Quantitative Network Engineering with Fault Tree Analysis

This is a simple paper outlining how to use some Risk Analysis Techniques with Network Engineering to obtain quantitative results. An attempt to turn network engineering from an artful guessing game into a science.

Equipment

For our example, we are going to do an analysis of one of the worst case events a router can ever experience -- isolation.

The router we will be using is a Blackhole Networks Megabox 2000 Turbo++ router. The Megabox 2000 Turbo++ has a fully redundant, modular chassis with a distributed forwarding architecture. Everything slides into the front of the Megabox 2000 Turbo++ and connects into a central backplane where individual components are provided power and connected to the router's cleverly named Switching Fabrics (SF)cards. The SFs all of the communication between components. Due to a really idiotic architecture that was designed by the marketing department, two SFs are needed to keep the component interconnections active (although one can handle the full bandwidth). A third switch fabric can be added to provide for some redundancy and so the sales department can sell more SFs. The control-plane duties are handled by the Routing Control Engine (RCE) which runs a UNIXlike network operating system called VaporOS. Each routing protocol and service in VaporOS is handled by it's own daemon. The asininity of the SFs was kept out of the logic for the RCE and one RCE handles the entire control plane duties. If a secondary RCE is installed, it is capable of providing stateless failover within a few minutes. The RCE is reponsible for pushing the forwarding table to the Forwarding Engines (FE) which can operate on their own once the Forwarding Information Base (FIB) is programmed into it by the RCE. Each FE has two slots for "Line Card" or LC line cards (more really clever naming). The LC contains the hardware that is responsible for all of the Layer1 operations and provides encapsulation and decapsulation functions for Layer2 traffic. To physically interface with a circuit, each LC needs to have a small form-factor pluggable (SFP) module installed. The router has dual power supplies, with each power supply able to fully power a fully populated chassis.

The Blackhole Networks Megabox 2000 Turbo++ Router




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