Re: Supervisor Failed Over to Standby - Page 2

Mano11 · ‎01-07-2018

Hi Guys,

We have a Cisco WS-C4500X-16 switch with a 2 Supervisors, one of the active supervisor has failed over and there are no relevant logs indicating why it failover to the standby. I have capture the following logs below. Currently, the standby supervisor is running as the active one.

Would it be possible if someone could advise what has caused the failover to happen? There are no crash file generated.

HS-C4500-01#show module
Switch Number: 1 Role: Virtual Switch Standby

Chassis Type : WS-C4500X-16

Power consumed by backplane : 0 Watts

Mod Ports Card Type Model Serial No.
---+-----+--------------------------------------+------------------+-----------
1 16 4500X-16 10GE (SFP+) WS-C4500X-16 JAE165206G0

M MAC addresses Hw Fw Sw Status
--+--------------------------------+---+------------+----------------+---------
1 e02f.6d43.8c18 to e02f.6d43.8c27 1.0 15.0(1r)SG7 03.04.00.SG Ok

Mod Redundancy role Operating mode Redundancy status
----+-------------------+-------------------+----------------------------------
1 Standby Supervisor SSO Standby hot

Switch Number: 2 Role: Virtual Switch Active

Chassis Type : WS-C4500X-16

Power consumed by backplane : 0 Watts

Mod Ports Card Type Model Serial No.
---+-----+--------------------------------------+------------------+-----------
1 16 4500X-16 10GE (SFP+) WS-C4500X-16 JAE170100W5

M MAC addresses Hw Fw Sw Status
--+--------------------------------+---+------------+----------------+---------
1 e02f.6d43.a200 to e02f.6d43.a20f 1.0 15.0(1r)SG7 03.04.00.SG Ok

Mod Redundancy role Operating mode Redundancy status
----+-------------------+-------------------+----------------------------------
1 Active Supervisor SSO Active

HS-C4500-01#show redundancy
Redundant System Information :

------------------------------
       Available system uptime = 1 year, 33 weeks, 7 hours, 0 minute
Switchovers system experienced = 1
              Standby failures = 0
        Last switchover reason = active unit removed

                 Hardware Mode = Duplex
    Configured Redundancy Mode = Stateful Switchover
     Operating Redundancy Mode = Stateful Switchover
              Maintenance Mode = Disabled
                Communications = Up

Current Processor Information :
------------------------------
               Active Location = slot 2/1
        Current Software state = ACTIVE
       Uptime in current state = 1 year, 9 weeks, 2 days, 9 hours, 4 minutes
                 Image Version = Cisco IOS Software, IOS-XE Software, Catalyst 4500 L3 Switch Software (cat4500e-UNIVERSALK9-M), Version 03.04.00.SG RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Wed 05-Dec-12 04:38 by prod
               BOOT = bootflash:/cat4500e-universalk9.SPA.03.04.00.SG.151-2.SG.bin,12;bootflash:/cat4500e-universal.SPA.03.03.01.SG.151-1.SG1.bin,12;
        Configuration register = 0x2102

Peer Processor Information :
------------------------------
              Standby Location = slot 1/1
        Current Software state = STANDBY HOT
       Uptime in current state = 3 hours, 38 minutes
                 Image Version = Cisco IOS Software, IOS-XE Software, Catalyst 4500 L3 Switch Software (cat4500e-UNIVERSALK9-M), Version 03.04.00.SG RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Wed 05-Dec-12 04:38 by pro
               BOOT = bootflash:/cat4500e-universalk9.SPA.03.04.00.SG.151-2.SG.bin,12;bootflash:/cat4500e-universal.SPA.03.03.01.SG.151-1.SG1.bin,12;
        Configuration register = 0x2102

HS-C4500-01#dir
Directory of bootflash:/

16163 -rw-     2460468 Feb 22 2013 09:09:27 +11:00 cat4500-e-ios-promupgrade-150-1r-SG7
16164 -rw-   123162032 Feb 22 2013 09:15:55 +11:00 cat4500e-universalk9.SPA.03.04.00.SG.151-2.SG.bin
16165 -rw-        1717 Feb 25 2013 06:33:48 +11:00 pre-vss.cfg
16166 -rw-        4816 Feb 25 2013 09:12:25 +11:00 startup-config.converted_vs-20130224-221221
16162 -rwx   112652444 Jan 14 2013 18:57:33 +11:00 cat4500e-universal.SPA.03.03.01.SG.151-1.SG1.bi

1692037120 bytes total (1453334528 bytes free)

014331: *Jan 7 13:31:14.674 ADST: %C4K_REDUNDANCY-4-KEEPALIVE_WARNING: STANDBY:Keepalive messages from peer Supervisor are missing for 27 seconds
014332: *Jan 7 13:31:17.912 ADST: %VSLP-3-VSLP_LMP_FAIL_REASON: STANDBY:Te2/1/16: Link down
014333: *Jan 7 13:31:17.912 ADST: %C4K_IOSINTF-5-LMPHWSESSIONSTATE: STANDBY:Lmp HW session DOWN on slot 11 port 16.
014334: *Jan 7 13:31:17.941 ADST: %VSLP-3-VSLP_LMP_FAIL_REASON: STANDBY:Te2/1/15: Link down
014335: *Jan 7 13:31:17.941 ADST: %VSLP-2-VSL_DOWN: STANDBY: All VSL links went down while switch is in Standby role

014336: *Jan 7 13:31:17.941 ADST: %EC-5-UNBUNDLE: STANDBY:Interface TenGigabitEthernet2/1/15 left the port-channel Port-channel62
014337: *Jan 7 13:31:17.943 ADST: %EC-5-UNBUNDLE: STANDBY:Interface TenGigabitEthernet2/1/16 left the port-channel Port-channel62
014338: *Jan 7 13:31:17.980 ADST: %C4K_IOSINTF-5-LMPHWSESSIONSTATE: STANDBY:Lmp HW session DOWN on slot 11 port 15.
014339: *Jan 7 13:31:17.982 ADST: %C4K_REDUNDANCY-6-INIT: Initializing as ACTIVE supervisor
014340: *Jan 7 13:31:18.018 ADST: %C4K_REDUNDANCY-3-COMMUNICATION: Communication with the peer Supervisor has been lost
014341: *Jan 7 13:31:18.105 ADST: %C4K_REDUNDANCY-3-SIMPLEX_MODE: The peer Supervisor has been lost
014342: *Jan 7 13:31:18.131 ADST: %EC-5-UNBUNDLE: Interface Te1/1/3 left the port-channel Po21
014343: *Jan 7 13:31:18.132 ADST: %EC-5-UNBUNDLE: Interface Te1/1/4 left the port-channel Po41
014344: *Jan 7 13:31:18.134 ADST: %EC-5-UNBUNDLE: Interface Te1/1/11 left the port-channel Po31
014345: *Jan 7 13:31:18.135 ADST: %EC-5-UNBUNDLE: Interface Te1/1/12 left the port-channel Po32
014346: *Jan 7 13:31:18.137 ADST: %EC-5-UNBUNDLE: Interface TenGigabitEthernet1/1/15 left the port-channel Port-channel61
014347: *Jan 7 13:31:18.142 ADST: %EC-5-UNBUNDLE: Interface TenGigabitEthernet1/1/16 left the port-channel Port-channel61
014348: *Jan 7 13:31:21.943 ADST: %BGP-5-ADJCHANGE: neighbor 172.20.192.227 Up
014349: *Jan 7 13:31:48.107 ADST: %TRACKING-5-STATE: 101 ip sla 1 reachability Down->Up
014350: *Jan 7 13:35:27.713 ADST: %C4K_IOSINTF-5-LMPHWSESSIONSTATE: Lmp HW session UP on slot 11 port 15.
014351: *Jan 7 13:35:27.821 ADST: %C4K_IOSINTF-5-LMPHWSESSIONSTATE: Lmp HW session UP on slot 11 port 16.
014352: *Jan 7 13:35:43.710 ADST: %VSLP-5-VSL_UP: Ready for control traffic

014353: *Jan 7 13:35:48.712 ADST: %VSLP-5-RRP_ROLE_RESOLVED: Role resolved as ACTIVE by VSLP
014354: *Jan 7 13:35:48.712 ADST: %EC-5-BUNDLE: Interface TenGigabitEthernet2/1/15 joined port-channel Port-channel62
014355: *Jan 7 13:35:48.723 ADST: %EC-5-BUNDLE: Interface TenGigabitEthernet2/1/16 joined port-channel Port-channel62
014356: *Jan 7 13:35:49.514 ADST: %C4K_REDUNDANCY-6-DUPLEX_MODE: The peer Supervisor has been detected
014357: *Jan 7 13:36:26.156 ADST: %C4K_REDUNDANCY-6-MODE: ACTIVE supervisor initializing for sso mode
014358: *Jan 7 13:36:26.547 ADST: %C4K_REDUNDANCY-3-COMMUNICATION: Communication with the peer Supervisor has been established
014359: *Jan 7 13:36:37.112 ADST: %C4K_REDUNDANCY-5-CONFIGSYNC: The bootvar has been successfully synchronized to the standby supervisor
014360: *Jan 7 13:36:37.113 ADST: %C4K_REDUNDANCY-5-CONFIGSYNC: The config-reg has been successfully synchronized to the standby supervisor
014361: *Jan 7 13:36:37.114 ADST: %C4K_REDUNDANCY-5-CALENDAR: The calendar has been successfully synchronized to the standby supervisor for the first time
014362: *Jan 7 13:36:37.114 ADST: %C4K_REDUNDANCY-5-CONFIGSYNC: The startup-config has been successfully synchronized to the standby supervisor
014363: *Jan 7 13:36:37.671 ADST: %C4K_REDUNDANCY-5-CONFIGSYNC: The private-config has been successfully synchronized to the standby supervisor
014364: *Jan 7 13:36:38.678 ADST: %C4K_REDUNDANCY-5-CONFIGSYNC_RATELIMIT: The vlan database has been successfully synchronized to the standby supervisor
014365: *Jan 7 13:37:08.083 ADST: %EC-5-BUNDLE: Interface TenGigabitEthernet1/1/15 joined port-channel Port-channel61
014366: *Jan 7 13:37:08.160 ADST: %EC-5-BUNDLE: Interface TenGigabitEthernet1/1/16 joined port-channel Port-channel61
014367: *Jan 7 13:37:09.070 ADST: %EC-5-UNBUNDLE: Interface TenGigabitEthernet1/1/15 left the port-channel Port-channel61
014368: *Jan 7 13:37:09.079 ADST: %EC-5-UNBUNDLE: Interface TenGigabitEthernet1/1/16 left the port-channel Port-channel61
014369: *Jan 7 13:37:10.075 ADST: %EC-5-BUNDLE: Interface TenGigabitEthernet1/1/15 joined port-channel Port-channel61
014370: *Jan 7 13:37:10.100 ADST: %EC-5-BUNDLE: Interface TenGigabitEthernet1/1/16 joined port-channel Port-channel61
014371: *Jan 7 13:37:10.188 ADST: %HA_CONFIG_SYNC-6-BULK_CFGSYNC_SUCCEED: Bulk Sync succeeded
014372: *Jan 7 13:37:10.220 ADST: %RF-5-RF_TERMINAL_STATE: Terminal state reached for (SSO)
014373: 000029: *Jan 7 13:37:09.615 ADST: %EC-5-BUNDLE: STANDBY:Interface TenGigabitEthernet1/1/15 joined port-channel Port-channel61
014374: 000030: *Jan 7 13:37:09.705 ADST: %EC-5-BUNDLE: STANDBY:Interface TenGigabitEthernet1/1/16 joined port-channel Port-channel61
014375: *Jan 7 13:37:59.066 ADST: %C4K_IOSINTF-5-TRANSCEIVERINSERTED: Slot=1 Port=2: Transceiver has been inserted
014376: *Jan 7 13:38:00.066 ADST: %C4K_IOSINTF-5-TRANSCEIVERINSERTED: Slot=1 Port=3: Transceiver has been inserted
014377: 000031: *Jan 7 13:38:01.005 ADST: %C4K_TRANSCEIVERMAN-3-INCOMPATIBLE: STANDBY:Port Te1/1/4: New transceiver (speed 0Mbps) is incompatible with this module
014378: *Jan 7 13:38:03.081 ADST: %C4K_IOSINTF-5-TRANSCEIVERINSERTED: Slot=1 Port=9: Transceiver has been inserted
014379: *Jan 7 13:38:05.066 ADST: %C4K_IOSINTF-5-TRANSCEIVERINSERTED: Slot=1 Port=10: Transceiver has been inserted
014380: *Jan 7 13:38:07.066 ADST: %C4K_IOSINTF-5-TRANSCEIVERINSERTED: Slot=1 Port=11: Transceiver has been inserted
014381: *Jan 7 13:38:09.825 ADST: %EC-5-BUNDLE: Interface Te1/1/3 joined port-channel Po21
014382: *Jan 7 13:38:10.076 ADST: %C4K_IOSINTF-5-TRANSCEIVERINSERTED: Slot=1 Port=12: Transceiver has been inserted
014383: *Jan 7 13:38:11.071 ADST: %C4K_IOSINTF-5-TRANSCEIVERINSERTED: Slot=1 Port=14: Transceiver has been inserted
014384: 000032: *Jan 7 13:38:13.227 ADST: %EC-5-BUNDLE: STANDBY:Interface Te1/1/3 joined port-channel Po21
014385: 000033: *Jan 7 13:38:14.546 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -36.9 dBm, Threshold value: -13.9 dBm.
014386: 000034: *Jan 7 13:38:15.545 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
014387: *Jan 7 13:38:16.830 ADST: %EC-5-BUNDLE: Interface Te1/1/11 joined port-channel Po31
014388: 000035: *Jan 7 13:38:17.220 ADST: %EC-5-BUNDLE: STANDBY:Interface Te1/1/11 joined port-channel Po31
014389: *Jan 7 13:38:18.778 ADST: %EC-5-BUNDLE: Interface Te1/1/12 joined port-channel Po32
014390: *Jan 7 13:38:19.591 ADST: %EC-5-BUNDLE: Interface Te1/1/4 joined port-channel Po41
014391: 000036: *Jan 7 13:38:19.090 ADST: %EC-5-BUNDLE: STANDBY:Interface Te1/1/12 joined port-channel Po32
014392: 000037: *Jan 7 13:38:19.794 ADST: %EC-5-BUNDLE: STANDBY:Interface Te1/1/4 joined port-channel Po41
014393: *Jan 7 13:38:52.627 ADST: %BGP-5-ADJCHANGE: neighbor 172.20.192.226 Up
014394: 000038: *Jan 7 13:48:14.644 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -35.2 dBm, Threshold value: -13.9 dBm.
014395: 000039: *Jan 7 13:48:15.644 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
014396: 000040: *Jan 7 13:58:14.730 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -36.9 dBm, Threshold value: -13.9 dBm.
014397: 000041: *Jan 7 13:58:15.730 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
014398: 000042: *Jan 7 14:08:14.842 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -35.2 dBm, Threshold value: -13.9 dBm.
014399: 000043: *Jan 7 14:08:15.842 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
014400: 000044: *Jan 7 14:18:14.938 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -33.0 dBm, Threshold value: -13.9 dBm.
014401: 000045: *Jan 7 14:18:15.938 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
014402: 000046: *Jan 7 14:28:15.030 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -36.9 dBm, Threshold value: -13.9 dBm.
014403: 000047: *Jan 7 14:28:16.028 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
014404: 000048: *Jan 7 14:38:15.142 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -35.2 dBm, Threshold value: -13.9 dBm.
014405: 000049: *Jan 7 14:38:16.142 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
014406: 000050: *Jan 7 14:48:15.238 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -35.2 dBm, Threshold value: -13.9 dBm.
014407: 000051: *Jan 7 14:48:16.238 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
014408: 000052: *Jan 7 14:58:15.334 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/9: Rx power low alarm; Operating value: -35.2 dBm, Threshold value: -13.9 dBm.
014409: 000053: *Jan 7 14:58:16.334 ADST: %SFF8472-5-THRESHOLD_VIOLATION: STANDBY:Te1/1/10: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.

educruz · ‎01-07-2018

Thank you for this information.

From this statement:

Initially there was multiple interfaces were down. Upon checking, we noticed that the active supervisor failed over. There are no high or low input and output rate on the interfaces. The interfaces are running fine. There are no CRC or input errors noticed on the interfaces. I have also checked on the CPU usage and there is no spikes noticed based from the history and utilization logs. At this point of time, there was no recent changes done.

Could I just confirm that CPU and port stats that you uploaded were collected before the actual failure of the Supervisor Engine? Otherwise, is there any way that you can retrieve the same information before the failure? (e.g. via a syslog server or a monitoring NMS system?)

While I understand the need of a root cause, the information provided so far about the switchover is very generic (not anyone's fault of course), so a search for a specific bug would be very broad, and not very fruitful. We could spend a very good amount of time looking for bugs that are just "similar" but that would be as close as we could get.

Kind regards,

Eduardo.

Mano11 · ‎01-10-2018

Hi Guys,

The logs were collected after the failed over happened. As of now, we are trying to get an access to the supervisor to capture some logs for further investigation. At the moment, we are unable to access the supervisor due to privilege issue and we are currently sorting that issue first. Will give you guys an update once we received the logs.

Thank you.

sbhadrav@cisco.com · ‎02-26-2018

Console into the standby Supervisor Engine in order to check whether it is in ROMmon mode or in continuous reboot. If the standby Supervisor Engine is in either of these two states, refer to Recover a Cisco IOS Catalyst 4500/4000 Series Switch from a Corrupt or Missing Image or in Rommon Mode.

4507#show module

Mod Ports Card Type                              Model             Serial No.
----+-----+--------------------------------------+-----------------+-----------
1      2 1000BaseX (GBIC) Supervisor(active)    WS-X4515          JAB0627065V
2         Standby Supervisor
3     48 10/100/1000BaseTX (RJ45)               WS-X4448-GB-RJ45 JAB053606AG
4     48 10/100BaseTX (RJ45)V                   WS-X4148-RJ45V    JAE060800BL

M MAC addresses                    Hw Fw           Sw               Status
--+--------------------------------+---+------------+----------------+---------
1 0009.e845.6300 to 0009.e845.6301 0.4 12.1(12r)EW( 12.1(12c)EW, EAR Ok
2 Unknown                              Unknown      Unknown          Other
3 0001.6443.dd20 to 0001.6443.dd4f 0.0                               Ok
4 0008.2138.d900 to 0008.2138.d92f 1.6                               Ok
Make sure that the Supervisor Engine module properly seats in the backplane connector and that you have completely screwed down the Supervisor Engine installation screw. For more information, refer to the Installing and Removing the Supervisor Engine section of the document Installation and Configuration Note for the Catalyst 4000 Family Supervisor Engine

In order to identify whether the standby Supervisor Engine is faulty, issue the redundancy reload peer command from the active Supervisor Engine and through the console to the standby Supervisor Engine. Observe the bootup sequence in order to identify any hardware failures. Currently, the active Supervisor Engine cannot access the power-on diagnostics results of the standby Supervisor Engine.

sbhadrav@cisco.com · ‎05-22-2018

Check the software versions in both supervisors from output of "show module". Also the communication seems to be "Simplex". It should be Duplex mode. I have a 4500 series switch with SSO. Below is the output of various commands.

L3_SW#sh redundancy
Redundant System Information :
------------------------------
Available system uptime = 6 weeks, 4 days, 18 hours, 12 minutes
Switchovers system experienced = 1
Standby failures = 0
Last switchover reason = active unit failed

Hardware Mode = Duplex
Configured Redundancy Mode = Stateful Switchover
Operating Redundancy Mode = Stateful Switchover
Maintenance Mode = Disabled
Communications = Up

Current Processor Information :
-------------------------------
Active Location = slot 2
Current Software state = ACTIVE
Uptime in current state = 6 weeks, 4 days, 18 hours, 12 minutes
Image Version = Cisco IOS Software, Catalyst 4500 L3 Switch Sof
tware (cat4500-ENTSERVICESK9-M), Version 15.0(2)SG5, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Tue 31-Jul-12 03:44 by prod_rel_team
BOOT = bootflash:cat4500-entservicesk9-mz.150-2.SG5.bi
n,12;
Configuration register = 0x2102

Peer Processor Information :
----------------------------
Standby Location = slot 1
Current Software state = STANDBY HOT
Uptime in current state = 3 weeks, 1 day, 13 hours, 3 minutes
Image Version = Cisco IOS Software, Catalyst 4500 L3 Switch Sof
tware (cat4500-ENTSERVICESK9-M), Version 15.0(2)SG5, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Tue 31-Jul-12 03:44 by p
BOOT = bootflash:cat4500-entservicesk9-mz.150-2.SG5.bi
n,12;
Configuration register = 0x2102

L3_SW#sh redundancy states
my state = 13 -ACTIVE
peer state = 8 -STANDBY HOT
Mode = Duplex
Unit = Secondary
Unit ID = 2

Redundancy Mode (Operational) = Stateful Switchover
Redundancy Mode (Configured) = Stateful Switchover
Redundancy State = Stateful Switchover
Maintenance Mode = Disabled
Manual Swact = enabled
Communications = Up

client count = 60
client_notification_TMR = 240000 milliseconds
keep_alive TMR = 9000 milliseconds
keep_alive count = 1
keep_alive threshold = 18
RF debug mask = 0x0

sbhadrav@cisco.com · ‎06-01-2018

The following guidelines and restrictions apply to supervisor engine redundancy:

•If SSO mode cannot be established between the active and standby supervisor engines because of an incompatibility in the configuration file, a mismatched command list (MCL) is generated at the active supervisor engine and a reload into RPR mode is forced for the standby supervisor engine. Subsequent attempts to establish SSO, after removing the offending configuration and rebooting the standby supervisor engine with the exact same image, might cause the C4K_REDUNDANCY-2-IOS_VERSION_CHECK_FAIL and ISSU-3-PEER_IMAGE_INCOMPATIBLE messages to appear because the peer image is listed as incompatible. If the configuration problem can be corrected, you can clear the peer image from the incompatible list with the redundancy config-sync ignore mismatched-commands EXEC command while the peer is in a standby cold (RPR) state. This action allows the standy supervisor engine to boot in standby hot (SSO) state when it reloads.

Here are the steps:
Step 1 Clear the offending configuration (that caused an MCL) while the standby supervisor engine is in standby cold (RPR) state.

Step 2 Enter the redundancy config-sync ignore mismatched-commands EXEC command at the active standby supervisor engine.

Step 3 Perform write memory.

Step 4 Reload the standy supervisor engine with the redundancy reload peer command.
•RPR and SSO requires Cisco IOS-XE Release 3.1.0 SG and later releases.

•SSO is not supported if the IOS-XE software is running in the LAN Base mode.

•WS-C4507R-E, WS-C4510R-E, WS-C4507R+E, and WS-C4510R+E are the only Catalyst 4500 series switches that support Supervisor Engine 7-E redundancy.

•SSO requires both supervisor engines in the chassis to have the same components ( model and memory), and to use the same Cisco IOS XE software image.

•When you use WS-X45-SUP7-E in RPR or SSO mode, only the first two uplinks on each supervisor engine are available. The second two uplinks are unavailable.

•The active and standby supervisor engines in the chassis must be in slots 3 and 4 for 7-slot chassis and slot 5 and 6 for 10-slot chassis.

•Each supervisor engine in the chassis must have its own flash device and console port connections to operate the switch on its own.

•Each supervisor engine must have a unique console connection. Do not connect a Y cable to the console ports.

•Supervisor engine redundancy does not provide supervisor engine load balancing.

•The Cisco Express Forwarding (CEF) table is cleared on a switchover. As a result, routed traffic is interrupted until route tables reconverge. This reconvergence time is minimal because the SSO feature reduces the supervisor engine redundancy switchover time from 30+ seconds to subsecond, so Layer 3 also has a faster failover time if the switch is configured for SSO.

•Static IP routes are maintained across a switchover because they are configured from entries in the configuration file.

•Information about Layer 3 dynamic states that is maintained on the active supervisor engine is not synchronized to the standby supervisor engine and is lost on switchover.

•If configuration changes on a redundant swtich are made through SNMP set operations, the changes are not synchronized to the standby supervisor engine even in SSO mode. You might experience unexpected behavior.

•After you configure the switch through SNMP in SSO mode, copy the running-config file to the startup-config file on the active supervisor engine to trigger synchronization of the startup-config file to the standby supervisor engine. Then, reload the standby supervisor engine so that the new configuration is applied on the standby supervisor engine.

•You cannot perform configuration changes during the startup (bulk) synchronization. If you attempt to make configuration changes during this process, the following message is generated:

Config mode locked out till standby initializes
•If configuration changes occur at the same time as a supervisor engine switchover, these configuration changes are lost.

•If you remove a line card from a redundant switch and initiate an SSO switchover, then reinsert the line card, and all interfaces are shutdown. The rest of the original line card configuration is preserved.