Time Synchronization Solution for FPGA-based Distributed Network Monitoring

Abstract

Distributed network monitoring solutions face various challenges with the increase of line speed, the extending variety of protocols, and new services with complex KPIs. This paper addresses one part of the first challenge: faster line speed necessitates time-stamping with higher granularity and higher precision than ever. Proper, system-wide time-stamping is inevitable for network monitoring and traffic analysis point of view. It is hard to find feasible time synchronization solutions for those systems that have nation-wide, physically distributed probes. Current networking equipment reside in server rooms, and have many legacy nodes. Access to GPS signal is complicated in these places, and Precision Time Protocol (PTP) does not seem to be supported by all network nodes in the near future – so high precision time-stamping is indeed a current problem. This paper suggests a novel, practical solution to overcome the obstacles. The core idea is that in real-life, distributed network monitoring systems operate with a few, finite number of probeclusters, and their site should have a precise clock provided by PTP or GPS somewhere in the building. The distribution of time information within a site is still troublesome, even within a server rack. This paper presents a closed control loop solution implemented in an FPGA-based device in order to minimize the jitter, and compensate the calculated delay.