The SR OS node preserves statistics from a subscriber even when the subscriber is disconnected, and the subscriber’s policers or queues are released. This prevents statistics fluctuation in relation to the subscriber’s presence and ensures that a statistic counter remains stable. After being counted on a VLAN, subscriber interface, or a group interface, the octet or packet remains accounted for during the life time of that VLAN, subscriber interface, or group interface. However, statistics can be manually cleared with the clear>subscr-mgmt>interface-statistics command.
Reporting absolute (or cumulative) counts in aggregated statistics allows smooth measurement of bandwidth per VLAN, subscriber interface, or group interface without dips caused by departing subscribers. The rate measurement can be performed externally by calculating the difference in byte count between two consecutive statistics polls, divided by the collection interval.
Sudden changes in rates can give an indication of a path failure in the network.