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Weird: Wireless Ethernet Bridge works...kind of

Discussion in 'Tomato Firmware' started by arc86, Mar 11, 2009.

  1. arc86

    arc86 Addicted to LI Member

    Hi all,

    My setup is as follows:

    Linksys WRT54GL
    Tomato 1.23
    WPA Personal (PSK) + TKIP
    Wireless Ethernet Bridge mode
    Win XP SP3

    I have my desktop PC connected to the router running Wireless Eth. Bridge mode, which in turn connects wirelessly to my home network. I have this working well, with good speeds and low latency.

    The problem is that my connection to the home network gets interrupted occasionally and I'll be off the network until I notice and fix it. I've been Disabling the LAN adapter in Windows network connections, and then re-enabling it, and I'm back on the network again. It seems very random, and I may only get disconnected like this 3 or 4 times a day.

    If I troubleshoot a little bit before this step, I find that I can still ping the router at 192.168.1.1. I cannot ping my home gateway at 192.168.1.254. HOWEVER I can connect the tomato page at 192.168.1.1 and run its Ping tool and successfully ping 192.168.1.254.

    I switched to Tomato from DD-WRT hoping to escape this problem, but it's still here. Can anyone diagnose my problem? Thanks.
     
  2. RonWessels

    RonWessels Network Guru Member

    Ok, let me see if I understand your setup.

    Your Internet gateway has a LAN address of 192.168.1.254. Presumably this is a wireless router that is also serving as the wireless access point? In addition to that, you have a WRT54GL configured in WET mode with a static address of 192.168.1.1. Connected to a LAN port of the WRT54GL is your WinXP machine.

    Is your internet gateway (192.168.1.254) also serving as the DHCP server? If so, check to make sure the DHCP server on your WRT54GL is turned off. There should be only one DHCP server running on your entire 192.168.1.X home network.

    From the sounds of it, you have some kind of routing problem, either at the IP level or at the ARP level, and either on your WinXP machine or your WRT54GL or even on both.
     
  3. arc86

    arc86 Addicted to LI Member

    Thanks for your response, RonWessels.

    This gateway is a 3800HGV-B Gateway, which AT&T UVerse set me up with. It serves as the modem, router, and wireless access point.

    I believe DHCP is enabled; here is the current status of the network as reported by the Gateway:

    Router Address: 192.168.1.254
    Subnet Mask: 255.255.255.0
    DHCP Range: 192.168.1.64 - 192.168.1.253
    Allocated: 13
    Available: 177

    The WRT54GL (edit: My PC) appears as 192.168.1.72 to the gateway, so that's within the "DHCP Range." I think that's a good thing? If something is blatantly wrong here please point it out. I had been assuming that the side of the router that connects to the gateway would have a different IP address than the side of the router that connects to my PC.

    DHCP is disabled on the WRT54GL. Here is the table from the tomato overview page:

    LAN
    Router MAC Address 00:21:29:68:80:E6
    Router IP Address 192.168.1.1
    Subnet Mask 255.255.255.0
    Gateway 192.168.1.254
    DNS
    DHCP Disabled

    I don't know what WET mode is. It says wireless mode is "Wireless Ethernet Bridge"

    Thanks again.
     
  4. jza80

    jza80 Network Guru Member

    Would you happen to have the WRT54GL cabled to your gateway using the WAN/internet port? Doing so and setting the WAN/internet port for DHCP would cause what your seeing (WRT with WAN IP address of 192.168.1.72 and appearing to the gateway as such).



    These settings are fine.
     
  5. RonWessels

    RonWessels Network Guru Member

    Wireless Ethernet Bridge mode is also known as WET mode. Sorry for the confusion.

    The fact that your WRT54GL seems to have two IP addresses is certainly a problem. According to your settings, it it assigned a static address of 192.168.1.1. However, you also said that "The WRT54GL appears as 192.168.1.72 to the gateway". Did you really mean that, or did you mean that your WinXP box has been assigned 192.168.1.72?

    When you set up WET mode, you are essentially expanding an existing network, so any attached clients should have an IP address in the same subnet as the wireless network. To have the LAN of your WRT54GL on a different subnet, you want to use "Wireless Client" (STA) mode. In both cases, the radio in the WRT54GL acts as a wireless client to the 3800HGV. However, in STA mode, the wireless link acts like a WAN connection and the router will act as a firewall and perform NAT translation to devices connected on the LAN ports. Also, the LAN network should be on a different subnet than the wireless network to allow routing to happen properly. In WET mode, the WRT54GL simply bridges the LAN ports wired connections to the wireless link. No firewall or NAT activity is performed. So the LAN network needs to be on the same subnet as the wireless network and DHCP on the WRT54GL should be turned off, since devices connected to the LAN ports will get DHCP allocation from whoever is performing DHCP allocation for the wireless network.

    I'm having trouble understanding how you could have set up two IP addresses on your WRT54GL. When I put the wireless mode into "Wireless Ethernet Bridge", the WAN configuration section disappears for me. When you loaded the Tomato firmware, did you reset the NVRAM settings (Administration -> Configuration -> Restore Default Configuration -> Erase all data in NVRAM memory)?
     
  6. arc86

    arc86 Addicted to LI Member

    Sorry I misrepresented what was going on there. The .72 address is my PC after all. The Gateway does not "see" the router at 192.168.1.1 at all, just my PC. So back to square one.

    It sounds like WET (which I'm in currently) is the right mode for what I want. I'm very much stumped here.
     
  7. arc86

    arc86 Addicted to LI Member

    I just wanted to let you know I figured out a working solution, though I'm still not sure why the problem happened in the first place.

    If I change my network adapter to use a static IP address, I no longer lose my connection. So maybe the problem was that my network card/tomato router didn't keep up with my gateway whenever it assigned me a new IP address with DHCP. Either way, if anyone has a similar problem using a static IP might be a good enough fix.
     
  8. krzyk

    krzyk Addicted to LI Member

    Is that really so :)frown:)?
    So I can's setup two routers in the following configuration:
    Router A (WAN): IP: 192.168.1.1, dhcp enabled: 192.168.1.2-127
    Router B (WRT54GL in STA): IP: 192.168.1.128, dhcp enabled: 192.168.1.129-252
    Will that make one subnet and allow proper routing between 1-127 subgroup and 129-252 subgroup?
     
  9. RonWessels

    RonWessels Network Guru Member

    @arc86: Good to hear that you found a solution. From what you describe, it sounds like the machine is losing its default route when a DHCP renew is performed.

    @krzyk: You can set up anything you like. However, you will find connectivity and routing problems if you don't set it up correctly.

    In your particular case, how is router B supposed to know that the packet is not a LAN packet (ie. does not need to be sent over the radio) if one of its clients sends to 192.168.1.10? I suppose you could set up a netmask of 255.255.255.128 so that your two ranges are two networks, but then why not use 192.168.1.* and 192.168.2.* with netmasks of 255.255.255.0?
     
  10. krzyk

    krzyk Addicted to LI Member

    Thanks Ron - yes it's all matter of configuration which I am still trying to work out to fit my needs. Previously when I configured router B (in STA mode) to another IP range (that was 10.0.0.*), I had problems reaching it and devices in that network from PCs in 192.168.1.*. But I guess I messed something with configuration.

    Do you know if there are any possibilities to affect routing on router working in WET mode? I made some unsuccessfull attempts to redirect traffic based on destination IP (which was external), but it seems that router in WET mode was only just redirecting packets to main router and all I was able to see were dest IP of the main router (I know that I may sound ignorant).
     

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