[c-nsp] In Service Software Upgrade

[Darin Herteen]

I may be incorrect here but I don't believe SSO ISSU is supported for upgrades from 12.2(33)SRB/SRC to 12.2(33)SRDx

I received the following from TAC when opening a case quite similar to this a while back:

Thank you for all of the information you have provided.  The failure you are seeing with the ISSU upgrade from 12.2(33)SRB5 to 12.2(33)SRD or
SRD1 is because SSO ISSU is not supported for upgrades from 12.2(33)SRB and 12.2(33)SRC images to 12.2(33)SRD.  To upgrade from SRB and SRC releases to SRD, RPR mode must be used and should be the configured redundancy mode prior to the upgrade process.
  CSCsm32582
SSO based ISSU process needs to be blocked between SRB/SRC and SRD Internally found moderate (Sev3) bug: R-Resolved

The following software bug was filed because because when trying to upgrade from SRB or SRC to SRD via SSO ISSU, the router should default back to RPR and not SSO, which leads to the failure.  This is an external bug you can access on Cisco.com, however, I have included the release notes below as well.

  CSCsv90323
SRB2/SRB4 CCO to SRD CCO upgrade failed
Externally found severe (Sev2) bug: A-Assigned

Release-note:

Symptoms:

ISSU upgrade to Cisco IOS Release 12.2(33)SRD did not put router into route processor redundancy (RPR) mode.

Conditions:

Occurs when "no service image-version efsu" is enabled. During ISSU upgrade from Cisco IOS Release 12.2(33)SRB or SRC to Cisco IOS Release 12.2(33)SRD, the router incorrectly goes into stateful switchover (SSO). 
The correct mode is RPR because SSO ISSU from these releases to Cisco IOS Release 12.2(33)SRD is not supported.

Workaround:

Remove the "no service image-version efsu" configuration by the default "service image-version efsu" and continue the upgrade process.

Further Problem Description:

If any of the following Config, Exec or ROMMON variables are set, the SSO-based ISSU will not be blocked:

   Config:

   "no service image-version efsu",

   "no service image-version compatibility",


   Exec:

   "issu image-version compatibility disable",


   ROMMON variable:

   RED_MODE = "RPR_PLUS'

   RED_MODE_SSO

   RF_REDUN_COMP = 1

When performing any ISSU upgrade from SRB/SRC to SRD, make sure none of the above overrides is set on the router. The "service image-version efsu" command detects the incompatibility and puts the router in RPR mode.

I hope some of this information was helpful. I have been in the process of upgrading about 8 7600's and I have run into bug after bug with regards to the upgrade process..

Darin Herteen.


> Date: Thu, 8 Oct 2009 14:32:19 +0400
> From: kron at linkey.ru
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] In Service Software Upgrade
> 
> Hello,
> 
> I want upgrade IOS on the cisco 7600 with two Sup32 without rebooting. I use for this ISSU procedure.
> I try migrate from SRC to SRD branch. IOS is upgraded, but downtime duration is about 280 seconds. All sessions(ospf, mpls, bgp) with neighbors was lost. NSF and GR(for mpls,ospf,bgp) are turned on.
> In ISSU process I saw that c7600 has switched from SSO to RPR mode. All interface cards have been reloaded. I thought that the problem in IOS, because I use different branches of IOS(SRC->SRD3). For the test, I tried to switch from SRD2 to SRD3 - the result is the same. 	
> I think the problem is in the switching mode(from SSO to RPR).
> 
> How to upgrade IOS without downtime?
> 
> -- 
> Aleksandr Gurbo
> 
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