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Deep data analysis in gigabit passive optical networks

Horvath T., Krkos R., Dubravec L.

Optica Applicata

2017

Vol. 47, nr 1

157--170

This paper focuses on practical aspects of gigabit passive optical networks (GPON) diagnostics during deployment, for root-cause analysis and for research purposes. While GPON signalling analysis is already quite commonly used for diagnostics, the aim of this work is a holistic approach, including both signalling and user plane (payload) analysis. User plane analysis, especially if targeted at payload Ethernet, IP and transport layers, enables detection of additional group of problems that could limit or even prevent GPON internetworking and thus degrade the user perceived service quality. Integrated signalling and payload analysis is also interesting from the research point of view, leading to the ability to study equipment idiosyncrasies that would be hard to detect otherwise and it is also one of the enablers of equipment security verification. The mentioned theories were tested during a practical diagnostic session on a real GPON network deployment and this paper presents the findings.

Novel rogue optical network unit detection algorithm for gigabit passive optical networks

Horvath T., Munster P., Dubravec L., Filka M.

Optica Applicata

2016

Vol. 46, nr 3

421--433

Passive optical networks are widely used as a promising solution for future access networks. Currently, the bandwidth is still increasing which means the current copper networks are not able to transfer new services such as 4K video, live streaming, etc. In other words, they reached their capacity limit. The passive optical networks rely on point-to-multipoint technology. That means each customer uses a share medium by time slots. Each time slot exactly specifies who and when is able to transfer data. In general, this control mechanism is implemented in the optical network unit by worst transmission convergence layer. On the other hand, there are cases when the optical network unit (it is called rogue optical network unit) does not follow instructions provided by the optical line termination, for example, if an attacker modifies a firmware of the end unit and/or when the control protocol is not loaded properly inside optical network unit. In worst case, the optical network unit transmits data in a continual mode (other optical network units cannot send data). Thestandard defines finding of the rogue optical network unit but it does not specify how the rogue optical network unit should be allocated because the frames of the rogue optical network unit do not contain the proper parameters. We realized a measurement in a real network with the rogue optical network unit and then we analyzed the captured data. A new algorithm for the rogue optical network unit allocation is presented. We do not consider any modification of the transmission convergence layer in gigabit passive optical networks.