EASSy Network Topology
EASSy is a two fibre pair system and is the only East Africa submarine system to be based on a "collapsed ring" architecture, which provides a high degree of robustness, high reliability and low outage time.
This network topology allows internal restoration routing which minimises outage time to a few milliseconds in the event of a cable break in one branch or failure of an entire landing station (except for the traffic originated or terminated in the failed branch).
The collapsed ring configuration also provides equipment protection on a 1+1 basis, which prevents disruption to traffic if a single card fails in the Submarine Line Terminating Equipment (SLTE) or SDH Interconnection Equipment (SIE) within the landing station.
The system is electrically powered by redundant Power Feed Equipment (PFE). Whilst the system trunk is usually double-end fed (i.e. power is supplied by two end stations), it can also be single-end fed in case of total failure of one PFE. Switchable branching units (BUs) allow for power reconfiguration in case of complete failure of a branch PFE.
Records show that most cable breaks are due to anchoring and fishing. EASSy’s trunk is located in deep waters and hence is unlikely to be subject to external interference of this type. This further reduces the probability of complete system failure. Marine surveys have been undertaken to optimise routing and minimise risks and all equipment models (SLTE, SDH, cable, repeaters, BUs) used in EASSy have previously been successfully deployed in other networks.
The EASSy system is connected to terrestrial fibre-optic backhaul networks that reach into the African interior, linking coastal and land-locked countries.
Technical Information
Submarine
- System length: 10,000 km
- Landings: 9
- Transmission: SDH
- Technology: Dense Wavelength Division Multiplexing (DWDM), Direct Optical Amplification
- Topology: 2 fibre pair system configured as a collapsed ring
- Proposed ultimate capacity per fibre pair:
- 59 fibre pairs, 40Gbps wavelengths
- Total capacity of 4.72Tbps
- System design life: 25 years
- Supplier: Alcatel-Lucent
- Cost: US$263 million
The submarine solution is based on Alcatel-Lucent 1620 Light Manager next-generation DWDM submarine platform, and also includes cables and submarine repeaters.
Branching units ensure direct connectivity to landing stations where Alcatel-Lucent has deployed its 1678 Metro Core Connect (MCC) for terrestrial interconnection.
The Alcatel-Lucent 1350 management system supervises all the equipment supplied.
NOC
The EASSy system is managed from Telkom SA's Network Operations Centre, which has long-standing experience and expertise in managing international submarine cable systems.
