where Ci is the link capacity of the ith hop in an H-hop path. Equation 1 has been the foundation of several clever active probing capacity estimation techniques, such as Pathrate, described by Dovrolis et al. (2004), and CapProbe, described by Kapoor et al. (2004), for example. Similarly, the link available bandwidth for the ith hop in an interval of time (t− τ, t], has been defined by Prasad et al. (2003) as: