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

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

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?

>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

network failover/serial cable for HA

13 Replies

nitass_89166
Noctilucent
May 25, 2015
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
  Nimbostratus
  May 26, 2015
  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
  Noctilucent
  May 26, 2015
  >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
  Nimbostratus
  May 26, 2015
  Hi Nitass, what is the outcome if both network and serial cable failed in this case?
nitass
Employee
May 25, 2015
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
  Nimbostratus
  May 26, 2015
  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
  Employee
  May 26, 2015
  >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
  Nimbostratus
  May 26, 2015
  Hi Nitass, what is the outcome if both network and serial cable failed in this case?
svs
Cirrus
May 25, 2015
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