IP aliases on a DHCP'ed interface

Discussion in 'Server Networking' started by Vide, Apr 22, 2009.

  1. Vide

    Vide Guest

    Hi

    maybe this is a FAQ but I cannot ind a clear answer (apart from "it's not
    possible"): is there a way to add another IP (an alias) to the same network
    interface if the NIC is configured to get its address from a DHCP server?
    Graphically, now way
    Via netsh, if I +add* an address it replaces the DHCP configuration. Any
    other more obscure way?

    Thanks in advance
     
    Vide, Apr 22, 2009
    #1
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  2. If you want to setup one static IP and another is dynamic IP, yes, you can.
    This how to may help.
    ipconfig
    How to ping on the entire subnet. How to setup multiple IPs on NIC ...
    windows server with just one NIC and have multiple public IPs for different
    websites. ...
    www.howtonetworking.com/Networking/ipconfig.htm


    --
    Bob Lin, MS-MVP, MCSE & CNE
    Networking, Internet, Routing, VPN Troubleshooting on
    http://www.ChicagoTech.net
    How to Setup Windows, Network, VPN & Remote Access on
    http://www.HowToNetworking.com
     
    Bob Lin \(MS-MVP\), Apr 22, 2009
    #2
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  3. Vide

    Vide Guest


    Sorry but from the FAQ you linked

    "Q: I have a windows server with just one NIC and have multiple public IPs
    for different websites. Can I have multiple IPs on one NIC?

    A: Yes, the Properties of the NIC>Properties of TCP/IP>Advanced, add
    additional IPs."

    but as I said if the interface is configured as DHCP, then the additional
    IPs section is greyed out. I need a WinXP/Vista/7 client in a DHCP
    environment to have 2 IPs on the same NIC, one dynamic and one static. With
    your solution is still not possible.
     
    Vide, Apr 22, 2009
    #3
  4. Please read one below How to setup multiple IPs on NIC: How to setup two
    IPs on a computer

    --
    Bob Lin, MS-MVP, MCSE & CNE
    Networking, Internet, Routing, VPN Troubleshooting on
    http://www.ChicagoTech.net
    How to Setup Windows, Network, VPN & Remote Access on
    http://www.HowToNetworking.com
     
    Bob Lin \(MS-MVP\), Apr 22, 2009
    #4
  5. Vide

    Vide Guest

    But the "Alternate Configuration" is used only if DHCP fails, while I need
    two IPs at the *same time*.
     
    Vide, Apr 23, 2009
    #5
  6. Then you have to stop using DHCP on that machine. It is that simple.

    DHCP is nothing but a "convenience tool" for dealing with mass workstations
    operating in a normal way in a normal situation.
     
    Phillip Windell, Apr 23, 2009
    #6

  7. I have to agree with Paul. DHCP configured clients do NOT support what you
    are trying to do. The machine needs to set to a static config in order to
    use multiple IPs that work together.

    --
    Ace

    This posting is provided "AS-IS" with no warranties or guarantees and
    confers no rights.

    Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSA Messaging, MCT
    Microsoft Certified Trainer


    For urgent issues, you may want to contact Microsoft PSS directly. Please
    check http://support.microsoft.com for regional support phone numbers.
     
    Ace Fekay [Microsoft Certified Trainer], Apr 23, 2009
    #7
  8. Err.. sorry Phillip!!! My apologies!!!

    Ace
     
    Ace Fekay [Microsoft Certified Trainer], Apr 23, 2009
    #8
  9. Vide

    Vide Guest

    So going back to my first post :) Well at least now I'm sure there's no
    other way.
    Definitely, but through DHCP you can push far more network settings than
    just the plain IP, so just disabling it for a number of machines is not
    convenient at all. But on the other hand I *need* this second aliased IP due
    to an integration with an external system that I cannot touch :/

    Thanks anyway.
     
    Vide, Apr 23, 2009
    #9
  10. Unfortunately, it's the way it works. I agree DHCP provides numerous (scope
    or server) options compared to a statically configured client, and some of
    them can be statically set, but it depends on the options.

    Are you using any specific scope options that you need set on all machines
    that is required, which is holding you back from statically configuring a
    client to intergrate wtih that external system?

    Also, curious, what or how exactly do you mean this client must "integrate"
    with this external system? IS it running some sort of app that needs
    specific connectivity? Is there a separate router on a different IP subnet
    on your local subnet that it needs to connect? (This of course will require
    more thought in the design with multiple gateways on the cilent.). By
    external, do you mean it is outside your subnet (internet or in a different
    location), or is not part of your domain but is internal on your subnet?
    What kind of system is it? If we knew some specifics about what you are
    trying to accomplish, system type, protocols, client apps, etc, there is a
    possibility we *may* (no guarantees of course), come up with an alternate
    solution.

    Ace
     
    Ace Fekay [Microsoft Certified Trainer], Apr 23, 2009
    #10
  11. No problem,...I'll answer to most things if it isn't too bad :)

    I actually have another guy "in real life" that calls me that all the time
    too for some reason.

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------


     
    Phillip Windell, Apr 23, 2009
    #11
  12. There is no such thing as an "aliased IP". A machine either has multiple
    IP#s or it does not..

    I'll just bet that you don't really "need" it for this external
    system,...I'll bet that the whole project just simply has not been
    approached properly from the beginning and that is where you real problem is
    at. That is probably what we should be looking at.

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Apr 23, 2009
    #12
  13. Someone else actually calls you Paul? That is a coincidence!

    I glanced at your name and after typing a few minutes and not double
    checking, I could have sworn I saw Paul Bergson's name. After I hit send,
    and looked again, is when I saw I messed up!!!

    Ace
     
    Ace Fekay [Microsoft Certified Trainer], Apr 23, 2009
    #13
  14. I agree with the others that I doubt this is the requirement, but just for
    fun:
    - do a dhcp request to obtain a spare IP and other settings
    - read the obtained values into a script
    - write a netsh to set the networking properties,
    Anthony
    http://www.airdesk.co.uk
     
    Anthony [MVP], Apr 23, 2009
    #14
  15. Vide

    Vide Guest

    Yep, there's a separate router on the same LAN but in a different subnet,
    and apparently we cannot touch the router at all (not even a static route).

    To clarify:

    MyLAN: 10.0.0.0/20
    MyGW: 10.0.0.1

    TheirLAN 10.1.1.0/24
    TheirGW: 10.1.1.1

    so, different subnets. Actually TheirGW is attached to the same switches as
    MyGW (and all the rest of MyLAN) is. I can put a static route on MyGW to
    direct all traffic to TheirLAN through theirGW but as I told, I cannot even
    add a static route on TheirGW to drive the traffic back, because they have
    their default GW set in TheirGW so traffic to MyLAN would go through that
    other GW.
    So, there's this ugly hack of assigning a second IP to MyLAN machines to
    become part of TheirLAN as well (as they are all in the same physical LAN)
    but at the same time I don't want to loose DHCP
     
    Vide, Apr 27, 2009
    #15
  16. Vide

    Vide Guest

    Linux jargon, sorry :p (although to be correct NIC is being aliased in this
    case, not the IP)
     
    Vide, Apr 27, 2009
    #16

  17. Then it sounds like you have no choice but to use a static config.

    Ace
     
    Ace Fekay [Microsoft Certified Trainer], Apr 27, 2009
    #17
  18. Your subnet is too big. You should be using /24.
    That is another "unrelated" debate for later.
    There is your Core Design flaw!

    It should *not* be plugged into the same switch.

    Think this through. Every LAN router has two subnets (minimum),...if it
    didn't it could not even exist. That means they have two subnets,...the one
    on your side of their Router and one on their side of their Router.
    Therefore you have to add an interface to your LAN Router that matches the
    subnet of their Router. If that means your router ends up with three
    interfaces,...then that is axactly what it means. This subnet (10.1.1.0/24)
    will exist *only* between the two routers and should *not* be on the same
    "logical wire" that the 10.0.0.0/20

    [their LAN main subnet]
    |
    |
    <their router>
    |
    |
    [their second subnet]
    |
    |
    <your router>-------(your router going elsewhere)
    |
    |
    [your LAN]

    The proverbial "they" in the discussion need to do their jobs,..that is what
    their bosses pay them to do. If something on their LAN needs to communicate
    with something your LAN,...and if that requires a static route on their
    router,...then that is their job whether they like it or not and they have
    to do it whether they like it or not.

    People have tried that kind of stuff with me on occasion,...they didn't get
    very far,...I'll do my job (and I'll do it the right way),...but they have
    to do theirs,...and I haven't hesitated to put their back to the wall to get
    them to do it when that is what needed to be done.

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Apr 27, 2009
    #18
  19. I don't mind being mistaken for him at all,...he just may not want it to be
    the other way around,...so don't call him Phil :)

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Apr 27, 2009
    #19
  20. Ya'know ,...if this "they" would just configure the interface on their
    router that faces your LAN with a proper IP# for your LAN there would never
    have been a problem and this whole thread wounld't even exist.

    That's what I would still be fighting them over. It is silly for you to
    have to go through all this non-sense just because of their bull-headed
    lazyness. Sorry, I just have a hard time letting these things
    drop,...computers I can deal with,...humans,..sometimes I just want to slap
    'em across the head.

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Apr 27, 2009
    #20
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