The SCA Control Program (SCACP) utility is designed to monitor
    and manage cluster communications. It is derived from the
    Systems Communications Architecture (SCA), which defines the
    communications mechanisms that allow nodes in an OpenVMS Cluster
    system to cooperate.

    SCA does the following:

    o  Governs the sharing of data between resources at the nodes

    o  Binds together System Applications (SYSAPs) that run on
       different Alpha and VAX computers

    Historically, LAN cluster port information has been available
    only in the System Dump Analyzer (SDA) utility and by using
    the Availability Manager management tool. The ability to
    start and stop PEdriver on a LAN device was provided by
    SYS$EXAMPLES:SYS$LAVC_START_BUS.EXE and SYS$LAVC_STOP_BUS.EXE.
    No way existed to prioritize use of LAN devices or individual
    channels.

    SCACP provides an alternative method of collecting cluster
    management data and exercising management control over cluster
    communications. OpenVMS Version 7.3 introduced SCACP's ability to
    manage SCA use of LAN paths. Beginning with OpenVMS Version 7.3-
    1, you can use SCACP to manage all OpenVMS Cluster interconnects.

    Starting with OpenVMS Version 8.4, OpenVMS is enhanced to use IP
    (Internet Protocol) for cluster communications. OpenVMS cluster
    over IP (also referred to as IP Cluster Interconnect) is the
    ability to use IP stacks for cluster communications. PEdriver
    which implements the cluster communication protocol uses UDP
    (User datagram protocol).

    Format

      RUN SYS$SYSTEM:SCACP

    To invoke SCACP, enter the following command at the DCL prompt:

    $ RUN SYS$SYSTEM:SCACP

    SCACP displays the following prompt, at which you can enter SCACP
    commands using the standard rules of DCL syntax:

    SCACP>

    To exit SCACP and return to the DCL command level, enter the EXIT
    command at the SCACP> prompt or press Ctrl/Z.