Can we control a TCP path?
It is increasingly common that multiple TCP connections are initiated between the same source- destination pair. Different shortest paths are taken by these TCP connections between the same two hosts because of Equal-Cost Multi-Path (ECMP). However, these connections may also overlap in time and traverse a common path. This may result in competition since each connection uses its own congestion control instance and tries to maximize its sending rate. This often leads to undesirable spikes in queuing delay and packet losses. Such competition can be eliminated by using a coupled congestion control mechanism which combines the congestion control mechanisms of all the flows sharing a common path. In , we have shown with our proposed TCP congestion control mechanism (ctrlTCP) that coupling can significantly improve the overall performance by reducing overall delay and loss and exerting precise allocation of the available bandwidth. If we can deduce that flows can share a common network path, we can always apply our congestion control coupling mechanism.
The main research question that this thesis attempts to answer is: “Can we control a TCP path”? We want to address this by running Internet-wide measurements to figure out if we can enforce this situation by:
- Common IPV6 flow label
- Choice of port numbers
Using a traditional traceroute tool to identify the network path can result in routes as shown in the figure above. As a starting point, the relevant tools for this thesis are therefore Paris/Dublin traceroute.
- Brice Augustin, Renata Teixeira, and Timur Friedman, "Measuring Load-balanced Paths in the Internet", in Proc. Internet Measurement Conference , October 2007.
- S.Islam, M.Welzl, K.Hiorth, D.Hayes, G.Armitage and S. Gjessing, "ctrlTCP: Reducing latency through coupled, heterogeneous multi-flow TCP congestion control," IEEE INFOCOM 2018 - IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Honolulu, HI, 2018, pp. 214-219, doi: 10.1109/INFCOMW.2018.8406887.
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