NDK Terminology

This chapter explains frequently used terms.

Ethernet Port

In our terminology, the Ethernet Port corresponds to one physical network port, typically one optical cage (for example, QSFP28 or QSFP-DD).

Ethernet Lanes

The term Ethernet Lanes refer to high-speed serial lines used in the physical layer of the Ethernet protocol. Each type of Ethernet Port can use a different number of Ethernet Lanes (for example, QSFP28 uses 4, and QSFP-DD uses 8).

Ethernet Channel

Each Ethernet Port can use a different number of high-speed serial lines (Ethernet Lanes), typically 4 or 8. Different Ethernet standards (like 100 GbE, 25 GbE,…) require one or more of these lanes. For port QSFP28, where there are 4 lanes running at 28 Gbps, 100 GbE standard would take up all 4 lanes together forming one Ethernet channel. For another Ethernet standard like 25 GbE, one lane is enough. Using all 4 lanes, we would get 4 separate 25 Gigabit Ethernet channels.

Ethernet Stream

An Ethernet Stream is a group of data interfaces (RX and TX) that transmits Ethernet packets from/to a selected number of Ethernet Channels. In our platform, the number of Ethernet Streams typically corresponds to the number of Ethernet Ports.

DMA Stream

An DMA Stream is a group of data interfaces (RX and TX) that transmits DMA packets from/to DMA module. In our platform, the number of DMA Streams typically corresponds to the number of Ethernet Streams (and therefore Ethernet Ports).

DMA Channel

The DMA controller supports data transmission in each direction (RX and TX) in multiple independent queues, which in our terminology we refer to as DMA channels.