3560 switch dhcp question

Answered Question
Aug 13th, 2007

3560 switch out of the box. It is not getting an ip through dhcp.Should'nt it get an ip through dhcp.


Do i need to enable some dhcp feature in it.


My understanding was that the switch should be dhcp enabled.


Any help is appreciated.

Correct Answer by mohammedmahmoud about 9 years 6 months ago

Hi,


What you are asking about, is the command "ip address dhcp" there under the interface vlan1 by default, and AFAIK the answer will be no, you'll have to enter it for you switch to get an IP from the DHCP server.


HTH,

Mohammed Mahmoud.

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a.mir Mon, 08/13/2007 - 13:04

thanks for the reply, but i am still not sure what you mean.


Once the new switch is connected on the network, should the interface vlan 1 show an ip addressed recieved through dhcp.


Thanks.

Typically you'd provide addressing. Or have the/a switch in the layer 2 domain be a VTP server where you'd provide the VLAN addressing and it would propogate via VTP to Client switches.


It's a little more complex than just plugging it in.


I'd recommend you really read the doc I referenced and IP addressing reference docs linked in the DHCP document.



a.mir Mon, 08/13/2007 - 13:28

what if there is only one vlan, and a switch is connected to a hot port, the switch should come up with the ip address for the same vlan.


no vtp involved since there is only one vlan which is the management vlan.



You really need to read about DHCP as well as what a VLAN really is. For a host to get a DHCP address there needs to be a DHCP server and a pool of addressed to be served. These all need to be configured manually.


And with a VLAN, you need to manually assign it an IP Address/network subnet somewhere in the layer 2 of the subject network.


If you want that switch to also be a DHCP server, you need to configure a pool of addresses for the server to hand out to DHCP clients.


If you have an external DHCP server using the

ip name-server x.x.x.x


command you turn off DCHP services on the switch and let your external servers give out the addresses.


There's no automatic way to get a DHCP address automaticaly for a VLAN segment, as far as I know.




a.mir Mon, 08/13/2007 - 13:57

again i appreciate your help in this, but i believe you have misunderstood my question. i am not trying to make the switch hand out the ip addresses or make it a dhcp server.


Here is a scenerio, a remote site with a cisco 2811 router with an ip helper address configured to received ip's for the local lan through a dhcp server remotely for the clients/hosts.There are 4 preconfigured switches with ip's connected and up and running with one vlan which is the management vlan.No multiple vlans so i believe no trunking would be required.would you agree to that?


The whole purpose to the question is to add one more switch to that lan to increase the port density and i wanted the vendor to send the switch directly to the site so it could be connected on the network and get an ip dynamically and i could configure it remotly with standard parameters.




Correct Answer
mohammedmahmoud Mon, 08/13/2007 - 14:05

Hi,


What you are asking about, is the command "ip address dhcp" there under the interface vlan1 by default, and AFAIK the answer will be no, you'll have to enter it for you switch to get an IP from the DHCP server.


HTH,

Mohammed Mahmoud.

a.mir Mon, 08/13/2007 - 14:08

Thanks Mohammad,


that was my question. perfect, thanks.

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