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Cisco Bug: CSCvt75704 - Unicast ARP requests are reflected back on received ports when Dynamic APR Inspection is enabled

Last Modified

Sep 01, 2020

Products (68)

  • Cisco IOS
  • Cisco Catalyst 9400 Supervisor Engine-1XL-Y
  • Cisco Catalyst C9500-16X-E Switch
  • Cisco Catalyst 9300-48UXM-A Switch
  • Cisco Catalyst 9300-48T-A Switch
  • Cisco ASR 1000 Series IOS XE SD-WAN
  • Cisco Catalyst 9300-48U-A Switch
  • Cisco Catalyst 9300-48P-A Switch
  • Cisco 4221 Integrated Services Router
  • Cisco Catalyst 9800-40 Wireless Controller
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Known Affected Releases


Description (partial)

The customer may see the symptoms like:
[*] MAC flaps.
[*] ARP flooding
The issue is that the Unicast ARP requests are reflected back on the port where the unicast ARP request was received if the Dynamic ARP Inspection is enabled and the destination MAC is in the MAC address table.

[*] IE3x00 running 16.12.x release
[*] Dynamic ARP inspection enabled
[*] Unicast ARP request
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Bug Details Include

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