Intro to Cisco Operating Systems

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Cisco Operating Systems

Lecture description

In this lecture, you'll learn about the different operating systems that run on Cisco's different router and switch platforms. You don't actually need to know this for the CCNA exam, but it's beneficial to have an understanding of Cisco's wider portfolio. Cisco's different operating systems are very similar from a management and administrative point-of-view, so it's easy to transfer your skills between platforms.


I'll start off by giving you a bit of history. Many people think of Cisco as being a routing and switching company, but they actually were just a purely routing company when they started out. IOS was the original operating system that they used on their routers. It's the same operating system that's used today, although obviously it's gone through quite a few upgrades in the time since Cisco started back in 1984.


Cisco then bought the company 'Crescendo' in 1993. The Catalyst switch product line came about because of that acquisition. The original operating system on the Catalyst switches was CatOS, but that's been deprecated for a long time now.


Cisco firewalls evolved from another acquisition, that of 'Network Translation' back in 1995. Cisco got their PIX firewall from that acqusition, which used the Finesse operating system. The PIX firewall has since evolved into the ASA Adaptive Security Compliance.


Both the CatOS and Finesse operating systems were ported over to IOS over the following years. Cisco standardised on IOS for all of their network infrastructure devices.


There are also some other operating systems on some of the newer router and switch platforms. IOS runs on the majority of Cisco routers and switches, but some of the newer platforms have new operating systems.


The Cisco Nexus and MDS Data Centre switches run on NX-OS.


The high-end NCS and CRS service provider routers and also the ASR9K and XR12K routers run on IOS-XR.


The ASR1K service provider routers run on IOS-XE.


You may be thinking "all these different operating systems are going to make things more difficult for network engineers." But they don't really, because all of the different Cisco operating systems have incredibly similar Command Line syntax. If you know a command in IOS, it's probably going to be exactly the same command in all of the other operating systems as well.


If you're now wondering why Cisco have different operating systems for their routers and switches then, the main difference is under the hood. IOS has a monolithic kernel, meaning that if one process running on the router crashes it can crash the entire router. The other, newer operating systems have microkernels, with processes running in separate, protected memory address space. If one of the processes crashes, it should restart without affect the rest of the system.


These operating systems other than IOS are mainly on the higher-end routers and switches, with the standard routers and switches still running IOS. Now, don't think that IOS is an inferior or unreliable operating system. It's been purpose-built by Cisco, who are the biggest networking company in the world, to run on enterprise-grade routers and switches. It is very hardened and still very, very reliable.

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English
In this lecture, you'll learn about the different Operating Systems that run on Cisco's different router and switch platforms. Now, you don't actually need to know this for the exam. The exam focuses purely on IOS on Cisco routers and switches. So if you're wondering why am I including this then, the reason is that it's something that you would wonder about anyway, and I want to explain to you that, by taking this course and learning how to configure Cisco IOS, it's going to enable you to work on any of the different Cisco routers and switches, because, from a management and administrative point of view, it's pretty much identical no matter which actual Operating System you're working on. So, I'll start off by giving you a bit of history. Many people think of Cisco as being a routing and switching company, but they actually were just a purely routing company when they started off. And when they did start off, IOS was the original Operating System that they used on routers, the same Operating System that's used today, although obviously it's gone through quite a few upgrades in the time since Cisco started back in 1984. So, they were originally a routing company. To offer switches, that was through an acquisition. They bought Crescendo in 1993. The Catalyst switch product line came about because of that acquisition. The original Operating System on the Catalyst switches was CatOS, but that's been deprecated quite a long time ago now. Cisco firewalls evolved from another acquisition. That was the acquisition of Network Translation back in 1995. Cisco got their PIX firewall from that, which uses the Finesse Operating System. Now, both the Catalyst switches and the originally PIX firewalls, it's now the ASA firewall, were ported over to the IOS operating system over the following years. So, Cisco standardized on IOS for all of their network infrastructure devices. There are some other Operating Systems on some of the newer router and switch platforms, though. IOS runs on the majority of Cisco routers and switches, but some of the newer platforms do have these new Operating Systems. Let's look at those now. So, on the Cisco Nexus and the MDS Data Centre switches, they run on NX-OS. On the high-end service provider routers, the NCS and the CRS, and also on the ASR9000 and XR12000 routers, they run on IOS-XR, and on the ASR1000 service provider routers, they run on IOS-XE. So, you're maybe thinking, "Oh well, this is going to make things more difficult if there's all these different Operating Systems." But really, it doesn't, because all of the different Cisco Operating Systems, they are incredibly similar from the Command Line point of view. If you know a command in IOS, it's probably going to be exactly the same command in all of the different Operating Systems, as well. As far as administering and managing them, they're all nearly exactly the same. So, you're maybe wondering, "Well, if managing them is exactly the same, why is there the different Operating Systems?" The main reason, and where they're different, is under the hood. IOS has got a monolithic kernel, meaning that if one process running on the router crashes, it can crash the entire router. The other newer Operating Systems have got microkernels, and the processes run in separate, protected memory address space. So if one of the processes crashes, it shouldn't affect the running on the rest of the system. These other Operating Systems are mainly on the higher-end routers and switches, but on the enterprise-grade routers and switches, they're still running IOS. Now, don't think that IOS is a bad or an unreliable Operating System. It's been purpose-built and by Cisco, who are the biggest networking company in the world, to run on enterprise-grade routers and switches. So, it is very hardened. It's still very, very reliable.