Installing and Administering PPP

Chapter 4 65
Common pppd Options
Link Management
Link Management
Link management options define how PPP establishes, maintains and
monitors a communications link. These factors, and the condition of the
link, help PPP decide when to bring a link up and down in situations
other than on-demand dialups.
Active vs. Passive PPP Negotiations
HP-UX PPP, like most PPP implementations, expects to actively initiate
the negotiation process. By default, when a line is connected, pppd
immediately sends PPP messages, anticipating that a PPP
implementation on the other end is ready to negotiate. In auto mode, this
directly follows completion of a Systems chat script login procedure.
When pppd is not in auto mode, messages are sent when the daemon
starts.
Outbound
The default behavior works correctly in almost all situations. However,
sometimes it is better to let the other end send its messages first when
calling another system's dial-up modem. A few PPP implementations get
confused when a peer speaks first and negotiations may be slow if both
ends are active. In these situations, assign pppd the passive option. The
passive option makes pppd wait until the other end communicates before
it sends messages.
This is an example of the pppd command line for outbound passive
connection:
pppd hostname:peer auto passive
Inbound
When a PPP implementation that gets confused by the other end's active
negotiations dials an HP-UX PPP system, it would be wise to make the
calling pppd passive if possible. However, if it is not possible,
negotiations may proceed faster if the Login script invokes the passive
option on the receiving pppd.