multihoming a small web farm

Discussion in 'Cisco' started by john rambo, Feb 18, 2004.

  1. john rambo

    john rambo Guest

    sure this has been asked before, but couldn't find a "good" answer.

    given: we have a small web farm and no portable address space and want to
    multihome for availability
    likely we'll get two /27s or something like that, one from each ISP
    so the DNS entry for the web server (or vip in this case) will have two
    addresses, one in each /27
    this is cool, round robin will give us approximate load balancing between
    the two ISP links
    but then one goes down. dns is still passing out a bad address. even with
    a low TTL, half the users will have unnecessary time-outs.

    is there a better way to approach this? this has to be a common problem and
    should by now have a most excellent solution available.

    how/where to locate the dns server, which could of course have the same
    problem?

    advTHANKSance
    =j
     
    john rambo, Feb 18, 2004
    #1
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  2. Give your DNS servers addresses in each address block, and used BIND's
    "views" feature to have them give out a different address for the web
    server depending on which address was used. E.g. if you query
    192.168.10.1 for the address of www.yourcompany.com, it returns
    192.168.10.2, but if you query 172.16.99.1 it returns 172.16.99.2. If
    one of the connections goes down, the DNS queries will all go to the
    other addresses, and they'll return the web server addresses that also
    work.

    Give your DNS entries short TTLs so that the window of failure is short.
     
    Barry Margolin, Feb 18, 2004
    #2
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