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A Client IP Address Conflict Occurs When an ME60 Is Connected to an External DHCP Server

Publication Date:  2019-03-27 Views:  22 Downloads:  0
Issue Description

Issue Description

PC1----------ME60--------DHCP Server

                       |

                       |

                     PC2

Users are connected to an ME60 through IPoE. The ME60 checks whether IPoE users are online for five times by default. Because the uplink from PC1 to the ME60 is faulty, the ME60 detects that PC1 has gone offline. The ME60 sends DHCP Release messages to the external DHCP server for PC1. In this case, PC2 is connected to the ME60, and the IP address expected to be assigned to PC1 is now assigned to PC2. Because PC1 still uses this IP address, an IP address conflict exists.

Handling Process

When the ME60 is connected to an external DHCP server, the ME60 detects whether IPoE users are online and sends DHCP Release packets to the DHCP server based on the detection result to release user IP addresses.

Root Cause

When the ME60 is connected to an external DHCP server, the quality of the PPPoE Layer 2 link is not good. As a result, when detecting user offline, the ME60 sends DHCP Release packets to the DHCP server. The DHCP server reclaims IP addresses and assigns them to other users, causing an IP address conflict.

Solution

Run the undo release-agent command on the ME60 to disable the function to send DHCP Release packets to reclaim IP addresses upon detection of user offline.


Example
# Disable the DHCPv4 server group from remotely sending DHCPv4 Release messages.

<HUAWEI> system-view

[~HUAWEI] dhcp-server group remote

[*HUAWEI-dhcp-server-group-remote] undo release-agent





END