I've worked with several network device vendors in my 10+ years of being in the industry and my favorite continues to be Cisco IOS. Overall, Cisco IOS tends to be the most stable, the most intuitive, has the best TAC support, and has the best knowledge base articles and white papers.
IBM AIX is well suited for mission-critical applications, especially the ones that need to run on well-performing hardware and need less downtime. It is also perfect for applications that need a lot of CPU, because AIX scales well on the IBM POWER hardware, so adding additional CPU almost always generates higher performance/throughput. IBM AIX runs unmodified from the smallest IBM POWER machine (S1022, with 12 Power10 cores) to the biggest machine (E1080, with 240 Power10 cores). Because IBM POWER systems have very fast CPU’s, you typically need a lower number of CPU’s when compared to alternatives. This may bring a reduction in cost for software licensed per core. Unfortunately, not all software vendors port their software to IBM AIX, so sometimes you may have to run Linux on POWER, or skip the POWER platform altogether. But many vendors happily support AIX and POWER.
Stability. In the 14 years that I have used the product, I cannot think of a single time that we had an OS level failure. It is rock solid. We have had systems that have been booted and run for literally years without interruption.
Virtualization. We run IBM AIX as LPARS on Power infrastructure. All of our AIX infrastructure is virtualized making it easy to scale as needed.
Their logical volume manager makes the task of managing storage very simple. It is feature complete and they have mitigated much of the complexity that usually is inherent in LVM implementations.
I have a love/hate relationship with Smit. It is their administrative interface. It is very powerful and very complete which is why I marked it as a pro. It is also a bit clunky and somewhat arcane in its interface but still usable.
By this point, there are several "flavors" of the Cisco IOS such as XE, XR, and the standard Cisco IOS. While they are all fairly similar, there does exist syntax differences between them. It would be ideal if at some point in the future, Cisco is able to unify all of them into one standard operating system which would use the same syntax across all platforms.
While overall Cisco does a great job of QA'ing their IOS, no matter the release, there's always some minor bugs. I think it's important that Cisco continue to pour resources into their QA team to test their software.
While I'm very familiar with the graphical readouts of "show processes cpu history" I would love for Cisco to eventually find a more intuitive way to display this data. I can't begin to count how many times I've had to teach more entry level (and even mid level) engineers how this graph is interpreted.
I do wish that Cisco had something similar to Juniper's "commit check" or "commit confirmed". This helps validate the changes you're about to apply, and catch errors, so that you have a better idea of the impact of the change.
A lot of the built-in commands have not been updated in years. If you're used to some fancy CLI options in Linux, you may be out of luck with AIX.
Out of the box, you cannot run open-source Linux utilities on AIX. There is a toolbox you can install, however, it's not the same versions as you would get in different Linux flavors.
Tab completion for files and Up arrow to re-run previous commands don't work out of the box without running a Korn shell. A small annoyance, but one that catches me every time!
The data that Cisco IOS is able to provide is extremely relevant, it's fast, and it's intuitive. I also love that you're able to leverage things like macros or EEM scrips to run multiple commands at once. This is especially useful when you have more junior or entry level engineers in your environment and you want to provide them with a "shortcut" by having them type a single command to execute multiple commands.
AIX is robust, helps the systems administrator, is built to prevent easily made mistakes. If you are used to other variants of Unix (in particularly Linux) there is no steep learning curve to get started with AIX. You need to learn the intricacies of the operating system, but that is true for any new operating system. AIX has built-in tools for almost anything you want and has the AIX Toolbox (on the web) for tools that are not included with AIX by default, but can be installed. Installation of AIX is modular, you can select with components and features you want to have installed. Installation of additional components (and usually also removal of installed components) is easy and straight-forward.
We have found other Cisco software to be filled with added functionalities as compared to iOS. New NCS software has certain programmability features that are advantageous to legacy iOS software but are more complex to use for some users. Hence, we still have most areas of the network that functions using iOS software.
IBM AIX operating system is advanced with most features and also it's more reliable unlike Redhat Linux, Sun solaris, HP-UX and also we will have well support from the vendor if we run into any issues. IBM AIX is more user-friendly when compared to linux and easy to use so i would prefer the customers to have their operating system as IBM AIX for companies who has more customers.
