Internet
Bandwidth allocation
Passive optical networks
Transport protocols
CUBIC
H-TCP
Reno
TCP performance
XG-PON
Asymmetric bandwidth
Bandwidth allocation mechanism
Dominant transport protocol
Large delay-bandwidth product
Medium access control
Network simulation cradle
Bandwidth
Channel allocation
Convergence
Optical network units
Standards
Throughput
XG-PON is the next-generation standard for passive optical networks operating at 10Gb/s and TCP is the dominant transport protocol of the Internet. In this paper, we present the first performance evaluation of TCP over XG-PON, considering efficiency, fairness, responsiveness, and convergence. The impact of XG-PON's large delay-bandwidth product and asymmetric bandwidth provision are assessed, together with the dynamic bandwidth allocation mechanism. Our state-of-the-art NS3 simulation uses real implementations of three TCP variants (Reno, CUBIC and H-TCP) from the Network Simulation Cradle. Our results highlight several issues that arise for TCP over XG-PON, and emphasise the need for improved awareness of medium access control and scheduling in the context of specific TCP congestion control behaviour.