHCPD: DHCPREQUEST received from client 0100.1c23.3541.98


Step 3, configure DHCP
ip dhcp pool ItalkBB
  host 10.0.0.127 255.255.255.0 //no mask configured, IP’s class mask assigned
  client-identifier  0100.1c23.3541
  default-router 10.10.10.99


But italkBB can’t get IP from Cisco router 2811,Error msg in debug info:
DHCPD: client’s VPN is .
DHCPD: No option 125
As checked DHCPREQUEST in debug info:
DHCPD: DHCPREQUEST received from client 0100.1c23.3541.98


Step 4,Just change client-identifier  by command :
client-identifier  0100.1c23.3541.98


ItalkBB works.


Another case from blog : Embedded System Testing Blog
“No option 125” error from Cisco DHCP server
Problem : “No option 125” error was continuosly repeating and DHCP Server on Cisco was not offering any IP address to the clients.
 =========================================
Jul 24 05:36:21.147: DHCPD: No option 125
Jul 24 05:36:21.147: DHCPD: DHCPDISCOVER received from client 001e.e5dc.ae.c0 on interface GigabitEthernet0/1.
Jul 24 05:36:30.707: DHCPD: client’s VPN is .
Jul 24 05:36:30.707: DHCPD: No option 125
 ========================================
Solution: After some debugging, came to know that the problem is with the subnet configured on the Gigabit ethernet. For DHCP Server to offer the ipa ddress atleast one interface should be in the same network as the pool is defined. Once the subnet is properly configured, the Server started replying.


The basic config file  for configuring DHCP SERVER on Cisco router
service dhcp
no ip dhcp conflict logging
!

ip dhcp pool 1
 network 11.0.0.0 255.0.0.0
 default-router 11.0.0.1
!
interface GigabitEthernet0/1
 ip address 11.0.0.1 255.0.0.0

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