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  1. #1
    Join Date
    Oct 2003
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    Taiwan
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    Unanswered: The First IP on Server for MS-SQL Connection

    Hello , everybody.
    I have a problem with SQL Connection.
    My Server has 3 IPs on the only one LAN card. For example, they are 10.0.0.1, 10.0.0.2, 10.0.0.3 .
    I set 10.0.0.1 into my LAN card setting at the first time. And after that, I append 10.0.0.2 and 10.0.0.3 into my LAN card setting.
    But my ASP scripts can only connect the MS-SQL Server through 10.0.0.1 , it can't connect through those IPs I appended.
    Why?
    My English is poor, so... please forgive me if I make mistakes.

  2. #2
    Join Date
    Aug 2002
    Location
    Scotland
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    1,578
    How are you connecting from ASP using IP or Named?

    Either provide some reliable means for performing a reverse lookup of the SQL Server server's IP address, use the SQL Server machine name instead of the IP address.
    --Satya SKJ
    Microsoft SQL Server MVP
    [IMG]http://sqlserver-qa.net/google_bart.gif[/IMG]

  3. #3
    Join Date
    Jul 2003
    Location
    San Antonio, TX
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    3,662
    Wow, I didn't even know you can do that. Please tell us how it works!
    I append 10.0.0.2 and 10.0.0.3 into my LAN card setting.

  4. #4
    Join Date
    Feb 2004
    Location
    San Antonio, TX
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    565
    check your dns server for host records for the server with each of the ip's.
    if this is external you will have to make sure that the external dns is resolving (or forwarding) these host records.

  5. #5
    Join Date
    Oct 2003
    Location
    Taiwan
    Posts
    16
    Originally posted by rdjabarov
    Wow, I didn't even know you can do that. Please tell us how it works!
    I click a button in the Internet Protocol(TCP/IP) setting page. The button maybe named "Advance" or something ... I'm not sure. Because my Windows 2000 Server is Chinese version. After I click the button, I can Add 2nd or 3rd or many IPs although there is only one LAN card in my machine. So that I can use these 3 IPs for setting up 3 web sites in one machine with one LAN card.
    My English is poor, so... please forgive me if I make mistakes.

  6. #6
    Join Date
    Oct 2003
    Location
    Taiwan
    Posts
    16
    Thank you , everybody.
    I can't use Named pipe for connecting because sometimes my ASP web site do not setup in the same netmask with my MS-SQL server. So I can only use TCP/IP for connecting.
    For example, my client IP is 10.0.0.10 .
    If I use the option "server=10.0.0.1" in my connection string, I can connect to my MS-SQL Server. But if I use the option "server=10.0.0.2" or "server=10.0.0.3" , I will unable to connect to my SQL server. :s
    My English is poor, so... please forgive me if I make mistakes.

  7. #7
    Join Date
    Feb 2004
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    Provided Answers: 54
    The process is called Multi-homing. It is a common TCP/IP thing for both ISPs and web-hosts to do for their clients.

    -PatP

  8. #8
    Join Date
    Oct 2003
    Location
    Taiwan
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    Originally posted by Pat Phelan
    The process is called Multi-homing.

    -PatP
    m... Does MS-SQL Server not support multi-homing ?
    My English is poor, so... please forgive me if I make mistakes.

  9. #9
    Join Date
    Feb 2004
    Location
    San Antonio, TX
    Posts
    565
    multihomed

    (adj.) Typically used to describe a host connected to two or more networks or having two or more network addresses. For example, a network server may be connected to a serial line and a LAN or to multiple LANs.
    adding multiple ip's to a single NIC simulates multiple adapters on the machine but does not give the actual benefit of the process nor is it truly multihomed
    you are just sharing the ip connection and in this case since it appears that your ip address is on the same subnet (10.0.0.0/8) then his adapter will pick up the traffic from the first configured address

    we use this process on a few servers where i work and it requires multiple adapters to get the true effect.

    and to quote the kb article there are many reasons not to do this
    The primary disadvantages to this method concern bandwidth and network card failure. If multiple IP addresses reside on one NIC card, then they each have to share the available bandwidth. Also, if that NIC fails, then all of the IP addresses on that NIC will become inaccessible.

  10. #10
    Join Date
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    Provided Answers: 54
    While the definition of the term multi-homed has come to include having two or more TCP/IP adapters, it wasn't originally that way. Back in the long ago, any machine that responded to more than one IP address was considered multi-homed, and that is what most of the folks that write device drivers call it today.

    In order to take real advantage of multiple TCP/IP addresses, the TCP/IP adapters need to be "smart" to the point of being nearly autonomous, and it helps a bunch if they have private busses. Very few real world boxes have those characteristics, but in the ideal world they'd be nifty!

    When you multi-home a single adapater, you make life quite "interesting" for the poor beggar that has to support the box! The UPD problems that this can create are nothing short of horrendous... That doesn't mean that people don't do it.

    Particularly when hosting a number of relatively low traffic web sites (usually contracting for 512 Kb of bandwidth or less), it makes great sense to put in one large box and give it four to twelve IP addresses than it does to put up that many smaller boxes. It does introduce a single point of failure (look at what happend last year to http://www.welovetheiraqiinformationminister.com/ and the other three sites on that machine!), but that isn't usually a huge problem for that kind of site.

    -PatP

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