Verify install state, ISSU state, and redundancy

Verify install and ISSU readiness

1. Verify install-mode boot variables.

   Example:

   switch# show boot
   Current Boot Variables:
   BOOT variable = flash:packages.conf;
   
   Boot Variables on next reload:
   BOOT variable = flash:packages.conf;
   Manual Boot = no

   The packages.conf confirms install-mode boot.

   Manual Boot = no confirms that automatic boot is enabled.

2. Verify committed install package state.

   Example:

   switch# show install summary
   [ Switch 1 2 ] Installed Package(s) Information:
   State (St): I - Inactive, U - Activated & Uncommitted,
               C - Activated & Committed,
               D - Deactivated & Uncommitted
   ----------------------------------------------------------------
   Type  St   Filename/Version
   ----------------------------------------------------------------
   IMG   C    <CURRENT_RELEASE>
   ----------------------------------------------------------------
   Auto abort timer: inactive
   ----------------------------------------------------------------

   C means that the running image is activated and committed.

   An inactive auto-abort timer means that no uncommitted installation is waiting to roll back.

   Investigate an unexpected U, D, active timer, or different image state across members.

3. Confirm that no ISSU operation is in progress.

   Example:

   switch# show issu state detail
   --- Starting local lock acquisition on switch 1 ---
   Finished local lock acquisition on switch 1
   
   No ISSU operation is in progress

   This is the expected state before starting ISSU and after ISSU has completed.

   Do not start another upgrade if the output reports an active, pending, added, activated, failed, or stalled ISSU operation.

4. Review ISSU operation history.

   Example:

   switch# show install issu history
   >>> Most recent ISSU operation is displayed

   Verify that the most recent entry belongs to the intended change window and completed successfully.

   Failed, aborted, rolled-back, or incomplete entries require review. Output fields vary by IOS XE release.

Verify redundancy health.

1. Verify SSO redundancy health

   Example:

   switch# show redundancy
   Redundant System Information:
   -----------------------------
   Switchovers system experienced = 1
   Standby failures = 0
   Last switchover reason = ISSU
   
   Hardware Mode = Duplex
   Configured Redundancy Mode = sso
   Operating Redundancy Mode = sso
   Communications = Up
   
   Current Processor Information:
   ------------------------------
   Current Software state = ACTIVE
   BOOT = flash:packages.conf;
   
   Peer Processor Information:
   ---------------------------
   Current Software state = STANDBY HOT
   BOOT = flash:packages.conf;

   A healthy redundant system has SSO configured and operating, Communications as Up, one ACTIVE processor, and one STANDBY HOT processor.

   Both processors must run the intended release and use packages.conf.

   A standalone switch has no standby peer; STANDBY HOT is therefore not expected.

2. Verify redundancy state synchronization.

   Example:

   switch# show redundancy states
          my state = 13 -ACTIVE
        peer state = 8  -STANDBY HOT
              Mode = Duplex
   
   Redundancy Mode (Operational) = sso
   Redundancy Mode (Configured)  = sso
   Redundancy State              = sso
   Communications                = Up

   The peer has completed synchronization and reached STANDBY HOT.

   Do not begin ISSU while the peer is COLD, INIT, RECOVERY, DISABLED, absent, or changing state.

Verify configuration synchronization

1. Confirm that there are no MCL configuration-synchronization failures.

   Example:

   
   switch# show redundancy config-sync failures mcl
   Mismatched Command List
   -----------------------
   The list is Empty

   No configured command is unsupported or mismatched on the standby.

2. Confirm that there are no PRC configuration-synchronization failures.

   Example:

   switch# show redundancy config-sync failures prc
   PRC Failed Command List
   -----------------------
   The list is Empty

   Active and standby parser return codes match.

3. Confirm that there are no BEM configuration-synchronization failures.

   Example:

   switch# show redundancy config-sync failures bem
   BEM Failed Command List
   -----------------------
   The list is Empty

   No best-effort configuration-synchronization failure is recorded.