Managing Cisco DHCP Client Identifier

In scenarios where Internet access is provided by cable providers or local vendors, generally the IP address assigned to Cisco CPE at home is via DHCP. By default Cisco Router is assigned IP address by DHCP on its Client ID.The Client ID has the format of “Cisco-MAC address ”. However, this becomes a cumbersome job at times for Internet provider and customer to manage Client ID or perform troubleshooting on the same. Cisco has devised a solution to this problem. It has provision to replace Client ID with MAC address of DHCP Client. Now let’s see how this can be done –

1^st, we see the mac address of DHCP Client(Cisco Router at Customer end) –

Now , we enable DHCP debugging on Cisco Router to view how DHCP communication between Client and server happens –

Next , configure Client Router Interface Fa0/0 to get IP address through DHCP –

Debug displays below output –

As shown above , Client ID of Cisco Router is cisco-c200.10fc.0000-Fa0/0.

Now configure Router to use mac address as the Clinet ID –

Now we can see Cisco Router has been assigned IP address with MAC address as Client ID.

ABOUT THE AUTHOR

Rashmi Bhardwaj

I am here to share my knowledge and experience in the field of networking with the goal being – “The more you share, the more you learn.”

I am a biotechnologist by qualification and a Network Enthusiast by interest. I developed interest in networking being in the company of a passionate Network Professional, my husband.

I am a strong believer of the fact that “learning is a constant process of discovering yourself.”
– Rashmi Bhardwaj (Author/Editor)