The end of “classic” IOS

If you’ve been in IT and networking in the last 5 years, you definitely know the 1st family of Cisco ISR (Integrated Service Routers) 1800, 2800 and 3800. If that’s true, you also seen the transition to ISR G2 (1900, 2900 and 3900) and felt the frustration of the new licensing model.

Well, last month, the end of ISR G2 was also announced and the recommended platform to migrate to in this range are the 4000 ISR.

7600 routers, the old school warriors also had their End-of-Sale announcement and the replacement should be the ASR 9000.

What does this have to do with the title?

Lately (15 years?) Cisco has been introducing new routers working with new operating systems:

  • ASR 1000 running IOS XE in the enterprise edge and aggregation
  • ASR 9000 running IOS XR in the Service Provider core and edge
  • Nexus switches running NX-OS in the Data Center

All of these new OS’s are modular and bring only advantages when compared to the old IOS (Internetwork Operating System).

ISR 4000’s are no longer running IOS but IOS XE. ASR 9000 – recommended for the replacement of 7600’s – runs IOS XR. 2960 and 4500 switches have left IOS and have been running IOS XR for some years now.

This trend clearly shows us that the well known “classic” and monolithic IOS we came to love and hate since the 90’s is coming to an end. After these announcements, there are very few that still run “pure” IOS.

Is there a reason to worry?

No. Fortunately, NX-OS and especially IOS XE is keeping syntax and CLI (Command Line Interface) similarities with the original IOS. The notable differences are underneath in software architecture (Linux Kernel), modularity, memory protection and high availability. Only IOS XR has big differences but you can get the hang of it quickly with a few month’s practice (have a look at XRv)

You want to know a bit more?

Difference between IOS, IOS XE and IOS XR

Cisco NX-OS

Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide: Software Packaging and Architecture

2900 End-of-Sale Announcement

3900 End-of-Sale Announcement