breakout cable design in DC

[Ezzedine]

hello,

I would be grateful for any feedback on the design.
I wonder if I might ask your advice on the following: I have two N9K-C9332D-GX2BX in two separate rooms, which are interconnected with OM4.
I believe the best solution would be to use a QDD-400G-SR4.2-BD breakout cable to connect to the other room, the peer switch and another storage system.

According to the optic-to-optic guide, it seems that either a QSFP-100G-SR1.2 or a QDD-400G-SR4.2-BD may be suitable.

I am wondering if it would be possible to use a breakout cable to connect the peer device in the other room and the storage system that has a different SFP100G vendor. I will use another Breakout cable for redundancy, but I would be very grateful for any advice on whether this is a valid approach. I would also be very happy to hear any suggestions for improvements.

[AshSe]

Hello @Ezzedine 

Your approach to interconnecting the two Cisco Nexus N9K-C9332D-GX2BX switches and the storage system using breakout cables is valid, but there are a few considerations and recommendations to ensure compatibility, performance, and reliability.

Key Considerations:

1. Compatibility of Optics and Breakout Cables:

   1. The QDD-400G-SR4.2-BD (400G BiDi) transceiver is a good choice for short-range connections over OM4 multimode fiber. It supports breakout into 4x100G lanes, which can be used to connect to devices with 100G ports.
   2. The QSFP-100G-SR1.2 is also a valid option for 100G connections, but it does not support 400G breakout. If you plan to use breakout cables, the QDD-400G-SR4.2-BD is the better choice.

2. Interoperability with Different Vendors:

   1. When connecting to a storage system with a different SFP100G vendor, ensure that the optics on both ends are compatible. Cisco devices often require Cisco-certified optics for full support, but they can sometimes work with third-party optics if the vendor guarantees compatibility.
   2. Check the storage system's documentation to confirm it supports the specific 100G optics you plan to use. If the storage system uses non-Cisco optics, you may need to test the connection to ensure it works reliably.

3. Breakout Cable Configuration:

   1. Using a breakout cable from the QDD-400G-SR4.2-BD transceiver, you can split the 400G link into 4x100G connections. This allows you to connect:
      1. One 100G lane to the peer switch in the other room.
      2. Another 100G lane to the storage system.
   2. Ensure that the breakout cable and transceiver are properly configured in the switch. You may need to configure the ports on the N9K switches to operate in breakout mode.

4. Redundancy:

   1. Using a second breakout cable for redundancy is a good practice. This ensures high availability in case of a failure in one of the cables or transceivers.
   2. You can configure the redundant links using a protocol like vPC (Virtual Port Channel) or LACP (Link Aggregation Control Protocol) for load balancing and failover.

5. Distance and Fiber Type:

   1. The QDD-400G-SR4.2-BD transceiver supports distances of up to 100 meters over OM4 multimode fiber. Ensure that the distance between the rooms is within this range.
   2. If the distance exceeds 100 meters, you may need to consider other transceivers, such as LR (Long Range) optics, which would require single-mode fiber.

6. Switch Configuration:

   1. Ensure that the N9K switches are running a compatible NX-OS version that supports the QDD-400G-SR4.2-BD transceiver and breakout mode.
   2. Configure the ports correctly for breakout operation and verify the link status after connecting the devices.

Recommendations for Improvement:

1. Test Compatibility:

   1. Before deploying in production, test the connection between the switches and the storage system to ensure compatibility and performance. Use diagnostic tools to verify link stability and throughput.

2. Consider Future Scalability:

   1. If you anticipate needing more bandwidth or additional connections in the future, consider using dedicated 100G links for the storage system and the peer switch instead of breakout cables. This would provide more flexibility and reduce potential bottlenecks.

3. Use Cisco-Certified Optics:

   1. To ensure full support and avoid potential issues, use Cisco-certified optics for the N9K switches. If you must use third-party optics, choose a reputable vendor that guarantees compatibility with Cisco devices.

4. Monitor and Maintain Redundancy:

   1. Regularly monitor the redundant links to ensure they are functioning correctly. Perform failover tests periodically to verify that redundancy mechanisms are working as expected.

5. Documentation and Support:

   1. Document the configuration and connections for future reference. If you encounter issues, having detailed documentation will help when working with Cisco support or troubleshooting the setup.

Conclusion:

Your proposed solution of using QDD-400G-SR4.2-BD breakout cables is valid and should work well if the devices and optics are compatible. Ensure proper configuration, test the setup thoroughly, and consider the recommendations above to optimize the design and ensure reliability. If you have any doubts about compatibility or configuration, consult Cisco's documentation or reach out to their support team for guidance.

Hope This Helps!!!

AshSe

Forum Tips: 

1. Insert photos/images inline - don't attach.
2. Always mark helpful and correct answers, it helps others find what they need.
3. For a prompt reply, kindly tag @name. An email will be automatically sent to the member.