Loading...
Please wait, while we are loading the content...
Similar Documents
Window (frames) Window (frames)
| Content Provider | Semantic Scholar |
|---|---|
| Abstract | Fig. 5. SSCOP maximum throughput vs. window size (100 Mbit/s link, rtd = 10 ms, and frame size = 1024 bytes, and POLL intervals of 5, 50, and 500 ms) In Figure 6, simulation results are presented for a hypothetical link on a very lossy channel (p ≈ 10 −2). Again, three independent simulation runs have been averaged, and the duration of each run was 5 seconds (approximately 2500 frame errors). The frame window was varied while the Timer_POLL (2 ms) and the frame size (128 bytes) were held constant. In addition, to highlight the impact of the USTAT on protocol performance, a hypothetical modified SSCOP (labeled "SSCOP without USTAT"), in which USTAT message transmission is disabled, is compared to SSCOP. High throughput efficiency is possible in this environment, but the performance degrades more quickly when the window is reduced. In Figure 5, a high throughput (often greater than 0.8) was achievable when the window was reduced to W = TR + TP, but in this case, the throughput at that window size was only approximately 0.5. The USTAT mechanism allows the throughput to be maintained longer when the window is reduced. The difference between the two protocols (with or without USTAT) becomes more pronounced as the POLL interval is increased. Although these results do illustrate that inappropriate parameter settings can cause throughput degradation, they also illustrate that the performance of SSCOP can be quite high in poor error environments or in networks that experience severe congestion losses. This performance can be largely attributed to SSCOP's selective retransmission ARQ mechanism, which significantly outperforms go-back-N in a lossy, high bandwidth-delay product environment. VI. CONCLUSIONS AND FUTURE DIRECTIONS SSCOP has been designed as a high speed protocol that can offer high throughput efficiency in a broadband or lossy environment. The main function of the protocol is to correct for lost or errored frames through retransmission. The protocol uses a selective retransmission strategy which offers optimal efficiency performance in the broadband environment. A number of other high speed design features were also incorporated. SSCOP was originally intended to provide end-to-end error recovery for user data and link protection for ATM signaling. Since that time, ATM has evolved from being primarily a carrier backbone technology to being an IP subnet technology, and since SSCOP cannot operate over connectionless IP, there has been less interest in using it for user data transfer. SSCOP will see … |
| File Format | PDF HTM / HTML |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
