Yes, 2 6880 chassis and each chassis with single Supervisor Engine.

Yes, 2 chassis and each chassis with 1 PFC (routing engine)

The "system" had no downtime when I run "redundancy reload peer". The standby unit had a downtime for about 10 minutes.We have 2 pc of 6880-X.

I upgraded my 6880 in VVS this morning from 15.2(1)SY6 to 15.5(1)SY3.It went fine.Here is the guide I got and followed:  Command Purpose Step 1 Router# copy tftp disk_nameUses TFTP to copy the new software image to flash memory on the VSS active and ...