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Upgrading from ISR 2851 to ISR G2 2951 - config compatibility

Due to throughput limitations, I would like to upgrade from a ISR 2851 to a ISR G2 2951.

I would like to know if the configuration can be exported from the 2851 and loaded to the 2951.

Is there configuration compatibility or will I have to manually re-make the configuration for the 2951 ?

Reza Sharifi
Hall of Fame Expert

For most commands, the configuration should be similar but there maybe some commands you need to modify or enter manually.  I suggest taking one portion of the config at a time, copy it to notepad  and than past it into the new 2951.  This way you can see if some commands don't work correctly.  Once that section is completed move to another section and so on....


Joseph W. Doherty
Hall of Fame Expert


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Much depends on what IOS versions, and feature sets, are being used on the two routers; and also on your actual configuration.

Often you'll need to address interface naming changes, but beyond that, it's a "it depends" kind of answer.

However, usually configuration differences are minimal.  New IOS versions will often accept old(er) syntax (and convert it).

You can do what Reza suggests, which is a good approach, or you can try pushing the whole old config onto your newer router.  In either case, watch for errors.  Carefully review the results.