Subject: [Pce] When should we start the Keepalive timer?

From: "Iksoon Hwang" <[email-masked]>
Date: Tue, 9 Dec 2008 16:45:58 +0100

Dear all,

It seems that there are some problems in the explanation of Appendix A
concerning with the Keepalive timer.

In section 4.2.1, Keepalive messages are used to acknowledge Open messages,
and once the PCEP session has been successfully established.

In section 6.2, the PCEP session is considered as established once both PCEP
peers have received a Keepalive message from their peer.

In Appendix A, if a system in OpenWait state receives an Open message from
the PCEP peer before the expiration of the OpenWait timer, it performs
collision resolution procedure. If there is no collision, no errors are
detected in Open message, and the session characteristics are acceptable to
the local system, the system:

   o  Sends a Keepalive message to the PCEP peer,

   o  Starts the Keepalive timer,

   o  Sets the RemoteOK variable to 1.

If LocalOK=0 the system clears the OpenWait timer, starts the KeepWait timer
and moves to the KeepWait state.

The statement in section 4.2.1 and starting the Keepalive timer in OpenWait
state when LocalOK=0 are contradictory because the system starts keepalive
mechanism although the session is not established yet. 

Also, it seems that there is another problem. In section 7.3, it is
explained that "A sends an Open message to B with Keepalive=10 seconds and
Deadtimer=40 seconds.  This means that A sends Keepalive messages (or any
other PCEP message) to B every 10 seconds and B can declare the PCEP session
with A down if no PCEP message has been received from A within any 40 second
period". The Keepalive timer should follow the Keepalive value in the Open
message that was sent to its peer (not the Keepalive value in the Open
message received from its peer). Therefore, the Keepalive timer can be set
only after the peer accepted the parameter values in the Open, i.e. only
after the system receives a Keepalive message from its peer. 

I think the Keepalive timer and the Deadtimer should be started when the
system moves to SessionUP state. Is there anybody who can give me any
advice?

Thanks in advance.

    Iksoon

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