[c-nsp] route processor redundancy basics (RPR)

[murchison link]

Hi all,

I'm just trying to wrap my head around RPR.

I have the following topology:
RTR1 [fe0]--------[fe1] asr1006 [fe2]------[fe3] RTR3

RPR: standby RP is partially initialised. That is, only the startup-config
of the active router and standby router are sync'ed.
On the asr1006, I have dual rp's. fe1/fe2 are both on and I ensured to save
the configurations in startup-config.

I sent a ping from RTR1 to RTR3 and at the same time, I forced a switchover
from RP0 to RP1 in the asr1006. However, instead of RP1 taking over
instantaneously, it seemed to go through a reset phase. That is, I saw the
folloing output "This product contains cryptographic features and is
subject to United States and local country laws governing import, export,
trans..."

I lost about 1 or 2 minutes of pings during this stage, then RP1 stabilised
and the pings started going through.

Is this expected behaviour?
Please note, RP0 and RP1 had different ios versions. I still expected the
switchover to be hitless, then, lose some pings after some time due to SIP
upgrade.

Also, why would anyone use RPR over SSO?

thank you,
Bob