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Failure of Power Supply
Problem — Ensuring that the unit survives the loss of
one power supply and making it possible to replace a
failed power supply without affecting the availability of the
system.
Solution — The Intel NetStructure SIU520 SS7 signaling
gateway can be optionally configured with a redundant
and hot swappable power supply.
Details — Please refer to Intel NetStructure SIU520/Intel
NetStructure SG430 Hardware User Manual, Issue 3 to
obtain part numbers for redundant power supplies for the
SIU520.
Failure of Signaling Interface Unit
Problem — Since the SIU520 provides an SS7 interface
to a distributed application, it is usually deployed for
high-density service platforms. Should the SIU of a single
SIU-based system fail, many resources (telephony cir-
cuits to TCAP dialogues) would become unavailable and
would cause major service disruption.
Solution — A major feature of the SIU architecture is
that two units can be configured to operate as a single
entity, sharing the same local SS7 point code. In normal
operation, signaling can be shared between two units. In
the event of a failure, signaling is maintained by the
remaining unit.
Details — In a dual configuration, one unit is assigned
as SIUA, the other as SIUB. Under normal operation, the
application uses both the resources of SIUA and SIUB
(see Figure 5).
The distributed layer 4 management is achieved using a
LAN connection and allows SS7 messages for any trans-
action or call to be received by either unit, regardless of
the unit that is actually processing the call or transaction.
The distributed MTP3 functionality is achieved using a
specially configured inter-SIU link set, containing one or
more signaling links. Transmit messages from each SIU
are load shared between links that connect to the local
SIU, if these are available. If all local network-facing SS7
links have failed, transmit messages are relayed to the
Application Note Building Fault-tolerant SS7 Systems Using the Intel
®
NetStructure™ SIU520 SS7 Signaling Gateway
6
Figure 5. Dual SIU Architecture
API Layer/Ethernet Driver
MAP or INAP
or IS41
TCAP
SCCP
MTP Levels 1-3
ISUP TUP
API Layer/Ethernet Driver
TCAP
SCCP
MTP Levels 1-3
ISUP TUP
Distributed Layer 4
Management
Distributed MTP3
Management
Link Set
Application
SIUA SIUB
MAP or INAP
or IS41
Ethernet
Ethernet
SS7
SS7