I have two OpenBSD boxes on running as Gen1 VMs on Hyper-V 2016; the VMs are split across two Hyper-V hosts. The NICs associated with the CARP pseudo interface do have MAC address spoofing enabled; the CARP pseudo interfaces have a static MAC address in Hyper-V. I'm unable to ping the CARP interface, but can ping the IP of the NICs which support the CARP pseudo interface. In addition, the CARP interface is correctly assigning MASTER/BACKUP and I can see CARP traffic from the OpenBSD box when using tcpdump -ni hnv1 (the physical interface).

My /etc/sysctl.conf file is:


There's no change if I move them to the same Hyper-V host. Pf on the OpenBSD boxes is disabled.

HAProxy is performing as a TCP proxy for multiple web servers. I do not want/need offloading, etc. hence not operating as an HTTPS proxy; will also be load balancing an RDS box over tcp/443. HAProxy works if I target the IP for the FQDN at the non-CARP interface.

What else can I look at here? Are there any other groups I can look to for help with CARP? Most of the CARP information out there surrounds pfSense box configurations.

The switching infrastructure is simple. Both Hyper-V boxes are attached to an Ubnt ES-250W-PoE and there is a Ubnt ERLite as the router.

ERL ( untagged; VLAN ID 1:; VLAN ID 4: -> ES-250W (; LACP bonds for Hyper-V boxes carry untagged, VLAN ID 1 & 4). Hyper-V boxes LACP switch passes on traffic, no IP assigned. OpenBSD boxes have hnv0 on the untagged VLAN, assigned space in the subnet. hnv1 is used by the carp0 pseudo interface. hvn1 NICs use and, for the respective OpenBSD VM. carp0 is assigned at

The hnv1 NICs and carp0 do not have a gateway address assigned. Web servers are on the VLAN ID 1 assigned subnet.

I can ping and .3 from any location on the network. I cannot ping from any location except for the OpenBSD boxes themselves.


Turns out there must simply have been a bug in the CentOS 6.1 release build. I upgraded to -current from 7/13/2017 and CARP immediately began working with no other changes.

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