Symptom
A vPC domain's interfaces are suspended/down when its peer node is decommissioned.
# show vpc brief >>>> on the operational vPC switch whose peer has been decommissioned
Legend:
(*) - local vPC is down, forwarding via vPC peer-link
vPC domain id : 300
Peer status : peer link is down
(vPC domain/system id mismatch)
vPC status
----------------------------------------------------------------------
id Port Status Consistency Reason Active vlans
-- ---- ------ ----------- ------ ------------
343 Po1 down success success
# show int po1
port-channel1 is down (suspend-by-vpc)
Conditions
If your Cisco APIC is running the 5.2(4) release or later and your switches are running an ACI-mode switch software release that is earlier than 15.2(4) (Mixed Version Fabric), a vPC domain's interfaces become suspended/down when its peer node is decommissioned or during graceful insertion (maintenance mode).
In the following example scenarios, you will encounter this issue:
• Your Cisco APIC is running the 5.2(4), 6.0(1) release or later and your vPC switches are running the ACI-mode switch 14.2(7u) or earlier release.
• Your Cisco APIC is running the 5.2(4), 6.0(1) release or later and your vPC switches are running the ACI-mode switch 15.2(3) or earlier release.
• In the following example scenarios, you will not encounter this issue:
• Your Cisco APIC is running the 5.2(4), 6.0(1) release or later and your vPC switches are running the ACI-mode switch 14.2(7v), 15.2(4), 16.0(1) or later release.
• Cisco APIC is running the 5.2(3) release or earlier.
Workaround
Upgrade the vPC switches in a given domain first to the same release as the Cisco APIC (if running release 5.2(4d), 6.0(1g), or later) prior decommissioning/replacing them.
Further Problem Description
Changes were made since releases 5.2(4d), 6.0(1g) that resets the peer IP field to 0.0.0.0 for the node decommissioned, which affects VPC functioning on the operational node.
