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Cisco Bug: CSCuq45643 - N9K: Mbuf Exceeded causes all port-channel down

Last Modified

Mar 06, 2018

Products (2)

  • Cisco Nexus 9000 Series Switches
  • Cisco Nexus 9508 Switch

Known Affected Releases

6.1(2)I1(1)

Description (partial)

Symptom:
All port-channels go down and device is not accessible via ssh/telnet.

Conditions:
This issue is seen when advertising many routes (in this case 10,000) each with a different AS path.  When this occurs the switch sends out TCP packets with one BGP update each quickly. Due to this the neighbor does not ack the TCP packet. Because of this the sender then sends a tcp re-transmission with as many of the previous BGP updates not acked as it can up to the MTU size.  This copying of many of the BGP updates into one packet causes an overflow in the mbuf buffer. This causes all interfaces to not send out any traffic. This causes all port-channels to go down as well as device not to be accessible via SSH/telnet (only accessible via console)
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