MicroLegend SS7 Routing Systems
SCCP Relay System
Overview
As the number of wireless subscribers continues to increase dramatically each year, wireless carriers
are facing the challenges that rapid growth creates. One such challenge is the migration from a single
Home Location Register (HLR) to a multiple HLR topology.
The HLR, which stores critical identification and subscription information about each customer, can
become a network bottleneck either because of the sheer number of subscribers contained in the data-
base, or because of the number of SS7 messages arriving at the HLR. A single HLR also poses a risk to
the overall survivability of the entire wireless service.
Deploying additional HLRs to a wireless network presents significant challenges. However. If the existing
routing algorithms are simply extended, then every Mobile Switching Center (MSC) and Signal Transfer
Point (STP) on the network is affected, and the routing table management becomes extremely complicated
and error prone.
To address the challenge of multiple HLR deployment, PTI's Signaling Systems Group developed a central-
ized SS7 message routing system called the MicroLegend
TM
SCCP Relay. The SCCP Relay supports all
of the necessary GSM SS7 message routing tables to allow wireless carriers to easily expand to a multiple
HLR topology.
Benefits
Reduces operations and maintenance overhead.
The routing information for each subscriber is centralized in the SCCP Relays, rather than being distrib-
uted among all of the STPs and MSCs. This simplifies the process of entering and maintaining the
information. Troubleshooting routing problems is also greatly simplified.
Improves overall network reliability.
The SCCP Relay supports the automatic routing of SS7 messages to a backup HLR in the event of a
Primary HLR failure. This feature enables the multiple HLRs to be configured in a redundant fashion,
ensuring that the service remains available even in the case of an HLR failure.
Automatic and immediate provisioning.
The provisioning data in the SCCP Relays can be automatically updated when service subscriber data is
entered into one of the HLRs. Network routing changes are then effective immediately.
Flexible connection options.
The SCCP Relay supports all types of SS7 links. It can operate as an STP, connecting directly to mobile
switching centers (MSCs), Home Location Registers (HLRs) and other end nodes. Alternatively, it can be
configured as an adjunct to an existing Signal Transfer Points (STP).
Scalable from four to over seventy SS7 links.
The SCCP Relay, with its distributed processor architecture, can scale up smoothly as the volume of
SS7 message traffic increases. From the cost-effective three slot version to the fully-loaded twenty slot
version, the MicroLegend platform offers a full range of configurations.
Proven SS7 interface for both ANSI and ITU-T networks.
The MicroLegend SS7 stack, upon which the SCCP Relay is built, has been deployed in numerous
configurations in networks all over the world, including the United States, Canada, Brazil and China.
The
SCCP Relay
System
simplifies the
deployment
of multiple
Home
Location
Registers
in a GSM
network.
Mated pair deployment supported, with automatic re-routing of message traffic.
The SCCP Relay is deployed in a mated pair configuration, with each link fully redundant. Each system
is capable of handling the full load of network traffic. In the event of a link or route failure, the messages
will be automatically re-routed without losing any information.
NEBS compatible equipment.
The MicroLegend SCCP Relay has been engineered for NEBS compatibility. All of the strenuous NEBS
requirements, including electrical, physical and mechanical issues, were incorporated into the design.
Comprehensive 7 x 24 support package.
PTI supports all of its equipment 24 hours a day, 7 days a week to ensure that the system continues to
perform reliably. Support is provided directly by the engineering team that developed the platform and the
application. Using a dial-in connection, PTI can perform system diagnosis and software updating with
maximum efficiency.
Functional Description
The MicroLegend SCCP Relay provides a central point for GTT provisioning and execution on behalf of an
entire GSM carrier's SS7 network. The SCCP Relay performs GTT capabilities for both the IMSI and
MSISDN Address types, eliminating the need to continually manage the routing tables within STPs or
MSCs.
The SCCP Relay is deployed as a redundant pair of
signaling nodes that can be accessed via SS7 links
connected to currently deployed STPs or can be utilized
as the STPs themselves.
Where STPs previously have been deployed, the SCCP
messages are routed to the Relay (partial GTT) by the
STP/MSC. The SCCP Relay then performs translation
(either full or partial, depending on the provisioned
data), and routes the message back to the network to be
forwarded to the destination HLR.
The SCCP Relay can also perform the MTP routing that
is the function of the STPs. This capability enables the
SCCP Relay to be deployed in networks without STPs.
SCCP Relay Software Architecture
The SCCP Relay System is a solution built upon the MicroLegend SS7 Signaling Platform. At the heart of
the SCCP Relay is an object oriented SS7 Stack that provides all the basic capabilities of a Signaling
Transfer Point (STP). The SS7 stack includes MTP and SCCP layer functionality.
A configurable GTT application also runs on the MicroLegend platform, along with user interface, log file
and SCSI Disk processes. The GTT process supports both IMSI and MSISDN numbering formats. As a
group, these processes are referred to as the SS7 Message Handler Unit (MHU). The SS7 MHU termi-
nates the SS7 links, performs the GTT on incoming SS7 messages, and then re-routes the messages
back onto the SS7 network. To optimize its performance, the MHU runs on a real-time UNIX operating
system called VxWorks.
The system also includes an independent
Database Administration Unit (DAU), which
supports the provisioning and administration of
the GTT data. The DAU, which runs on the UNIX
operating system (AIX), includes a command
parser, database manager, and a SCSI disk
interface. The DAU and MHU communicate with
each other over 10BaseT Ethernet LAN. An
Ethernet WAN is used to connect the SCCP
Relays, to ensure that they remain synchro-
nized.
STP/MSC
MSC
HLR
GatewaySTP
STP/MSC
MicroLegend
SCCP Relay
System
MicroLegend
SCCP Relay
System
MicroLegend
SCCP Relay
System
MSC
HLR
Gateway STP
MicroLegend
SCCP Relay
System
The
International
Roaming
Signaling
Converter
application
supports
wireless
roaming
between
North
American and
other GSM
networks.
www
.pt.com
2000 Performance Technologies, Inc. All rights reserved. R507200
Performance Technologies, Inc.
315 Science Parkway
Rochester, New York 14620
Tel:
716-256-0200
Fax:
716-256-0791
Email:
sales@microlegend.com
Web:
http://www.pt.com
In addition to the software running on the DAU
and MHU, the SCCP Relay system incorporates a
graphical user interface program that can be
installed on the operation stations. This user
interface provides the ability to provision and view
the GTT data that resides on the DAU, as well as
view the log information collected about GTT
database transactions. The operation stations
connect to the SCCP Relay through a LAN or
WAN. Additionally, a custom interface to an
existing provisioning system can be developed to
provision and view the GTT database.
SCCP Relay Hardware Architecture
The MicroLegend
TM
platform, on which the SCCP
Relay System is built, is available in a variety of
configurations and sizes. The platform scales
smoothly from an economical system with only
four SS7 links to a fully loaded system with over
70 SS7 links. The basic hardware components of the SCCP Relay, regardless of the size and configura-
tion, are the same. The only differences between small systems and large systems are the number of
cards, and the size of the chassis itself.
The MHU is controlled by a System Controller card, based on a 200MHz PowerPC
TM
processor. This
processor controls the system level functions, including the TCP/IP port, the serial ports, and the SCSI
interface for the disk drive. It also provides control for two Link Interface cards, with up to four SS7 links
on each. As these Link Interface cards are added, every third card is a Link controller card, with its own
300 MHz PowerPC processor. This distributed processor architecture ensures that the SCCP Relay has
sufficient power to handle very large numbers of subscribers (over 5,000,000).
Each Link Interface card can support as many
as four SS7 Links. The V.35 cards provide four
SS7 ports, while the E1 and T1 versions provide
two SS7 ports each.
The DAU runs in its own independent chassis,
with its own independent fan, SCSI disk and
power supply. It uses the same System Control-
ler card as the MHU, without the need for any
Link Interface or Link Controller cards.
The MicroLegend
TM
SCCP Relay enables GSM
network operators to control the growth and
evolution of their networks. The SCCP Relay
manages the complex GTT processes that are
required as an operator deploys multiple HLRs.
With MicroLegend's proven SS7 stack, and a
standards-based distributed processor computer
platform, the SCCP Relay offers powerful SS7
routing capabilities for GSM networks worldwide.
CommandParser
SCSI
Control
GTT Application
MTP UI
SCSIControl
SS7
Stack
SCCP Layer
MTP Layer
SerialCable
Console
SCCP
Relay
DB AdminUnit
SS7 MsgHandler
10BaseT
Customer
Defined Admin
Interface
OpsS tation
Provisioning
UI
MateSR Sytem
SS7 Links
AIX
VxW orks
LogServer
DBManager
...
...
Fan
Disk(AIX)
Processor-SystemController
Power
Supply
Disk
(VxW orks)
Pr
ocessor
-SystemContr
oller
LinkInterfaceCar
d(4SS7links)
LinkInterfaceCar
d(4SS7links)
Pr
ocessor
-LinkContr
oller(4SS7links)
LinkInterfaceCar
d(4SS7links)
LinkInterfaceCar
d(4SS7links)
PowerSupply
PowerSupply
Fan
Database AdministrationUnit
10BaseT
Serial(Console)
10BaseT
Serial(Console)
Serial(Logs)
SS7MessageHandlingUnit
E1/T1/V.35
DCSupply
DCSupply
DCSupply
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