Nortel Communication Server 1000 Manual page 70

70 Virtual Network Services in the UK with DASS2/DPNSS1 Bearers
Figure 11
MCDN/VNS with DPNSS1 node
•
If a congestion is encountered inside the VNS portion of the path, the
node behaves as an MCDN/MCDN tandem. The ISDN Drop Back
Busy (IDBB) and ISDN Off-Hook Queuing (IOHQ) are transmitted, so
that they may be applied further along the VNS portion of the path, or
at the tandem node.
•
If a congestion is encountered within the DPNSS1 network, the VNS
portion of the call is cleared and the disconnection is propagated back
to the originating side of the MCDN path. Neither Drop Back Busy nor
Off-Hook Queuing is activated at the tandem node, even if IDBB or
IOHQ are activated.
Figure 12
VNS with DPNSS1/DPNSS1 node
Hybrid Networks This scenario is considered as an MCDN/DPNSS1
gateway. The functionality is the same as for the Step Back on Congestion
feature, as documented in DPNSS1 (NN43001-572).
Figure 13
DPNSS1/VNS with DPNSS1 node
•
If a congestion is encountered inside the VNS portion of the path, the
VNS portion of the call is cleared and the disconnection is propagated
Nortel Communication Server 1000
DASS2 Fundamentals
NN43001-571 04.01 4 June 2010
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