1. A system for measuring network latency, comprising: a first network tap configured to passively copy, from a first network data point, data packets moving across a network; a second network tap configured to passively copy, from a second network data point, the data packets moving across the network; a first electronic device synced to a time source and configured to receive the data packets copied by the first network tap, wherein each of the data packets copied by the first network tap contains data representing a predetermined time, wherein said first electronic device is further configured to ascertain, according to said time source, a time when a first data packet from the data packets copied by the first network tap arrived at said first electronic device and to calculate a first difference between said first data packet's arrival time and said first data packet's predetermined time, wherein the first data packet comprises a message associated with a transaction in a financial market, the predetermined time represents a time of trade or a posting of a quote in an order book associated with the financial market and the first difference represents a one-way latency between the time of trade or the posting of the quote and the arrival of the first packet at the first electronic device and wherein the first electronic device is further configured to calculate the one-way latency for each of the data packets copied by the first network tap using the predetermined time representing the time of trade or the posting of a quote in the order book associated with the financial market in each of the plurality of data packets, and to compute a mean and a standard deviation of the one-way latency using the one-way latencies of the data packets copied by the first network tap; wherein said first electronic device is further configured to ascertain, according to said time source, a time when a second data packet from the data packets copied by the first network tap arrived at said first electronic device, to calculate a second difference between said second data packet's arrival time to said second data packet's predetermined time, and to average said first difference and said second difference, resulting in a first average one-way latency; a second electronic device synced to said time source and configured to receive said plurality of data packets copied by the second network tap, wherein said second electronic device is further configured to ascertain, according to said time source, a time when said first data packet from said data packets copied by said second network tap arrived at said second electronic device and to calculate a third difference between said first data packet's arrival time at said second electronic device and said first data packet's predetermined time, to ascertain, according to said time source, a time when said second data packet from said data packets copied by said second network tap arrived at said second electronic device, to calculate a fourth difference between said second data packet's arrival time at said second electronic device to said second data packet's predetermined time, and to average said third difference with said fourth difference resulting in a second average one-way latency; and a management device for querying the first electronic device to obtain the first average one-way latency and the mean and the standard deviation of the one-way latency, wherein said management device is further capable of querying said second electronic device and receiving said second average one-way latency from said second electronic device, and to calculate the difference between said first average one-way latency and said second average one-way latency.