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Cisco Bug: CSCvu94706 - FXOS dynamically learning mac-address of external machine causing outage

Last Modified

Oct 04, 2020

Products (1)

  • Cisco Firepower 9300 Series

Known Affected Releases

2.7(1.106)

Description (partial)

Symptom:
All traffic egressing the ASA/FTD logical app destined to a machine that is directly connected (e.g. via layer2) is being dropped via FXOS.

Conditions:
FXOS dynamically learns mac address of external machine via the backplane interface veth<123>.  Example below:

Firepower(fxos)# show mac address-table 
Legend: 
        * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC
        age - seconds since first seen,+ - primary entry using vPC Peer-Link
   VLAN     MAC Address      Type      age     Secure NTFY   Ports/SWID.SSID.LID
---------+-----------------+--------+---------+------+----+------------------
* 1011     cafe.dead.babe    dynamic   489240     F    F  Veth857

Issue has been observed with the following attributes:

- ASA logical device deployment in multi-context
- ASA logical device context is transparent
- ASA logical device configured as active/active HA (with multiple failovers)

*** Note: There should not be any dynamic learning of mac addresses via fxos as the mac address table is populated on boot. ***
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