How are utilization statistics collected?

Map statistics collection

Information in the Utilization map is based on port egress statistics collected for IP links on Ethernet physical ports. Statistics must be supported and available for utilization to be displayed. The Operational State of NEs and ports must be Up.

Utilization statistics are collected from NEs using SNMP for NFMP NEs and gRPC for MDM NEs.

When a user switches from the Operational Map to the Utilization Map, the first two telemetry subscriptions listed below are created. If LAG links are present on the map, the third subscription listed below is created.

1. Subscription for SNMP and MDM managed NEs and ports on the current map.

   SNMP-managed 7750 SR family NEs respond to the filter.

   The following MDM-managed NEs respond to the filter: 7750 SR, 7250 IXR / VSR(I), 7450 ESS, and 7950 XRS

   This subscription determines utilization directly from the output-utilization statistic counter.

2. Subscription for SNMP managed 7705 SAR and 7210 SAS NEs and ports on the current map.

   This subscription calculates utilization from the following statistics: operational-speed, transmitted-broadcast-packets-periodic, transmitted-multicast-packets-periodic, transmitted-octets-periodic, and transmitted-unicast-packets-periodic.

   SNMP utilization statistics are calculated from NFM-P counters using this formula:

   output-utilization(%) = (transmittedTotalOctetsPeriodic + ((transmitted-unicast-packets-periodic + transmitted-multicast-packets-periodic + transmitted-broadcast-packets-periodic) * 20)) * 8/t/operational-speed/1000 * 100

   Where t is the collection interval in seconds, as specified in the Utilization Map preferences.

3. Subscription for SNMP-managed NEs and LAG links on the current map.

   This subscription calculates utilization from the following statistics: speed, transmitted-broadcast-packets-periodic, transmitted-multicast-packets-periodic, transmitted-octets-periodic, and transmitted-unicast-packets-periodic.

   SNMP utilization statistics are calculated from NFM-P counters using this formula:

   output-utilization = (transmitted-octets-periodic + ((transmitted-unicast-packets-periodic + transmitted-multicast-packets-periodic + transmitted-broadcast-packets-periodic) * 20)) * 8/t/operational-speed/1000 * 100

   Where t is the collection interval in seconds, as specified in the Utilization Map preferences.

For SNMP, NEs must be managed by the NFM-P and reachable using SNMP. The following are used for utilization data:

• MIB name: TIMETRA-PORT-MIB

• MIB entry name: tmnxPortEtherEntry

• MIB counter name: tmnxPortEtherUtilStatsOutput

• Statistics group: Additional Ethernet Stats

• Counter: utilStatsOutput (in centi-percent)

The following NEs support the required SNMP statistics for the Utilization map:

• 7250 IXR

• 7450 ESS

• 7750 SR and VSR

• 7950 XRS

For MDM, the following gRPC schema path is used for utilization data:

• /state/port[port-id]/ethernet/statistics/out-utilization

SR OS NEs support the required MDM statistics for the Utilization map. The supporting chassis types are:

• 7250 IXR

• 7450 ESS

• 7750 SR

• 7950 XRS

Utilization statistics for the 7705 SAR and 7210 SAS

The following (periodic) counters are used for utilization calculation for the 7705 SAR and 7210 SAS:

• MIB name: IF-MIB

• MIB entry name: ifXEntry

• MIB counter names: ifHCOutOctets, ifHCOutUcastPkts, ifHCOutMulticastPkts, ifHCOutBroadcastPkts

• NFMP statistics group: Interface Additional Statistics

• NFMP counters: transmittedBroadcastPackets, transmittedMulticastPackets, transmittedTotalOctets, transmittedUnicastPackets

The following information is used to establish a reference speed:

• MIB name: TIMETRA-PORT-MIB

• MIB entry name: tmnxPortEtherEntry

• MIB counter name: tmnxPortEtherOperSpeed (mbps)

• NFMP class: equipment.PhysicalPort

• NFMP counter: actualSpeed (kbps)