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switches:dhcp-helper [2019/03/15 18:20] (current)
ericclaus created
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 +======DHCP Helper Addresses and DHCP Sooping======
 +=====DHCP Helper Addresses=====
 +DHCP helper addresses are configured on the routing switch to forward DHCP request broadcasts to each DHCP server and each System Center Configuration Manager server (required for PXE booting). ​
 +Run the following command to see existing IP helper addresses:
 +<​code>​show ip helper-address</​code>​
 +In order to add or remove a DHCP server or PXE bootable SCCM server, run the following command for each VLAN that needs DHCP or PXE boot capabilities:​
 +<​code>​[no] vlan <VLAN ID> ip helper-address <​IP></​code>​
 +For example, to add a server with the IP address to VLAN 260:
 +<​code>​vlan 260 ip helper-address</​code>​
 +Make sure to delete any old IP helper addresses for servers no longer in use by adding ''​no''​ to the beginning of the command.
 +=====DHCP Snooping=====
 +DHCP snooping is used to allow DHCP (and PXE) from authorized servers only. These authorized servers need to be added to the core switch, along with any other switches that perform routing. ​
 +To view the current DHCP snooping authorized servers:
 +<​code>​show dhcp-snooping</​code>​
 +To add or remove a server as a DHCP snooping authorized server:
 +<​code>​[no] dhcp-snooping authorized-server <​IP></​code>​
 +Make sure to delete any old servers no longer in use by adding ''​no''​ to the beginning of the command.
  • switches/dhcp-helper.txt
  • Last modified: 2019/03/15 18:20
  • by ericclaus