DHCP On Cisco Router

[Khrysis]

Does Cisco DHCP server on switches & routers support options configuration? I saw this on Cisco Secure Firewalls but not on the aforementioned. Can someone lead me to a resource where I can find the how-to, if at all options are supported?

[David Ruess]

Hello,

The options supported depend entirely on what IOS version you're running and on what platform. You can refer to Cisco documentation of your specific device to show you the supported commands. I have linked a couple below. That being said it will not have all DHCP options and is limited compared to an actual DHCP server. In fact I believe a centralized DHCP sever would be preferred over configuring it on the network device. In addition if the router goes down then you lose DHCP functionality. A reason why you might want to configure it on the router/switch is because maybe its in a remote location and you don't need DHCP traffic all the way to the site so you set up a local pool devices can pull form and access the network.

https://www.cisco.com/en/US/docs/ios/12_4t/ip_addr/configuration/guide/htdhcpsv.html

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/15-sy/dhcp-15-sy-book/config-dhcp-server.html#GUID-DCB20ADF-1F8E-434B-AE97-54802879F34F

-David

[Khrysis]

That response was pretty quick David, thanks a bunch.

We use infoblox but having challenge so this is a temporary fix as I get to resolve the infoblox issue. It seems to be serving pretty well except for the Options part. I will go through your recommended links above try to implement. By the way, it's a Cisco 4331 router.

[David Ruess]

I doubt you will get the feature rich option on a router as you do in infoblox but hope you are able to get he functionality you need. here was the DHCP config guide for the 4331 specifically. I know it says ISR but I went through the 4331 config guide to get to it so they may be very similar in functioin.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/xe-16/dhcp-xe-16-book.html

[M02@rt37]

Hello @Khrysis,

Cisco switches and routers that include DHCP server functionality do support DHCP options configuration.

option <option-code> <option-value>

For example ton configure DNS:

option 6 <DNS-server-IP>

--

https://www.cisco.com/c/en/us/td/docs/net_mgmt/prime/network_registrar/9-0/dhcp/guide/DHCP_Guide/DHCP_Guide_appendix_01101.pdf

https://www.computernetworkingnotes.com/ccna-study-guide/how-to-configure-dhcp-server-on-cisco-routers.html

Also, depend of your router's model; check its datasheet to see DHCP option limitation.