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Cisco Bug: CSCur57579 - N7K: MTS queue builds up or get full, results in LACP instability

Last Modified

Sep 10, 2019

Products (8)

  • Cisco Nexus 7000 Series Switches
  • Cisco Nexus 7000 10-Slot Switch
  • Cisco Nexus 7000 4-Slot Switch
  • Cisco Nexus 7700 6-Slot Switch
  • Cisco Nexus 7000 18-Slot Switch
  • Cisco Nexus 7700 18-Slot Switch
  • Cisco Nexus 7000 9-Slot Switch
  • Cisco Nexus 7700 10-Slot Switch

Known Affected Releases

6.2(10) 6.2(8a)

Description (partial)

Symptom:
Log message:
%LACP-5-LACP_SUSPEND_INDIVIDUAL: LACP port Ethernet7/18(0x1a311000) of port-channel Ethernet7/18(0x1a311000) not receiving any LACP BPDUs  suspending (individual) port

MTS messages destined to LACP (SAP 347) are stuck in the persistent queue of MTS

N7K#show system internal mts buffers summary  
node    sapno   recv_q  pers_q  npers_q log_q
<snip>
sup     347     0       128281  0       0
<snip>

SAP 347 is LACP, and "sup" refers to default VDC.
This issue can happen in any VDC.

Conditions:
Currently the known condition is executing "show lacp interface <fex interface>"and the specific interface using LACP.
This issue is seen when the Nexus is using either fast-rate or normal rate LACP PDU's.
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
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