If user does not configure the remote-id of pppoe-ia explicitly on a port, then the user can self-designed format to generate the remote-id, the format options include mac,hostname and self-designed string, the remoteId may be only one or any combination of them, and is strictly generated according to the sequence of format options, the maximum length of self-designed striing is 64. If user input the NULL, then delete the last configuration. For example, if select hostname,mac,and string 'str' format, the user input the string like as 'hostname mac string str'.