Restrict deletion of interface operations on all SDX devices

Restrict deletion of interface operations on all SDX devices

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Article ID: CTX296958

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Description

Deletion of an interface or an LA channel after the VPX has been created on an SDX may cause renumbering of the interfaces after a reboot. The renumbering may cause the SVM to not be able to contact that VPX instance and the SVM will display the instance in Down state.

Affected Versions and Builds: 13.0 build 71.x and later or release 12.1 build 60.x and later.

Example of a Deletion operation: An ADC being provisioned with LA/1 and LA/2 channels each comprising of 10/1, 10/2 and 10/3, 10/4 virtual interfaces respectively. When the User goes to unbind and edit the Citrix ADC to remove to LA/1 channel, this will cause a reboot. (the edit of the ADC config happens after it reboots, while it is rebooting it still has the old config, but the underlying interfaces have shifted numbering). After boot up the LA/1 is removed but LA/2 VFs (virtual interface on VPX) which originally had 10/3 and 10/4 have shifted to 10/1 and 10/2.

Impact: The SVM can now no longer reach the VPX and the instance state will be reported as Down. Customers cannot go and renumber the instance themselves.

Resolution

Once a VPX is created and assigned to an interface/channel the SVM will disallow deletion of the channel or interfaces associated with that VPX with any type of deployment. This change will be in 13.0 build 71.x and later or release 12.1 build 60.x and later.

What this means: In order to assign a new interface/channel, the user will create a new VPX with a new configuration and delete the old VPX completely. This change will prevent the renumbering issue above, which in turn prevents serious connectivity and outage issues.

Issue/Introduction

Deletion of an interface or an LA channel after the VPX has been created on an SDX may cause renumbering of the interfaces after a reboot, affecting SVM access to that VPX instance.

Additional Information

FAQ

  • Does this occur for NSVLAN cases only?
No, the renumbering issue is also applicable when Citrix ADC is configured with L2 VLAN settings, as well as when Citrix ADC is unbinded with standalone interface.
 
  • If you create the LA Channel on the SVM and attach it to a VPX will you not be able to delete or modify that channel unless you delete all VPX instances associated with it?  Will you be able to modify any aspect of that channel until it is removed from all instances?
Modification of channel/interface would be allowed even if it is bound to any Citrix ADC Example: In the SVM UI -> Configuration -> System -> Channels -> Edit LA.
Editing MTU, adding/removing members, changing timeout etc. would be still allowed.
 
  • If you create the LA channel on the SVM and delete the VPX instances it is attached to will you then be able to modify it or will you have to delete and recreate the LA channel?
Channels at System would continue to exist, and properties can be modified.
 
  • Will we be restricting any modifications on the LA channel once it is created on the VPX? 
No, modifications on LA would be still allowed as usual.
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