A channel is defined as a single hardware connection to an Ethernet cable. Each channel implements the cross-company Ethernet standard. The following diagram shows the relationship of these users to the DNA Ethernet Data Link and its relationship to the standard Ethernet Data Link. In Ethernet terminology, the DNA Ethernet Data Link is the lowest level module in the Client Layer. The user of the DNA Ethernet Data Link is concerned with two different levels of identification.
Users identify either a channel or a portal.
A portal is assigned by the data link in response to a user's initial call. The user then uses that portal in subsequent related calls. Many users can simultaneously have their own portal associated by the data link with the same channel. A portal data base contains the lists of protocol types and multicast addresses that the user has enabled for receipt of incoming frames. The user will receive frames only for enabled protocol types and multicast addresses.