Cisco Bug: CSCuo78312 - Packet drop due to TX MTU verification for specific frame sizes
Mar 05, 2018
- Cisco Catalyst 6000 Series Switches
Known Affected Releases
Symptom: Packet drop seen for locally sourced traffic when generating packets below configured system jumbomtu. Drops are caused by Dhanush port ASIC at WS-X6148A-GE-45AF line card. Additional tests showed the following behavior: a) for configured jumbomtu less or equal to 1603 bytes: ICMP traffic is dropped above Jumbomtu-8 bytes. b) for configured jumbomtu higher or equal to 1604 bytes and less or equal to 1606 bytes: ICMP traffic is dropped between 1597 and 1600 bytes. c) for configured jumbomtu equal to 1607 bytes: ICMP traffic is dropped for size equal to 1600 bytes. d) for configured jumbomtu higher than 1607 bytes: packet drops are no longer seen irrespective of MTU size Conditions: Drop behavior seen for locally sourced traffic only (example: routing protocols related packets, icmp request packets). Only locally sourced TX traffic is affected by this behavior. RX traffic or L2 switched traffic are not affected.
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