Rational
The MTELGateway
operates from the MTEL Offices and operates on redundant hardware with
independent WBB Routers, workstations and power sources.
Whilst the systems are entirely independent the WBB
routers communicates to the same Telstra cell tower. The WBB router however
is backed up by a VPN connection to Sydney which provides the same WBB
connectivity through the Sydney Gateway.
To make the system more resilient, the MTELGateway
should be duplicated in a independent geographical location to avoid natural
disaster, major power interruption and any other potential threat which
would disable the system.
The following proposal is to duplicate the
MTELGateway in a secure DCS location. Not only will this provide the
redundancy necessary, it will also significantly improve message throughput
and latency into the single seconds for an end to end message delivery.
Equipment
The MTELGateway contains several applications
running in a Windows environment. These applications operate from
configuration databases in Access format. The hardware contains workstations
running Windows 7 64 bit dedicated to the gateway. There are WBB routers,
SMS gateways and cable and ADSL2 internet connections. Connection to the
internet is important as it is the main form of error reporting to Comms
centres.
The SMS gateway creates urgent alerts and daily
summary reports to a mobile phone.
All hardware devices and the applications
intercommunicate using sockets, therefore the MTEL Gateway and database can
run in virtual environments pending sociability testing with the operating
system. Currently it has been proven to run on Windows 7 64bit,
Windows 2008 R2 Enterprise.
Operation
MTELRelay in the remote Comms centres opens a TCP connection to the MTELGateway
in the DMZ via the Direct Hub. The Direct Hub has a fixed port for
listening. As each Relay makes a request to connect, the Hub accepts with a
temporary port number. This frees up the fixed port for another connection.
The Direct Hub then can handle many simultaneous TCP connections. This is
important as the connection will last until the picocell has been sent the
message and an acknowledgement has been received. This connection could last
up to 5 seconds, though it is generally 2-3 seconds.
If the listener socket can not be opened the Relay
returns the message to MTELPage to send it locally via dialup into the PET
Gateway at MTEL. (see the purple arrows on the diagram below)
There is a WBB Link between MTELGateway at DCS and
MTELGateway at MTEL. The link performs the same function as the redundant
systems in MTEL. If the WBB fails at DCS it sets up an immediate changeover
to the MTEL based system.
If this link breaks then the systems fall back to a
default setting of Master/Slave wherein the designated Master assumes control of the
WBB and slaves release the WBB connections.
The MTEL WBB Interface is a TCP connected UniMAX
which is a WBB router. It will have a TCP port for the MTELGateway and a
separate TCP port which is a Lantronics device used to power off/on the
UniMAX interface. Any software capable of a Telnet session will be able to
power this device on and off.
The MTELGateway will also have the ability to power
the UniMAX off.
The WBB Interface also contains hardware to send SMS
alerts directly into the Telstra mobile network.
In the diagram below the red arrows are the primary paths.
The purple arrows are the backup paths. There are two distinct messaging
systems, MTELPage and VisiCAD via MDS. Both messaging systems would connect
to the Direct Hub using the same listener port.
