Sub-option 1: Circuit ID
The Circuit ID (CID) identifies the circuit or port from which a DHCP client request was sent. The ICX switch uses this information to relay DHCP responses back to the proper circuit; for example, the port number on which the DHCP client request packet was received.
RUCKUS ICX devices support the general CID packet format. This simple format encodes the CID type, actual information length, VLAN ID, slot number, and port number. This format is compatible with the format used by other vendors’ devices. The following figure illustrates the general CID packet format.
