In the current internet, congestions are detected by the TCP transport protocol only when a packet is dropped. The paper presented a new mechanism where detection of congestion is in the gateway itself. The Random Early Detection (RED) Gateways is proposed to maintain high throughput and low delay in the network. Aside from this, the paper also discussed other congestion avoidance gateways, described simple simulations and specific details of the algorithm used in calculating the average queue size and the packet marking probability for RED gateways.
In a nutshell, the main goal of RED gateway is to provide congestion avoidance by controlling the average queue size. It drops packets when the average queue size exceeds a preset threshold providing an upper bound on the average delay at the gateway. Also, as the gateway can monitor the size of the queue overtime, it is the appropriate agent to detect incipient congestion. It has a unified view of all the contributing sources to the congestion thus it is able to decide which sources to notify of said congestion.The RED gateway is designed to do all the following objectives in order to avoid bias to bursty traffic and global synchronization that may result to notifying all connections to reduce their windows at the same time. They are important points to consider to maintain high throughput in the network. It chooses a particular connection to be dropped using a probability that is roughly proportional to that connection’s share of the bandwidth at the gateway.
Overall, it is a simple gateway algorithm that can be implemented in the current system we have today. This is the first paper I’ve read that present congestion avoidance algorithm on a layer apart from the transport layer. I hope further studies as cited in its recommendation can be done so it can be deployed gradually in the internet.
Reference:
S. Floyd and V. Jacobson, Random Early Detection Gateways for Congestion Avoidance
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