EXFO ETS-1000G - Manual (Page 188)

Glossary
178 ETS-1000G
VLAN Priority
Three bits which carry information about a frame's priority. There are eight
possible priority values.
Data link layer
It enables the interaction between networks on the physical layer and the
monitoring of errors that may occur. The data link layer can interact with
one or several physical layers, control them and manage this interaction.
Learning frame
A frame that has the source MAC address identical with the destination
MAC address. When a switch receives this frame, it filters it as the output
interface is identical with the input one. At the same time, the switch reads
the source MAC address and stores the interface from which it was
received.
Network switch
A device that is used for interconnecting several nodes in a computer
network. It transmits data directly to the recipient. The switch operates on
the data link layer of the OSI model.
Network hub
A device that is used for joining several nodes in a computer network. All
the devices connected to the hub ports receive the same information.
Network layer
It enables determining a data transmission route. It is responsible for
translating logic addresses and names into physical ones, determining the
shortest routes, switching and routing, tracing faults in the network.
Transport layer
It ensures the reliable packet transport between two network end points.
Despite the fact that lower layer protocols check whether each data
transmission operation is being executed correctly, this layer ensures that
the data being transmitted are additionally checked for correctness.