> Source: [sk167206](https://support.checkpoint.com/results/sk/sk167206)

# sk167206 - Multiple clusters with Automatic MAC Magic configuration on same network maintain their default MAC Magic value

| Property | Value |
|----------|-------|
| Solution ID | sk167206 |
| Date Created | 2020-06-03 |
| Last Modified | 2021-02-28 |
| Technical Level | General |

## Symptoms

- * Multiple Gateway Clusters with Automatic MAC Magic configuration are connected to the same network segment.
* The Cluster Control Protocol (CCP) is operating in Unicast mode.
* When a new Gateway Cluster is introduced on the same network segment, it does not change its MAC Magic value automatically.
* The two cluster have the same magic MAC, example:  

  **First Cluster:**   

  ```
  
  [Expert@CL1:0]# cphaprob -a if
   
  CCP mode: Automatic
  Required interfaces: 3
  Required secured interfaces: 1
  
  eth0       Non-Monitored         non sync(non secured)
  eth1       UP                    non sync(non secured), unicast
  eth2       UP                    sync(secured), unicast
  eth3       UP                    non sync(non secured), unicast
  
  Virtual cluster interfaces: 2
  
  eth1            10.10.1.1
  eth3            173.26.172.1
  
  [Expert@GW1C1:0]# cphaprob mmagic
  
  Configuration mode:  Automatic
  Configuration phase: Stable
  
  MAC magic: 1
  MAC forward magic: 254
  
  Used MAC magic values: None.
   
  ```

  **Second Cluster:**   

  ```
  
  [Expert@GW1C2:0]# cphaprob -a if
   
  CCP mode: Automatic
  Required interfaces: 3
  Required secured interfaces: 1
  
  eth0       Non-Monitored         non sync(non secured)
  eth1       UP                    non sync(non secured), unicast
  eth2       UP                    sync(secured), unicast
  eth3       UP                    non sync(non secured), unicast
  
  Virtual cluster interfaces: 2
  
  eth1            10.10.10.1
  eth3            173.26.172.11
  
  [Expert@CL2:0]# cphaprob mmagic
  
  Configuration mode:  Automatic
  Configuration phase: Stable
   
  MAC magic: 1
  MAC forward magic: 254
  
  Used MAC magic values: None.
   
  ```

## Cause

When creating/introducing a new cluster to network with an existing cluster already in unicast mode, the switch port might flap. Under normal operation with unicast mode, the clusters do not see CCP packets from each other, which results in both clusters using default MAC Magic. The duplicate/conflicting MAC Magic causes the switch port to flap.

## Solution

This problem was fixed. The fix is included in:

* [Jumbo Hotfix Accumulator for R80.30](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk153152) starting from Take 228
* [Jumbo Hotfix Accumulator for R80.20](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk137592) starting from Take 190

**Note:** In Gaia with kernel 3.10 this scenario is not relevant because the source MAC is the MAC of the machine, and no "MAC Magic" is used in this version.

This case can be addressed by configuring the MAC Magic value manually. If this is not desired, one can implement the following workarounds to initiate the automatic selection of the MAC Magic value.

<br />

If you choose not to upgrade:

#### First workaround:

After creating the second cluster, restart one of the cluster members (Standby for example) by running: `cpstop` and `cpstart`  

This will cause a broadcast on the network, and the other clusters on the same network will become aware of the new cluster.

#### Second workaround:

Switch the CCP mode to broadcast on the cluster members temporarily:

* In CLISH: `set cluster member ccp broadcast`
* In Expert: `cphaconf set_ccp broadcast`

Once the new cluster selects a new MAC Magic value automatically, you may switch the CCP mode back to Auto.

**Notes:**

* Automatic Mac selection may take up to 30 seconds   
* If both members are rebooted at same time then the cluster will loose its Magic MAC when it comes up, however there should be a broadcast before second member is up at which point the other cluster will modify its Magic Mac.

**Related solution:** [sk25977 - sk25977: Connecting multiple clusters to the same network segment (same VLAN, same switch)](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk25977)

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