Setting DHCP Excluded Addresses on VRF Interfaces

[studentuser]

I am currently using the Cisco C9300 series with iOS version 16.12.
Some interfaces are configured with VRF interfaces, and DHCP services are configured on all of these VRF interfaces. The configuration command used is as follows

ip dhcp excluded-addresses [lower-address] [higher-address]

However, contrary to expectations, the addresses specified in the command were not excluded and were assigned to the PCs. While checking the command help by chance, I discovered the following command:

ip dhcp excluded-addresses vrf [vrf-XXX] [lower-address] [higher-address]

After applying this command, it worked as intended, and the specified addresses were correctly excluded.

I noticed this while looking at the help documentation, but I couldn't find any explanation for the ip dhcp excluded-address command for VRF interfaces in the command reference. I also couldn’t find relevant information through a Google search.

Do you know where I can find a manual or reference guide that explains this?

[balaji.bandi]

check reference VRF aware DHCP config :

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/xe-16-6/dhcp-xe-16-6-book/config-dhcp-addr-pm-xe.html

good discussion post :

https://community.cisco.com/t5/routing/dhcp-issue-on-vrf/td-p/4117807

[Jens Albrecht]

Hello @studentuser,

the documentation from Cisco does not include much details about this.

Looking at the IP Addressing Configuration Guide, Cisco IOS XE 17.x you can find a short note:

From Cisco IOS Release 17.6.1, you can use the ip dhcp excluded-address vrf-name global configuration command to exclude addresses from the VRF associated pools.

Obviously earlier versions offer this command as well but it appears not to be documented for whatever reasons.

HTH!