Multihomed Multi ISP/Internet - packets go out the wrong interface

Hi all, i hope someone got some suggestions.
I have a Server 2003, 2 Network Cards, 2 Networks (10.10.x.x and
10.4.x.x)
The 10.10.x.x goes to a router, connected to a DSL Line (whis is also
the default gateway).
The 10.4.x.x also goes to a router whis is connected to an E1 Line.

The Server is running IIS. I am trying to make the website reachable
from both internet/ISP connections.
The problem is, if i connect from the E1, the server actually receives
the traffic, but sends the replies out the wrong interface. Pretty
stupid, since a packet arriving at one interface, the reply should go
out (automatically) the same interface.

Well, its not doing it. It goes in one interface and out the wrong one.

I know some basic routing, but none like Rip or OSPF. But i also know,
that Routers or Firewalls like Cisco Pix is not doing things like the
server does. What goes in one way come out the same way and not
another.

Is there a way to fix that issu with Routing and RAS enabled and what
exactly do i have to configure in order to make that work.

Or do i have to change things on my IIS settings?

Any help would greatly be appreciated.

Regardless of the number of adapters or default gateways you configure on a
Windows machine, it will use one and only one such gateway unless and until
it fails. If traffic received on the 10.4.x.x adapter has a limited number
of known source IPs or networks, then you could configure static routes
pointing to the E1 router.

Doug Sherman
MCSE, MCSA, MCP+I, MVP

"Shirkan" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ups.com...
> Hi all, i hope someone got some suggestions.
> I have a Server 2003, 2 Network Cards, 2 Networks (10.10.x.x and
> 10.4.x.x)
> The 10.10.x.x goes to a router, connected to a DSL Line (whis is also
> the default gateway).
> The 10.4.x.x also goes to a router whis is connected to an E1 Line.
>
> The Server is running IIS. I am trying to make the website reachable
> from both internet/ISP connections.
> The problem is, if i connect from the E1, the server actually receives
> the traffic, but sends the replies out the wrong interface. Pretty
> stupid, since a packet arriving at one interface, the reply should go
> out (automatically) the same interface.
>
> Well, its not doing it. It goes in one interface and out the wrong one.
>
> I know some basic routing, but none like Rip or OSPF. But i also know,
> that Routers or Firewalls like Cisco Pix is not doing things like the
> server does. What goes in one way come out the same way and not
> another.
>
> Is there a way to fix that issu with Routing and RAS enabled and what
> exactly do i have to configure in order to make that work.
>
> Or do i have to change things on my IIS settings?
>
> Any help would greatly be appreciated.
>

Doug Sherman [MVP] schrieb:

> Regardless of the number of adapters or default gateways you configure on a
> Windows machine, it will use one and only one such gateway unless and until
> it fails. If traffic received on the 10.4.x.x adapter has a limited number
> of known source IPs or networks, then you could configure static routes
> pointing to the E1 router.


Yes, thats fine for traffic "source outgoing" but, i have incoming
traffic from the internet (random ip's) and i want it to send the reply
packet through the (of course) same NIC - any cheap router does it, so
should windows

Basically, once it receives incoming traffic, the roiute "SHOULD" be
known and the reply 'SHOULD" be sent through the correct interface, and
not the default gateway since thats the one for "unknown" routes....

or in other words, if i have 2 NICS on a PIX Firewall, - same situation
- one default gateway -

if traffic comes in from one interface, the Pix knows to send the
replies back through the same interface and NOT thorugh the default
gateway.
To my understanding, thats basic routing functionality - but of course
that may not ne thrue with windows.
I just wonder, if that can be resolved with OSPF - but i have no idea
how to configure that and i was trying to avoid having to learn that.

I can solve that issue with Vlans on my Pix firewall, since it will
route the way it shoud be, but that would mean at least a day of
downtime (cost money) and a headache in reconfiguring the Pix (lots of
acess-list lines and static mapping with vpn)

So if there is no way to teach windumb how to route correctly i may
have no other way......

Thanks anyways to all that replay

"so should windows"

When Windows does not behave the way we wish, we call this a 'feature.'
With standard routing there is no distinction between an outgoing reply and
any other out going directed packet. You need dynamic routing or a hardware
solution to alter this behavior.

Doug Sherman
MCSE, MCSA, MCP+I, MVP

"Shirkan" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
>
> Doug Sherman [MVP] schrieb:
>
> > Regardless of the number of adapters or default gateways you configure
on a
> > Windows machine, it will use one and only one such gateway unless and
until
> > it fails. If traffic received on the 10.4.x.x adapter has a limited
number
> > of known source IPs or networks, then you could configure static routes
> > pointing to the E1 router.
>
>
> Yes, thats fine for traffic "source outgoing" but, i have incoming
> traffic from the internet (random ip's) and i want it to send the reply
> packet through the (of course) same NIC - any cheap router does it, so
> should windows
>