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I was wondering, is there any limit of how many virtual IPs can be set in a single NIC? Again, can two hosts have the same Virtual IP configured without ...
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  1. #1
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    Number of Virtual IP in a single NIC


    I was wondering, is there any limit of how many virtual IPs can be set in a single NIC? Again, can two hosts have the same Virtual IP configured without causing trouble in the LAN?

    Personally, I had an incident where an NIC card started malfunctioning after assigning the 9th IP to it (physical IP + 8 virtual). I'm not sure whether it was the problem of the NIC card or there is any sort of limit.

    Thanks in advance
    Sarmed

  2. #2
    Trusted Penguin Irithori's Avatar
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    I am not aware of a limit, but that doesnt mean that there is none.
    For sure you can have more than 9, as I run multiple servers with dozens (ca 40) IPs each.

    How did you add and test the IPs?
    Nowadays, the command ip from the package iproute2 is best used for network interface tasks.

    As for the same IP for two hosts: If you talk about unicast IP addresses, then: No.
    Duplicate unicast IPs *will* cause problems. One host needs this IP removed.
    You must always face the curtain with a bow.

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    Thanks Irithori.

    For configuration, I manually copied the ifcfg-eth0 file and created instances as ifcfg-eth0:1, ifcfg-eth0:2, ifcfg-eth0:3 and so on. Then I made necessary adjustments to all of the interfaces. Haven't faced any trouble regarding configuration any time.

    About the same virtual IP address: I was experimenting clustering with Heartbeat. I'm using two CentOS 5.5 hosts in oracle virtual box. Both of the hosts have the same virtual IP configured i.e 192.168.10.254 in of their NICs. Simulation was successful, but I'm not sure whether there would be any problem in the future.

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