Using router as switch, cannot access internet

Discussion in 'Cisco/Linksys Wireless Routers' started by thetawaverider, Mar 7, 2007.

  1. thetawaverider

    thetawaverider LI Guru Member


    I'm using a Linksys BEFSR41 ver. 4 as a switch behind a Cisco Pix firewall (which serves as the gateway, handles DHCP). The local IP address of the Linksys is set to (not currently used, out of DHCP range of Pix). Internet Setup on Linksys should not matter, as there is no WAN connection - only the 4 ports (one going to Pix and the rest to local machines). Currently, the machines connected to the Linksys cannot access the internet. The can, though, receive email and IM. Any ideas on why this would be, and any suggestions of what can be done to allow internet access?

    One more thing - this was working perfectly yesterday until someone messed with the Linksys. Nothing has changed on the Pix at all, so the problem should be able to be solved by adjusting the BEFSR41 settings.

  2. sirsquishy

    sirsquishy LI Guru Member

    If you are using Ports 1-4 on the Linksys, that makes the Linksys router a layer2 swtich. It only cares about ARP and MAC addresses, it will not block traffic based on DNS/TCP/UDP...ect.

    I bet your ISP is whats causing issues.....

    If you are using the WAN port on the linksys then that would be causing your issues.

    My question for you is, PIX + Linksys for a swtich...what are you thinking?
  3. thetawaverider

    thetawaverider LI Guru Member

    I know, using this Linksys as a switch behind a Pix is somewhat unusual, but that is how it was setup when I got here. I'm just trying to work with what we have at the moment.

    Question - if my ISP were the culprit here, it seems that the other machines here on the network that are not using the switch (the ones connected to the Pix directly) would not be able to access the internet either. As far as I know, my ISP does not have knowledge of my private network setup, only my public IP, which definitely doesn't have port 80 blocked.

    Any other ideas?

  4. NateHoy

    NateHoy Network Guru Member

    Make sure DHCP is turned off in the Linksys.
  5. ifican

    ifican Network Guru Member

    Yes as stated above make sure dhcp was not turned on and make sure that all of your host machines are getting the correct dns settings from the pix. If you have a host plugged into the pix and it works but doesnt work plugged into the linksys then yes there is something wrong with the switch. Check all those settings then let us know we can proceed from there if there is a need.
  6. thetawaverider

    thetawaverider LI Guru Member

    DHCP is turned off, DNS settings are correct from the pix. I wonder if port 80 is fried on this router. Whether it is or not, a new switch is being picked up as I write this. Thanks for the help, everyone.
  7. sirsquishy

    sirsquishy LI Guru Member

    Other then the DHCP thing that I overlooked, what I already posted is true.

    If you are NOT using the WAN port on the Linksys then there is no way for it to block traffic ( unless its blocking all traffic cause its dead ), because at this point its a layer2 device.
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