On Friday 22 June 2007 15:22, Grant Taylor wrote:
> (Off thread topic.)
>
> On 06/22/07 06:54, Gustavo Homem wrote:
> > This is absolutetly the way to do it with ADSL.
>
> I could not agree more.
>
> > Using a modem in bridged mode minimizes the responsability of the
> > modem/router which is a potentially unstable device. Let the stable
> > Linux box do the work (routing+nat) and get the public IP. And
> > firewall the Linux box itself with iptables. This is the most
> > flexible and stable way to go.
>
> *nod* About the only thing that I'm looking at doing differently at my
> house is to use the Thompson USB SpeedTouch (330) USB ADSL modem to put
> the ATM stack on the Linux box its self.
I've done this, but I think it's unreliable for professional use. The USB
modems are non-standard so if one burns you can't exchange it for a different
one without feasible but time consuming tweaking (tried more then one USB
devices...).
Even for Ethernet briding devices I only use models which are delivered by
ISPs (rather than retail shop devices), to garantee they were tested for
stability:
POTS:
http://www.huawei.com/products/terminal/products/view.do?id=87
ISDN:
http://www.acbs-dsl-store.com/contenu/Articles/Article.asp?PdtNum=DSLGP628LP
These models run forever in bridged mode. The second one accepts multiple
PPPoE clients on different ports.
> This way the Linux kernel will
> handle the bridging and buffering verses an external device that has
> arbitrary pauses waiting for buffers to fill prior to transmitting data.
>
> My preliminary tests with the ATM stack on Linux show a speed increase
> over the external bridging modem too. :) My tests show that Linux /
That's expectable since using PPPoA instead of PPPoEoA, reduces the overhead.
But I don't know a standard PPPoA setup.
But if we want QoS working, we can't use the full line capability anyway.
> Windows think the raw ATM with bridging circuit will get close to 1.6
> Mbps while the bridged devices get closer to 1.5 Mbps. I also see a
> lower latency between the device connected to the DSL and the upstream
> gateway by a factor of 3 - 5 ms.
Even if that happens, it would hardly compensate the risk of lower
reliability.
Cheers
Gustavo
--
Angulo Sólido - Tecnologias de Informação
http://angulosolido.pt
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