Understanding Distributed Periodic Packet Management on EX Series Switches
Periodic packet management (PPM) is responsible for processing a variety of time-sensitive periodic tasks for particular processes so that other processes on the Juniper Networks EX Series Ethernet Switch can more optimally direct their resources. PPM is responsible for the periodic transmission of packets on behalf of its various client processes, which include the process that controls Link Aggregation Control Protocol (LACP), and also for receiving packets on behalf of these client processes. PPM also gathers some statistics and sends process-specific packets. PPM cannot be disabled and is always running on any operational switch.
The responsibility for PPM processing on the switch is distributed between the Routing Engine and either the access interfaces (on EX3200 and EX4200 switches) or the line cards (on EX8200 switches) for all protocols that use PPM by default. This distributed model provides a faster response time for protocols that use PPM than the response time provided by the nondistributed model.
If distributed PPM is disabled, the PPM process runs on the Routing Engine only.
Distributed PPM can be disabled for all protocols that use PPM or for a single protocol that uses PPM. There is no way to disable PPM entirely.
 | Best Practice: We recommend that, generally, you disable distributed PPM only if Juniper Networks Customer Service advises you to do so. You should disable distributed PPM only if you have a compelling reason to disable it. |
