Expand Configuration and Management Manual (G06.24+)

Subsystem Description
Expand Configuration and Management Manual—523347-008
18-60
Expand-over-ATM Connection Establishment
SVC Connections
An SVC is a dynamically established virtual circuit. Each SVC is automatically
assigned an SVC name by the ATM3SA when the circuit is established. An SVC is
described by the SVC object, which is subordinate to the LINE object.
An Expand-over-ATM line-handler process that uses an SVC connection performs
addressing by specifying the following information:
•
The ATM address configured for the ATM line used by the remote Expand-over-
ATM line-handler process.
•
The selector bytes for the ATM lines used by the Expand-over-ATM line-handler
processes on both the local and remote systems.
An ATM line is associated with a 20-byte hexadecimal ATM address. The last
(rightmost) byte of the ATM address is called the selector byte. The selector byte is
used by the ATM subsystem to direct incoming call requests to the correct ATM
subsystem client. An SVC is established when the system with the higher system
number sends an SVC call request to the system with the lower system number.
ATMSAP Connections
The SLSA ATM protocol direct service access point (ATMSAP) connection offers an
ATM Native Mode network interconnect support similar to that offered by the PVC
object within the ATM subsystem. Expand issues native mode frames directly to the
ATM product via a LIF associated with an ATMSAP object.
An ATMSAP object can be configured to interface to a permanent virtual circuit (PVC)
object. A LIF object must be associated with the ATMSAP object in order to provide
host access to the ATMSAP object. A PVC connection provides a static permanent
virtual circuit. A PVC is defined with a VCC attribute for the ATMSAP. The VCC is
comprised of a VPI, VCI pair.
LIF objects are associated with either a CIP object, a LEC object, or an ATMSAP
object. No objects can be configured subordinate to an ATMSAP object.
Expand-over-ATM Connection Establishment
When the system is started up, the Expand-over-ATM line-handler process waits for
the ATM line it will use and the QIO Monitor process (QIOMON) to start. The ATM line
and the QIOMON process must be running before Expand-over-ATM lines can be
started. Next, the Expand-over-ATM line-handler process binds to the ATM subsystem.
Once the Expand-over-ATM line-handler process has successfully bound to the ATM
line, it attempts to establish a connection to the remote Expand-over-ATM line-handler
process. There are two ways the Expand-over-ATM line-handler process can attempt
to establish a connection: active connect or passive connect.
Note. Selector bytes must be coordinated among ATM clients using the same ATM line.