BGP and carp slaves

[Luca Bodini]

Hi folks,

I’m just having a strange issue using OpenBSD 6.6 and BGP .
I have two OpenBSD firewalls with a carp configuration, let’s suppose the 
shared IP is 10.10.10.100, and I am able to announce 10.10.10.100/32 via BGP.
Now, here is my /etc/bgpd.conf configuration:

# define our own ASN as a macro
ASN=“65000"
rde med compare always

# global configuration
AS $ASN
router-id 172.10.10.3 

# list of networks that may be originated by our ASN
prefix-set mynetworks {         \
        10.10.10.100/32        \
}

# Generate routes for the networks our ASN will originate.
# The communities (read 'tags') are later used to match on what
# is announced to EBGP neighbors
network prefix-set mynetworks set { community $ASN:1 med 10 } 

# upstream providers
group "upstreams" {
        remote-as 20746
        neighbor 172.10.10.1  {
                descr “provider router 01"
        }
        neighbor 172.10.10.2 {
                descr “provider router 02"
        }
}

## rules section
allow from group upstreams prefix 0.0.0.0/0

# IBGP: allow all updates to and from our IBGP neighbors
allow from ibgp
allow to ibgp
allow to ebgp prefix-set mynetworks 

The problem I’m facing is due to (i guess) provider router misconfiguration, in 
fact, routers are forwarding traffic to carp slave and unexpectedly everything 
is working fine: firewall is accepting connections and forwarding traffic, for 
example if I try to SSH:
~# ssh -l root 10.10.10.100
[root@fw-02 root]# ifconfig | grep vhid
        carp: BACKUP carpdev vlan100 vhid 10 advbase 1 advskew 10 

I’ve asked provider to change BGP configuration and everything now is stetted 
up correctly, now, the question is:
Is the carp slave accepting and forwarding connections by design or is it un 
“unintended" feature?

thank you for your time!
keep rock on!
Luca