> Source: [sk169893](https://support.checkpoint.com/results/sk/sk169893)

# sk169893 - MAC flaps on the switch because Active chassis is forwarding packets to the standby chassis without changing the SRC-MAC address of the Source IP

| Property | Value |
|----------|-------|
| Solution ID | sk169893 |
| Date Created | 2020-10-05 |
| Last Modified | 2020-10-08 |
| Technical Level | Advanced |
| Products | Scalable Platforms |
| Versions | R82, R81.20 |
| OS | Gaia |
| Platform | 41000 (EOL), 44000, 64000 |

## Symptoms

- * Traffic initiated by the standby chassis is sent correctly to the network, and the return traffic is sent to the active chassis as expected.   
  However, the active chassis forwards the reply to the standby chassis without changing the SRC-MAC address. This causes a port flap on the switch and possible outage.
* The following log appears for the switch:   
  `
  L2FM-4-L2FM_MAC_MOVE2: Mac 0123.abcd.4567 in vlan XX has moved between PoYY to PoZZ
  `

  <br />

## Cause

The correction mechanism does not change the SRC-MAC address before it forwards the packet to the originator SGM. As a result, the switch mistakenly "thinks" that the destination server moved to the port connected to the SGMs.

<br />

## Solution

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