# A Single-Rate Multicast Congestion Control (SRMCC) Mechanism in Information-Centric Networking
## 4 Rate Adaptation
### Rate Selection Strategy
**(a)** The variation in throughput over time under four multicast groups; **(b)** The variation in packet loss rate under different numbers of multicast groups; **(c)** The variation in total bandwidth utilization under different numbers of multicast groups. ### Performance Comparison with ASMP, TFMCC, and PerfwithECN

#### 5.3.1 Throughput

Figure 7 presents the achieved throughput of multicast receivers of each mechanism under different bottleneck link bandwidths and the scenario of dynamic competing traffic, respectively. Figure 8 presents the comparison of average throughput of the multicast and TCP under different scenarios. From Figure 7, it can be seen that the throughput of SRMCC is significantly improved, and SRMCC responds faster to the dynamic changes of competing traffic than the other three mechanisms. Compared with ASMP, the throughput of SRMCC is improved by 11.3%, 8.3%, 0.9% in scenarios 1-3, respectively. The throughput of TFMCC is the largest. However, in Figure 8, except for in scenario 4, TFMCC consumes a higher bandwidth share than TCP connections. For example, we observe that TFMCC consumes on average 151.8% of the expected bandwidth share, while a TCP only consumes 72.6% of its share under a bottleneck link bandwidth of 5 Mbps. Our assessment is that, given the multiple TFMCC streams in the internet, TCP will suffer from starvation because TFMCC consumes more bandwidth than TCP streams when sharing the same bottleneck link. It can be seen that TFMCC is the least TCP-friendly, and the increase in its throughput comes at the expense of TCP's throughput. Figure 7: The variation in throughput over time under different scenarios. (**a**) The variation in throughput over time under scenario 1; (**b**) The variation in throughput over time under scenario 2; (**c**) The variation in throughput over time under scenario 3; (**d**) The variation in throughput over time under scenario 4. In contrast, ASMP and SRMCC are more TCP-friendly than TFMCC. ASMP consumes less bandwidth than TCP, except in the scenario 3. In all of the experiments, SRMCC consumes less bandwidth share than TCP connections. Therefore, SRMCC is more TCP-friendly than ASMP. Moreover, it is worth noting that, as can be seen from Figure 8, it is not only the throughput of SRMCC which is improved, but also the throughput of TCP. However, in the four scenarios, the throughput of multicast under PerIfwithECN is significantly lower than that of TCP. Since the router detects congestion, it will display a notification to the source to slow down, and TCP will preempt more bandwidth resources, resulting in extremely low multicast throughput. Overall, SRMCC achieves higher throughput and improves transmission efficiency while improving TCP friendliness. #### 5.3.2 Bandwidth Utilization

Bandwidth utilization is an important indicator that should not be ignored. To evaluate transmission performance, we also tested the bandwidth utilization of multicast traffic and total bandwidth utilization of all traffic under different bottleneck link bandwidths and scenarios. Owing to the fact that each competing stream in scenario 4 started and stopped at different times, we compared the bandwidth utilization between the 80 th second and the 120 th second, since four streams coexisted during this period. Figure 8: The comparison of average throughput of multicast and TCP under different scenarios. (**a**) The comparison of average throughput of multicast and TCP under scenario 1; (**b**) The comparison of average throughput of multicast and TCP under scenario 2; (**c**) The comparison of average throughput of multicast and TCP under scenario 3; (**d**) The comparison of average throughput of multicast and TCP under scenario 4. On the one hand, from Figure 9b, it can be seen that the proposed SRMCC mechanism can achieve almost the same total bandwidth utilization as TFMCC and PerfwithECN under different scenarios, and the total bandwidth utilization of SRMCC is 7.1-9.5% higher than that of ASMP under the same link conditions.