Juniper 4300

Earliest date associated with this switch is Feb 2013.

switch circuit board seen with lid removed

The datasheet in spite of its length does not disclose the packet buffer memory. The datasheet says that the switch has a single switching ASIC which they refer to as the EX-PFE. I suspect, however, that this is actually a Marvell ASIC and not Juniper custom silicon. Other information on EX buffers from NANOG.