3.1.5.5.1.1 DisconnectInfo
A receiving node MUST process a Disconnect message as follows:
If the neighbor connection is not in the Connected state, the connection MUST be aborted.
If the DisconnectReason identified in the message is illegal, the connection MUST be aborted.
The receiving node SHOULD cache the Referrals received in the message in its Referral cache.
The receiving node MUST close the connection.