ADSL to build VPN

Chris Carlson carlsonmail at YAHOO.COM
Wed Jan 24 17:57:47 EST 2001

Hi Clayton,

Two things about ADSL to be concerned with, you've
already hit on the first.  Yes, the speeds are
asynchronous, but what do you estimate the transfer
path to be?  Is one office mostly downloading instead
of uploading?  If so, perhaps the mostly downloading
office can get ADSL and the "HQ" office with uploading
can get SDSL.

(Also, I'm surprised you can get ADSL to a business
address.  I know that Covad doesn't allow that....)

The second thing about DSL is that it certainly isn't
mission critical.  Beside the massive oversubscription
that ISPs put on DSL lines (especially ADSL), and your
reliance on the low cost phone-quality copper loops,
I've seen failure rates in the multiples per month
with outages as long as 4 days!

In life, you get what you pay for.  $89/mo is worth
that.  T-1 service from $500 - $1200 is more reliable.

As for your address space issue, I would really really
renumber one of them.  I'm not saying it wouldn't
work, but NT has issues with NATting.  Normally, the
real IP address of the server is embeded in the
payload of the packet; it doesn't rely on the source
address.  So, NAT won't work.

Plus, it'll be pain to setup and manage a
bidirectional NAT pool on an on-going basis.

It almost seems like you should renumber ONE of the
locations, preferably the easiest.  :)  Are there
other reasons why you prefer not to renumber?

Lastly, does Cisco make DSL routers??  We use
Efficient Networks at my company, works like a champ!

Good luck!

--- Clayton Nash <cnash at BTCONNECT.COM> wrote:
> Hi All,
> I've a client who's looking at using ADSL as their
> connection to the Internet from two remote offices
> upon which they want to build a VPN using Cisco
> Routers. Is there any implication in using ADSL --
> will I get bitten by the asynchronous speeds for
> example?
> The other issue that's come up is that they have
> managed to use the same addresses at both offices
> (192.168.0.x) and cannot change either easily. What
> issues will I face doing NAT and still allowing
> things like NT drive shares and remote DB access
> over such a link?
> Any comments appreciated.
> Thanks,
> Clayton

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