Unanswered Question
Feb 25th, 2010
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Which Cisco router platforms use IOS XR?

Is it just the CRS-1, ASR 9000 and GSR 12000? What about the asr 1000?

What is the big difference between regular IOS and IOS XR?

What is the ASR 9000 used for? WAN edge? SP PE? SP core?

So for so many questions...


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Overall Rating: 5 (1 ratings)
Giuseppe Larosa Thu, 02/25/2010 - 09:59
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Hello Joe,

IOS XR is supported on CRS and GSR 12000 XR and ASR 9000


about different IOS flavors:

ASR 1000 supports IOS XE and Nexus supports NX-OS

IOS XR has a different architecture then IOS: it uses a real-time microkernel OS that provides basic services.

Over this common layer other SW layers are added for example OSPF or ISIS module, MPLS module and so on.

It is not a monolithic image, but rather it has a unix derived approach. Modularity provides also for the capability to perform partial updates of one or more SW modules. They are called SMU.

IOS XR is designed with service provider carrier class needs

ASR 9000 is designed for PE role and aggregation services and it is a young platform.

to be noted also an ASR 14000 has been introduced recently but I cannot find info about it.

Hope to help


kzryumov1 Fri, 08/24/2012 - 01:54
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Could you explain what is the difference between SMU software?

For example: asr9k-p-4.2.1.CSCub48041.tar

This SMU only for A9K-RSP-4G or for A9K-RSP440 too?

I mean -p- -px- prefixes.


wbr, Konstantin.

Nicolas Fevrier Fri, 08/24/2012 - 01:58
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Hi Konstantin.

-p code is only for A9K-RSP-4G

-px code is only for A9K-RSP440

a "-p" SMU can only be applied on a -p code (running on a A9K-RSP)

and a "-px" SMU can only be applied on a -px code (running on a A9K-RSP440)

You can not mix them.



Nicolas Fevrier Fri, 08/24/2012 - 01:59
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And if I can complete this answer, a ASR9k SMU can only be applied on ASR9k code (not XR12K or CRS).

kzryumov1 Sun, 08/26/2012 - 22:51
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Hello Nicolas,

I have another question.

For example from we have only asr9k-p-4.2.1.CSCub48041.tar.

Is it mean that on -px code these bugs doesn't exist?


Nicolas Fevrier Sun, 08/26/2012 - 23:24
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Hi Konstantin,

It's not a given but it's a case by case.

In the particular case of CSCub48041, I see that the SMU is also available for download for -px code.

(-p has been publish the 20th of August, -px the 24th).

Please recheck the download center:

Downloads > Home > Products > Routers > Service Provider > > Edge Routers Cisco ASR 9000 Series Aggregation Services Routers > Cisco ASR 9006 Router > IOS XR Software Maintenance Upgrades (SMU)-4.2.




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