Improvements to Interface Transmit Statistics Reporting

The offered load on an interface can be defined as the amount of data the interface is capable of transmitting during a given time period. The actual traffic that goes out of the interface is the transmitted load. However, when outgoing interfaces are oversubscribed, there could be traffic drops in the schedulers attached to the outgoing interfaces. Hence, the offered load is not always the same as the actual transmitted load because the offered load calculation does not take into account possible packet drop or traffic loss.

On MX Series routers, the logical interface-level statistics show the offered load, which is often different from the actual transmitted load. To address this limitation, Junos OS introduces a new configuration option in Release 11.4 R3 and later. The new configuration option, interface-transmit-statistics, at the [edit interface interface-name] hierarchy level, enables you to configure Junos OS to accurately capture and report the transmitted load on interfaces.

Aggregated Ethernet interfaces do not support reporting of the transmitted load statistics. You cannot configure aggregated Ethernet interfaces to capture and report the actual transmitted load statistics.

When the interface-transmit-statistics statement is included at the [edit interface interface-name] hierarchy level, the following operational mode commands report the actual transmitted load:

• show interface interface-name <detail | extensive>

• monitor interface interface-name

• show snmp mib get objectID.ifIndex

The show interface interface-name command also shows whether the interface-transmit-statistics configuration is enabled or disabled on the interface.