DHCP option 60 : Vendor Class Identifier (VCI)
DHCP option 60 : Vendor Class Identifier (VCI)
DHCP option 60 is a standard option in the DHCP protocol that allows a DHCP client to identify the type of device it is, to the DHCP server. It is also known as the Vendor Class Identifier (VCI).
When a DHCP client requests an IP address from a DHCP server, it sends a DHCP discover message that includes its MAC address and other information. The DHCP server uses this information to assign an IP address to the client. However, in some cases, the DHCP server needs to know the type of device that is making the request in order to assign an appropriate IP address or provide specific configuration options.
This is where DHCP option 60 comes in. When a DHCP client sends a DHCP discover message, it can include an option 60 field that specifies the vendor class identifier for the device. This allows the DHCP server to identify the type of device and provide the appropriate IP address and configuration options.
If the access point is ordered with the Service Provider option (AIR-OPT60-DHCP selected), the VCI string for that access point is different than those listed above. The VCI string includes the Service Provider option. For example, a Cisco Access point 1240 with this option returns this VCI string: Cisco AP c1240-ServiceProvider.
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| Fig 1.1- DHCP Option 60 |
If the Cisco AP runs 7.0.116.0 or above (12.4 (23c) JA2 or above) and if a bootloader environmental variable (env_vars) named DHCP_OPTION_60 exists in flash, the value is appended to the VCI. If you order a Cisco AP with the Service Provider option, it will (by default) include the -Service Provider suffix; however, you can include other values into DHCP_OPTION_60 as well.
So we can say that some Internet Service Providers (ISPs) use DHCP option 60 to identify the type of modem or router that is requesting an IP address. This allows the ISP to provide specific configuration settings for the device and ensure that it is properly connected to the network.
Exploring the Benefits of DHCP Option 60 in Cisco DNA Center
In the context of Cisco DNA Center, DHCP option 60 is used to help automate the process of onboarding and provisioning network devices. Specifically, when a Cisco device (wireless access point) is first powered on and connects to the network, it will send a DHCP discover message to request an IP address from the DHCP server.
If the DHCP server is configured to recognize the device's vendor class identifier (VCI) in the DHCP option 60 field, it can provide the device with an IP address and other configuration parameters that are specific to that device type. This can include information such as the management IP address for Cisco DNA Center, the device's hostname, and other configuration settings.
By using DHCP option 60 in this way, Cisco DNA Center can automatically detect when new devices are added to the network and initiate the onboarding process without the need for manual intervention. This can help to streamline network operations and reduce the potential for human error in the device provisioning process.
Basic Configuration
ip dhcp pool NETDNA
network 10.10.10.0 255.255.255.0
default-router 10.10.10.1
option 43 hex f104.0a0a.0a01
option 60 ascii "Cisco AP c1240"
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