Showing results for 
Search instead for 
Did you mean: 

Cisco IOS XR

Level 1
Level 1

I am interested to hear of peoples experiences of moving from IOS to IOS XR ? I work on a network with several GSR running IOS and I am putting together a proposal of the benefits of moving to XR.

I am waiting on confirmation from the BU to see whether IOS will continue to be developed for the GSR as the new PRP (PRP3) is IOS XR only.

5 Replies 5

Laurent Aubert
Cisco Employee
Cisco Employee


12.0(33)S is the last IOS version for GSR platform and all new development are now based on XR so don't expect any new feature being added to IOS from now.

XR is really the next OS generation for any Cisco core platform (ASR9k, CRS-1 and GSR) so you're right to prepare your migration. Most of the SP are currently doing it or going to start the migration.



Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello Mdwheadon,

the conversion process takes time in order of hours.

One point is important: the conversion procedure at least the one we used was not clear about basic requirements it just says to do not delete the IOS configuration file.

Actually what is needed is to give an ip address to a management ethernet on PRP2 to be able to use it from rommonitor to perform FTP transfers.

This point was not clearly stated in the procedure we used.

In our case the first system we were converting was a new one and we discovered the above requirement on the job.

Our customer choice has been to introduce new chassis with IOS XR in substitution of older ones

Other colleagues of other teams working for other customers have talked about saving time by skipping FTP transfer having another compact flash with IOS XR loaded on.

Hope to help


Our deployment plan was to swap the current PRP cards with ones we have prebuilt within our lab. This will make it easier when migrating to IOS XR and reverting back if things go seriously wrong.

How are you finding the OS ? Do you think it's more stable and easier to manage. The bug list on CCO seems to suggest not many issues have been filled against the OS although I have a sneaky feeling it isn't giving a true representation. I don't know how popular the take up has been from IOS ? When we purchased our new GSR's it was decided to stay with IOS as the software was too new for our liking. The release at the time was 3.4. I have noticed the latest version requires 2G of flash which is going to be a cost to the business.

From your experience would you say moving to XR has been benefital ? I don't think we will have much choice especially as 12.0(33) is the last release.

Hello Mdwheadon,

we had already to patch, to install a SMU on GSR with IOS XR 3.8.0.

For the moment it is too early to say what are the advantages of IOS XR over standard IOS.

It takes 20 minutes to come up for a system with 2 PRP2 two SIP 600 and another linecard.

SSO switchover is automatic but IOS is faster to come up and you examine the coming up log messages for a short time the system executes an IOS image before booting IOS XR. It takes time also to configure the linecards so the more you have more time is needed.

also we have noticed some more sensitivity (more up/downs ) on E3 or POS lines but other have reported more serious problems (line down) with older IOS XR.

I can tell that I was able to patch a CRS-1 with IOS 3.4.1 installing 26 SMU in 4 reloads in two hours.

CRS-1 is faster in coming up after reloads.

Of course, because Cisco is pushing IOS XR the conversion is a needed step.

Hope to help


20 minutes to boot ? I am sure our GSR's takes less than 10 minutes with IOS. I guess that maybe a drawback of having a modular operating system, maybe in future revisions of the software they will improve the loading time.

Have you raised a TAC case regarding the instability of the interfaces since you have moved to IOS XR ?

I think we will most likely lab test the IOS XR and if it proves itself within the lab we will pick a GSR which is low risk and preupgrade 2x PRP cards and hotswap them during a downtime window and see how the operating system proves itself in our live environment before rolling out a mass upgrade program.

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: