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RFC1661 - часть 15


4.3. Events

Transitions and actions in the automaton are caused by events.

Up

This event occurs when a lower layer indicates that it is ready to

carry packets.

Typically, this event is used by a modem handling or calling

process, or by some other coupling of the PPP link to the physical

media, to signal LCP that the link is entering Link Establishment

phase.

It also can be used by LCP to signal each NCP that the link is

entering Network-Layer Protocol phase. That is, the This-Layer-Up

action from LCP triggers the Up event in the NCP.

Down

This event occurs when a lower layer indicates that it is no

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RFC 1661 Point-to-Point Protocol July 1994

longer ready to carry packets.

Typically, this event is used by a modem handling or calling

process, or by some other coupling of the PPP link to the physical

media, to signal LCP that the link is entering Link Dead phase.

It also can be used by LCP to signal each NCP that the link is

leaving Network-Layer Protocol phase. That is, the This-Layer-

Down action from LCP triggers the Down event in the NCP.

Open

This event indicates that the link is administratively available

for traffic; that is, the network administrator (human or program)

has indicated that the link is allowed to be Opened. When this

event occurs, and the link is not in the Opened state, the

automaton attempts to send configuration packets to the peer.

If the automaton is not able to begin configuration (the lower

layer is Down, or a previous Close event has not completed), the

establishment of the link is automatically delayed.

When a Terminate-Request is received, or other events occur which

cause the link to become unavailable, the automaton will progress

to a state where the link is ready to re-open. No additional

administrative intervention is necessary.

Implementation Option:

Experience has shown that users will execute an additional Open

command when they want to renegotiate the link. This might

indicate that new values are to be negotiated.




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