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[M/MX] How to check PPMD mode and troubleshooting tips

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Article ID: KB31595 KB Last Updated: 27 Apr 2017Version: 1.0
Summary:

This article provides 3 methods for identifying Periodic Packet Management Daemon​ (PPMD) work mode, troubleshooting tips, and data collection commands for PPMD issues issue.

Symptoms:

PPMD off-loads time-sensitive periodic processing from various clients to a single daemon. It is responsible for periodic transmission of packets on behalf of its various clients. Clients establish adjacencies with PPMD to send/receive packets on their behalf. When packets are not received, the adjacency is marked down and the client is informed.

There are two types of PPMD:

  1. ​Centralized Mode - RE based; PPMD runs on RE
  2. Distributed Mode - PFE based. Currently BFD, LFM, CFM, LACP and VRRP are in distribute mode as default. (except BFD for OSPFv3)
Solution:

How to check PPMD Mode:

Method 1

'show ppm adjacencies detail'

OSPFv2
lab@mx240-3-re0> show ppm adjacencies detail
Protocol: OSPF2, Hold time: 40000, IFL-index: 359
Distributed: FALSE
OSPF source key: 88.1.1.2, OSPF area ID: 0.0.0.0
In the example above, the “Distributed” flag is false. Hence, OSPF is running on RE PPMD

BFD
lab@mx240-3-re0# run show ppm adjacencies detail
Protocol: BFD, Hold time: 900, IFL-index: 359
Distributed: TRUE
BFD discriminator: 16, BFD routing table index: 0
Here, the “Distributed” flag is TRUE. Hence BFD is distributed to PFE

Method 2

Go to PFE shell and run 'show ppm adjacencies' or 'show ppm transmits' . It will list all the distributed PPMD:
NPC1(mx240-3-re0 vty)# show ppm adjacencies
PPM distributed adjacencies
Protocol   Holdtime (msec) PPM handle  Inline
BFD        900             2           No
Total adjacencies: 1
NPC1(mx240-3-re0 vty)# show ppm transmits
Protocol    Tx Interval (msec)  PPM handle  Inline     Quick Xmit
BFD         300                 1           No         No
Total transmit entries: 1

Method 3

Run 'show ppm adjacencies protocol XXX detail'
lab@mx240-3-re0# run show ppm adjacencies protocol lacp detail
Protocol: LACP, Hold time: 3000, IFL-index: 361
Distributed: TRUE
Distribution handle: 30, Distribution address: fpc1
Adjacencies: 1, Remote adjacencies: 1

Troubleshooting Tips

As a troubleshooting method, use the command 'set routing-options ppm no-delegate-processing' to make PPMD centralized. This will reveal if the issue is due to PFE failure itself or not. In other words, if a protocol is having an issue running on distributed mode, but not with centralized mode. Then we can narrow down the issue.

lab@mx240-3-re0#set routing-options ppm no-delegate-processing
lab@mx240-3-re0#commit
lab@mx240-3-re0#run clear bfd session
lab@mx240-3-re0#run show ppm adjacencies detail
Protocol: BFD, Hold time: 900, IFL-index: 359
Distributed: FALSE
BFD discriminator: 17, BFD routing table index: 0

 

Useful Commands

Collect the below from RE:

  • show ppm connections detail
  • show bfd session extensive (if BFD is what we are interested in)
  • show ppm interfaces detail
  • show ppm adjacencies detail
  • show ppm transmissions detail
  • After JUNOS 12.1 release, collect the below additional commands
  • show ppm distribution-statistics
  • show ppm dfw-statistics
  • show ppm packet-snapshot
  • show ppm reques-queue
  • show ppm rpd-statistics

Collect the below from PFE (for distributed):

  • show ppm adjacencies
  • show ppm info
  • show ppm local adjacencies protocol cfm (for CFM)
  • show ppm objects
  • show ppm statistics detail
  • show ppm statistics protocol <bfd lacp cfm lfm stp vrrp>
  • show ppm transmits
  • show threads
  • show pfe statistics traffic [5 snapshots 30 sec apart]
  • show pfe statistics error
  • show pfe statistics notification
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