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Cisco Bug: CSCvt60639 - client link-layer address option only showing 32-bit from the client RFC6939

Last Modified

Aug 12, 2020

Products (9)

  • Cisco Nexus 7000 Series Switches
  • Cisco Nexus 7000 10-Slot Switch
  • Cisco Nexus 7000 4-Slot Switch
  • Cisco Nexus 7700 6-Slot Switch
  • Cisco Nexus 7700 18-Slot Switch
  • Cisco Nexus 7000 18-Slot Switch
  • Cisco Nexus 7700 2-Slot Switch
  • Cisco Nexus 7700 10-Slot Switch
  • Cisco Nexus 7000 9-Slot Switch

Known Affected Releases


Description (partial)

In DHCPv6 environment with Nexus 7k as a DHCP relay, the client link-layer address option 79 is only showing 32-bit from the client mac address, not the full one.
it's replacing the last 2-bytes with zero value.

Client mac address : 084f.a974.dc10
Under option 79 : 

    Client Link-Layer Address
        Option: Client Link-Layer Address (79)
        Length: 8
        Value: 0001084fa9740000

The issue occurred on Nexus 7k switch with a DHCP relay configuration for IPv6.
Version: 8.4(1)
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
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