loop

Loops

Posted by robd on August 06, 2014
Networking / No Comments

So recently we had a total network failure, urrrgghhh!

HP Intelligent Management and VMware VCentre started to report that there was a network issue. The reports included a lost connection to every switch on the network and a critical temperate warning on our ESX server of 101 Celsius!!

Well after rebooting some switches and rebuilding a few more the issue was still present, no traffic over the switches….

So we started unplugging cables from the core switch as a last ditched attempt to fix the issue.  After unplugging about 30 suddenly the network came back to life!!

Long story short we had two days of total network failure because a cleaner plugged a one network cable into two active ports! NETWORK LOOP and no we didnt have spanning tree enabled.

So the next job was to biwire everything to separate switches and enable Spanning tree on every switch:

Or on a Vlan:

Note: When you configure a VLAN, the VLAN inherits the global STP settings. However, once you begin to define a VLAN, you can no longer configure standard STP parameters globally using the CLI. From that point on, you can configure STP only within individual VLANs.

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