Cisco Bug: CSCuq26920 - 3850/3650 Access-List not permitting ICMP Fragments
Nov 27, 2020
- Cisco Catalyst 3850 Series Switches
Known Affected Releases
Symptom: 3650 and 3850 switches will drop ICMP Fragments when passing through an access-list with any kind of "deny icmp" statement configured. Conditions: Any 3650 or 3850 switches with an access-list applied where there is a "deny icmp" statement before a "permit ip any any" statement will trigger this issue. Specifically the ICMP fragments will be dropped, the initial ICMP packet with header information will check against the access-list correctly. ICMP Fragments occur when an ICMP frame has to be broken into multiple parts due to MTU settings on nodes on the network.
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Bug Details Include
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