Ethernet switches provide dual redundancy
09 March 2009
For many organisations today, IT infrastructure and related networking technology must operate continuously with minimal downtime or redundancy. Network recovery time is therefore critical.
Ethernet switches provide dual redundancy of airport refueling control system
Based in Bath, Rotork designs and manufactures a range of electric, pneumatic and hydraulic valve actuators and associated control systems, valve gearboxes and valve accessories. The company has recently specified industrial managed Ethernet switches from Korenix UK as part of a valve actuation control system for a major airport expansion project in Saudi Arabia. The control system must provide complete redundancy in the event of equipment or network failure.
Over the next five years, the General Authority for Civil Aviation plans a significant development of the King Abdul Aziz International Airport in Jeddah, which will enable it to accommodate 35 million passengers a year. Included in this is a new terminal with 74 jet bridges that will receive aircraft of all sizes, including the Airbus A380.
Rotork is supplying 120 of its IQPro intelligent electric valve actuators to Cameron Valves for the control of double block and bleed valves that are installed on the airport’s hydrant refueling network for the A380. The refueling system is part of the Airfield Facilities Upgrade, the first phase of the development programme, and is critical to airport operations.
Two Pakscan Master Stations from Rotork have also been supplied, which the airport will use to control and monitor actuators and associated equipment on the refueling installations. In the control cabinet supplied, two Master Stations, which appear as a single control system, each have two Ethernet ports. One Master Station acts as the operating system, the other as a standby unit in case of equipment or network failure. This is referred to as a ‘Hot Standby’ system.
In the same control cabinet are the two Korenix managed Ethernet switches, which provide loop-based control and dual redundancy. If there is a network or equipment failure, these switches communicate with the Pakscan Master Station, ensuring that the refueling system experiences zero downtime and that system recovery is instantaneous.
For dual redundancy functionality, Rotork considered four different suppliers of Ethernet switches, eventually selecting Korenix’s JetNet 5010G, an innovative, reliable and cost effective Gigabit Managed Ethernet switch, which offers the fastest Ethernet recovery time in the world today - less than 5 milliseconds.
As Mike Howard, Senior Systems Sales Engineer at Rotork stated: “In our acceptance tests, the Korenix switch was the only one that conformed to our redundancy requirements. It was also very cost effective.”
According to Howard, many of Rotork’s control systems are used in critical applications such as hydrocarbon plants and airports. This means customers require complete redundancy in their control systems. Howard continued: “Security of the installation and minimal downtime are what matters to our customers. A high proportion of our control systems are therefore sold as hot standby units. In addition, technical assistance is often difficult in these remote areas and so complete redundancy is often the customer’s preferred solution.”
“When we used a single Ethernet switch connected to both sides of our Master Station, everything worked well. However, when we introduced a second Ethernet switch to provide the dual redundancy, we began to experience significant Ethernet ‘broadcast storms’ or network freeze, where the control networks became swamped with Ethernet messages. We therefore needed to find a suitable solution.”
Korenix designs and manufactures a range of industrial Ethernet switches, device servers, Power-over-Ethernet switches and embedded industrial computers. Korenix products are found in a diverse range of network applications, including industrial environments, manufacturing, transportation, medical establishments, energy and utility companies, point-of-sale, industrial automation, airports, security and surveillance systems.
The number of features and patented technology provided in the JetNet 5010G is astounding. The device is the only industrial Ethernet switch in the world to provide three Gigabit SFP connections in one modular design. Most competing suppliers can only offer two SFP connections per switch at best. Other vendors require users to purchase three separate SFP models and three separate RJ45 models to achieve the desired connectivity.
For most industrial applications, the most common redundant Ethernet LAN (Local Area Network) topology is a ‘ring’. Korenix’s Multi Super Ring (MSR) is a set of five patented technologies that can work individually or in combination, in an incredibly simple way for the user. One of these patented technologies is the Rapid Super Ring II (RSR II), which is specifically designed to meet the fastest recovery times in industrial ring networks, of just 5 milliseconds and a reconnect time of 0 milliseconds!
Interoperability between different ring topologies and vendors is critical. The JetNet 5010G works with all ‘open’ network topologies, enabling companies to integrate the device quickly and easily into their existing IT infrastructure at minimal cost and disruption. Korenix’s ‘ANY Ring’ technology enables integration with a number of Third Party ring systems, which is a time and cost saving capability.
Another of the patented technologies is ‘Dual Homing II’, which connects the Super Ring to other ring redundancy protocols, such as RSTP (Rapid Spanning Tree Protocol). This technology ensures that the rings communicate well and the dual homing paths can backup each other, providing a world-beating disconnect time of 50 milliseconds and a reconnect time of 0 milliseconds. For example, the user, in just two mouse-clicks, can auto-select one Dual Homing uplink path as an ‘Active Link’, while the other is a ‘hot standby’ link.
To further reduce recovery time and increase link capacity, the JetNet 5010G is equipped with IEEE 802.3ad Link Aggregation Control Protocol (LACP). This enables the device to automatically port bundle dynamically between switches. Two or more Fast Ethernet or Gigabit Ethernet connections are combined in order to increase the bandwidth and to create resilient and redundant links.
Another feature is the ‘auto elect ring master’ functionality. Most other Managed Ethernet switches employ a master-slave relationship across a network ring. This means appointing a master switch and slave units. The problem here is if the master switch fails, the consequences can be disastrous. With the JetNet 5010G, each switch on the network is defined by a priority number using its MAC address (unique ID number). If the elected master switch fails, the master tag is passed to the next highest priority weighted switch and this unit becomes the new master switch.
As well as offering a fast recovery time, the units provide a number of benefits and technical advantages, including modular design technologies, excellent software and connectivity features, protection against harsh environments, power redundancy, high port density and Gigabit SX multi-mode 550M, LX single-mode 10km or more, as well as 1000Mbps Fibre. Providing Gigabit fibre technology offers noise immunity, greater cable distances and electrical isolation.
There are three SFP modules on the unit, which cater for all user requirements. A range of fibre optic cabling options are provided by modular connectors, up to 2km lengths with multi-mode and up to 30km in single mode. Two digital inputs and two digital outputs are also provided.
As well as fibre optic ports, the device uniquely offers three Gigabit copper ports. These enable companies to ‘mix media’ i.e. use copper and fibre optic cabling, using copper between lower cost network devices if they desire.
The JetNet 5010G supports a comprehensive range of interfaces and connectivity management tools, including VLAN/GVRP/QoS/IGMP Snooping/Rate Control and Online Multi-Port Mirroring, SNMP/RMON Network Management, web Interface, and Cisco-like CLI via RS232 console. Event notification is also possible via email, SNMP trap and Syslog.
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