Disabling Distributed Periodic Packet Management on the Packet Forwarding Engine
Periodic packet management (PPM) is responsible for periodic transmission of packets on behalf of its various client processes, such as Bidirectional Forwarding Detection (BFD). PPM also receives packets on behalf of client processes. By default, PPM handles time-sensitive periodic processing and performs such processes as the gathering of statistics and the sending of process-specific packets. Distributing PPM to the Packet Forwarding Engine allows you to run such processes as BFD on the Packet Forwarding Engine. In Junos OS Release 9.4 and later, PPM automatically runs on both the Routing Engine and the host subsystem of the Packet Forwarding Engine or Dense Port Concentrator (DPC).
 | Note: Distributed PPM runs on access ports on EX3200 and EX4200 switches and on line cards on EX8200 switches. Therefore, each instance of “Packet Forwarding Engine” in this topic is a shortened version of “Packet Forwarding Engine, access ports, or line cards.” |
PPM runs on the Routing Engine and Packet Forwarding Engine by default. You can only disable PPM on the Packet Forwarding Engine. To disable distributed PPM on the Packet Forwarding Engine, include the ppm statement:
For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.
| Note: Distributed PPM is supported only on the M7i and M10i routers with Enhanced CFEB (CFEB-E); M120 and M320 routers; and all MX Series, T Series, TX Matrix routers, and EX Series switches. |
The following types of sessions are supported by distributed PPM:
- BFD single-hop session for both IPv4 and IPv6, including EBGP, ISIS, and OSPF
- Connectivity fault management (CFM) sessions
- Link fault management (LFM) sessions
- Rapid Spanning Tree Protocol (RSTP) and Multiple Spanning Tree Protocol (MSTP) interface sessions
- Link Aggregation Control Protocol (LACP) sessions (MX Series and M320 routers only)
- BFD over an aggregated interface for IPv4
The following types of sessions are not supported by distributed PPM:
- BFD over an aggregated interface for IPv6, RSTP, MSTP, and LACP
- BFD over an IPv6 interface that does not have the global IPv6 address (or only has a link local address)
- Multihop BFD with IBGP, static routes, EBGP multihop, and MPLS LSP
- BFD over an MPLS path using OAM
In addition, on the M120 router, when Forwarding Engine Board (FEB) redundancy is configured and a FEB fails over, PPM sessions do not automatically switch over to the newly active FEB. For more information about FEB redundancy, see the Junos System Basics Configuration Guide.
