TCP FOR HIGH-PERFORMANCE IN HYBRID FIBER COAXIAL BROAD-BAND ACCESS NETWORKS

Motivated by the phenomenal growth of the Internet in recent years, a number of cable operators are in the process of upgrading their cable networks to offer data services to residential subscribers, providing them direct access to a variety of community content as well as to the Internet, Using cable modems that implement sophisticated modulation- demodulation circuitry, these services promise to offer a several hund redfold increase in access speeds to the home compared to conventional telephone modems, Initial experiences indicate that cable networks ar e susceptible to a variety of radio-frequency (RF) impairments that ca n result in significant packet loss during data communication, In the face of such losses, the transmission control protocol (TCP) that is p redominantly used by data applications degrades dramatically in perfor mance, Consequently, subscribers of broad-band data services may not p erceive the projected hundredfold increase in performance, In this pap er, we analyze the performance of TCP under different network conditio ns using simulations and propose simple modifications that can offer u p to threefold increase in performance in access networks that are pro ne to losses, These modifications require only minor changes to TCP im plementations at the local network servers alone (and not at subscribe rs' PC's).