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User Receiving Congestion Control Message with "Receiver
Ready"
If the far end user receives a Congestion Control message with Congestion
Level IE set to "Receiver Ready", the far end user resumes sending User
Information messages to the remote end user.
The cause value that is received in the Q.931 Congestion Control message
with "Receiver Not Ready" is the same cause value that is sent in
the Q.931 Congestion Control message with "Receiver Ready"
For example, if the near end user is congested, the near end user sends a
Q.931 Congestion Control message with "Receiver Not Ready" and a cause
value of 42 "switch equipment congestion" to the near end switch. Once the
near end switch receives the Q.931 Congestion Control message, it generates
and sends an SCCP DT1 message with a Congestion Control Parameter
Code of #F1 and a Congestion Level of "Receiver Not Ready" to the far end
switch. When the far end receives the SCCP DT1 message, it builds and
sends a Q.931 Congestion Control message with "Receiver Not Ready" and
a cause value of 42 "switch equipment congestion" to the far end user.
When the near end congestion is cleared, the near end user sends a Q.931
Congestion Control message with "Receiver Ready" to the near end switch.
Once the near end switch receives the Q.931 Congestion Control message, it
generates and sends an SCCP DT1 message with a Congestion Control
Parameter Code of #F1 and a Congestion Level of "Receiver Ready" to the
far end switch. When the far end receives the SCCP DT1 message, it builds
and sends a Q.931 Congestion Control message with "Receiver Ready" and
a cause value of 42 "switch equipment congestion" to the far end user
regardless if a cause value is received or a different cause value is received
in the Q.931 Congestion Control message with "Receiver Ready".
Network Flow Control
Flow control of User Information messages at the DMS-250 switch is done
using the following algorithm:
burst parameter X, initialized to office parameter UUS_BURST
User Information message counter N, initialized to X,
the replenishment parameter Y, initialized to X/2,
the DMS-250 switch timer TUUS, which is 10 seconds.
A burst capability of sending N User Information messages is immediately
available to each PRI agent in each direction, . The value of N is
decremented by one for each User Information message sent by the user and
incremented by Y at regular interval of TUUS subject to the limitation that
Digital Switching Systems DMS-250 ISDN Reference Manual MWC14 (CSP14)
NCAUUI 15-17
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