Do you remember the article ‘How to schedule a reload‘? This feature (reload in ‘x’) is useful when you must apply a critical configuration on a remote device, for instance new route or new acl. In fact, if you happen to lose connection to device after a change, you must wait the device reload to reconnect to it. This can be a solution but there is a better solution: the replace/roolback feature.
Introduced in 12.3(7)T IOS, the Configuration Replace and Configuration Rollback features provide the capability to replace the current running configuration with any saved Cisco IOS configuration file. This functionality can be used to revert to a previous configuration state, rolling back any configuration changes that were made since that configuration file was saved.
Prerequisites:
The format of the configuration files must comply with standard as follows:
- Start all commands on a new line with no indentation, unless the command is within a configuration submode.
- Indent commands within a first-level configuration submode one space.
- Indent commands within a second-level configuration submode two spaces.
- Indent commands within subsequent submodes accordingly.
Restrictions:
- If the router does not have free memory larger than the combined size of the two configuration files, the configuration replace operation is not performed.
- Certain Cisco IOS configuration commands such as those pertaining to physical components of a networking device (for example, physical interfaces) cannot be added or removed from the running configuration.
- In very rare cases, certain Cisco IOS configuration commands cannot be removed from the Cisco IOS running configuration without reloading the router. A configuration replace operation that attempts to remove this type of command results in error messages indicating that these specific command lines failed.
First of all, enable the archive command, otherwise an error occurs:
%Turn config archive on before using Rollback Confirmed Change
In this tutorial, the archive will have these settings:
Ciscozine-Beta(config)#archive Ciscozine-Beta(config-archive)#path disk0:/Backup/backup- Ciscozine-Beta(config-archive)#write-memory
You can follow two different ways to rollback your configuration:
- Replace saved configuration from tftp, flash, scp and so on…
- Rollback the last saved configuration
In this article, I will use the same configurations for all examples:
The current configuration is:
Ciscozine#sh run Building configuration... Current configuration : 1158 bytes ! ! Last configuration change at 14:26:41 UTC Thu May 8 2013 upgrade fpd auto version 15.1 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname Ciscozine ! boot-start-marker boot-end-marker ! ! ! no aaa new-model ! ip source-route ip cef ! ! ! ! ! no ip domain lookup ip domain name lab.local no ipv6 cef ! multilink bundle-name authenticated ! ! ! ! ! ! ! crypto pki token default removal timeout 0 ! ! ! redundancy ! ! ! ! ! ! ! ! ! ! interface Loopback1 ip address 10.0.0.48 255.255.255.255 ! interface FastEthernet0/0 ip address 192.168.1.10 255.255.255.0 duplex half ! router ospf 1 redistribute static network 192.168.1.0 0.0.0.255 area 0 ! ip forward-protocol nd no ip http server no ip http secure-server ! ! ip route 0.0.0.0 0.0.0.0 192.168.1.1 ! ! ! ! ! snmp-server community ciscozine RO ! ! control-plane ! ! ! mgcp profile default ! ! ! gatekeeper shutdown ! ! line con 0 exec-timeout 0 0 privilege level 15 logging synchronous stopbits 1 line aux 0 exec-timeout 0 0 privilege level 15 logging synchronous stopbits 1 line vty 0 4 login transport input all ! end Ciscozine#
while the startup configuration / Ciscozine.conf configurations (they are the same to simplify the tutorial) is:
Ciscozine-Beta#sh startup-config Building configuration... Current configuration : 993 bytes ! ! Last configuration change at 14:23:58 UTC Thu May 8 2013 upgrade fpd auto version 15.1 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname Ciscozine-Beta ! boot-start-marker boot-end-marker ! ! ! no aaa new-model ! ip source-route ip cef ! ! ! ! ! no ip domain lookup ip domain name lab.local no ipv6 cef ! multilink bundle-name authenticated ! ! ! ! ! ! ! crypto pki token default removal timeout 0 ! ! ! redundancy ! ! ! ! ! ! ! ! ! ! interface FastEthernet0/0 ip address 192.168.1.10 255.255.255.0 duplex half ! ip forward-protocol nd no ip http server no ip http secure-server ! ! ip route 0.0.0.0 0.0.0.0 192.168.1.1 ! ! ! ! ! ! ! control-plane ! ! ! mgcp profile default ! ! ! gatekeeper shutdown ! ! line con 0 exec-timeout 0 0 privilege level 15 logging synchronous stopbits 1 line aux 0 exec-timeout 0 0 privilege level 15 logging synchronous stopbits 1 line vty 0 4 login transport input all ! end Ciscozine-Beta#
The difference between the running configuration and the startup / ciscozine.conf configuration are:
Ciscozine-Beta(config)#hostname Ciscozine Ciscozine(config)#router ospf 1 Ciscozine(config-router)#network 192.168.1.0 0.0.0.255 area 0 Ciscozine(config-router)#redistribute static Ciscozine(config-router)#snmp-server community ciscozine RO Ciscozine(config)#interface Loopback1 Ciscozine(config-if)#ip address 10.0.0.48 255.255.255.255
Replace saved configuration
Example #1:
Suppose that you want replace your current configuration with the startup configuration and you want display a list of the command lines applied by the Cisco IOS software parser during each pass of the configuration replace operation.
Ciscozine#configure replace nvram:startup-config list This will apply all necessary additions and deletions to replace the current running configuration with the contents of the specified configuration file, which is assumed to be a complete configuration, not a partial configuration. Enter Y if you are sure you want to proceed. ? [no]: yes *May 8 14:32:51.843: Rollback:Acquired Configuration lock. !Pass 1 !List of Rollback Commands: no snmp-server community ciscozine RO router ospf 1 no network 192.168.1.0 0.0.0.255 area 0 no redistribute static no router ospf 1 interface Loopback1 no ip address 10.0.0.48 255.255.255.255 no interface Loopback1 no hostname Ciscozine hostname Ciscozine-Beta end Total number of passes: 1 Rollback Done Ciscozine-Beta# *May 8 14:32:57.455: %LINK-5-CHANGED: Interface Loopback1, changed state to administratively down *May 8 14:32:58.455: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to down Ciscozine-Beta#
Note: This is the only method that does not require the archive feature enabled.
Example #2:
Suppose that you want replace your current configuration with a configuration stored on the disk0 (disk0:/backup/Ciscozine.conf) in 5 minutes.
The time value specifies the time (in minutes) within which you must enter the “configure confirm” command to confirm replacement of the current running configuration file. If the configure “confirm command” is not entered within the specified time limit, the configuration replace operation is automatically reversed (in other words, the current running configuration file is restored to the configuration state that existed prior to entering the “configure replace” command).
Ciscozine-Beta#configure replace disk0:/Backup/Ciscozine.conf time 5 Rollback Confirmed Change: Backing up current running config to disk0:/Backup/backup-May--8-18-09-00.235-0 This will apply all necessary additions and deletions to replace the current running configuration with the contents of the specified configuration file, which is assumed to be a complete configuration, not a partial configuration. Enter Y if you are sure you want to proceed. ? [no]: yes May 8 18:09:01.707: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_BACKUP: Backing up current running config to disk0:/Backup/backup-May--8-18-09-00.235-0 May 8 18:09:02.267: Rollback:Acquired Configuration lock. % Only classful networks will be redistributed May 8 18:09:05.659: %LINK-3-UPDOWN: Interface Loopback1, changed state to up May 8 18:09:06.695: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to up Total number of passes: 2 Rollback Done Ciscozine# May 8 18:09:09.011: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_START_ABSTIMER: User: console: Scheduled to rollback to config disk0:/Backup/backup-May--8-18-09-00.235-0 in 5 minutes Ciscozine#
As you can see above, the system tells that if you do not confirm the new configuration in 5 minutes it will rollback with the previous configuration. The same message will be displayed one minute before the start of the rollback.
Ciscozine#Rollback Confirmed Change: Rollback will begin in one minute. Enter "configure confirm" if you wish to keep what you've configured May 8 18:13:09.011: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_WARNING_ABSTIMER: System will rollback to config disk0:/Backup/backup-May--8-18-09-00.235-0 in one minute. Enter "configure confirm" if you wish to keep what you've configured Ciscozine#
And after 5 minutes the system will start the rollback procedure:
Ciscozine#Rollback Confirmed Change: rolling to:disk0:/Backup/backup-May--8-18-09-00.235-0 May 8 18:14:09.007: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_ROLLBACK_START: Start rolling to: disk0:/Backup/backup-May--8-18-09-00.235-0 May 8 18:14:09.043: Rollback:Acquired Configuration lock. Ciscozine# !Pass 1 !List of Rollback Commands: no snmp-server community ciscozine RO router ospf 1 no network 192.168.1.0 0.0.0.255 area 0 no redistribute static no router ospf 1 interface FastEthernet0/0 no shutdown interface Loopback1 no ip address 10.0.0.48 255.255.255.255 no interface Loopback1 archive no path disk0:/Backup/backup.conf no hostname Ciscozine hostname Ciscozine-Beta archive path disk0:/Backup/backup- end !Pass 2 !List of Rollback Commands: --More-- May 8 18:14:12.735: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to down May 8 18:14:13.147: %LINK-5-CHANGED: Interface Loopback1, changed state to administratively down May 8 18:14:14.339: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to down archive write-memory end Total number of passes: 2 Rollback Done Ciscozine-Beta#
The same result occurs with the command “configure revert now” that triggers the rollback immediately.
And how can I save the new configuration? You must simple confirm the new configuration before the time expires (in this case 5 minutes):
Ciscozine#configure confirm Ciscozine# May 8 18:45:39.123: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_CONFIRM: User: console: Confirm the configuration change Ciscozine#
Note: There are many options with the “configuration replace” command; the most importants are:
- The force keyword replaces the current running configuration file with the specified saved Cisco IOS configuration file without prompting you for confirmation.
- The nolock keyword disables the locking of the running configuration file that prevents other users from changing the running configuration during a configuration replace operation.
Rollback the last saved configuration
Example#1
Suppose that you are implementing a new configuration on a remote Cisco devices but you want restore in 5 minutes the previous configuration if the configure “confirm command” is not entered.
Ciscozine-Beta#configure terminal revert timer 5 Rollback Confirmed Change: Backing up current running config to disk0:/Backup/backup-May--8-18-50-13.087-1 Enter configuration commands, one per line. End with CNTL/Z. Ciscozine-Beta(config)# Ciscozine-Beta(config)# May 8 18:50:14.555: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_BACKUP: Backing up current running config to disk0:/Backup/backup-May--8-18-50-13.087-1 May 8 18:50:14.563: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_START_ABSTIMER: User: console: Scheduled to rollback to config disk0:/Backup/backup-May--8-18-50-13.087-1 in 5 minutes Ciscozine-Beta(config)#
As you can see above, the system tells that if you do not confirm the new configuration in 5 minutes it will rollback with the previous configuration. The same message will be displayed one minute before the start of the rollback.
Ciscozine(config-if)#Rollback Confirmed Change: Rollback will begin in one minute. Enter "configure confirm" if you wish to keep what you've configured May 8 18:54:14.563: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_WARNING_ABSTIMER: System will rollback to config disk0:/Backup/backup-May--8-18-50-13.087-1 in one minute. Enter "configure confirm" if you wish to keep what you've configured Ciscozine(config-if)#
Now suppose that you want add these commands:
Ciscozine-Beta(config)#hostname Ciscozine Ciscozine(config)#router ospf 1 Ciscozine(config-router)#network 192.168.1.0 0.0.0.255 area 0 Ciscozine(config-router)#redistribute static Ciscozine(config-router)#snmp-server community ciscozine RO Ciscozine(config)#interface Loopback1 Ciscozine(config-if)#ip address 10.0.0.48 255.255.255.255
If you don’t confirm the new configuration, after 5 minutes the system will start the rollback procedure:
Ciscozine(config-if)#Rollback Confirmed Change: rolling to:disk0:/Backup/backup-May--8-18-50-13.087-1 May 8 18:55:14.563: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_ROLLBACK_START: Start rolling to: disk0:/Backup/backup-May--8-18-50-13.087-1 May 8 18:55:14.583: Rollback:Acquired Configuration lock. Ciscozine(config-if)# !Pass 1 !List of Rollback Commands: no snmp-server community ciscozine RO router ospf 1 no network 192.168.1.0 0.0.0.255 area 0 no redistribute static no router ospf 1 interface Loopback1 no ip address 10.0.0.48 255.255.255.255 no interface Loopback1 no hostname Ciscozine hostname Ciscozine-Beta end Total number of passes: 1 Rollback Done May 8 18:55:18.411: %LINK-5-CHANGED: Interface Loopback1, changed state to administratively down Ciscozine-Beta(config-if)# May 8 18:55:19.411: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to down Ciscozine-Beta(config-if)#
The same result occurs with the command “configure revert now” that triggers the rollback immediately.
Ciscozine#configure revert now Rollback Confirmed Change: rolling to:disk0:/Backup/backup-May--8-18-59-40.975-2 May 8 19:00:05.063: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_REVERTNOW: User: console: Rollback immediately. May 8 19:00:05.067: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_ROLLBACK_START: Start rolling to: disk0:/Backup/backup-May--8-18-59-40.975-2 May 8 19:00:05.083: Rollback:Acquired Configuration lock. !Pass 1 !List of Rollback Commands: no snmp-server community ciscozine RO router ospf 1 no network 192.168.1.0 0.0.0.255 area 0 no redistribute static no router ospf 1 interface Loopback1 no ip address 10.0.0.48 255.255.255.255 no interface Loopback1 no hostname Ciscozine hostname Ciscozine-Beta end Total number of passes: 1 Rollback Done Ciscozine-Beta# May 8 19:00:08.675: %LINK-5-CHANGED: Interface Loopback1, changed state to administratively down May 8 19:00:09.675: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to down Ciscozine-Beta#
And how can I save the new configuration? You must simple confirm the new configuration before the time expires (in this case 5 minutes):
Ciscozine-Beta#configure confirm Ciscozine-Beta# May 8 19:00:58.571: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_CONFIRM: User: console: Confirm the configuration change Ciscozine#
Remember: The running configuration lock is automatically cleared at the end of the configuration replace operation. You can display any locks that may be currently applied to the running configuration using the show configuration lock command.
References:
