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Cisco Bug: CSCvv40252 - TCP SYN dropped on established connection for telemetry/TPA session

Last Modified

Oct 24, 2020

Products (1)

  • Cisco ASR 9000 Series Aggregation Services Routers

Known Affected Releases

6.5.3.BASE

Description (partial)

Symptom:
Regular inbound telemetry probes intermittently fail for a small number of particular TCP ports.
tcpdump of connection during failure shows repeated SYNs being sent for the same port, but no response from the router.

Conditions:
Could impact any TCP session to TPA application (e.g. telemetry)
Only seen when there are stale TCP sessions in TPA. This may be caused by RPFO or by a s/w reload of IOS-XR (reload location all).
Existing TCP sessions can be checked using netstat from bash.
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Bug Details Include

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