What happen in my network architecture?

[MaskerTim]

Hi, I'm MaskerTim.
and I attach a diagram about my network architecture and what problem I have.

Under the premise on my network setting:

1. All firewall in host I close.
2. I set some route table. (That describes in picture)
3. Device A at the LAN side can succeed to ping to Server A at the WAN side, however, Server A didn't ping successfully to Device A. (Also in picture)

I don't know why fault it is?

[Banfa]

Can you ping the wif brouter from the server? I'd say the problem is in you WiFi router especially given its configuration.

[MaskerTim]

Oh, I forgot to mention. Indeed, I also can't ping to wifi router gateway. And static route setting in wifi router, I only can set WAN in interface column. Is wifi router only one NIC? I think Server A need to send WAN IP and transform into LAN IP and then send to Device A. Is my knowledge wrong?

[Banfa]

I am not at all sure what you are trying to do is possible, I am sure that with some hardware it would definitely be impossible. The problem is around how a router works.

A lot of the time a router works by using NAT forwarding, this only works in 1 direction, inside the network to outside because what the router does is replace the IP address in the packets it receives with it's own IP address before forwarding on a different port selected for the purpose of that communication. When it receives replies to that port it then knows which internal IP address the packet is destined for and re-writes the correct IP address into the packet.

What this means is that the router is just not expecting to see packets with IP addresses for its internal network on its external port so it ignores them (also why your routing table is limited to the WAN interface).

I think if you want that network topology to work you will need a Wireless AP rather than a Wireless router. An access point acts a bit more like a bridge, connecting 2 networks together seamlessly.

[MaskerTim]

If I want to build a internal network and two different sub-network. Like Device A and Server A in my diagram. They are two different internal network domain then I want to communicate each other. Can Wireless AP split two sub-network and connect between?

In my mind, two different network domain need to use router to transform IP into the other network domain (just NAT you mentioned) whatever they are internal or external. Do you have any opinion on my point of view?

[Banfa]

No with a Wireless AP you would effectively have a single sub-net with a single DHCP server somewhere (on the server??); unless of course your switch is a layer 3 switch supporting VLANs and routing between them.

With the Wireless Router the router is running a DHCP server for the Wireless sub-net while you must have another DHCP server running on the wired portion of the network. The problem is that the oruter you have doesn't appear to route traffic from the wired to the wireless side.

Keeping the wireless and wired devices in different sub-nets (or VLANs) is a good idea, for problem solving and security reasons but it requires the right hardware to do it; since you have not specified what your hardware is it is hard to know but I have been assuming consumer level kit (dumb switch, consumer Wireless router) which generally are not so easy to configure as the manufactures tend to lock down their functionality, presumable for cost reasons but I expect they'd say they were assisting the user in not displaying a dizzying array of configuration options which the user won't understand.

[MaskerTim]

My wifi router I use is DIR-859, Dlink manufacturer. I think that's a consumer kit. It can set QoS, route table, bind ip with Mac..., so I think that's not complex setting.

I'm still network beginner. Although I don't know what VLAN is, but I think it doesn't provide this function (I think that's for user not network manager).

I use static IP setting on server. So server A doesn't by dhcp. Wireless side use dhcp setting, so Devic A's IP is assigned from wireless router.

You point out a important view about router may not have router traffic from wired side to wireless side.

I want to connect with each other in different sub-net. If I want to solve this problem, do I need to use two router to connect? I use the switch (layer 2) with wifi router(WAN port) and server A. I just think I set static IP on server A to make different sub-net from device A below wireless router.

[MaskerTim]

Okay, I would try to search the case that is similar to mine on this forum and do more try-error in lab.

[MaskerTim]

Thanks. It's not assignment in college. I just learn to build network for the future of designing and constructing network architecture.

My problem is that I want to build two sub-net, and one side use wireless then another side use wired connected to wifi router's WAN port (just the diagram I draw). I can send from device below wifi router to WAN connected to Server, but reversely can't send successfully.

Just like Banfa says. Maybe I choose the fault hardware to do that. Maybe that architecture is not correct. I don't know If I want to split two sub-net and connect each other, Is wrong my network architecture and need to change it or How do I build to solve my problem?

[MaskerTim]

Thanks for Banfa. You give me lots of advices. I have some direction to try-error my network. If you have other opinion, I'm pleasure to communicate with you and tell what my point of view is.