02-04-2026 04:09 AM
Good day team!
We have 2 servers connected to each other with 2 patch-cords.
On vCenter admin configured 2 ports
Port14-VLAN-1111-1114 VLAN trunk range: 1111-1114 Virtual Machines (4) ----! 3 ASAv Primary and FTDV-1 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Port15-VLAN-1115-1118 VLAN trunk range: 1115-1118 Virtual Machines (4) ----! 3 ASAv- Secondary and FTDv-2
ASAv failover works perfect as for example one of them
interface GigabitEthernet0/3.1111 description LAN Failover Interface vlan 1111 ! interface GigabitEthernet0/4.1115 description STATE Failover Interface vlan 1115 ! failover interface ip LFO 192.168.1.1 255.255.255.252 standby 192.168.1.2 failover interface ip SFO 192.168.1.5 255.255.255.252 standby 192.168.1.6
So I configured the same on both FTDv-s, but when I start to configure HA, these port not shown up in drop down...
more to say, I recieved an alarm that subinterfaces not recieving any packets, so i remove Logicalname from subs, and alarm goes away. But still cannot see neither interfaces no subinterfaces...
May be FTDv\FMC does not support this kind of config?
If this kind of config is supported, please help to sort it out, i will be appreciated a lot.
attached screenshots shows config
02-04-2026 05:26 AM
I am not sure sub-interface supported for failover and state link, as per my experience and deployment : (if new version has changed no idea, but happy to hear from other engineers).
Check the guidelines for the version. Here is the 7.4 code
=====️ Preenayamo Vasudevam ️=====
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02-04-2026 05:30 AM
@s_SiD_s as per the guides:-
You can use an unused data interface (physical, or EtherChannel) as the failover link; however, you cannot specify an interface that is currently configured with a name. You also cannot use a subinterface with the exception of a subinterface defined on the chassis for multi-instance mode.
02-04-2026 05:41 AM
on the chassis - means hardware device, not virtual?
02-04-2026 05:50 AM
@s_SiD_s yes, multi instance which it is referring to is only supported on 3100, 4100, 4200 and 9300 hardware.
02-04-2026 06:21 AM
So, we need to go to DataCenter and install 2 more (or 1 will be enough) patch-cords between servers for FTDv-HA? >_<
02-04-2026 05:34 AM
oh...I think I found the answer... 1 more patch-cord need to be placed between servers... no trunking supported
Interface for the Failover Link
You can use an unused data interface (physical, or EtherChannel) as the failover link; however, you cannot specify an interface that is currently configured with a name. You also cannot use a subinterface with the exception of a subinterface defined on the chassis for multi-instance mode. The failover link interface is not configured as a normal networking interface; it exists for failover communication only. This interface can only be used for the failover link (and also for the state link).
The Firewall Threat Defense does not support sharing interfaces between user data and the failover link. You also cannot use separate subinterfaces on the same parent for the failover link and for data (multi-instance chassis subinterfaces only). If you use a chassis subinterface for the failover link, then all subinterfaces on that parent, and the parent itself, are restricted for use as failover links.
02-04-2026 06:58 AM
team! what about clustering? if subinterfaces not supported, can I make cluster?
02-04-2026 07:02 AM
@s_SiD_s clustering is supported on virtual FTD in private cloud using Vmware or KVM as per the cisco documents https://www.cisco.com/c/en/us/td/docs/security/secure-firewall/management-center/device-config/760/management-center-device-config-76/device-ops-cluster-ftdv-private.html
02-06-2026 07:06 AM
Thank you for link!
admin went to DC and connected another interfaces on servers to each other.
Another thing to consider...do we need to create a dummy vlan on vCenter that is not routing and assing it to intertfaces proposed for failover? Right now...there is VM Netwiork pointing nowhere....
so my HA not working in this case...
02-06-2026 07:45 AM
Hi,
@s_SiD_s From technical point of view, as long as there is layer 2 connectivity between the two FTD's, the VLAN does not have to be dedicated. Practically speaking, to avoid potential VLAN noise from other hosts, always use a dedicated VLAN.
Also, ensure, if there's physical switches in the path, ensure to run RSTP and the ports connected to the FTD's are in STP EDGE mode, otherwise, any STP topology change for the VLAN will result in 30 seconds of communication downtime between FTD's. Obviously, to avoid split brain scenarios, ensure to use Standby IP's for all your layer 3 interfaces.
Thanks,
Cristian.
02-09-2026 05:22 AM - edited 02-09-2026 05:26 AM
I have done HA after ESXi admin created dummy vlan and assignet to intergface for LAN\STATE
HA raised smooth and nicely without any errors.
Now I am seeting up logging to Graloylog and noticed that there is mees up with time)
for example: admin setting show right time
logs on Graylog are not...
FMC shows right time
02-09-2026 11:07 AM
Hi,
@s_SiD_s Not sure I exactly understand the problem. If you're speaking about the 3 hours difference, that because of timezone vs your logging configuration settings.
Thanks,
Cristian.
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