help: WRT300N uplink through hub/switch

Discussion in 'Networking Issues' started by tai4ji2x, Aug 31, 2006.

  1. tai4ji2x

    tai4ji2x LI Guru Member

    i subscribe to cable along with an additional block of 4 IP's. therefore until now, i've never bothered with NAT or wireless, as i just used a hub/switch with the modem attached to the uplink port and all my client computers connected to the hub/switch's downlink ports (each client with their own software firewall installed, of course).

    i'm currently just trying to see if i can keep this general setup, but also have one of the public IP's be assigned to a WRT300N router. the problem is, if i connect that router to any of my EZXS55W switch's ports, all the other systems lose their connection. apparently my router needs exclusive access to the cable modem. thus i can't seem to use BOTH my extra public IP's AND a wireless router at the same time. ie, if i turn off or unplug all the other computers from the hub, the router will pick up an IP. and vice versa - unplugging or turning off the router will revive internet connection for everyone else connected to the hub

    what's happening? basically, what i'd like to do is: keep the separate public IP's for some more dedicated server-like applications, meanwhile the rest of the network for casual internet use would share the router's connection.

    ps- the MAC address is NOT cloned, if that matters.
  2. pablito

    pablito Network Guru Member

    First off, bad idea to run without a firewall like you originally did. The Windoze firewall isn't good enough by itself. Your new wireless unit is a router yes? You should run the cable modem to the WAN port of the router and one of the LAN ports of the router to your switch (or use the switch on the new router).

    I don't know the router you bought except you might regret it once the N spec is finalized but that is another story...
    I don't know how that router will or if it can handle the multiple public IPs that you have. On the RV0x series of routers you would use One-One NAT. Or you can run with a single public IP since you'll be NATting the internal network anyway and using the router as a firewall.

    Briefly, you want an unroutable network for the internal net (192.168.x.x/24 for example) The public IPs are on the WAN side. And configure to taste.

    Cable_Modem-->(pub_ip)->[WRT(WAN)---(LAN port)]--->Internal_net (192.168.x.x)
  3. tai4ji2x

    tai4ji2x LI Guru Member

    lol, you think i actually used windows' firewall? hey, i know i'm not the smartest guy on the block, but i'm not THAT stupid. :tongue: i used third-party software firewalls and tested them at sites like

    as for the rest of your post, do you mean that i can somehow use the router to assign the public IP's to the systems connected to the router's LAN ports?
  4. tai4ji2x

    tai4ji2x LI Guru Member

    bump... anyone?
  5. Thibor

    Thibor Super Moderator Staff Member Member

    the 300N cannot perform "One-To-One NAT" which is the name of the function you are describing.
  6. tai4ji2x

    tai4ji2x LI Guru Member

    the one i described in my OP or in my reply to pablito?
  7. pablito

    pablito Network Guru Member

    I don't know the 300N except that the "N" tells me it might be abandonware once the draft is finalized. If tai4ji2x says it won't do One-One NAT then no, you can't easily use the extra IPs. The RV series and maybe others (and any homemade linux router) can do the multiple IPs.

    With NAT you don't really need multiple IPs unless you have a lot of internal servers being offered to the public side. You can have a lot of normal pcs with a single IP. NAT and port forwarding can serve up a lot.

    You could also run a switch like you do now *and* run a router. I wouldn't ever run a machine without a real firewall. I don't know what 3rd party stuff you mean but to me dedicated firewalls are the only right way.
  8. tai4ji2x

    tai4ji2x LI Guru Member

    ok, i suppose i'll be discontinuing my additional IP's and just going entirely through the router, if only to avoid being castigated around here :tongue:

    still, i'm confused as to why my original setup (router uplink connected to client port of hub simultaneously with other computers) didn't work at all?

    so lemme see if i have this straight... one-to-one NAT is the function pablito described where the router's uplink is connected to the cable modem, and the other comnputers connected to the router. meanwhile the router will associate each of the internal NAT IP's with one of the public IP's provided by my ISP. correct?

    if so, that still leaves me wondering why MY original setup doesn't work. forgive my ignorance.
  9. Guyfromhe

    Guyfromhe Network Guru Member

    if you have your setup like this:

    PC PC PC
    | | |
    S w i t c h
    | |
    Modem Router

    Switch connects to 3 PCs, your modem and the WAN or Internet port on your router (NOT THE UPLINK PORT!)

    That SHOULD work.
    The 3 PCs should get a live IP from your ISP and the router should get a live IP from your ISP and allow any clients that connect through the router to access the internet via NAT.

    You'd need to make sure the internet port (or WAN) of the router was connected to the switch and not one of the lan ports.

    If that still does break your internet connection and you have it wired the way I have it pictured, there is something else wrong and I can probably help you fix it if you care to.

    As for One to One NAT it means the router basically routes each IP to a single machine and then routes traffic form that same machine back out the same IP. Most NAT is one to many where many machines route out a single public IP.

    You won't get this functionality in any consumer Linksys router, and you likely don't need it.
  10. tai4ji2x

    tai4ji2x LI Guru Member

    yes, i believe i have it set up as you described. the router's blue "internet" port is connected to one of the switch's numbered ports, as are other computers. the modem is connected to the switch's uplink port. things work only when either the router OR any/all of the other computers are plugged in, but not both at the same time. the connection immediately stops once either one is plugged into the switch when the other(s) are already there.
  11. Guyfromhe

    Guyfromhe Network Guru Member

    try resetting the router to factory defaults by holding down the reset button for 30 seconds... see if that helps...
  12. tai4ji2x

    tai4ji2x LI Guru Member

    yeah, i've tried the reset button many times. no help :(
  13. Guyfromhe

    Guyfromhe Network Guru Member

    Ok this will likely take a bit of troubleshooting then...
    i'm going to need a bunch of info to find out whats going on.

    First off, what IP does each of the 3 computers get?

    Can the 3 computers ping eachother?

    Run a tracert to, what are the first 3 hops? (copy and paste)

    Run an arp -a from a dos prompt for me and paste the results

    Next, plug the router in, does the router get a public IP from your ISP?


    Do the switch activity lights change when you plug the router in?

    Can your computers still ping eachother?

    Do the computers still have the same IPs they had before?

    Run a tracert to again and see what the results are, where does it stop responding?

    run another arp -a and paste the results.

    Unplug the router.

    does your internet start working again immediately?
    Do you have to reset the switch or reset the computer?

    Please respond with the results of all those tests and all that info, that should help me find out whats going on... If you need help with any of that let me know.
  14. tai4ji2x

    tai4ji2x LI Guru Member

    ok, i'm a little pressed for time, but i'll try to get those things tested out sometime today or tomorrow. thx
  15. Guyfromhe

    Guyfromhe Network Guru Member

    ok, i'll be waiting.
  16. tai4ji2x

    tai4ji2x LI Guru Member

    guyfromhe: sorry, i've been moving to a new apartment for school, so it's taken away time. i should be more free the following weekend, if you're still around to help. thanks again
  17. Guyfromhe

    Guyfromhe Network Guru Member

    i should be around.
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