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This one really has me confused, so hopefully someone has a good idea. I have 2 servers, one running Fedora Core 4 called Ricky and another running RHEL 5.2 called ...
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  1. #1
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    Angry Cannot get Virtual IP to take


    This one really has me confused, so hopefully someone has a good idea.

    I have 2 servers, one running Fedora Core 4 called Ricky and another running RHEL 5.2 called Lucy. Ricky acts as a web server on IP 192.168.0.140 and Lucy is another web server on 192.168.0.183. I want to configure Lucy to act as a backup to Ricky in case of catastrophic failure. The idea being that I would bind 192.168.0.140 to Lucy's eth0. I did a dry run today by unplugging the network cable of Ricky and I issued the following command on Lucy:

    ifconfig eth0:1 192.168.0.140 netmask 255.255.255.0 up

    If I run ifconfig, it shows that eth0:1 is up at that IP, yet I cannot ping it (192.168.0.140) from another machine. If I were to choose an IP address that is not currently being used, for example 192.168.0.186, and try this command on Lucy:

    ifconfig eth0:1 192.168.0.186 netmask 255.255.255.0 up

    I CAN ping and connect to it (192.168.0.186) from another machine.

    The first thing I think is it must be the switch and some sort of cached arp table, but then I use the network GUI on Lucy (system-config-network) and add 192.168.0.140 and it works and I can connect to it (192.168.0.140) from another machine. But if I undo that config in the GUI and try the CLI again, it doesn't work.

    So this is why I am confused. Has anyone ever had a similar experience and found a solution?

    Grendelos

  2. #2
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    Talking Solution: Cannot get Virtual IP to take

    It appears that this does have something to do with arp tables being cached on neighboring hosts. If I first issue the command:

    ifconfig eth0:1 192.168.0.140 netmask 255.255.255.0 up

    Followed by:

    arping -q -A -c 1 -I eth0 192.168.0.140

    Then all appears to be well. I got this idea by looking at the /sbin/ifcfg script on the RHEL box.

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