2.6.15.4 Egress Transport Congestion

When a DSR peer connection becomes blocked due to transport layer congestion the DSR acts in the following manner:

• When a DSR peer connection becomes blocked, the DSR sets the connection’s congestion level to CL-4 (Requests nor Answers can be sent on the connection).
• The DSR waits for the connection to unblock and then abate a connection’s egress transport congestion using a time-based step-wise abatement algorithm similar to Remote BUSY Congestion.
• A user-configurable Egress Transport Abatement Timer exists for each DSR Peer Connection. The abatement timer defines the time spent abating each congestion level during abatement and is not started until the socket unblocks and becomes writable.
• Messages already committed to the connection by the DSR routing layer when a connection initially becomes transport congested will be discarded.

The above can be summarized using the chart below.

Figure 2-20 Example Congestion level abatement