Re: SyncPPP IPCP/LCP loop problem and patch

Paul Mackerras wrote:
> 
> [e-mail] writes:
> > I've hit a problem with the syncPPP module within Linux.
> 
> Seems to me that when you get the conf-request in opened state, you
> should send your conf-request before sending the conf-ack to the
> peer's conf-request.  I think this would short-circuit the loop (I
> could be wrong though, it's getting late).

Thanks but I've already tried that. You get a slightly different pattern
to the loop but it still loops.

> That behaviour would be in line with the FSM in rfc1661, where the
> action for event RCR+ in Opened state is "tld,scr,sca/8", i.e. the one
> action involves sending both the conf-request and the conf-ack.  It is
> debatable to what extent that specifies the order of the messages but
> it does list the conf-request first FWIW.

RFC1661 states: multiple actions may be implemented in any convenient order.
So if it had worked we'd still have been conformant.

I've also tried dropping selected packets when I see the condition, simulating
a noisy line or buggy driver whilst keeping the PPP state machine conformant.
Problem is you need to generate the conf-ack to get the remote end into the
LCP opened state whilst not dropping out of it yourself.

-- 
        Bob Dunlop                      FarSite Communications
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