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New Member

CIsco 3560X DHCP Permanent allocation

Hello,

I am interesting if it is possible to configure DHCP Server on 3560X switches in such way, that when PC takes ip address, this ip should stay to that pc permanently even after reboot.

  • LAN Switching and Routing
7 REPLIES
New Member

CIsco 3560X DHCP Permanent allocation

Yes its possible, its something called DHCP Reservations when using Windows Server but its not a feature as such with Cisco devices.

It can be done by creating a seperate pool for the reserved device as per the guide below.

http://inetpro.org/wiki/DHCP_Sample_Config_With_Static_Reservation

Effectively you create a second pool with a host address and a client-identifier so you will need the MAC address of the device you want to reseve an address for,

Thanks

New Member

CIsco 3560X DHCP Permanent allocation

You can use lease infinite command inside pool configuration terminal or (i  think this is more robust solution) use static/manual bindings for only devices that realy need it.

Regards,

New Member

CIsco 3560X DHCP Permanent allocation

Hello,

The problem is that i don't want to write separete pools for each host.

I found  remember command under the DHCP pool ?

Does anyone know what it is doing ?


Purple

CIsco 3560X DHCP Permanent allocation

Hi,

I'm afraid this is the only way to do static bindings in the 3560 as I don't think it supports the origin file command.

So if you don't want to configure host pools you'll have to use the infinite lease but it will apply for all the leased IP addresses. I've never seen this remember command, could you post a screenshot with the Question mark following this command and post which version of IOS you're using.

Regards

Alain

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New Member

CIsco 3560X DHCP Permanent allocation

Hello,

Hire is screenshot. it seems that remember command is exactly for my requirements. I was unable to find this command description in documentation

Purple

CIsco 3560X DHCP Permanent allocation

Hi,

You've got the origin command and this is for sure for static bindings without using host pools, I'll have to look for this remember command on one of my switches.I thought this was not available on switches but it seems it is now.

http://www.cisco.com/en/US/docs/ios-xml/ios/ipaddr_dhcp/configuration/15-mt/config-dhcp-server.html#GUID-BCEB43D4-8C44-4C86-BBAA-6B977196D35C

Regards

Alain

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Hall of Fame Super Gold

Re: CIsco 3560X DHCP Permanent allocation

Yes, it's very do-able.

Here's how you do it easily ...

1.  Get the client to obtain a dynamic IP Address (I'll explain why in the next two lines);

2.  Enter the command "sh ip dhcp bind".

3.  Do not look at the second column, yet.  Look at the first column, the IP address.  Match the IP address of your client and go to the second column.  In the second column, EVERYTHING starts with a "01".  The next 12 chararcters is the original MAC address of the client.  COPY THIS ENTIRE STRING DOWN.  From "01" until the end.  Do not remove the ".".

4.  Your DHCP Pool reservation should now look like this ...

conf t

do clear ip dhcp bind *

ip dhcp pool BLAH

host --- Note:  For subnet mask, you can also you the "slash" annotation, like /24

dns-server

domain-name

client-identifier

end

Hope this helps.

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