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Network setup:

telephone socket
  |
  |cable
  |                            ____|-------|
|---------------|             / :  |ClientZ|
|Wireless-Router|-------------  :  |_______|
|_______________| radio-waves \ :
  |                            \___|-------|
  |cable                           |ClientW|
  |                                |_______|
|--------------|
|Gigabit-Switch|
|______________|
  | ... |
  cables
  | ... |_______
  |             |
|-------|     |-------|
|ClientX| ... |ClientY| 
|_______|     |_______|

Configuration:

  • Switch (D-Link DGS-1005D)
  • Router: (FritzBox Fon-Wlan 7113)
    • IP: 192.168.0.1
    • Subnet-mask: 255.255.255.0
    • DHCP active, assign IPs from 192.168.0.2 to 192.168.0.99
  • Clients:
    • IP: Retrieve dynamic IP via DHCP
    • Subnet-mask: 255.255.255.0
    • Gate-way: 192.168.0.1
    • DNS-server: 192.168.0.1
  • All clients use the IP protocol version 4
  • Clients are a wild mix of Windows XP, Windows 7, Mac OS X, iOS (+1 new wlan-printer)
  • All clients use basically the same network/firewall configuration (windows and mac os respectively)

Problem:

  1. All clients can access the internet. fine
  2. All clients can access the router (ping it, access its configuration site via http). fine
  3. All clients connected via cables to the gigabit-switch can see each other and exchange files. fine
  4. None of the wirelessly connected clients can see/ping any other client. bad =,(
  5. None of the clients connected via cables to the switch can see/ping any of the clients wirelessly connected to the router.bad =,(

This problem existed since I setup the network. It never bothered my since I was satisfied by being able to exchange files between the clients connected to the switch. But now I would like to access the ones connected wirelessly as well (mainly because of the printer).

I tried to ping them via their IP address (visible in the router), but got a timeout. Since the clients connected to the switch don't suffer from this problem I suspect the problem is with the router. Somehow it doesn't correctly route access to clients in the local network.

Unfortunately I don't know where to start trouble shooting, since I know nothing about networks. So I'm looking very much forward to Your suggestions/hints/advise.

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Can you clarify - from your statement, the clients on the wire can ping each other by IP address. No one can see any wireless clients. No one can ping anyone else by name. Is this correct? – Blackbeagle Mar 9 '11 at 20:05
Would you say exactly what OS the clients are using eg :client Z = Windows, Client W = ... etc... – Linker3000 Mar 9 '11 at 20:17
@blackbeagle @linker3000 There are 8 clients, 4 connected to the switch via cable, 4 wirelessly to the router. Both of these groups contain windows xp, 7 and mac os x. After the changes maqleod proposed the situation has slightly changed: The wired clients can ping any other client by ip/name. The wireless clients can't ping anybody by anything (but they can access the internet). – Dave O. Mar 9 '11 at 21:58
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1 Answer

up vote 1 down vote accepted

As long as the wireless and wired clients are on the same subnet (as you have noted, you are using 192.168.0.x) then they are all on the same local network and should have no problems pinging each other, as long as ICMP is enabled on those computers. Are you certain that you have enabled ICMP responses on all computers involved?

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Thank you for your answer. I've basically copied the network settings from the wired clients to the wireless ones (since they have no communication problems). I'm going to investigate ICMP now.. – Dave O. Mar 9 '11 at 20:24
So, I have deactivated the built-in firewall of all windows machines (they don't have any additional ones) and explicitly enabled echos in the ICMP settings. For the mac machines I've deactivated their firewalls. Now: Every wired client can ping any wireless client BUT NOT vice versa. Any ideas? – Dave O. Mar 9 '11 at 20:49
This somehow reinforces my suspicion that it has something to do with the router (who doesn't correctly route traffic between wireless clients). Although it's strange that it now correctly routes wired->wireless. I looked through the router settings but they hardly tell me anything - could it have anything to do with ip routes? (none are defined) – Dave O. Mar 9 '11 at 20:53
@Dave: usually Firewalls and ICMP responses being disabled cause this sort of behavior. We know that all layers of the OSI model are functioning correctly, we also know that both sides can ping, but only dependent on certain system settings, which in my opinion rules out the router entirely. You can probably try an MTR or traceroute just to prove that the router is routing correctly and is being blocked/ignored by the client, or it may prove me wrong, but at least you'll be able to better see where it is stopping. – MaQleod Mar 9 '11 at 20:58
I really appreciate your help (wish could give you more points). I'm going to investigate MTR right now. In the meantime: I've taken one of the wired clients (which doesn't have any communication issues), disconnected its cable and turned on its built in wlan adapter. The same effect: wired->wireless ok, wireless->wired nada. Have we thus ruled out the system settings? If I don't have any success with MTR, I'll probably have to hire a sys admin.. Once again, thank you very much for your help and sorry for bothering! – Dave O. Mar 9 '11 at 21:16
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