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Cisco Bug: CSCta24404 - ISSU to 4.2(1) may result in port-channel packet forwarding issues

Last Modified

Feb 23, 2018

Products (1)

  • Cisco Nexus 7000 Series Switches

Known Affected Releases


Description (partial)


ISSU from a lower version into 4.2(1) image may result in issues regarding packet forwarding on port channels. 

A software inconsistency defect may result in the following symptoms:
Upon module reload or port-channel member flaps: 
- the Egress VSL bit can get incorrectly programmed, resulting in loops. 
- the vlan membership in ELTM can be incorrect, resulting in the vlans not enabled on certain port-channels - resulting in packet drops.

ISSU from a lower version into 4.2(1) image is a necessary condition for this problem. The underlying issues may not show up right after ISSU. It may show up only after some ports flap, or modules get reloaded.
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