The length (i.e. number of octets) of a Peer (Key Server) ID.
If no length is given (i.e. it has a value of 0), the default
length of its cgmGdoiCoopPeerIdType should be used as long as it
is not reprsented by an ASCII string. If the value has a type
that is represented by an ASCII string, a length MUST be
included. If the length given is not 0, it should match the
'SRC ID Data Len' and 'DST ID Data Len' fields sent in the KEK
and TEK payloads for GDOI GROUPKEY-PULL and GROUPKEY-PUSH
exchanges.