The value to be used as the Authentication Key in Level 2
and Point-to-Point hello packets while transmitting,
whenever the corresponding instance of isisCircL2AuthType
has a value of plaintext or md5. A modification of the
corresponding instance of isisCircL2AuthType does not
modify the hwIsisCircL2TransPassword value.
Reading this object always results in an OCTET
STRING of length zero; authentication may not
be bypassed by reading the MIB object.