Performance of TCP over ABR service class

The performance of TCP over ATM networks is evaluated using a simulation technique for the model where the multiple ATM switches are interconnected. In multihop networks, the unfairness among connections possibly become a problem due to the difference of the number of hops or the round trip times among connections. We first compare three methods For supporting TCP traffic; available bit rate (ABR), unspecified bit rate (UBR) with EPD (early packet discard), and EPD with per-VC accounting. Results show that the performance of TCP over ABR is degraded once the cell loss takes place due to the inappropriate control parameter setting. We then consider TCP over ABR with an EPD enhancement in which an EPD mechanism is incorporated into ABR.