Packet loss when pinging Carp vip

  • Hello !

    I have packet loss problems with a vip carp on a private lan.
    The configuration I set up is the following:
    network address:
    pfsense-1 : (LAN interface)
    pfsense-2 : (LAN interface)
    Carp vip defined on pfsense-1 : (LAN interface)

    This vip appears on pfsense-2 (xmlrpc sync) with a skew increased by 100.

    Outbound Nat rule:
    Interface: LAN
    Source: Any
    Translation: Address:
    The firewall allows all traffic on the LAN interface.

    When I ping the pfsense-1 ip from a machine on the network, it works fine.
    But when I ping the carp vip, I get a lot of packet loss:
    olav@client-1:~$ ping
    PING ( 56(84) bytes of data.
    64 bytes from icmp_seq=3 ttl=64 time=0.939 ms
    64 bytes from icmp_seq=5 ttl=64 time=0.597 ms
    64 bytes from icmp_seq=6 ttl=64 time=0.537 ms
    64 bytes from icmp_seq=7 ttl=64 time=0.574 ms
    64 bytes from icmp_seq=8 ttl=64 time=0.379 ms
    64 bytes from icmp_seq=9 ttl=64 time=0.438 ms
    64 bytes from icmp_seq=11 ttl=64 time=1.16 ms
    64 bytes from icmp_seq=12 ttl=64 time=0.534 ms
    64 bytes from icmp_seq=13 ttl=64 time=0.546 ms
    --- ping statistics ---
    13 packets transmitted, 9 received, 30.7692% packet loss, time 236ms
    rtt min/avg/max/mdev = 0.379/0.633/1.156/0.236 ms

    Does anyone know what mistake I may have made in configuring this vip? Or how to diagnose the problem?

    Thank you,


  • Both of the routers show as Master for this vip.
    Does anyone have any idea what may cause tis problem ?

  • I have just realized that I had the mtu set to 9000 everywhere except on the routers. Setting it to 9000 on the routers solved the problem...

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