Cisco Router 7206 VXR

[IrfanKhan4904]

We are using router Cisco 7206VXR
Bought a new router ISR 4451. We want to restore the configuration of the previous router to the new router. Is it possible?

[M02@rt37 · Accepted solution]

Hello @IrfanKhan4904 

The Cisco 7206VXR router and the ISR 4451 router run different types of IOS software.

The Cisco 7206VXR router uses Cisco IOS Software, which is a monolithic operating system that includes all of the features and functions of the router, including routing protocols, security features, and management interfaces. The specific version of IOS software running on the Cisco 7206VXR router may vary depending on the model and configuration of the router, as well as the date of the IOS release.

The ISR 4451 router, on the other hand, uses IOS XE Software, which is a modular operating system that separates the control plane and data plane functions of the router. IOS XE Software uses a Linux-based kernel to manage the hardware resources of the router, while the control plane and data plane functions are implemented as separate software modules that can be upgraded or replaced independently of each other. The specific version of IOS XE software running on the ISR 4451 router may vary depending on the model, configuration, and date of the IOS XE release.

Both IOS and IOS XE software are part of the Cisco IOS family, but they have some differences in terms of architecture, features, and fonctionnaliteis. If you are migrating from an IOS-based router to an IOS XE-based router, it's important to familiarize yourself with the differences between the two software types and any specific requirements or limitation of the new IOS XE-based platform.

Then, you can still use the same configuration file on both routers, as long as you modify any commands that are not supported by the IOS version running on your new ISR 4451 router.

[Richard Burts · Accepted solution]

The original post asks "We want to restore the configuration of the previous router to the new router". It is highly unlikely that you would be able to just restore the previous config to the new router. It is highly likely that some of the interface names might be different. It is also highly likely that the syntax of some commands might have changed from one version of software to the other. And it is possible that some functions supported on the old router might not be supported on the new router. Also possible that some functions supported by the license of the old router might not be supported by the license of the new router. I would suggest that you take a copy of the current running config of the old router and compare it to the (minimal) running config of the new router. Look for changes in naming of interfaces, and for changes in syntax of commands. Modify a copy of the old config based on changes identified and load the modified config to the new router a few lines at a time (section by section, interface by interface) being alert to any error messages generated.

[Joseph W. Doherty]

7206VXR config => 4451?

99% chance 4451 will load it.

Also, 99% chance 4451 will have "issues".  (Starting with, as Rick notes, interface names/IDs.)

What can be very helpful is to load 7206 config into running 4451 config and then do a diff between the 7206 config and the just updated 4451 running config and "fix" config as needed.

One side benefit of using the diff, it will also show things like syntax changes the router already applied. (I've also used diff to compare startup vs. running after booting into a different IOS version.)

[Joseph W. Doherty]

BTW, in my experience, some don't appear to be aware of the "diff" feature,  What I described in my earlier posts looks like:

#sh archive config differences nvram:startup-config system:running-config

!Contextual Config Diffs:
line con 0
+length 0

PS:  (additional examples)

inserthostname-here#conf t
Enter configuration commands, one per line. End with CNTL/Z.
inserthostname-here(config)#no router ei 1 
inserthostname-here(config)#end
inserthostname-here#$ferences nvram:startup-config system:running-config
*Apr 19 15:11:41.933: %SYS-5-CONFIG_I: Configured from console by console
!Contextual Config Diffs:
line con 0
+length 0
-router eigrp 1
-network 192.168.1.0
-network 192.168.2.0

inserthostname-here#conf t
Enter configuration commands, one per line. End with CNTL/Z.
inserthostname-here(config)#default int g0/1
Interface GigabitEthernet0/1 set to default configuration
inserthostname-here(config)#end
inserthostname-here#$ferences nvram:startup-config system:running-config
*Apr 19 15:13:29.534: %SYS-5-CONFIG_I: Configured from console by console
*Apr 19 15:13:30.058: %LINK-5-CHANGED: Interface GigabitEthernet0/1, changed state to reset
!Contextual Config Diffs:
interface GigabitEthernet0/1
+no ip address
line con 0
+length 0
interface GigabitEthernet0/1
-ip address 192.168.1.2 255.255.255.0
-media-type rj45
-router eigrp 1
-network 192.168.1.0
-network 192.168.2.0

nserthostname-here#copy startup-config running-config
Destination filename [running-config]? 
% Hostname "INSERTHOSTNAME-H " is not a legal LAT node name, Using "CISCO_18C39C"
3028 bytes copied in 0.109 secs (27780 bytes/sec)

inserthostname-here#
*Apr 19 15:15:58.896: %DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 192.168.2.1 (GigabitEthernet0/2) is up: new adjacency$ferences nvram:startup-config system:running-config
*Apr 19 15:16:00.796: %LINK-5-CHANGED: Interface GigabitEthernet0/1, changed state to reset
*Apr 19 15:16:01.796: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to down
!Contextual Config Diffs:
line con 0
+length 0

[Richard Burts]

Very interesting suggestion for using config differences. Thanks for the examples.

[Joseph W. Doherty]

Rick, BTW, I've also found the diff feature useful whenever I'm about to make configuration changes.

Before making any changes, I compare startup to running.  (Surprising how often I used to find unsaved changes.)

After making any changes, but before saving running to startup, I run diff again.  This to confirm I "see" all the changes I expect to see, and not any others.

Lastly, although this diff command is part of the archive/rollback feature set, archiving does not need to be configured to use it.

Old IOS versions, though, don't support the archive/rollback feature set.  Recall it was added starting in the 12.x IOS versions (found 3rd party mentions that archive commands added starting with 12.3[4]T or with 12.4[20]T).