Ethernet Data Packet
All communication between a local and remote station is accomplished by the transmission of a packet that contains the Ethernet headers and trailers and an encapsulated LLC protocol data unit (LPDU). This packet format is specifically designed for the SNA protocol, but other protocols can use this format as well.
The The DLCETHER Frame Encapsulation figure (Figure 1) illustrates the Ethernet data packet.
The Ethernet data packet consists of the following:
Item | Description |
---|---|
LPDU | LLC protocol data unit |
DSAP | Destination service access point (SAP) address field |
SSAP | Source SAP address field |
CRC | Cyclic redundancy check or frame-check sequence |
m bytes | Integer value greater than or equal to 46 and less than or equal to 1500 |
n bytes | Integer value greater than or equal to 43 and less than or equal to 1497 |
p bytes | Integer value greater than or equal to 0 and less than or equal to 1493 |
Note: The Preamble and CRC identify both of these as something that
is added and deleted by the hardware adapter.