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Cisco Bug: CSCvi55910 - Add a check to Quad sup ISSU FSM to confirm VSL is ready

Last Modified

Dec 13, 2018

Products (1)

  • Cisco Catalyst 6000 Series Switches

Known Affected Releases


Description (partial)

An ISSU upgrade may fail if module diagnostics are delayed during certain ISSU phases. Switch may become dual-active for a short period of time before reloading, and reverting the software to the pre-ISSU image.

First seen on quad-sup 6500s performing ISSU upgrade process where the VSLs are equally distributed between the 4 supervisors.

Logs leading up to the issue may show the physical VSL interfaces of the reloaded sup coming up, but do not show the VSLP LMP state as up (meaning the physical state of the port was up, but the protocol was not yet bundled into the port-channel) 

Switch diagnostics have been found as the primary delay to cause these ports not to come up prior the the ISSU progression.
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