Applies only to FDDI lines.  ECHO LENGTH number of bytes of type
 ECHO DATA will be used to compose the next echo request frame which
 will be sent to the address specified by ECHO TARGET.  Count must be
 a decimal value from 0 to 4478.  The default ECHO LENGTH is 1.  ECHO
 LENGTH can be set in the volatile database, but it cannot be defined
 in the permanent database.