The SR OS supports both Option 61 (client ID) and Option 77 (user class) DHCP discovery options.
Option 61 provides the client ID; the serial ID of the chassis is used by default. Option 61 is used for DHCP server pool selection. By default, the chassis serial ID is sent in Option 61 with a type of 0. This option is configurable using the bof auto-boot [client-identifier {string | hex | chassis-mac}] command.
Option 77 provides the user class, describing what the device is and other information, such as the OS version. This option is set automatically, but can be removed using the BOF configuration. For example, the user can omit include-user-class in the BOF auto-boot configuration, to avoid sending Option 77.
For ZTP, the DHCP discovery message should be sent with Option 77; the following information is automatically configured:
platform;timos-release;ztp
For auto-provisioning, Option 77 should use the following information:
platform;timos-release;AP