Frame relay networks minimize satellite bandwidth
- Privately operated integrated frame relays for voice/data communications are expanding into the North Sea.
The systems are some of the most modern in the North Sea, and reflect both the high need for security as well as CRINE efforts to minimize offshore costs and maximize functionality.
Rather than go to traditional services based on links via public telecommunications operations, Arco British elected to go to very small aperture terminal (VSAT) systems for security reasons. The system takes advantage of dropping satellite bandwidth cost. Until recently, VSAT was more common in North America, where satellite capacity was much less expensive, but that is changing now.
The system links the company's unmanned operations on the Trent and Tyne platforms with the onshore control room. Each of the two platforms is equipped with voice, data, and local area network (LAN) services.
The services are multiplexed together for transmission over satellite links. The multiplexer manages available bandwidth, dedicating maximum bandwidth and prioritizing the traffic. The data is transferred at an aggregate 256 Kbps from each platform direct to Arco British in Great Yarmouth. The Orion 1 satellite handles the communications from its orbit position, 37.5 degrees west.
The aggregate bandwidth from each platform enables the following to take place:
- Production monitoring and control.
- Emergency shutdown protocol.
- Eight longline extension voice channels.
- Remote VHF access.
- A hotline service for priority messaging.
- LAN/LAN bridge extension.
A 2.4 meter rooftop satellite dish at onshore control downlinks the integrated voice and data carriers from both platforms. The satellite service's earth station assumes backup as a downlink site with automatic switching.
EAE of Dyce and Kingston Satellite Services designed and services the network for Arco British, based on VSAT frame relay equipment and procedures. The system was delivered in March of this year.
Lasmo's system is based on the ACT net private frame relay network. The network is interconnected with Lasmo's headquarters in London and Dutch base in Beverwijk, Netherlands. Lasmo claims it is saving 28% on telecommunications costs and expects a seven-month return on investment.
As with the Arco British system, the private Lasmo network integrates voice and data from offshore platforms. The alternatives to the ACT network were standard ocean cables to the UK and the Netherlands, or to switch voice calls through a PBX station in Beverwijk. The latter would necessitate double compression and provide poor voice quality.
Lasmo leases a single Dutch PTT 128 Kbps line from the oil platform to Beverwijk. That link carries data from Ethernet LANs at two platforms plus voice and fax integrated by an ACTnet SDM-FP integrated frame relay access device located on one of the platforms. The packets can be switched to London or Beverwijk to complete the call.
In the network, a second 128 Kbps circuit is required from the Netherlands to England at a lower cost that a circuit directly from the platform to England. From the PBS boards in London and Beverwijk, voice calls can then be switched to the respective public telephone networks. ACTnet's ability to hand voice without degradation in quality after double compression was a factor in the decision to implement.
Lasmo now has twice the bandwidth than it would have gained otherwise. The firm's prior network supported data communications only at 64 Kbps. The network now operates at 128 Kbps using frame relay, a faster and more efficient protocol, particularly for local area network (LAN) to wide area network communications. The LANs in this network are running in a Novell environment with some DECnet protocols.
ACTnet's packetizing techniques allow it to handle LAN traffic with critical gas production and drilling operational data.
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