ENCODING THE DATA TYPE:
The figure explain a frame in which the data kind is specified by using the data area.
To ensure interoperability format of encoding location must be universally agreed upon it typically set by standards only.
IEEE 802.2 LLC:
IEEE 802.2 standard adds logical link control (LLC) sub network attachment point (SNAP) header. SNAP/LLC format is commonly used for example by Ethernet. This is given in figure below:
Figure: SNAP/LLC format
In the figure LLC portion shows SNAP field to follow OUI shows Ethernet specification organization.
Also the type format is interpreted as in Ethernet as given in diagram above.
For either encoding format some device may not be prepared to accept frames of some kinds, which are unknown e.g. protocol type is not used and the newly defined kind. The receiving computer calculating the field and discards any frame with unknown kind.