Hi there! I hope someone will be kind enough to help me with the following question:
If DSAP (Destination Service Access Protocol) from the Ethernet header identifies the type of layer 3 protocol that follows, then what is SSAP for?
Thank you in advance for your help.
The DSAP field contains a Destination Service Access Point. A DSAP is a unique user-level address that identifies the higher-level protocol used on the destination machine.
The DSAP address is one byte in length. The least significant bit in the DSAP identifies whether an individual or a group of individuals should receive the packet. The remaining seven bits, or the most significant bits of the DSAP, are the address.
The SSAP field contains a Source Service Access Point. An SSAP is a unique user-level address that identifies the higher-level protocol used on the source machine. The SSAP and the DSAP must be the same in order for two nodes to communicate.