Point-To-Multipoint Calls; Displaying Connections; Signaling Sequences - 3Com CoreBuilder 7000 Operation Manual

Point-to-Multipoint
Calls
Displaying
Connections

Signaling Sequences

A point-to-multipoint call is a collection of associated ATM VC or VP links,
with associated endpoint nodes. A connection is defined as a section of a
call. A point-to-multipoint call has the following properties:


The source endpoint serves as the root in a simple tree topology.
When this link node sends information, all of the remaining nodes on
the call receive copies of the information.


Data flows only from the root to the destination nodes.


There is no data flow between the destination nodes.
For information about displaying port connections see "Example - Display
Info for a Specific SVC Call" on page 170 in the Management Guide.
Point-to-Point Connection
Figure 38 shows the sequence of signaling messages for setting up a
point-to-point external link (connection) by signaling.
From the Calling Party to Switch: The calling edge device initiates the
establishment of a connection by sending a SETUP message that contains
the connection characteristics except for VPI/VCI. If the switch can
provide the requested service and finds the route to the destination, it
allocates a value of VPI/VCI, optionally answers with CALL PROCEEDING
and passes the call through to the destination end station. If the receiving
side accepts the call, the switch informs the sender by sending a
CONNECT message. The sender may then acknowledge this by
CONNECT ACKNOWLEDGE. This completes the connection setup
sequence and the call is now in ACTIVE state, that is, data cells may be
transferred from source to destination.
From the Switch to the Called Party: The switch sends a SETUP request to
the receiving edge device after having allocated resources for the call
(VPI/VCI, QOS, traffic parameters). The receiving edge device carries out a
compatibility check by comparing the address information, QOS
parameters, and traffic parameters in the SETUP message. If the check
passes and the connection specifications are accepted, the receiving edge
device replies with a CALL PROCEEDING or CONNECT. The switch then
acknowledges the CONNECT by CONNECT ACK and the connection then
transfers into ACTIVE state.
The release procedures are similar to the establishment procedures.
Signaling — External Links 109