we are going to upgrade ASR 9000 series from 6.2.3 to the 6.4.2. The ASR have 2 RSP each, so we wanted to know if before the upgrade we can remove a RSP to keep the 6.2.3 version, and if the upgrade at some point has issues, we can power off the ASR, put the RSP 6.2.3, and let the ASR boot with that RSP as a rollback.
In case that the upgrade goes ok, after finishing the upgrade to 6.4.2 we would insert the RSP with 6.2.3 and let the sync start. As we understand that syncronization shouldnt have affectation.
Is it possible to make this?
We also arent sure about the fpd auto-upgrade function, since sometimes we see advice against it and sometimes we see the recomendation to use it to shorten the service interruption.
Thanks for your help.
We're preparing for a similar upgrade from 5.1.3 to 6.4.2 (32-bit).
From my perspective, you shouldn't have issues with that RSP plan. In a similar fashion, I was planning on taking two pre-configured RSP's to each site, and would then have the original RSP's on-hand as the backout plan. But, after seeing your post, now realize it could be done with a single pre-configured RSP, and then re-insert the standby for sync'ing, once network is operationally verified.
In my MOP, I will be disabling fpd autoupgrade prior to doing any work, and then manually run the upgrade commands as needed. Once all work is complete, I'll add the autoupgrade command back into the config.
I'm still working on this in our lab, so it will be interesting to see what input is given from the Cisco team and other network engineers.
Also be aware that there is a route reflector issue mentioned as a review for the 6.4.2 code. I verified this issue does exist with TAC, but I need to fully test in our lab in order to know if we'll be affected.
You can perform ISSU (In Software Service Upgrade) installation with minimal disruption in a single step or as multiple phases. You need to perform the pre-installation tasks before executing ISSU. During the pre-installation tasks and ISSU execution, V1 refers to the image currently running on the router and V2 will be the upgraded image.
ISSU execution contains the following phases:
Prepare phase: The installable files are pre-checked and loaded on the router before activation. This phase is optional.
Activate phase: The new image (V2) is downloaded to all nodes in the router replacing the old image (V1). This phase can be run in step-by-step phases like Load, Run, and Cleanup or by using a one-shot Activate phase.
Commit phase: The ISSU installation is complete with V2 on all nodes.
Besides, IOS-XR can abort the upgrade if something is wrong and rollback to the V1.