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Ask the Expert:Upgrading CRS1 System to CRS3

Community Manager
Community Manager

With Milivoje Mirovic and Bryan Garland

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Welcome to the Cisco Support Community Ask the Expert conversation. This is an opportunity to learn how to upgrade your existing CRS-1 system to CRS-3 and how to avoid common issues with Cisco experts Milivoje Mirovic and Bryan Garland. Milivoje Mirovic is a senior customer support engineer at the Cisco Technical Assistance Center in Brussels, Belgium. He covers many technologies including routing protocols, service provider, and CRS/IOS-XR. He holds a master of science degree in electrical engineering from the University of Belgrade, Serbia, as well as CCIE certification #23472 in Routing & Switching and Service Provider.Bryan Garland works in Cisco's Technical Assistance Center as the team lead for Cisco IOS-XR support. He serves as the escalation point for technical issues supporting IOS-XR customers on the Cisco Carrier Routing System, Cisco XR 12000 Series Routers, and Cisco ASR 9000 Series Aggregation Services Routers. He previously was an escalation engineer for areas including LAN switching and enterprise voice technologies. Garland has been with Cisco for more than 16 years. He holds CCIE certification #1942 in Routing & Switching.

Remember to use the rating system to let Milivoje and Bryan know if you have received an adequate response.  

They might not be able to answer each question due to the volume expected during this event. Remember that you can continue the conversation on the Service Provider sub-community, discussion forum shortly after the event. This event lasts through October 7, 2011.. Visit this forum often to view responses to your questions and the questions of other community members.

8 Replies 8

John Ventura

Can you provide best practices on going from a CRS-1 to a CRS-3? What are the main considerations I should have and make me sure I don't overlook?

Hi John,

As always we commend you to follow official upgrade instructions published on our website.

Please check here:

Since CRS3 platform runs 4.0.0T(PX) or higher software revisions, typical precaution measures should be taken when upgrading from 3.x to 4.x release:

- 'upgrade' PIE should be used for upgrade and removed before software commit

- Make sure you have enough space on flash disks. 4.x releases require 2GB disks at minimum.

Also there are some CRS3 specifics you should pay attention on:

- Minimum ROMMON version on RP should be 1.54, however if you're doing TURBOBOOT procedure you will need ROMMON 2.01

- When upgrading hardware be sure that you upgrade fabric cards fist. New MSC-140 should not be be inserted together with old CRS1 fabric cards.

Hope this helps,


Hello Irina,

The big advantage in performance is in a couple of things.  First is your per slot performance.  Basically you go from a 40gb per slot to a 140gb per slot.  What this does is allow for greater port density as well.  Obviously we can now have 14 and 20 tengige PLIMs in CRS-3 over the 4 and 8 tengige PLIMs on the CRS-1, for example.  This also allows for the next generation interfaces like the 100 gige PLIM.

Hope this helps. 


Hi, What is advantage in performance if I upgrade from CRS1 to CRS3?

Hello, I wonder if I can upgrade from 'p' to 'px' software and stay on same release? Is this possible?

Hi Christopher,

Just to give a bit of insight on difference between P and PX releases.

P releases support only CRS-1 platform

PX release is superset of P and supports both CRS-1 and CRS-3 platform.

For more info on this plase check:

When you'r upgrading to CRS-3 platform you will need to run PX release.

However upgrades from P to PX release in same software version are not supported.

For example you cannot upgrade from 4.0.1 P to 4.0.1 PX.

In this case correct way to upgrade would be to 4.0.3 or 4.1.x PX release.



Jorge Guimaraes


I mixed 'p' and 'px' packages on my CRS. What should I do?


So this is a problem and should be corrected right away.  The incorrect packages should be deactivated and removed.  We do have a bug, CSCtg53836, which is integrated into 4.1.0 and 4.0.2 and higher to help prevent this from occuring. 



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