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Old 9th November 2016
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jggimi jggimi is offline
More noise than signal
Join Date: May 2008
Location: USA
Posts: 6,907

I don't understand the address definition you show. But I don't think its important as you state you are using DHCP so an IP address will be assigned by your gateway router.

You are using something as an inner router, if your diagram is still sufficiently accurate. Perhaps you are using a commercial router, or perhaps this is a general purpose computer with two NICs.


As you've learned, a bridge logically connects two (or more) networks into a single logical network,

As discussed earlier in this thread, a router ... well... routes (or forwards) packets between two (or more) networks.

According to the Netis documentation readily and publicly available to me -- web site, data sheet, quick installation guide -- your device does not state it can operate as a bridge. That doesn't mean it won't, just that the documentation I've seen doesn't state this.


Setting all of that aside, let us look at configurations for an inner network, using an "inner" router such as you likely have.

An inner router defines two local networks: 1) a network between the gateway modem and the router, and 2) a network between the router and all of your local devices. That outer network might just consist of a single Ethernet cable.

[outer router / ISP gateway] - {net 1} - [inner router] - {net 2} - [devices...]

If the inner router is configured to use NAT, then the outer router only sees a single inner device - the inner router. All of the devices on network 2 have NAT applied to their packets, and appear to all share the same IP address -- whatever the outer router has assigned to your inner router.

I believe you are using NAT on an inner router, but are unaware of it, because otherwise you would have to add a route to the inner network on your outer router

Here's why:

If the inner router is not using NAT, the outer router needs to have a route added to its routing table, so it can route packets destined for the inner network to the inner router.

If your inner router happens to be a general purpose computer running OpenBSD, NAT is defined by a "nat-to" clause added to a PF filter rule, as described in the NAT section of the PF User's Guide. If its a different OS or a commercial router, you'll have to refer to the appropriate documentation for that OS or that equipment.


A brief introduction to routing tables:

TCP/IP is a routed protocol, so that traffic can span multiple networks. Any time there is a packet to be sent to a device on another network, the sending computer inspects in its routing table. Usually, there is only one router on any network, and so there is only a single, default route for all packets destined for other networks. These default routes point at the local router's IP address.

In the case of a tiered network topology -- without NAT -- as described above in this post, the outer router would require two routes in its route table: 1) a route to the innermost network, with a "next hop" pointing to the inner router, and 2) a default route, pointing outward to a router in your ISP's network.

Last edited by jggimi; 9th November 2016 at 05:45 PM. Reason: typos
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