Current use of dhcp on an access level router?

fmitawaps

One of my CCNA training videos just did a section on using DHCP, and putting it on an access layer router. The entire lab was an 1841 configured as router on a stick, to a 2960 core switch with 3 vlans with trunked ports, out to 3 other 2960 switches, getting their vlan info from the core switch in client mode, which fed 3 PCs. Each router sub-interface (f0/0.15, f0/0.16, f0/0.17) used DHCP excluded-address and default router commands, and the whole thing seemed to work quite smoothly. I did it in packet tracer, and will set it up on my live equipment tomorrow for practice.

But it was mentioned in the video that routers should not be doing DHCP server work, and maybe it was just the instructors' opinion, but I'd like to hear what other network admins think of this. Is using the router for DHCP acceptable, common, and reliable?

kohr-ah

Well it depends.

Your router's job is to route packets. Get them in and out of the network at a rapid pace.

For a while we had our router be the DHCP server for our Cisco phones but the people who set that up suddenly realized when that router died and we failed over (OOPS) we couldn't hand out phone IPs anymore and since I have moved them to the switch stack.

Usually in an environment you will have an iPAM server which will host your IP addresses in some fashion. Can it be used as a DHCP server yes but your devices shouldn't be going past your firewall to your router to get IPs.

james43026

Depends on the size of your network. In a small enough environment, you don't need a dedicated DHCP server, because your router / routers may not be doing that much work in the first place. That being said, it truly depends on the setup, if you have a router configured in a router on a stick setup, then you probably don't want to have your router also working as a DHCP server.