ASR9000 Netflow Configuration and Performance Issues

ASR9000 Netflow Configuration and Performance Issues

Do not forget to check for the newer documentation for netflow configuration and new hardware values!

For configuration and hardware architecture read the documents;

Limitations and problems ;

1. Supports configurable Sampling Rate 1:1 ~ 1: 65535
2. Supports only up to 4 Sampling Rates (or Intervals) per Ethernet LC LC; no such limit for Enhanced Ethernet LC.
3. Up to 4k interfaces/sub-interfaces (4K system limitation) can be configured with flow monitor per system.
4. Supports up to 8 flow exporters per flow monitor
5. Supports up to 1 million flow entries per LC
6. Supports up to 50k flows per second with LC CPU usage up to 50% per Ethernet LC LC
7. Supports upto 100K flows per second with LC CPU usage up to 50% per Enhanced Ethernet LC LC
8. Netflow scale is increased to 200Kpps on Enhanced Ethernet LC based LCs
9. Supports exporting packet rates up to 50k flows per second (100K flows per sec on Enhanced Ethernet LC based LCs) with LC CPU usage up to 50%

“Irrespective of the rate at which the NP punts the records to CPU, exporter picks up a maximum of 2000 records at a time from the cache that are eligible for export (timers, network/TCP session events, etc). This is basically to avoid NetIO dropping the packets due to lack of b/w. When the exporter wakes up again, it repeats the same.”

show flow monitor-map XXX
......
CacheAgingMode:    Normal
CacheMaxEntries:   1000000
CacheActiveTout:   60 seconds
CacheInactiveTout: 15 seconds
CacheUpdateTout:   N/A
CacheRateLimit:    2000

So, it can collect 100k flows per second, but can only export 2k each time it runs the exporter. The interval for the exporter is unclear however. There is a bug related to this issue.

Cisco BUG CSCul59517

flow monitor-map TN_TRANSIT_MON

cache timeout rate-limit <rate-limit> : You may change the 2000 limit with this command which may be hidden.

 

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