(July, 1998) : A good question. I think what you may have in mind
is more properly called an "association". An association is
a state that exists between peers who have authenticated (possibly mutually)
and established random cryptographic keys for the protection of messages between
them. An association has a lifetime, defined by policy.
The SECIOP protocol establishes an association between the peers and then protects
messages between them. The SECIOP protocol is security mechanism independent,
but carries more primitive messages for mechanisms such as Kerberos that "do
the hard work".