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DMZ IP ADDRESS ISSUE

Discussion in 'Networking Issues' started by SAPo57, Feb 14, 2006.

  1. SAPo57

    SAPo57 Network Guru Member

    My modem is set to give a DMZ IP address to my linksys router. Every 8 hours or so the IP address changes on the modem by itself to a different IP address. Now to connect to the internet I have to reboot my linksys router to obtain the new address.

    Is this normal? Is there any way around this problem to have a static DMZ IP address?
     
  2. Guyfromhe

    Guyfromhe Network Guru Member

    What do you set your DMZ ip to be? what IP does it change to?
    usually you can statically specify your DMZ ip...

    Your ISP really changes your IP every 8 hours? thats pretty harsh...
     
  3. SAPo57

    SAPo57 Network Guru Member

    Well not 8 hours but randomly or everyday.

    I do not set up a DMZ IP address, my ISP gives a random public WAN address.
     
  4. Guyfromhe

    Guyfromhe Network Guru Member

    if your public IP is on your Linksys (ie modem is bridged) then it's not really a DMZ situation, if thats the case your IP should last till your lease runs out then your linksys should request another IP from the DHCP server if this isn't working something may be foobared, check your lease time on your linksys then see if the problem happens right after the lease expires or before...
     
  5. SAPo57

    SAPo57 Network Guru Member

    My modem's ip address is 192.168.1.254 w/DHCP server(192.168.1.80 - 192.168.1.253)

    My linksys router by default conects to the gateway ip address (192.168.1.254) and its ip address is 192.168.1.xxx (VARIES FROM THE DHCP SERVER ON THE MODEM).

    Ex: gateway=192.168.1.254 & local ip=192.168.1.112

    When dmz is enabled on the modem for the linksys router the linksys router's gateway changes to a WAN ip xxx.xxx.xxx.1 and its local ip is a regular public WAN ip relating to the gateway IP address range.

    Ex: gateway=65.77.223.1 & local ip=65.77.223.209

    Now the DHCP server on the linksys router has an IP address range: 192.168.15.100 - 192.168.15.149 (sets a lease time for one day by default)

    It only shows and gives lease times only for those IP addresses, there's no way to change or know the lease time for the DMZ WAN IP address given to the linksys router from the modem.

    THE ONLY THING I'VE BEEN TOLD WAS THAT MY ISP, BELLSOUTH, DOESN'T GIVE PPP LEASE TIMES OR FOR WAN IP'S. (PPP LEASE TIMES? what does PPP have to do with IP address lease times?)
     
  6. Guyfromhe

    Guyfromhe Network Guru Member

    Check on the status screen on your router it should show your lease time... your ISP support will probably have no idea what your talking about, thats normal.
     
  7. SAPo57

    SAPo57 Network Guru Member

    Lease time for what? It only shows lease times for the dynamic IP addresses in the DHCP servers, nothing about DMZ.

    I know almost evreything about my router, but nothing what your talking about, lease times for DMZ IP's.

    I would like to know, by default, are DMZ IP addresses static or have lease times? And if static, then I have a feeling what my network problem is.
     
  8. SAPo57

    SAPo57 Network Guru Member

    One more thingabout my DSL MODEM:

    MAYBE THIS IS THE PROBLEM= my modem's internet connection is set to connect "ON-DEMAND" meaning when a device isn't using the internet for while it disconnects(THE MODEM REESTABLISHES A NEW CONNECTION WHEN A THE USER ON A COMPUTER OPENS A BROWSER AND THE PC's IP ADDRESS CHANGES)

    Now i can make this setting to connect "ALWAYS" meaning the modem won't disconnect, and if the line is accidentally dropped it'll quickly reestablish and the device keeps the same IP address.


    SINCE THE MODEM SPECIFIES THAT THE ''COMPUTER'' WILL GET DISCONNECTED DOES IT MEAN THAT IF A ROUTER IS HOOKED UP TO THE MODEM IT WILL GET DISCONNECTED AS WELL WHEN THE ''ON-DEMAND'' CONNECTION SETTING IS ENABLED?

    Then maybe that's why the DMZ ip address changes, right?
     
  9. Guyfromhe

    Guyfromhe Network Guru Member

    based on what you've told me your router is getting your internet IP so that would be the IP that has the lease time and would be dynamic per your ISP.. there would be no DMZ because a DMZ doesn't really exist in a bridged connection...

    and yes the router would be disconnected just like computers connected to the modem.
     
  10. SAPo57

    SAPo57 Network Guru Member

    Well my connection isn't bridged, i just hooked up my router to my modem normally, my modem takes care of the PPPoE connection(RT41-BU router doesn't need bridging, plus i've tried it and it won't work).
     
  11. Guyfromhe

    Guyfromhe Network Guru Member

    layer 2/3 bridge... if your live ip is passed directly from your DSL modem to your linksys unadulturated than it's bridged... if your linksys is getting a non routable IP than it's not.
     
  12. SAPo57

    SAPo57 Network Guru Member

    Well there is this option on my router that says if i want to bridge it or not. It is set to PPPoE and not to Bridge mode, if i set it to bridge mode my modem would not connect to the internet.

    Bridging would only let the linksys router take full support of the modem's DHCP server and PPPoE connection. Now i've tried that and my linksys router can't work with PPPoE for some reason.


    ROUTERS SEND THE APPROPIATE DATA TO THE APPROPIATE DEVICE, if I were to hook a router up directly to a modem that has router(basicly router to router) then i would need to bridge it.

    Bridging was added to new routers/modems that don't need a crossover cable to connect to another router, that's why linksys router's come with built in switches for the ethernet ports so that Straight through cables can be directly applied when connecting to another router.

    Bridging is a feature, by default it would be used when certain linksys routers(DSL/CABLE ROUTERS) are being used. My router is a broadband router, in other words it can only act as a local network for devices to connect to it, although it would also act as the gateway but it would need a gateway device to connect to, such as a modem that connects to the ISP or to a WAN DCE device(ISP's central gateway)

    Put it like this i know enough that my connection isn't bridge, ask CISCO and you'll see.





    Now my router obtains an IP address from my modem, a reserved address 192.168.xxx.xxx that only uses NAT to make it appear as a public address when connecting to the internet. But only this regular address doesn't meet my router's needs, so now i would use DMZ which gets a WAN address from my ISP (an exposed public address w/ no security benefits= the DMZ zone requests exposed application ports to be used from my ISP)

    I've found the solution to my IP address issue of why it would change. My MODEM is a modem (Note: a DTE device which is a rouiter can only connect to a DCE device which is a modem)connected to the DCE device, my ISP's transceiver, during the in between PPP connection of the two modems anything can interrupt it thus reestablishing a new WAN address. DMZ permanently means that a static address will be given, DHCP can't be used for public WAN addreses- if they do tell me because of what i know is that they use reserved addresses for a LAN to use and when connected to the internet it changes to a public address by NAT.

    SO I PUT MY MODEM'S CONNECTON TO "ALWAYS" ON a feature which doesn't have my modem disconnect during a certain time of inactivity and if the line is dropped it"ll quickly reestablish, like 0.5 seconds line drops, and either the WAN ip stays or if it doesn't I'll use my routers NETWORK PORTS TO REMOTELY ACCESS ITS INTERFACE OR USE HTTPS FROM ANY PC TO ACCESS IT and renew the new address.

    I JUST KNOW MY STUFF.... thanx for everyones help, too.
     

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