Bug#265183: pppoe workaround of the post-reboot problem
On Tuesday 21 September 2004 00:12, Marco d'Itri wrote:
> On Sep 20, Eduard Bloch <edi@gmx.de> wrote:
> > Which loop? I do not know why your modem has an own IP, maybe it is a
> > router and not a modem? Why does it give your local systems DHCP
> > adresses? How are they related to whatever is connected there? Or maybe
> > it is not a usual PPPoE modem but this other weird
> > ip-route-over-fake-internal-network-with-dhcp-over-DSL system (*).
>
> He is using an alcatel speedtouch ethernet modem which encapsulates
> PPP in PPTP, to allow using PPPoA. The modem has 10.0.0.138 and the host
> should have another address in that range.
> This page describes a similar but different (there is no ppp0, but eth0)
> configuration: http://pptpclient.sourceforge.net/diagrams.phtml .
> If the modem DHCP server is really providing a gateway then I
> consider this a modem bug.
Marco has pretty much summed it up. I fail to see though why the modem asking
the host to consider the modem the default gateway is a bug. The routing
table that is set up on the host once the modem has responded via DHCP
correctly reflects the situation - the only way to the outside from the host
at that time is via the modem. One can use the modem as a router (w/o
starting pppoe at all) and reach the provider's WAN, although the traffic
won't be routable outside.
> > PS: (*) I am still looking for somebody to explain me how this
> > "technology" works and can provide a reliable step-for-step howto to add
> > support for it to pppoeconf. Or even patches. From time to time people
> > asked me to add support for their "DHCP DSL" but for real support more >
> > is needed.
>
> It's not hard. Look at this example configuration:
> http://www.bytewise.at/knowhow/adsl-pptp/Konfiguration.html
The only piece of info that you asked for that Marco hasn't addressed was the
duplex LAN link - I was telling that the host is directly wired into the
modem, i.e. there is no hub sitting between them, so the LAN connection
MODEM <-> HOST is a full-duplex ethernet connection (as opposed to
half-duplex).
I think that to add to pppoeconf the support, the following needs to be done:
1) from the routing table, one must deduce that there is no direct route to
the modem, hence the default route will be used
2) that default route has to be cloned into a direct route to the modem
(better yet, make that a network route to the net specified by the network
portion of the modem address)
3) after that, ppp has to be invoked with the replacedefaultroute option, and
it will work
I'll be happy to elaborate further if needed.
V.
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