LACP intermittently stops distributing

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Article ID: 167792

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Updated On:

Products

XOS

Issue/Introduction

LACP may intermittently stop distributing when master VAP is overloaded.
LACP stops distributing for a short period of time. Following messages appear in /var/log/messages:
 
Mar 28 02:46:38 fw_1 kernel: veth: port 1,3 stop distributing. 
Mar 28 02:46:46 fw_1 kernel: veth: port 1,3 start distributing. 

Mar 28 12:14:54 fw_1 kernel: veth: port 1,5 stop distributing. 
Mar 28 12:14:55 fw_1 kernel: veth: port 1,5 start distributing. 

 

Cause

Problem:

When the master VAP is under high load, the exchange of LACP control messages with the neighbor switch may be delayed. This happens more likely when LACP is configured for fast updates and the control packets are sent every second. The normal rate at which LACP packets are sent is 30 seconds.

The current frequency (Slow or Fast) can be verified using the CLI command  show veth-stats:

Reporting Module            fw_1
    Load Balance State      Selected
    Slot/Port               1/3
    Circuit Name            lan
    Local Key               0x0200
    Partner Key             0x0008
    Partner Sys. Priority   32667 
    Partner ID              00:21:9a:12:c3:80
    TX State                Distributing
    RX State                Current
    Check Frequency         Fast Periodic
    Local Oper. State       LACP Activity, Aggregation, Synchronization, Collecting, Distributing
    Partner Oper. State     LACP Activity, LACP Timeout, Aggregation, Synchronization, Collecting, Distributing
 

Resolution

The LACP frequency isn't configurable on X-series. Please change the frequency on the neighbor switch to allow slow LACP updates. See your switch documentation for information how to change the frequency. On Cisco devices, the command is lacp rate normal in the interface context. 


 

Workaround