Route-assertion Process Summary
The CNA decision-maker process bases its routing decisions on traffic measurements that are obtained by the USTAT modules. These measurements are sent to a measurement queue maintained on the engine module.
As measurements are pulled off this queue, they are written to the internal database and an entry is placed on a prefix-event queue, which is also maintained on the engine module.
The decision-maker process removes events from this prefix-event queue in sequence (or according to user-defined priorities, if configured), and if the decision-maker process determines that a route assertion is due the event is sent to a scheduler queue.
You can follow the flow of events through each of these queues and processes using the following variations of the show statistics command:
- show statistics edgestats--displays number of measurements made of each type (.gif hits or active probes) by each USTAT
- show statistics dm-listener--displays the number of packets received from the USTATs and the number of measurements written to the internal database; also displays the SNMP polling status of service provider links
- show statistics dmaker event-queue--displays counts of measurements received by the prefix-event queue and number of measurements removed form the queue for processing; also tabulates outages
- show statistics dmaker decision-making--displays multiple tables showing numbers of decisions made; the amount of time prefixes spent waiting in the prefix-event queue; and the amount of time it took the decision-maker process to evaluate prefixes
- show statistics dmaker prefix-scheduling--displays a summary of prefix movement onto and off service provider links as a result of decision-maker process evaluations
- show statistics dmaker peerings--displays a summary of BGP announcements and withdrawals
In addition, the show ip bgp neighbor command shows configuration parameters and the up/down status of each of your BGP peerings.
