My apologies, I should clarify that Lars is quite correct, you cannot
control the flow on the tunnel. We do our shaping at the PPPoE box, using
the functionality of a BSD system. The tunnel (at least in PPPoE cannot have
flow control parameters specified).

----- Original Message -----
From: "Lars Gaarden" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, November 11, 2003 1:13 AM
Subject: Re: [smartBridges] sB Network Issue


> Roger Howard wrote:
> >>The only way you can make sure that an infected client can't wreak havoc
> >>on the AP is to have bwctrl on the CPE.
> >>
> >
> > This is what I was saying... but Colin Watson says that PPPoE
encapsulates
> > everything including ping packets into PPP which does have flow
control?? Is
> > this right?
>
> PPP over serial lines does have flow control (RTS/CTS and XON/XOFF).
>
> RTS/CTS can't be used with PPPoE because it uses the RTS/CTS wires on the
> serial port (out-of-band signalling).
>
> XON/XOFF is in-band, but requires escape codes to insure that payload data
> is not incorrectly interpreted as XON/XOFF. In order to use escape codes,
> the PPP peers must negotiate an Async-Control-Character-Map (ACCM) during
> the LCP phase. The PPPoE RFC states that:
>
> http://www.faqs.org/rfcs/rfc2516.html
> "7. LCP Considerations
>     [...] An implementation MUST NOT request any of the following options,
>     and MUST reject a request for such an option:
>     [...]
>        Asynchronous-Control-Character-Map (ACCM)"
>
> So neither RTS/CTS nor XON/XOFF can be used for PPPoE flow control.
>
> --
> LarsG
>
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