DHCP - Cable modem?

Daniel333

I might be going into a CCNP topic here. But is there a way to set a ethernet interface on a 2500 series to receive an DHCP address?

Seems to me if they can, I should be able to set default routes and use one of my 2500 to replace my netgear?

seuss_ssues

There have been several posts here in the past about hooking your cisco gear up to the internet. I would be able to post some links but im not on my normal computer.

I would suggest either manually browsing the cisco forums (im pretty sure CCNA) and trying the search function.

Darthn3ss

to get an IP from DHCP, simply use the command

"ip address dhcp" on the interface's config.. ie:

R1#conf t
R1(config)#int fa0/0
R1(config)#ip address dhcp
R1(config)#no shut
R1(config)#end


edit: the cisco IOS cookbook is your friend, you should check it out. this is from recipe 20.3

mikej412

ip address dhcp

But if you need to ask that, have you even considered the security implications?

You'd also probably want to configure NAT. A static route might get your traffic out -- where your ISP will drop your RFC 1918 addresses like a hot potato.

Find a good internet security/port scanner and run a before and after.

hectorjhrdz

but guys, Do all the IOS versions support DHCP on interfaces?


i tried it last week on a 2500 cisco router with an IOS 11.3 and it didn't support the command


cheers!!!!!!

mikej412

hectorjhrdz wrote:

i tried it last week on a 2500 cisco router with an IOS 11.3 and it didn't support the command

NAT was introduced in 11.2 -- but just like anything Cisco, you'd want to be running an IOS Version with a feature set that supports the command.

There probably wouldn't be any security issues running an IOS version with only IPX support attached to a Broadband connection

Darthn3ss

i think DHCP is supported in like 12.1 or 12.2 and above.could be wrong. don't feel like checking :P

mikej412

Darthn3ss wrote:

i think DHCP is supported in like 12.1 or 12.2 and above.could be wrong. don't feel like checking :P

Wow -- a "Lab moment." I gave the right answer to the wrong question I was going to put in the DHCP and NAT versions.... and only did NAT.

12.1(2)T for the client support "ip address dhcp" and 12.0(1)T for the server support (service dhcp).

I'm onsite tomorrow -- but after that, maybe I should consider just drinking beer and sleeping until my flight Thursday.