Computation of the Layer 2 overhead attribute in interface statistics

On MX Series routers, you can configure the physical interface and logical interface statistics to include the Layer 2 overhead size (header and trailer bytes) for both ingress and egress interfaces. Both the transit and total statistical information are computed and displayed for each logical interface. This functionality is supported on 1-Gigabit and 10-Gigabit Ethernet interfaces on Dense Port Concentrators (DPCs) and Modular Port Concentrators (MPCs). You can enable the Layer 2 overhead bytes for computation in the logical interface statistics by configuring the account-layer2-overhead (value | <ingress bytes | egress bytes>) statement at the [edit interface interface-name unit logical-unit-number] hierarchy level. If you configure this capability, all the Layer 2 header details (L2 header and cyclic redundancy check [CRC]) based on the Layer 2 encapsulation configured for an interface are calculated and displayed in the physical and logical interface statistics for ingress and egress interfaces in the output of the show interfaces interface-name commands. For physical and logical interfaces, the Input bytes and Output bytes fields under the Traffic statistics section in the output of the show interfaces interface-name <detail | extensive> command include the Layer 2 overhead of the packets. For physical and logical interfaces, the Input Rate and Output Rate fields under the Traffic statistics section in the output of the show interfaces interface-name <media | statistics> command include the Layer 2 overhead of the packets. For logical interfaces, the values for the newly added Egress accounting overhead and Ingress accounting overhead fields display the Layer 2 overhead size for transmitted and received packets respectively.