Demonstrate Cascading Failures in ns

Goal:

• Understand, detect, predict, and avoid network cascading failures;
• Cascading failure is a disruption at one point in the networks causes a disruption other points;
• Cascading failure could be caused by the sudden shift in network traffic and/or the propagation of router failures.

Current stage: 

• Demonstrate network cascading failure scenarios under simulations in ns (one example is given below)
• Investigate metrics to quantify failures (such as the RTTs of cross traffic)

Future plan:

• Verify simulation results with network traces
• Understand network cascading failure scenarios from network traffic perspective
• Implement mechanism to detect and predict network cascading failures

Sample Scenario:

Traffic in the simulation:

• Pulse UDP: ON/OFF traffic with short ON period but high packet rate within the ON period;
• Low rate CBR: UDP traffic with a small but constant packet rate;
• TCP cross traffic: TCP flows share no common links with the pulse UDP flow.

Simulation snapshots:

Initial state Low rate CBR does not affect TCP cross traffic flows No large queue or packet loss is observed
Pulse occurs Pulse UDP flow starts Packets in low rate CBR are blocked
Pulse "spreads" Pulse UDP flow ends Packets in the low rate CBR flow , which are queued, form a secondary pulse
Pulse hurts cross traffic The secondary pulse hurts cross traffic Large queue and packet loss are observed