W2K3 Dual Nic and 2 ISPs

I am in the process of switching ISP providers and doing a cut over.
I have 3 web servers that sit directly on the Internet (yeah, I know!!
separate topic for a different thread). Anyway, point is, I do not
have a router in front of this to provide communication to both
networks and handle it that way.

Instead, what I am trying to do is allow access to the web servers
from both networks (each ISP) in the process of transition. We are
not talking about a long duration but probably about a week. I want
to switch DNS, let it replicate but still allow the old network from
ISP1 to continue to respond properly and then eventually finish the
cutover to ISP2 and unplug the ISP1.

Can anyone tell me how to configure my 3 W2K3 servers in order to
accomplish this?

None of the servers are DCs or in a domain. They are standard
standalone servers.

I know you cannot have a gateway specified on the second nic, but if I
configure everything else (IP Addresses, Subnets) for ISP2 and then
configure IIS to respond to either or and then change DNS, will this
cause issues with traffic confusion? What is the best way to approach
this problem?

Thanks,

Kalvin

It doesn't take days.
At worst a few hours, at best 30 minutes.
My last DNS change took 10 minutes.
Pick a time late at night on the weekend to do the cut over an "just do it".

It is your ISP's job to help make this smooth, that is part of what you pay
them for. Make them do their job, get their advice on how to make it is
smooth as it can be.


--
Phillip Windell
www.wandtv.com

The views expressed, are my own and not those of my employer, or Microsoft,
or anyone else associated with me, including my cats.
-----------------------------------------------------


<(E-Mail Removed)> wrote in message
news:9d6385a5-717d-404c-a93e-(E-Mail Removed)...
>I am in the process of switching ISP providers and doing a cut over.
> I have 3 web servers that sit directly on the Internet (yeah, I know!!
> separate topic for a different thread). Anyway, point is, I do not
> have a router in front of this to provide communication to both
> networks and handle it that way.
>
> Instead, what I am trying to do is allow access to the web servers
> from both networks (each ISP) in the process of transition. We are
> not talking about a long duration but probably about a week. I want
> to switch DNS, let it replicate but still allow the old network from
> ISP1 to continue to respond properly and then eventually finish the
> cutover to ISP2 and unplug the ISP1.
>
> Can anyone tell me how to configure my 3 W2K3 servers in order to
> accomplish this?
>
> None of the servers are DCs or in a domain. They are standard
> standalone servers.
>
> I know you cannot have a gateway specified on the second nic, but if I
> configure everything else (IP Addresses, Subnets) for ISP2 and then
> configure IIS to respond to either or and then change DNS, will this
> cause issues with traffic confusion? What is the best way to approach
> this problem?
>
> Thanks,
>
> Kalvin

Thanks for the reply Phillip. Unfortunately these are 2 different
ISPs. This is a switch of T1 vendors and so there is not much they
can do. Does anyone have solution to my question? I am certain it
can be done, just not sure of the logistics of how to set it up?

Thanks,

Kevin

On Jan 29, 8:55*am, "Phillip Windell" <philwind...@hotmail.com> wrote:
> It doesn't take days.
> At worst a few hours, at best 30 minutes.
> My last DNS change took 10 minutes.
> Pick a time late at night on the weekend to do the cut over an "just do it".
>
> It is your ISP's job to help make this smooth, that is part of what you pay
> them for. Make them do their job, get their advice on how to make it is
> smooth as it can be.
>
> --
> Phillip Windellwww.wandtv.com
>
> The views expressed, are my own and not those of my employer, or Microsoft,
> or anyone else associated with me, including my cats.
> -----------------------------------------------------
>
> <klei...@gmail.com> wrote in message
>
> news:9d6385a5-717d-404c-a93e-(E-Mail Removed)...
>
>
>
> >I am in the process of switching ISP providers and doing a cut over.
> > I have 3 web servers that sit directly on the Internet (yeah, I know!!
> > separate topic for a different thread). *Anyway, point is, I do not
> > have a router in front of this to provide communication to both
> > networks and handle it that way.
>
> > Instead, what I am trying to do is allow access to the web servers
> > from both networks (each ISP) in the process of transition. *We are
> > not talking about a long duration but probably about a week. *I want
> > to switch DNS, let it replicate but still allow the old network from
> > ISP1 to continue to respond properly and then eventually finish the
> > cutover to ISP2 and unplug the ISP1.
>
> > Can anyone tell me how to configure my 3 W2K3 servers in order to
> > accomplish this?
>
> > None of the servers are DCs or in a domain. *They are standard
> > standalone servers.
>
> > I know you cannot have a gateway specified on the second nic, but if I
> > configure everything else (IP Addresses, Subnets) for ISP2 and then
> > configure IIS to respond to either or and then change DNS, will this
> > cause issues with traffic confusion? *What is the best way to approach
> > this problem?
>
> > Thanks,
>
> > Kalvin- Hide quoted text -
>
> - Show quoted text -

<(E-Mail Removed)> wrote in message
news:7a27c7e0-d5d7-48d9-9e61-(E-Mail Removed)...
> Thanks for the reply Phillip. Unfortunately these are 2 different
> ISPs. This is a switch of T1 vendors and so there is not much they
>can do.

Yes, that is the way it is. I didn't expect it to be otherwise. That
doesn't really change my answer. There is no
half-way-between-doing-two-things-at-the-same-time solution. You just have
to make the switch. Been there, done that.

The key is in who actually is the Authoritiative DNS Provider for your
Domain(s).

If neither ISP is your authoritative DNS Provider and it is done by some
other entity (like Network Solutions, goDaddy, etc),...then,...Whoever is
the authoritative DNS provider is the one that needs to make the change.
You just change the cabling to take the old connection out of the picture
and re-address your public facing devices accordingly to the new link,..and
then immediately call the DNS provider and give them the new IP#s for the
DNS Records (or follow whatever method they give you for doing that). In
this case since the Authoritative DNS Provider does not change then change
takes effect almost instantly.

If one ISP is the current Authoritative DNS Provider and it is going to
switch to the second ISP then you switch the cabling as above then call the
provder one after the other back to back and have them configure their DNSs
accordingly. There is additional time involved because the DNS Servers
higher in the "food chain" need time to become aware that the Authoritative
DNS Service for you Domain has changed. There isn't anything you can do
about that. When we did that 7 years ago it took 30 minutes and happened
late at night during a low traffic period.

There is no network manipulation you can do to make the devices respond
equally from two differenet connections like that. TCP/IP just doesn't work
like that. They will *not* respond over the link the incomming connection
came in on, but will always respond over the link associated with the
Default Gateway of the Device. So they might receive something via the old
provider but will "reply" via the new provider,...if that doesn't "break"
the session you are fine,...but it will probably break the session.

--
Phillip Windell
www.wandtv.com

The views expressed, are my own and not those of my employer, or Microsoft,
or anyone else associated with me, including my cats.
-----------------------------------------------------