3com S7906E Manuel De Montage

 

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If the server returns a DHCP-ACK message or does not return any message within a specified 

interval, which means the IP address is assignable now, the DHCP relay agent will age out the 

client entry with this IP address.  

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If the server returns a DHCP-NAK message, which means the IP address is still in use, the relay 

agent will not age it out. 

Follow these steps to configure periodic refresh of dynamic client entries: 

Enter system view 

— 

Enable periodic refresh of 
dynamic client entries 

Optional 

Enabled by default.  

Configure the refresh 
interval 

dhcp relay security 
tracker { interval | auto } 

Optional 

auto by default. (auto interval is 
calculated by the relay agent according 
to the number of client entries.) 

 

There are unauthorized DHCP servers on networks, which reply DHCP clients with wrong IP 

addresses. 

With this feature enabled, upon receiving a DHCP request, the DHCP relay agent will record the IP 

address of the DHCP server which assigned an IP address to the DHCP client and the receiving 

interface. The administrator can use this information to check out any DHCP unauthorized servers. 

Follow these steps to enable unauthorized DHCP server detection: 

Enter system view 

— 

Enable unauthorized DHCP 
server detection 

Required 

Disabled by default. 

 

With the unauthorized DHCP server detection enabled, the device puts a record once for each DHCP 

server. The administrator needs to find unauthorized DHCP servers from the log information. After the 

information of recorded DHCP servers is cleared, the relay agent will re-record server information 

following this mechanism. 

 

This task allows you to release a client’s IP address manually on the DHCP relay agent. After you 

configure this task, the DHCP relay agent actively sends a DHCP-RELEASE request that contains the 

client’s IP address to be released. Upon receiving the DHCP-RELEASE request, the DHCP server then 

releases the IP address for the client; meanwhile, the client’s IP-to-MAC binding entry is removed from 

the DHCP relay agent.