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Cisco Bug: CSCun87478 - DHCP proxy client cause duplicate IPV4 address on the PPP side

Last Modified

Apr 17, 2019

Products (9)

  • Cisco IOS
  • Cisco ASR 901-6CZ-F-D Router
  • Cisco ASR 901-4C-FT-D Router
  • Cisco ASR 901-6CZ-F-A Router
  • Cisco ASR 901-6CZ-FT-A Router
  • Cisco ASR 901-12C-FT-D Router
  • Cisco ASR 901-4C-F-D Router
  • Cisco ASR 901-6CZ-FT-D Router
  • Cisco ASR 901-12C-F-D Router

Known Affected Releases


Description (partial)

When a router is configured for DHCP-proxy-client, if the a second connection with the same 
username is received, a DHCP RELEASE is send. The behavior is normal for DHCP as the 
same username on PPP triggers the same CLIENT-ID, and CLIENT-ID should be unique.

The wrong behavior is that the PPP is left with the IP address, this cause duplicate ip address 
on the PPP side.

If it is expected to have multiple connection with the same username a command "ppp ipcp username unique" can be used in this case a unique CLIENT-ID will be build. 
But the above obviously will allocated more addresses, which render this solution not useful for service provider 
that do not wish to provide multiple address for the same subscriber

- Using dhcp-proxy-client in IOS
- Receiving the a ppp connection twice with the same username.
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
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  • Known Fixed Releases
  • Related Community Discussions
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