A circular node can be designed either with or without a head node. If it has a head node, start from the head node and traverse all the node directed by the link fields till you reach the head node.
If it has no head node, you will have address of any node. Start with that node and traverse till you reach the node in which you begin traversing.

CLL can be done for both singly and doubly linked lists,traversing begins at any node and follow the list in either direction until we return to the original node.