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  1. #1
    Join Date
    Mar 2003
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    Technical IP question

    I used up my block of 64 IP's, and am in need of more. The Sales/Accounts rep I spoke with at my Datacenter said that I would need to re-ip my entire server cluster to move to a larger IP block.

    I obviously do not want to do this.

    Is it possible to bind IP's in different subnets to the same adapter?

    I know you can bind multiple IP's within the same subnet to the same adapter, but I want to know if I can just add a block from a different subnet.


    I am running RedHat Linux 7.3.

    Thanks,
    ~Aaron

  2. #2
    Yes you can add different IPs from different subnets.

  3. #3
    Join Date
    Jun 2003
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    UK
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    There is no techincal reason that you have to renumber unless you want them all consecutive. I've got servers where there are IPs for 4 different subnets running of the same ethernet interface on Linux

    They may of course have managment reasons

    Rus
    Rus Foster - Director of Cloud @ UK2 Group
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  4. #4
    Join Date
    Mar 2003
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    Well, the Accounts person was under the impression that it wasnt possible to have more than one subnet per server... He is getting me the IP's I requested, and letting the techs add them to my account.

    How do I go about adding them? I can't have 2 gateways can I?

  5. #5
    You don't really need two gateways.. What operating system are you on?

    Typically you'd get a new gateway IP with the new subnet, but all the gateway IPs are all bound to the same router.

    On one of my FreeBSD machines I am using the gateway of one subnet and i can still use the IPs from another subnet with no problems.

  6. #6
    Join Date
    Aug 2002
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    I'm running several subnets on different servers. It is no problem at all.

    Mod Edit: Removing subscrption to fix thread..
    Last edited by The Prohacker; 10-13-2003 at 10:13 PM.
    SiteSouth
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  7. #7
    Join Date
    May 2001
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    Dayton, Ohio
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    Originally posted by volfman
    You don't really need two gateways.. What operating system are you on?

    Typically you'd get a new gateway IP with the new subnet, but all the gateway IPs are all bound to the same router.

    On one of my FreeBSD machines I am using the gateway of one subnet and i can still use the IPs from another subnet with no problems.

    Thats if you are on a small network.. Larger networks will have multiple boarder and core routers.. Also VLANs can limit you on what kind of IPs you can bind...
    -Mat

  8. #8
    Join Date
    Oct 2003
    Location
    Bay Area
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    214
    Originally posted by The Prohacker
    Thats if you are on a small network.. Larger networks will have multiple boarder and core routers.. Also VLANs can limit you on what kind of IPs you can bind...
    That is true under certain circumstances, but....
    Your ISP should be able to route additional netblocks to the gateway IP of your existing netblock and associated VLAN.
    The netblocks they route should not be associated with other VLANS already configured on the switch.
    For example:
    Let's say they assigned you a /27 (123.123.123.0/27)
    And this is bound to a VLAN interface you use. It's gateway/router IP is 123.123.123.1
    The ISP should be able to do this:
    ip route 222.222.222.0 255.255.255.224 123.123.123.1

    Doing this will send an additional /27 from a different network over your existing 123.123.123.0/27 down to your switch or server.
    Then all you need to do is configure machines connected to your small switch, hub or whatever to IP's on the 222.222.222.0/27 network and tell them to use 123.123.123.1 as the gateway to get out.

    I don't know wht your ISP can't do this. It is totally normal.... unless *ALL* of their IP space is already assigned to different VLAN interfaces on their switch. In which case they would not have free netblocks available for this type of routing.

    Yes, I am a network engineer.

  9. #9
    Join Date
    May 2003
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    Originally posted by The Prohacker
    Thats if you are on a small network.. Larger networks will have multiple boarder and core routers.. Also VLANs can limit you on what kind of IPs you can bind...

    EDIT: Beaten by a mile by Papa Smurff.
    Become an ISP; a great value-added service for any web host.
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  10. #10
    Join Date
    Mar 2003
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    Duluth MN
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    Cool, thanks guys... I got it all figured out now, and have 2 IP blocks from 2 different subnets shared between my 4 servers.

    Actually, I have 3 subnets/blocks between my 4 servers, but one server is on its own separate block of 8.

  11. #11
    Join Date
    Feb 2003
    Location
    Detroit
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    One thing I've ran into when doing this,

    My clients inter-server transfers transverse their port when transfering from one subnet to the other.

    Basically, it has to be routed since its not in the same subnet, and it shows on their port as billable bandwidth.

    Once I made them aware of the issue, they were carefull to transfer to IP's within the same subnet for local transfers and havent had an issue since.

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