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Im building an ASR 1001X, and I see so many versions of software !! Denali 16.3.5 (MD), vs Everest 16.6.2(ED), vs Fuji 16.7.1  (ED) .. Anyone knows what the difference is  ? and which is the stable version that I should go with ? I couldnt find any cisco live documents, though i saw a few posts in other forums, im still not clear !


why is IOS so confusing these days ? why cant it be like 5-6 years back.. so many numbers .. each IOS is has 2 or 3 different names ! uffff

4 Replies 4

Joseph W. Doherty
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I believe the names are "code names", which you can probably ignore spending more time on the version numbering and release status.

Feature differences should be documented in release notes.

Everything else being equal, older versions tend to be more stable, as they have had more to "cook" and often have had more patch releases. Confirmation of this, in this case, is your 16.3.5 has a MD status while 12.6.2 and 16.7.1 are ED. The patch numbers are also 5 to 2 to 1. Also for selecting stability, look for the "star" that Cisco places next to recommended releases on the IOS download page.



Thanks so much..  star recommendations change every now and then.. also with ASR there are  IOS's which have star.. 

I wanted to get views from people who have used these versions ? May be - Denali is the way to go !  IOS numbers are confusing these days :( 


Read the Release Notes and stay with 3.X.

So I'm trying to go through the release notes and figure out the primary differences. I still can't quite make heads or tails out of it. This month, both Denali and Everest are marked with the (star) (both in MD status) whereas the 3.x series is no longer recommended.


I'm currently running 3.16.7bS(MD) and was about to get 3.16.8S(MD) but noticed that it was released back in 10-Aug-2018 whereas all the 16 series are Mar-2019.  Is the 3 branch dead? Should I be thinking of upgrading? what do I gain/lose if I upgrade?


These are being used currently as BGP peering routers so the only protocols I really run on them are BGP, OSPF, tons of route-maps, and about 10-30 peering sessions per ASR. (rather minor bogon access-list filters).




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