Cisco DHCP Relay "IP Helper Address"

So today we wanted to move some servers over to a different switch... We went inside the switch, assigned the proper configurations to the ports and also assigned to our SERVER VLAN but for some reason when we plugged into these ports we were not getting ANY IP address from DHCP..

We double checked our DHCP scope, server and subnet. Everything was setup properly.. We already have other servers on this VLAN without any problems and other ports on this same switch using different VLANS are getting DHCP without any problems...

So it came to my attention the DHCP was not "RELAYING"

To do this you have to setup an ip-helper address like this:


1) log into switch via telnet
2) enable to get privliges
3) switch# conf t
4) switch(conf)# interface vlan 123
5) switch(if-conf)# ip helper-address 192.168.1.2


Here is the break down on what we just did..

1) Get on to your switch by telneting into it via IP address

2) You need to gain privleged acccess to get to configure the terminal

3) this command will get you in to the configuration mode

4) this will get you into the configuration of the VLAN - the default vlan is 1 normally

5) this command "ip helper-address" tells your switch where to find the DHCP server...



Hope this helps :)


Enjoy