[Gllug] re: DSL router not doing NAT

[Russell Howe]

On Mon, Oct 18, 2004 at 04:27:10PM +0100, t.clarke wrote:
> I have a Netgear DM602 which supposedly has a 'modem' mode, which, if I read
> the instructions right menas that it should pass all packets received
> transparently through.  Trouble is, I havn't actually been able to get it to
> work in this mode!  Maybe I was doing something wrong.  I didn't pursue
> the matter as I need the firewalling capabilities of NATing anyway.
> If I get a mo I will have another go and see if I can figure it out.

The problem I face, is that to bridge the connection onto Ethernet, it'd
have to be PPPoE on the DSL side. No ISP in the UK supports PPPoE, to my
knowledge, since BT don't officially support it on their equipment.

As it is, PPPoE works, but the telco end assumes an MTU of 1500. Correct
for PPPoA, but not oE.

So, I get my PPPoE packets bridged onto my ethernet segment, where my
firewall PC can be the PPPoE tunnel endpoint, but path MTU discovery is
broken, since the ISP end doesn't send fragmentation-needed messages
when it should do.

What I'm looking for now is either a box which will act as a DSL to ATM
bridge, and will bridge a PPPoA session onto something like ATMF25, for
which I can get an ATM adapter for the Linux box, and run PPPoA on that,
or a PCI DSL modem.

However, I don't know of a PCI DSL modem with open source drivers (they
all seem to have a closed source binary chunk in the middle), and I
don't know of anyone who provides a DSL to ATM bridge (some would call
it an ATM DSL modem). Cisco used to, a few years ago, but it's been
EOL'd and had security problems. The Alcatel 1000 which was one of the
standard bits of kit on early BT DSL rollouts no longer seems to work
with the equipment in today's exchanges.

-- 
Russell Howe       | Why be just another cog in the machine,
rhowe at siksai.co.uk | when you can be the spanner in the works?
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