To define a Point-to-Point Protocol (PPP) line that is associated with an analog modem, select this line service. This option is also used for leased lines where a modem is not required. The PPP connection profile always uses the same i5/OS® communications port resource.
An analog single line, if required, might be configured as shared between an answer profile and a dial profile. The dynamic resource sharing is a new function designed to enhance resource usability. Until V5R2, the modem resources were committed as soon as the profile using it was started. This was limiting the user to one resource per session, even if the resource was in the passive wait state. Now, new sharing rules apply when a specific resource has been accessed. There are two cases: first, a dial profile was started before an answer profile; second, an answer profile was started before a dial profile. The assumption is that the resource sharing is enabled. In the first case, the dial profile that was started will successfully connect. The answer profile that was started second, will wait for the line to become available. After the dial connection was ended, the answer profile will request the line, and will start. In the second case, the answer profile that was started will wait for the incoming connections. Unless an incoming connection was made, the dial profile that was started second, will "borrow" the line from the answer profile, which will "lend" the line. The outgoing connection will then be established. After the connection was ended, the dial profile will return the line to the answer profile which will again be ready to accept incoming connections. To enable the sharing function, click the modem tab for a switched line description, and select Enable Dynamic Resource Sharing.
Single line service is also used for L2TP (virtual line) and PPPoE (virtual line) connection types. For L2TP (virtual line) connection types, there is no hardware communications port resource used with the single line. Rather, the single line used with an L2TP connection is virtual in that there is no physical PPP hardware that is required to establish the tunnel. The single line used with a PPPoE connection is also virtual in that it provides a mechanism for treating a physical Ethernet line as if it were a PPP line that supports remote connections. The PPPoE virtual line is bound to a physical Ethernet line and is used to support PPP protocol data transfers over the Ethernet LAN connection to a DSL modem.