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    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 processes that control the Link Aggregation Control Protocol (LACP) and Bidirectional Forwarding Detection (BFD) protocols, 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, EX4200, and EX4500 switches) or the line cards (on EX6200 and 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.

    You can disable distributed PPM for all protocols that use PPM. You can also disable distributed PPM for LACP packets only.

    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.

    Modified: 2012-02-01