Forum Discussion
Can you start troubleshooting from layer 1 and go up in the layers? Is the network cable done correct, so if shutdown the port in the Cisco does it goes down in the correct F5? Do you learn the mac address of the standby unit?
One thing to take into account, is the fact that you have a forward vs, and if arp is enable for that virtual address, only the active will reply to pings. Secondly, the AFM can be configured in ADC mode or Firewall mode, I guess firewall mode will not reply to ICMP unless there a rule to allow that. Third thing is about the configuration when using HSRP or VRRP, because F5 auto last hop things complicate a little bit, but there are documentations about that.
You can also take a tcpdump in the active and standby unit, and check with listener is handling the ICMP, so virtual server/self ips/etc...
Some useful solutions:
https://support.f5.com/kb/en-us/solutions/public/9000/400/sol9487.html
https://support.f5.com/kb/en-us/solutions/public/13000/100/sol13142.html
https://support.f5.com/kb/en-us/solutions/public/0000/400/sol411.html