1  –  DATA hex byte

 Applies only to FDDI lines.  ECHO LENGTH number of bytes of value
 ECHO DATA will be used to compose the next echo request frame which
 will be sent to the address specified by ECHO TARGET.  Hex_byte must
 be a string of exactly two hexadecimal digits.  The default ECHO DATA
 is 55.  ECHO DATA can be set in the volatile database, but it cannot
 be defined in the permanent database.

2  –  LENGTH count

 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.

3  –  TARGET address

 Applies only to FDDI lines.  Specifies the address to which the next
 echo request frame will be sent.  The default ECHO TARGET is
 00-00-00-00-00-00.  The ECHO TARGET can be set in the volatile
 database, but it cannot be defined in the permanent database.