Italian QoS monitoring network: Impact on SLA control

Multilevel bandwidth measurements and capacity exploitation in gigabit passive optical networks

“…This results particularly evident in case of network conditions with high values of bandwidth-delay product [5], which are especially common in high capacity accesses with line rate higher than 20 Mb/s [13]. This difference between line capacity and throughput is a cause of several problems related to service level agreement (SLA) verification between customers and ISPs, since the ISP tends to consider the bandwidth in terms of line capacities while the customer tends to consider only the useful bandwidth (i.e.…”

“…Currently, for QoS evaluation, one of the most critical parameters is the 'bandwidth' that is also a subject of dispute between users and ISPs, and it is because of the fact that the bandwidth measured by the user depends on too many factors that are independent of the physical channel [3,13]. In particular, for the bandwidth definition, we have to specify the OSI layer we refer to, distinguishing between line capacity and bandwidth at disposal of the user.…”

“…Therefore, such speed tests measure the application layer goodput (or the transport throughput) and they are not reliable to evaluate the line capacity. For instance, in [13] it was shown that the goodput is quite close to the line capacity in case of conventional ADSL2+ connections having a channel bit rate lower than 10 Mb/s. However, for line rate higher than that, the obtained throughput can be very different from the actual line capacity.…”

Experimental Investigation on Transmission Control Protocol Throughput Behavior in Optical Fiber Access Networks

“…In particular this issue strongly regards the transmission control protocol (TCP), which it is the basis of most of the services and applications available today. From its introduction TCP was well known for its limits in terms of bandwidth exploitation [1]; so far this aspect was not in discussion since the available access capacities were the ones mainly offered by the asymmetrical digital subscriber line (ADSL)-ADSL2 lines, with values lower than 20 Mb/s [2]. Conversely in recent years the available bandwidth for users has become so great as to call into question the performance of TCP in networks with high bandwidth-delay product; furthermore, for instance, by 2020 according to the E.U.…”

“…It has to be pointed out that this aspect does not constitute a problem for the quality of current applications since they operate with much lower bit-rate, also adopting HD, 3D, and 4K video content. Conversely an important issue related to the full bandwidth exploitation regards the verification and the certification of the service-level agreement (SLA) and in particular the evaluation of the line capacity offered by the Internet service provider (ISP) to the user [2][3][4]. The measurement of the line capacity for high bandwidth-delay product links is a debate that has lasted years, but with the growth of the optical fiber penetration such a topic becomes very urgent.…”