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Cisco Bug: CSCtf21937 - UDP Modular IOS sends out DHCP Packet with diff source-IP comp. to IOS

Last Modified

Jan 29, 2017

Products (6)

  • Cisco IOS
  • Cisco Catalyst 6500 Series Virtual Switching Supervisor Engine 720 with 10GE uplinks
  • Cisco ME 6524-GS Ethernet Switch
  • Cisco Catalyst 6500 Series Supervisor Engine 32 / MSFC2A
  • Cisco ME 6524-GT Ethernet Switch
  • Cisco Catalyst 6500 Series Supervisor Engine 720 / MSFC3

Known Affected Releases


Description (partial)


On a 6500 running Modular IOS software running DHCP relay.

 DHCP packets might be send out with the secondary IP address as a source of the packet.

This might be seen on following :

interface Vlan166
 ip address secondary
 ip address

If the DHCP ack is destined towards a desintation in subnet it will be send out with the source


Modular IOS (12.2(33)SXH/12.2(33)SXI and DHCP Relay.
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Bug Details Include

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