For devices that are declared to be type DL_ETHER, GLDv2 provides support for both Ethernet V2 and ISO 8802-3 (IEEE 802.3) packet processing. Ethernet V2 enables a user to access a conforming provider of data link services without special knowledge of the provider's protocol. A service access point (SAP) is the point through which the user communicates with the service provider.
Streams bound to SAP values in the range [0-255] are treated as equivalent and denote that the user wants to use 8802-3 mode. If the SAP value of the DL_BIND_REQ is within this range, GLDv2 computes the length of each subsequent DL_UNITDATA_REQ message on that stream. The length does not include the 14-byte media access control (MAC) header. GLDv2 then transmits 8802-3 frames that have those lengths in the MAC frame header type fields. Such lengths do not exceed 1500.
Frames that have a type field in the range [0-1500] are assumed to be 8802-3 frames. These frames are routed up all open streams in 8802-3 mode. Those streams with SAP values in the [0-255] range are considered to be in 8802-3 mode. If more than one stream is in 8802-3 mode, the incoming frame is duplicated and routed up these streams.
Those streams that are bound to SAP values that are greater than 1500 are assumed to be in Ethernet V2 mode. These streams receive incoming packets whose Ethernet MAC header type value exactly matches the value of the SAP to which the stream is bound.