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Thong_196816's avatar
Thong_196816
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May 25, 2015
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network failover/serial cable for HA

for HA configurations, there are 3 options

 

  • network failover

in network failover the heartbeat is the network packet

 

  • serial failover

serial cable failover is just checking a voltage heartbeat between the two systems.

 

  • network and Serial failover

I not sure does it mean failover only take place when network and serial both are failed or ? if use both, how to test if it is working?

 

  • network and Serial failover

     

    If you configure a BIG-IP high-availability pair to use network failover, and the hardwired failover cable also connects the two units, hardwired failover always has precedence; if network failover traffic is compromised, the two units do not fail over because the hardwired failover cable still connects them.

     

    sol2397: Comparison of hardwired failover and network failover features

     

    https://support.f5.com/kb/en-us/solutions/public/2000/300/sol2397.html

     

14 Replies

  • network and Serial failover

     

    If you configure a BIG-IP high-availability pair to use network failover, and the hardwired failover cable also connects the two units, hardwired failover always has precedence; if network failover traffic is compromised, the two units do not fail over because the hardwired failover cable still connects them.

     

    sol2397: Comparison of hardwired failover and network failover features

     

    https://support.f5.com/kb/en-us/solutions/public/2000/300/sol2397.html

     

    • Thong_196816's avatar
      Thong_196816
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      Hi Nitass, Quoted " If network failover traffic is compromised, the two units do not fail over because the hardwired failover cable still connects them " - can give an example of such scenario ? - do you mean the 2 units still show as active-standby status?
    • nitass_89166's avatar
      nitass_89166
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      >can give an example of such scenario ? probably heartbeat packet is lost or delayed. >do you mean the 2 units still show as active-standby status? yes
    • Thong_196816's avatar
      Thong_196816
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      Hi Nitass, what is the outcome if both network and serial cable failed in this case?
  • network and Serial failover

     

    If you configure a BIG-IP high-availability pair to use network failover, and the hardwired failover cable also connects the two units, hardwired failover always has precedence; if network failover traffic is compromised, the two units do not fail over because the hardwired failover cable still connects them.

     

    sol2397: Comparison of hardwired failover and network failover features

     

    https://support.f5.com/kb/en-us/solutions/public/2000/300/sol2397.html

     

    • Thong_196816's avatar
      Thong_196816
      Icon for Nimbostratus rankNimbostratus
      Hi Nitass, Quoted " If network failover traffic is compromised, the two units do not fail over because the hardwired failover cable still connects them " - can give an example of such scenario ? - do you mean the 2 units still show as active-standby status?
    • nitass's avatar
      nitass
      Icon for Employee rankEmployee
      >can give an example of such scenario ? probably heartbeat packet is lost or delayed. >do you mean the 2 units still show as active-standby status? yes
    • Thong_196816's avatar
      Thong_196816
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      Hi Nitass, what is the outcome if both network and serial cable failed in this case?
  • Hi Thong,

     

    do not use the hardwired failover except you need failover times under 1 second. There is so much to keep in mind when the hardwired failover is used. For example, that in most cases there will be no failover during a reboot of a node. Also, as nitass already stated, there will be no software failover as long as the secondary node is still physically available through the serial cable.

     

    In my mind the hardwired failover doesn't make sense at all. There may be cases, where it makes perfect sense, but I'm pretty sure those cases are rare. I removed the hardwired failover on every single customer installation. Since there is no hardwired failover software updates are working as expected.

     

    Greets, svs