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Cisco Bug: CSCut58048 - FI May Create Switching Loop/Broadcast Storm in End-Host Mode

Last Modified

Feb 20, 2018

Products (1)

  • Cisco Unified Computing System

Known Affected Releases

2.2(3d)A

Description (partial)

Symptom:
Removal of an Po from a port-channel on the IOS switch, which leaves the FI's port in an I state:

F340.06.04-6500#show etherchannel summary 
Flags:  D - down        P - bundled in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      N - not in use, no aggregation
        f - failed to allocate aggregator

        M - not in use, no aggregation due to minimum links not met
        m - not in use, port not aggregated due to minimum links not met
        u - unsuitable for bundling
        d - default port

        w - waiting to be aggregated
Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
10    Po205(SU)       LACP      Te1/5(P)    				<----------   


===================================================================================

On the FI we see the Po has a link in the I state:

F241-03-09-UCS6-A(nxos)# show port-c sum
Flags:  D - Down        P - Up in port-channel (members)
        I - Individual  H - Hot-standby (LACP only)
        s - Suspended   r - Module-removed
        S - Switched    R - Routed
        U - Up (port-channel)
        M - Not in use. Min-links not met
--------------------------------------------------------------------------------
Group Port-       Type     Protocol  Member Ports
      Channel
--------------------------------------------------------------------------------
10    Po10(SU)    Eth      LACP      Eth1/15(P)   Eth1/16(I)   <----------

Conditions:
Fabric Interconnect in EHM and IOS switch upstream

On the IOS switch remove the interface from the port-channel via interface configuration.  

Ex:
conf t
int t1/4
no channel-group 20

NXOS devices should not be affected by this.  NXOS devices flap the port on configuration change.  IOS devices do not.
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