> Source: [sk178305](https://support.checkpoint.com/results/sk/sk178305)

# sk178305 - One of bond slave interfaces does not pass outgoing traffic

| Property | Value |
|----------|-------|
| Solution ID | sk178305 |
| Date Created | 2022-03-13 |
| Last Modified | 2022-04-04 |
| Technical Level | Advanced |
| Products | Hardware |
| Versions | Not Version-Specific |
| OS | Gaia |

## Symptoms

- * One or more bonds on the Security Gateway forward all outgoing traffic only on a single slave interface (for example, eth1-01). Incoming traffic is received on the two slave interfaces of the problematic bond/s (for example, eth1-01 and eth1-02).

* If you disable the switch port connected to eth1-02, it resolves the issue. If you disable the switch port connected to eth1-01, a full outage occurs.

* There is no problem with the interface and/or bond configuration.

* Replacing the line card, transceivers, cable and switchport does not resolve the issue.

* Switch was recently replaced to a new hardware.

## Cause

The switch learned the uplink MAC address through port-channel 1. The switch sends the traffic directed to this MAC through port-channel 2 because it is the destination port in the MAC address table.

This causes the switch to drop this traffic because of a vPC loop avoidance rule.

## Solution

This solution requires authentication. Please log in to view the full solution.

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