Troubleshooting SFP Connectivity Issues Between Zyxel XGS1930 Switch and USG FLEX 700 Firewall

Zyxel_Melen

This FAQ addresses a specific connectivity issue encountered when connecting a Zyxel XGS1930 switch to a Zyxel USG FLEX 700 firewall using SFP ports.

Scenario

You are trying to connect a Zyxel XGS1930 switch and a Zyxel USG FLEX 700 firewall using SFP ports and SFP+ modules. While a direct SFP connection between two XGS1930 switches works correctly, you experience no link when connecting the switch to the firewall's SFP port.

Issue and Solution

The Zyxel USG FLEX 700 firewall's SFP ports only support a 1G link speed. In contrast, the XGS1930 switch SFP ports default to auto-negotiation, which might result in a speed mismatch and consequently no link.

To resolve this issue:

1. Access the XGS1930 switch's web interface.
2. Navigate to the SFP port configuration where the USG FLEX 700 is connected.
3. Change the speed/duplex setting from "auto-nego" to either "auto-1G" or "fix 1G".
4. Save the configuration and verify if the link between the switch and firewall is established.

Additional Information:

• Ensure you are using compatible SFP+ modules for both devices.
• Verify the physical cabling between the devices is not faulty.
• After changing the speed/duplex settings, power cycle both the switch and the firewall to ensure the changes take effect.

What Could Go Wrong

• Incompatible SFP+ modules: Using incorrect or incompatible SFP+ modules can lead to connectivity problems. Always refer to the device's compatibility list for supported modules.
• Faulty cabling: Damaged or incorrect cabling can prevent a link from establishing. Use high-quality cables and inspect them for any physical damage.
• Incorrect port configuration: Double-check that you have selected the correct SFP port on both the switch and the firewall within their respective interfaces.

By following these troubleshooting steps and considering the additional information provided, you should be able to resolve any SFP connectivity issues encountered between your Zyxel XGS1930 switch and USG FLEX 700 firewall.