Re: adsl+sdsl+cable?

From: David Haggett (news-spam_at_haggett.demon.co.uk)
Date: 09/25/04 

Date: Sat, 25 Sep 2004 15:19:43 +0100

On Fri, 24 Sep 2004 14:27:48 +0200, philip wrote:

> i'd like to try adsl with sdsl and cable together.

Short answer: good luck :)

Longer Answer
=============
It depends on exactly what you're trying to achieve, and what your exact
setup is. The challenge is that each service has a different external
address, so the Internet will perceive you as three seperate hosts, on
three seperate networks.

Theoretically, outgoing connections could be handled by defining
static routes. Because the outgoing packets will always have the IP
address associated with the originating interface, replies will always be
made to the same address. By choosing different outgoing interfaces for
different destinations, you effectively specify the interface through
which the return packets will be received.

To manage incoming connections, you would first have to find a way of
ensuring the inbound connections are shared. Possibly just advertise your
web-site with three different host-names, each one resolving to a
different external address.

One way to ensure you share the return traffic correctly, would be to put
a router on each ISP interface to perform SOURCE NAT on incoming packets
as they enter your LAN. The server would see the router as the source
address, and respond to it. The router would then retranslate the
packet's source and destination fields as it forwarded the traffic back to
the client.

Caveat
======
These solutions are theories only, thought up by a bored network
technician on a rainy Sunday afternoon. Good Luck 

-- 
David Haggett
Linux user since 01/01/2003
Email: david<at>haggett<dot>demon<dot>co<dot>uk

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