> Source: [sk120073](https://support.checkpoint.com/results/sk/sk120073)

# sk120073 - Traffic through ClusterXL High Availability mode is interrupted when Standby member is rebooted

| Property | Value |
|----------|-------|
| Solution ID | sk120073 |
| Date Created | 2017-08-17 |
| Last Modified | 2018-10-24 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |

## Symptoms

- Traffic through ClusterXL High Availability mode is interrupted when Standby member is rebooted.

## Cause

Chain of events:

1. When a cluster member boots up, it sends Gratuitous ARP Request packets through its cluster interfaces.
2. These GARP packets are sent with the following data:  
   * Sender Hardware Address = MAC address of the local *physical* interface
   * Sender Protocol Address = Cluster Virtual IP defined on that cluster interface
   * Target Hardware Address = MAC address of the local *physical* interface
   * Target Protocol Address = Cluster Virtual IP defined on that cluster interface
3. Network devices (Routers, Switches) that until now held the ARP entry "Cluster-VIP is at MAC-of-Active-member",  
   receive these GARP packets and update their ARP tables with the new association "Cluster-VIP is at MAC-of-Standby-member".
4. Network devices now send traffic to the MAC address of the Standby member.
5. By design, Standby member does not process any traffic from the network.
6. Active member periodically sends its own GARP packets (to keep the network devices updated).
7. Traffic issue continues until GARP packets are received from the Active member.

## Solution

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