Symptoms
Both Parallels RAS HALB appliances simultaneously enter the MASTER state and assume ownership of the same virtual IP address (VIP).
The affected environment may show the following symptoms:
- Both active and passive HALB appliances own the same VIP.
- Connectivity through the VIP may be intermittent or unavailable.
- Both appliances report a VRRP advertisement timeout and transition to the MASTER state.
Example from HALB 10.122.230.242:
Jul 24 09:39:15 prls-halb Keepalived_vrrp[456]: VRRP sockpool: [ifindex(2), family(IPv4), proto(112), fd(13,14) multicast, address(224.0.0.18)]
Advertisement from the peer is not received:
Jul 24 09:39:18 prls-halb Keepalived_vrrp[456]: (Inst_01) Receive advertisement timeout
The HALB transitions to MASTER:
Jul 24 09:39:18 prls-halb Keepalived_vrrp[456]: (Inst_01) Entering MASTER STATE
The HALB assigns itself the VIP:
Jul 24 09:39:18 prls-halb Keepalived_vrrp[456]: (Inst_01) setting VIPs.
Example from HALB 10.122.230.244:
Jul 24 09:39:15 prls-halb Keepalived_vrrp[454]: VRRP sockpool: [ifindex(2), family(IPv4), proto(112), fd(13,14) multicast, address(224.0.0.18)]
Advertisement from the peer is not received:
Jul 24 09:39:19 prls-halb Keepalived_vrrp[454]: (Inst_01) Receive advertisement timeout
The second HALB also transitions to MASTER:
Jul 24 09:39:19 prls-halb Keepalived_vrrp[454]: (Inst_01) Entering MASTER STATE
The second HALB assigns itself the same VIP:
Jul 24 09:39:19 prls-halb Keepalived_vrrp[454]: (Inst_01) setting VIPs.
The highlighted entries confirm that both HALBs independently enter the MASTER state and assign themselves the VIP.
Cause
The HALB appliances use VRRP advertisements to determine which appliance owns the VIP.
If a HALB does not receive an advertisement from its peer within the expected timeout, it assumes that no other appliance owns the VIP. It then enters the MASTER state and assigns the VIP to itself.
If VRRP communication fails in both directions, both HALBs independently follow this process, resulting in a split-brain condition in which both appliances own the same VIP.
This occurs when the network blocks, filters, or otherwise prevents VRRP traffic between the HALBs. VRRP uses multicast address 224.0.0.18 and IP protocol 112.
Resolution
Verify the network path between the HALB appliances and ensure that VRRP traffic can pass in both directions.
The underlying issue is outside RAS when the network infrastructure prevents the HALBs from receiving each other’s VRRP advertisements.
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