Category Archives: NX-OS

Troubleshooting NX-OS Config Sync

I have spent last weeks configuring our new Cisco Nexus 5596UP switches in two data centers. The decision to use configuration synchronization feature (also known as Switch Profile) seemed logical as our new DC infrastructure design dictates to use Dual Homed FEXes with Active/Passive NIC teaming topology. This scenario (like any Dual Homed) requires almost all configuration to be identical on both switches that are part of vPC domain. Overall, I like this neat feature. In my humble opinion, Cisco had to come up with it years ago. It works like a charm if you are working on a clean deployment and follow Cisco guidelines. But… when it comes to the migration from Legacy configuration mode to the Switch Profile mode with both vPC domain switches already being pre-configured separately… well, you’ll definitely face some issues! I personally have spent few days trying to solve one puzzle that driven me nuts!  Read more …

vPC Domain Configuration Synchronization Guidelines

Configuration synchronization, also known as Switch Profiles, is a new feature that has been introduced by Cisco to primarily support Nexus vPC Domain topologies in modern data centers, specifically the Dual-Homed FEX scenarios. One of the main requirements in Dual-Homed FEX topologies is configuration consistency across both Nexus 5K switches. Remember that vPC domain switches represent one logical switch. Thus, must be consistent from QoS-, VLAN-, Spanning-Tree- and, in some cases, FEX interfaces- configuration perspective. Switch Profiles, if well understood, can help to lessen administration overhead. Read more …

FET-10G considerations

We are currently deploying new data centers using brand new Cisco Nexus 5596UP switches with Fabric Extenders (Cisco Nexus 2248TP-E). When you order a bundle from Cisco (switches and FEXes) it goes pre-packed with FET-10G modules (8 per FEX). Ok, not pre-packed, you actually need to include those modules into the order for free. The reason I am making notes on this is due to the additional configuration required for this module to be discovered. If you simply put it into the switch, it will show those modules as Invalidated. For them to work, it is required to manually change switchport mode to “fex-fabric” – switchport mode fex-fabric. Once you’ve done that, FET-10G will be recognized and any FEX behind it will be discovered.

This can be confusing if you’re deploying Nexus switches and FEXes using this modules for the first time. They have a limited scope of use – only switch to FEX connections. They go for free when you buy bundles, so make sure to include them into your order! You won’t be able to get them for free later (or even buy them). General SFP+ modules will discover any connected FEXes automatically.