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Cisco Bug: CSCvv26319 - Cisco ACI Virtual Edge Infra port group cannot be used for ERSPAN after pre 4.0 to Post 4.0

Last Modified

Aug 24, 2020

Products (1)

  • Cisco Application Policy Infrastructure Controller (APIC)

Known Affected Releases

4.2(4p)

Description (partial)

Symptom:
To support Cisco ACI Virtual Edge uplink scaling, we need to change the "switchingMode" of the infra PG from "ave" to "native", such that ERSPAN traffic can by pass Cisco ACI Virtual Edge. However, changing "switchingMode" of the infra EPG would result in packet loss on an established OpFlex channel between Cisco ACI Virtual Edge and TOR, due to a bug on TOR. The issue was fixed on the leaf nodes in the 3.2(7) release and later. However, since we would always upgrade the Cisco APIC first, fixing the issue on the leaf nodes alone will not be sufficient. 

Considering that supporting ERSPAN traffic for Cisco ACI Virtual Edge domains is not an important issue as interrupting the entire Cisco ACI Virtual Edge traffic, we have decided to not change "switchingMode" of the infra PG upon APIC upgrade from pre-3.2(7) to post-3.2(7). any further upgrades from post-3.2(7) to post-3.2(7) would update "switchingMode" to "native" safely (because post-3.2(7), TOR already has the fix). 

This way, we can avoid Cisco ACI Virtual Edge traffic interruption during upgrade from pre-3.2(7) to post-3.2(7). 
However, it also means that customer will see the erspan traffic loss after they upgrade from pre-3.2(7) to post-3.2(7). 

The workaround is to use testAPI to change the switchingMode of the "infra vmmEpPD" of all Cisco ACI Virtual Edge domains from "ave" to "native". note that by the time testAPI is used, TORs are already upgraded to post-3.2(7), Thus, it is safe to do this "switchingMode" modification

Conditions:
Infra portgroup has PVLAN setting if VMM domain was created before 4.0 release and then APIC was upgrade to post 4.0 release.   VMM created freshly on 4.0 release will have fabric vlan programmed in infra portgroup
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