We use IOS on various range of Cisco switches, mostly on the Datacenter and IT networks. It supports our L2 and L3 networking requirements such as switching and routing protocols. It helps connect users and customers spread out in various branches end to end and manages packet flow between server-client.
Pros
User friendly CLI.
Quick fixes for critical bugs.
Longer uptime.
Cons
No good element managers like Nokia.
Load balancing functionalities are not the best.
Memory issues.
Likelihood to Recommend
Well suited for building management networks across the organization as it has been reliable without much downtime. Since it has great switching qualities, it suites well for data center and end-user connectivity using access switches. It might not be the best for routing, as other XOR software has proven to be superior for routing.
VU
Verified User
Engineer in Information Technology (10,001+ employees)
Cisco IOS is the cornerstone of our network infrastructure. As a network engineer for my organization, there isn't a single day (or maybe even a couple of hours) that I'm not interacting with Cisco IOS in some capacity. My team and I use it to troubleshoot network issues, make network changes, fulfill user requests, plan network infrastructure changes, monitor device environmentals, apply configuration macros, check for system resource utilization (e.g. CPU, memory), and so much more.
Pros
Cisco IOS image upgrades usually go very smooth due to thorough quality assurance software testing from Cisco. It also helps that Cisco has very helpful white papers that helps walk you through the upgrade process in easy to follow steps.
Does a great job of providing network device health data via the various Cisco IOS commands
It's a fast operating system which makes it a dream to work with
Cons
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.
Likelihood to Recommend
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.
