"1388-2/HB" <(E-Mail Removed)> wrote in message
news:e6LCh.65137$(E-Mail Removed). net...
>
> "Phillip Windell" <@.> wrote in message
> news:(E-Mail Removed)...
>>
>> Traffic doesn't come from a "network",...traffic comes from a *Host*.
>
> Ok, I think I see the problem. You can't have 2 nics on a subnet because
> routing becomes ambiguous. I have a default gateway, but, which nic should it
> use to reply with?
Exactly.
> I gues Windows arbitrarily chooses one of the nics to be the host but this is
> not reliable.
It takes the first nic in the binding order (will also be the first listed in
the routing table),...but things can interferre with that and you get
unpredictable results.
> What's the typical resolution to this? ISP's typically assign static IPs in a
> block on the same subnet... what do people do, NAT the inbound traffic to
> split it up onto different subnets or just host each IP on a seperate box?
Depends on exactly what you are doing. You can do a *lot* with just one IP# if
handled properly. The "Line Technology" also matters.
With T1 lines you have an Internet Router (a real router) at the end of the line
that "faces" the nic of your Firewall,...this creates a network segment between
those two devices where machines can be placed if you want them to run "outside"
of the LAN on public numbers. For the internal machines that need exposed you
bind multiple IP#s to the same nic on the firewall and Static-NAT (aka
Reverse-NAT) the traffic "backwards" into the LAN to the target machines so they
become associated with the Public IP# that is bound to the firewall nic when
using the Protocol (port#) when setting it up. The port# is basically treated as
a "traffic indentifier" to be able to trigger the decision when the Static-NAT
occurs or does not occur.
With Home User Lines (xDSL, CableTV) you have a Broadband NAT Device which is
effectively still just a NAT based Firewall (commonly called "routers" but they
are *not* real routers). In the case of those you have to bind all of the IP#s
the ISP granted to the WAN interface of the box and then Static-NAT (aka
Reverse-NAT) the traffic "backwards" into the LAN to the target machines. These
home user devices often call this "Port Forwarding", but that is a non-sense
term,...there is no such thing as port forwarding,...the ports aren't going
anywhere and nothing is being done to them,...the ports are not even the true
focus of the action,..the IP#s are the focus of the action so Static-NAT (aka
Reverse-NAT) is the true accuarte term for the action. It is primarily a Layer3
action but the ports are Layer4 Addresses, this is two different layers. There
is a such thing as Port Address Translation (PAT) but that is not what this is
either.
I do not think it is possible to connect multiple devices between the Broadband
device and the DSL/Cable Modem like you can do with the T1s between the Router
and Firewall. But I admit that I have never tried that.
--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com
The views expressed (as annoying as they are, and as stupid as they sound), are
my own and not those of my employer, or Microsoft, or anyone else associated
with me, including my cats.
-----------------------------------------------------
Linear Mode
