HP 800 HP DLPI Programmer's Guide - Page 28

Introduction to DLPI The Data Link Layer An example of this can be to specify various ether_type values as DLSAPs. The DL_BIND_REQ, for example, can be issued with an ether_type value of IP, and a subsequent bind can be issued with an ether_type value of ARP. The provider may now multiplex off the ether_type field and allow both the IP and ARP traffic to be sent up this stream. When the DLS user requests hierarchical binding, the subsequent bind specifies a DLSAP that is used in addition to the DLSAP bound using a DL_BIND_REQ. This allows additional information to be specified, which will be used in a header or for demultiplexing. An example of this can be to use hierarchical bind to specify the Organizational Unique Identifier (OUI) to be used by SNAP. If a DLS provider supports peer subsequent bind operations, the first SAP that is bound is used as the source SAP when there is ambiguity. DLPI supports the ability to associate several streams with a single DLSAP, where each stream may be a unique data link connection endpoint. However, not all DLS providers can support such configurations, because some DLS providers may have no mechanism beyond the DLSAP address for distinguishing multiple connections. In such cases, the provider restricts the DLS user to one stream per DLSAP. 28 Chapter 1