Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

DHCP Lease process with static clients

Hi ,

I have a question regarding DHCP .

Let us assume that DHCP server has been configured with ip address pool,  say for ex: 192.168.1.2 to 192.168.2.254.

Now  assume that in the LAN network we have 3 clients which have got the  DHCP addresses from the above pool say from 192.168.1.2 to 192.168.1.4.

Now  I will add one more client with static ip address from the above pool say IP: 192.168.1.5.

Now if I add one more DHCP client, in the above LAN network, will the DHCP server come to know that there is already static client with IP address 192.168.1.5 is exist? and for the newly added client, will it give the same static ip address 192.168.1.5 or will give the next available IP address?

Basically I want to understand that whether DHCP server will have idea of static clients?

Regards, Raghavendra Sakhe
Everyone's tags (1)
5 REPLIES
Purple

DHCP Lease process with static clients

Hi,

Almost all implementations of DHCP Server will ping for the address they widh to allocate before proposing it to the client.

Now if there is no ping reply it will assume it can allocate this IP to the client and the client before accepting it will send a gratuitous ARP request for this IP and if it receives a reply it will know it is already assigned and it will send a DHCP decline message to the server which will try to allocate another IP.

Regards

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.
New Member

Re: DHCP Lease process with static clients

Thanks for your reply .

Regards,

Raghavendra Sakhe

Regards, Raghavendra Sakhe
New Member

Re: DHCP Lease process with static clients

Hello Alain,

I also wanted to clarify in regards to the topic above, that in a situation where an IP address already assigned to another host is statically assigned to an end host, the router should generate an error mesaging in its output stating that a duplicate IP address allocation has occured and the port at which the devices are connected also shows.

Regards,

DJ

Purple

DHCP Lease process with static clients

Hi,

end hosts should test the unicity of the ip address configured by sending a GARP request asking for the MAC corresponding to their IP and if they receive an answer then they know there is a duplicate address. Routers don't care if multiple hosts have the same IP.

Regards

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.

DHCP Lease process with static clients

Hi,

you can do this creating more than one dhcp server on your router, and you can provide the IP address from the different dhcp servers through assigning ip address from the blog to the specific interface in the router.

  regarding the static IP address that have been assigned to a host in your network, the dhcp try to lease the same IP address to another hosts in the network, but once it detected that this IP address is conflected the dhcp server remove this IP address and assign the next IP to the host.

please let me know if this is not cleare.

regards,

683
Views
22
Helpful
5
Replies
CreatePlease login to create content