Implementation of an Inside RTT monitoring technique in QUIC

Passive network monitoring is a vital activity for network operators that want to guarantee a good level of quality of service to the users of the network, as it allows them to observer real user data and detect performance and health issues. One of the variables that mostly impacts the effectiveness of passive network monitoring is the wire image of the protocol under analysis, which in the case of QUIC is very limited. Furthermore, the Spin Bit defined in the QUIC specification is optional and it is rarely implemented in existing QUIC libraries, making it unusable since it must be supported and agreed upon by both endpoints. This thesis aims to present and implement the Inside RTT monitoring technique, in order to provide an alternative that can be deployed in client applications to solve the issues of adoption and cooperation that render the traditional Spin Bit unusable in most cases. The idea of this technique is to rely on a client side estimation of the RTT and to use it to unilaterally generate a square wave that allows a passive observer to measure the RTT with accuracy. Using the Inside RTT monitoring technique, a passive observer is therefore immediately able to measure a RTT estimation provided by the client, where previously it would not be able to measure a value at all. The results obtained when testing with the Chromium browser highlight the fact that as long as the client can compute an accurate estimation, the observer can measure the actual RTT between the client and the server with a few milliseconds of error. The results also show that Inside RTT monitoring does not solve all the issues of the traditional Spin Bit, but since these problems are not introduced by the technique itself and they are not as crucial as the lack of adoption, the value of the implementation is still considerable and worth the upgrade over existing solutions.