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The router's buffer accommodates transient packets to guarantee that the network's links do not become idle. However, buffer overflow causes packet loss, which is a signal of congestion. In content centric networking (CCN), the interest packet, which is used for requesting content, may be dropped due to such congestion. Each interest packet is assigned a specific lifetime, and when the lifetime expires without obtaining the requested content, the consumer needs to resend the Interest. However, waiting for the expiration of an Interest's lifetime for retransmission is only appropriate for best effort traffic rather than services that are delay sensitive. In order to provide delay-sensitive applications with better quality of service, we propose a congestion control mechanism for CCN, in which, we prevent congestion before it happens through monitoring buffer size. Upon reaching the buffer threshold, the node notifies its downstream node. On receiving the notification, the downstream node adjusts traffic rate by allocating new incoming Interests to other face(s). However, when the downstream node fails to reduce traffic rate, the same procedure continues until the consumer node reduces sending rate. The simulation results show that the proposed mechanism is capable of significant performance improvements, with higher throughput. |
