Data Center (VDX)

 How do you block spanning tree packets on VDX?

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tmasuda's profile image
tmasuda posted 02-10-2021 07:13

I absolutely hate dealing with spanning-tree. Even till this day STP doesn’t work properly in switches. Today we had a Ruckus ICX connect to the network with spanning tree enabled and some how caused a loop/flood between two VDX clusters. We typically don’t configure spanning-tree and try to keep a loop free network for this exact reason. You never know what spanning-tree is doing. 

ICX ↔ VDX cluster1 ↔ VDX cluster2. 

We removed the ICX from the picture and it continued to wreak havoc. It took a long time to troubleshoot and we disabled so many ports and rebooted routers and switches connected to this and couldn’t isolate the issue until we just randomly decided to flap the link between the clusters. This just proves we had no loop inside our network and it was just bouncing between the clusters. Rebooting all those other devices connected to them was wasted effort.

Is there a way to to prevent this from happening? I see there’s a bpdu-drop command. Anybody tried this and can confirm it works? Anything else I can try?

Khalid27's profile image

Unfortunately, there is no systematic procedure to troubleshoot an STP issue. However, this section sums up some of the actions that are available to you. Most of the steps in this section apply to the troubleshooting of bridging loops in general. You can use a more conventional approach to identify other failures of the STP that lead to a loss of connectivity. For example, you can explore the path that the traffic that experiences a problem takes Prepaid Gift Balance.

Note: Most of these troubleshooting steps assume connectivity to the different devices of the bridge network. This connectivity means you have console access. During a bridging loop, for example, you probably cannot make a Telnet connection.

If you have the output of a show-tech support command from your Cisco device, you can use Cisco CLI Analyzer (registered customers only) to display potential issues and fixes.