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Etherchannel misconfig

Hi All,

We have two Cisco 6500 series that are used in order to provide resilient connectivity to the cloud platform as per the attached diagram. The two 6500 series have a port channel between them and that's been running without an issue for a while. This is the config of the port channel interface: 

interface Port-channel4
 description UAN Port-Channel to XXXXXX
 switchport trunk encapsulation dot1q
 switchport trunk native vlan 5
 switchport trunk allowed vlan 5,10-49,51-63,65-99,101,102,108-110,528,538,805
 switchport trunk allowed vlan add 813-818,821-832,834,835,839-843,847,849
 switchport trunk allowed vlan add 851-858,862,865-890,893-899,986,999,2020
 switchport trunk allowed vlan add 2100-2110
 switchport mode trunk

It's identical on each end. Part of the setup in the diagram already existed with one 6500 connecting to both layer 2 switches. I added the one on the left and configure new port channels. As soon as I brought up the new port channels everything went down. I expected STP to do some bits and bobs but didn't expect an outage of more than 1 minute. It turned out that as soon as I turned on the two new port channels, port channel 4 went into err-disabled mode due to etherchannel misconfig guard. I didn't have enough time to check the status of everything else due to this being an unplanned outage to our business and customers and concentrated on getting things reverted as the maintenance window was too small to carry out any decent diagnostics. 

Even though I didn't get a chance to troubleshoot other port channels I don't see why port channel 4 would go into err-disabled mode as it's been working fine until I no shut the two new port channels. Can anyone shed some light as to how two separate port channels affected another?

Another thing I've changed was to make one device root bridge for vlans 10-49 and the other for VLANs 50-110 to achieve some rough load balancing.

Please let me know if you need any more config to make a judgment. 

VIP Advisor



Is possible to share the STP configs, are you using any root guard or the STP type is the same for all the switches on your network?

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