TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
An Implementation of the
Server Cache Synchronization
Protocol (SCSP)
Jose Costa Requena
Raimo Kantola
jose@tct.hut.fi
Raimo.Kantola@hut.fi
SPIE Conference
Boston, September 1999
TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
Contents
Problem Definition
SCSP as Solution
Protocol Specifications (RFC 2334)
Basic Features
Our Implementation
Modules in the implementation
Interaction between modules
Applications
GLP Implementation
GLP Interoperability : IP
GSTN
Conclusions and Future Work
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TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
Problem Definition
Directories are key component for IP based communications networks.
The large amount of data is stored in distributed databases the changes
must be updated among the entities related to the same service.
Subscriber
& User
Database
Subscription &
Service Profile
Management
Service
Provider
User Data
Billing Managemen
Usage
t
Usage
Network
Operator
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Billing
Value Added
Service Provider
Usage
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TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
Problem Definition
Directories hold static and dynamic information about the users and
the services themselves.
Services need to interoperate across administrative boundaries and
directories need to be accessible from everywhere.
IP Telephony
Signaling server
Zone B
Database
Zone B
Zone A
Database
Zone A
IP Telephony
Signaling server
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Our Solution
TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
The SCSP solves the problem of data replication/synchronisation
in a group of distributed servers without heavy overheads like
in the actual tight consistency techniques.
IP Telephony
Signaling server
SCSP
SCSP
IP Telephony
Signaling server
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TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
SCSP Specifications
The SCSP elements
Server Group (SG). Is the group of servers to be synchronised.
Local Server (LS). Is the server under scrutiny.
Direct Connected Server (DCS). Is the server directly connected to LS.
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TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
SCSP Specifications
The SCSP is based on three sub-protocols.
Hello Protocol is used to
know whether the connection
between servers is available.
Cache State Update performs a
flooding mechanism where any
new information in one of the
servers is dynamically updated in
all other servers.
Cache Alignment Protocol allows a
server to synchronise its entire data:
exchanging short summaries from the
entire database, comparing of
summaries to know the newest data,
requesting the entire information to
the server which provided the
summary with the newest data
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SCSP Modules
TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
SCSP Algorithms module
User Interface
Databases module
DATA BASES
User
Interface
SCSP
OBJECT
TABLES
Communications module (TCP/IP)
Auto Configuration System
Object Tables
User
Interface
Auto Config
System
Auto Config.
System
TCP/IP
SCSP
TCP/IP
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DATA BASES
OBJECT
TABLES
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Modules Interaction
TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
Server i
Hello Packets
HFSM
HFSM
Server i+1
Cache Alignment packets
CAFSM
CAFSM
CLIENT USE
SCSP
PRIMITIVES
CLIENT USE
SCSP
PRIMITIVES
Cache State Update
packets
CSU
CSU
SCSP
SCSP
t
t
t
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TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
Applications
SCSP for data replication in the GLP Implementation
ITAD 3
LS GLP
ITAD 1
GLP
LS
SCSP
database
SCSP
database
ITAD 2
GLP
LS
SCSP
database
GLP: Gateway Location Protocol
LS: Location Server
ITAD: Internet Telephony Administrative Domain
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TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
Applications
SCSP as the common element for a global GLP
Implementation and interoperability between GSTN and IP
GLP
Database
SCSP
GATEKEEPER
SS7 PSTN
GATEKEEPER
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GLP
Database
SCSP
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Applications
TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
SCSP as basic component to allow interoperability between IN
databases and user information directories in IP
Databases
SCSP
GLP
Database
GLP
Database
SCSP
SCSP
SCP
GATEKEEPER
GATEKEEPER
IP
SS7 PSTN or GSM
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Conclusions
TEKNILLINEN KORKEAKOULU
HELSINKI UNIVERSITY OF
TECHNOLOGY
NOWADAYS ...
SCSP has been developed in a modular way to provide a generic
service to be used by other systems for their data replication.
SCSP follows a building-block design to permit its integration with
other mechanisms to achieve an efficient overall behaviour.
In terms of overall positioning we consider the SCSP as a key tool
for the future services globalisation.
NEXT...
SCSP could become a key
component of the emerging
directory enabled
networks.
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We continue working on
future applications of the
SCSP as the generic
component to allow
interoperability between IN
and IP services.
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