[j-nsp] Redundancy with MX

[Stephen Hon]

Ouch… I picked a single MX480 chassis design over a dual MX80 because of
the unavailability of the MS-DPC card in the MX80.

We're very new to Juniper here with close to no practical experience.
Nonetheless, we're migrating away from Brocade NetIron MLX to the MX and
we figured that dual RE and SCB would helpful relative to ISSU and NSR but
I guess the general consensus is that it's preferable to have separate
routers over redundant RE's.

I'm wondering though, would dividing some of the routing duties into
logical systems help to protect from a massive system-wide problem? From
what I understand the logical systems spin up their own set of processes
and have their own configuration so it would seem that there could be some
level of protection.