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Cisco 1720, how to enable DHCP?

We've got a 1720, installed prior to my arrival in the company, with no documentation, set up by a non-responsive ISP, and I'm assuming DHCP is disabled.  (I'm not familiar with routers at all.  I have configured home-use style hubs that let you into config screens through a browser, however.)

IPs need to be manually configured when new computers are added, and often we have clients who want to hook up to our T1 when they're in the facility for the day.

I'm assuming that if DHCP was enabled, their hookup would go a lot more smoothly, and could possibly be even close to plug-n-play.

The facility is about half mac and half win, and there is an apple airport available for those with 802.11b, but even then , I need to get into the client's computer and assign IP, DNS, etc...

Also, I don't know if this is relevant, but the 1720 feeds into a Dell gigabit switch.



Am I thinking along the right lines to get into the 1720 and enabling DHCP in order to make temporary connection setup easier?

What, in total luser detail, do I need to do to get into the 1720 configuration mode?

And what should I do once I get there?

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ppainter
Asked:
ppainter
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1 Solution
 
pedrowCommented:
Here's an example:
Here's an example...once you log into the router, you type 'enable' (or just 'en'). It will prompt you for your enable pw.

type conf t
and start entering commands.

The following is from a working router (mine).
Most of the commands are probably self explanatory, so you can change your addresses so they'll fit your environment.


telnet router
password:<password>

router> enable
password: <enable password>
router#
router# conf t
router(config)#

!
ip dhcp excluded-address 172.19.9.0 172.19.9.10
!
ip dhcp pool internal lan
   network 172.19.9.0 255.255.255.192
   domain-name arollo.net
   default-router 172.19.9.1
   netbios-name-server 172.19.9.5 172.19.9.6
   netbios-node-type h-node
   dns-server 172.19.9.7 206.13.28.12
   lease 0 2
!
end
wr

hope this helps.
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pedrowCommented:
oh...if you have any questions while entering commands, type a '?' at any point and ios will tell you what your options are.
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ppainterAuthor Commented:
Sorry, but I'm not familiar enough with this stuff to make heads or tails of it.

Interestingly enough, when I call the ISP to walk me through it, they say that DHCP can't be done on a 1720, and that we need to buy a firewall and perhaps even a new router.  (yes, I'm quoting him exactly, and not misunderstanding what he's said.)  The ISP also holds the PW to the router, and they're being hesitant about giving it out to me... (still waiting for their callback.)

But assuming that I ever actually make it in, enabling DHCP is not as easy as clicking on a radio button...  Is there any way to dumb down that info so that I won't screw everything up?

Our network uses 192.168.100.x for local IPs  is your 172.19.9.x an internal or external IP range?

I have no idea about netbios...  there is no computer set up as a name server... should there be?

Our DNS is an external IP#...  is that a problem?

How do I gather all the current settings before I go in and break something?

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pedrowCommented:
Hi-

no problem...you're right...it's not as easy as clicking a button. There may be some versions of IOS code that don't do dhcp, but I'd have to confirm that. Basically, if the router takes the commands, it'll work.

First and foremost...you need the enable password on the router. Without it this whole discussion is moot.

It aint buttons, but it's pretty easy...you can just type in the commands once you're in configuration mode or edit the information in a text file and then cut/paste.

let me annotate for more clarity and use your internal ip addresses(exclaimations points are comments):

! this defines range of addresses in subnet you *don't* want to
! be issued via dhcp...
ip dhcp excluded-address 192.168.100.1 192.168.100.10
!
! here's where you start defining the dhcp pool
!
! this is the global command ip dhcp pool <description-name>
ip dhcp pool internal lan
! this is the network that you want to enable dhcp on
  network 192.168.100.0 255.255.255.0
! this is the domain name suffix for your place
  domain-name yourdomainname.com
! This is the default gateway address(i.e. your router's inside ip address)
  default-router 192.168.100.1
! WINS Server addresses - usually domain controllers
  netbios-name-server 192.168.100.x 192.168.100.x
! this defines the netbios node-type
  netbios-node-type h-node
! These is where you define the dns servers (from your isp
! if you like or internal ones if you run them)
  dns-server <primary dns server> <secondary dns server>
! How long the dhcp lease is good for in days hours (i think)
! this one is set for two hours.
  lease 0 2

Internal dns or external DNS shouldn't be a problem.

Try looking at the ip configuration of a working pc in your network and write down the information so that you can confirm your settings for the router's dhcp config.

I used 172 addresses for my internal, you can use 192.168.x stuff as well :)

WINS servers are usually domain controllers, but not always(or in an Active Directory environment, there may not be any...just dns).

If this all seems too daunting, there are other dhcp servers that you can use as well (like win2k server), linux, the cheapest linksys-type routers do it.

Here's a link to a $15 dhcp server that you can run on one of your workstations if you don't have an NT/W2k/linux server hanging around
http://www.downlinx.com/proghtml/218/21801.htm
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ppainterAuthor Commented:
Well...  It's to be determined whether I can get it done, but you've certainly answered my questions, so Points to you.

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ppainterAuthor Commented:
thought i already awarded the points.....  sorry
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pedrowCommented:
np :) Glad to help.
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