400G Over Multimode Fiber: BiDi Changes the Game

400G Over Multimode Fiber: BiDi Changes the Game

For anyone who has managed a data center fiber plant over the past decade, the arrival of 400 Gigabit Ethernet came with a painful side effect: singlemode fiber. If your DC was built in the era of 10G or 40/100G BiDi, chances are your structured cabling was entirely multimode, a perfectly reasonable choice at the time. Then, 400G arrived, and all the dominant transceiver options (DR4, FR4, LR4) required singlemode. Overnight, that existing multimode plant became a liability for anyone planning to upgrade.

That situation is now changing, thanks to a transceiver Cisco quietly added to its QSFP-DD portfolio in the last few months: the QDD-400G-BD.

Cisco Live 2024 Wrap-Up – Cisco Nexus HyperFabric, Disaggregated Scheduled Fabric (DSF) and SONiC

Cisco Live 2024 Wrap-Up – Cisco Nexus HyperFabric, Disaggregated Scheduled Fabric (DSF) and SONiC

Last week, I attended my 11th Cisco Live in person, in the fabulous Las Vegas. This post is my Cisco Live 2024 Wrap-up.

I can already tell you that the next edition of Cisco Live US will be held June 8-12, 2025 in San Diego, California. If my company agrees to send me there, I’m already looking forward to it, because San Diego is a wonderful city.

Migrating Cisco FabricPath and Classic Ethernet Environments to VXLAN BGP/EVPN over a 400Gb-based Clos Topology, part 1 – the why

Migrating Cisco FabricPath and Classic Ethernet Environments to VXLAN BGP/EVPN over a 400Gb-based Clos Topology, part 1 – the why

During the past three years, I have spent a good portion of my time testing, planning, designing, and then migrating our DC network from Cisco FabricPath and Classic Ethernet environments to VXLAN BGP/EVPN. And simultaneously, from a hierarchical classic two-tier architecture to a more modern Clos 400Gb-based topology.

The migration is not yet 100% completed, but it is well underway. And I have gained significant experience on the subject, so I think it’s time to share my knowledge and experiments with our community.

Cisco DCAUTO exam study resources

Cisco DCAUTO exam study resources

I just passed the Cisco DevNet DCAUTO (300-635) exam (Yay!). This is my 3rd Cisco exam on network automation after NPDESI in 2018 (replaced now by the DevNet program), and DevNet CORE (DEVCOR) in 2020. But this time, I documented everything I read, so I could report it here and build a Cisco DCAUTO exam study resources. By doing this, I hope to help anyone who wants to study for this certification. And, as I have already passed the DevNet CORE exam, I am now Cisco certified DevNet Professional.

How to simulate a host

How to simulate a host in a real network?

Like some other posts, I didn’t think I would write this one because it seemed obvious. But, after talking to a lot of engineers and customers, I realized that not everyone knows this trick. So here it is.
The question is this: how to simulate a real host in a physical network environment when you don’t have computer at your disposal? Well, let’s take an example.

HDD

NVMe, NVMe over Fabrics and RDMA for network engineers

In the past, the evolution of network-based storage was not really a problem for network engineers: the network was fast and the spinning hard drives were slow. Natural network upgrades to 10Gb, 40Gb, and 100Gb Ethernet were more than sufficient to meet the networking needs of storage systems.
But now, with the introduction of ultra-fast solid-state disks (SSDs) and Non-Volatile Memory Express (NVMe), this is no longer true! Storage teams now have the ability to potentially saturate the network with incredibly fast devices.

Cisco GIR

Cisco NX-OS Graceful Insertion and Removal (GIR)

If you operate a data-center network with Cisco Nexus, you’ve probably already faced the problem of how to perform a maintenance on one of the two switches of a vPC pair, with minimum impact and risks for the production network. Cisco NX-OS contains a feature called “Graceful Insertion and Removal” or GIR to help you for that. Here is how it works.