Switches prevent broadcast storms on Qinghai-Tibet Railway

The Qinghai-Tibet Railway is the highest plateau rail line construction in the world, and also one of the most challenging in terms of the environmental conditions. Lying on frozen ground 3000m above sea level, the railway is subjected to extreme climactic conditions: strong winds, heavy sandstorms and frequent thunderstorms. During the course of the day, the temperature can fluctuate by more than 30degC.

Monitoring the railway system's live status, managing any unforeseen disasters instantly, and ensuring reliable operation are the most important issues for the rail operating authority. This authority has designed and built a comprehensive environmental monitoring and control system on a power SCADA system, wireless base stations and equipment rooms along the trackside.

In 2009, Korenix's industrial Ethernet switches were chosen as the main network system in the 763km-long Seager line, the main stem of the Qinghai-Tibet railway. To put this into perspective, the equivalent distance in the UK would be a 481-mile train journey from London to Dundee. Korenix switches are able to operate reliably in extreme environments with rapid, wide temperature variations. The switch has an IP31 protected aluminium housing, which acts as a large heat sink, offering excellent cooling effects, as well as protecting the device from heavy sandstorms. The EN50121-4 protection levels also protect the switches from frequent thunderstorms.

From July 2009 to August 2010, more than 120 JetNet 5428G industrial rack mount switches and JetNet 4510 Ethernet switches were installed in the 22 trackside railway stations and in the 96 field sites from Xining to Golmud. In order to ensure improved scaleability, two levels of redundant rings were designed, at the field-level and station-level. Each field-level ring consists of several JetNet 4510 DIN rail switches that run Korenix MSR (Multiple Super Ring) for fast recovery, and is connected to a JetNet 5428G at the station level. The JetNet 5428Gs at stations in turn form the station-level ring, with the 3rd party core switches in the central room by MSTP (Multiple Spanning Tree Protocol).

To connect 100 Korenix switches to the 3rd party core switches in the control room, network interoperability becomes a critical issue. In the customer's conformance and interoperability tests, Korenix switches passed more than 350 items with a 97 per cent pass ratio, which demonstrates outstanding conformance of RSTP and MSTP protocols. JetNet 4510 and JetNet 5428G switches successfully provided a stable, reliable option for this major project.

Broadcast storms resolved

By providing its broadcast storm prevention/protection technology, Korenix has further solved a long-term headache for the customer. The railway authority had been suffering from occasional broadcast storms (one or two per month) in the legacy redundant ring networks. These broadcast storms overwhelmed all the Ethernet equipment and crashed the complete network. This type of problem cannot be fixed remotely, and so personnel had to be physically sent to the problem station to fix the issue. Korenix switches can detect and break a malfunction loop topology and locate the root cause of a broadcast storm, helping the customer to maintain the environmental monitoring and control system network at all times, minimising downtime.

In order to react quickly to any network failures, the customer also required a visualisation management system for monitoring and control over its large networks. Korenix's JetView Pro system reports failures and the location of the failure to the customer, resulting in reduced troubleshooting and time spent locating the root cause of a failure on the network.

Korenix was selected as a partner on this project for several reasons:

• The wide temperature range of its Ethernet switches and their reliable operation in extreme environments with rapid temperature variation
• Strong EMS Protection - EN50121-4 EMC rated for trackside applications
• IP31 Aluminium Housing - for improved protection from heavy sandstorms
• High RSTP/MSTP Conformance - ensuring stable interoperability with 3rd party switches in the large network system
• Korenix's patented MSR Redundant Ring technology - 5ms fast recovery time and 0ms seamless restoration

For more information on Korenix and its products, including their industrial Ethernet switches, please visit the website at www.korenix.co.uk or email [email protected].