Netgear and Cisco Router/Switches DHCP

toe44

IP Addressing

Hi, quick question and probably a stupid one.


When you have DHCP enabled on a 3rd party router eg. ADSL Netgear DG834G which is used for a WAN connection and DHCP setup on the actual DG834G modem/router as follows:

Starting pool: 192.168.1.2
Available: 253

How are you meant to assign static IP address' to router interfaces eg interface fastethernet 0/0 or 0/1?

tha_dub

You should be able to login to the netgear router and limit the address scope. I will commonly set them to use 192.168.1.1 to 192.168.1.200 and that leaves the rest of the space for static assignment for servers and other gear you want to have static addresses.

On the other hand if you are studying for ccna then just turn off DHCP on the netgear entirely and run it from a cisco router.

peanutnoggin

Toe44,

First off... welcome to TE

2nd... there is no such thing as a stupid question... its a topic and/or subject in which you don't have the experience with! There's nothing wrong with that!

Now, to answer your question... a DHCP pool is typically a reservation of addresses, those addresses however aren't reserved until a device requests it (i.e. a PC, printer, etc...). You typically would setup an exclusion on a DHCP server which tells the server not to assign IP addresses from that particular range. So if your range is 192.168.1.2 with a 255.255.255.0 (/24) mask, you would only have the IP address of 192.168.1.1/24 excluded. You can still assign an IP address to the router's interface from that pool. Remember, DHCP is a service that runs on your router. It does not govern how the router itself receives its IP address (unless you set the interface to receive its IP address via DHCP). HTH.

-Peanut

toe44

peanutnoggin wrote: »

Toe44,

First off... welcome to TE

2nd... there is no such thing as a stupid question... its a topic and/or subject in which you don't have the experience with! There's nothing wrong with that!

Now, to answer your question... a DHCP pool is typically a reservation of addresses, those addresses however aren't reserved until a device requests it (i.e. a PC, printer, etc...). You typically would setup an exclusion on a DHCP server which tells the server not to assign IP addresses from that particular range. So if your range is 192.168.1.2 with a 255.255.255.0 (/24) mask, you would only have the IP address of 192.168.1.1/24 excluded. You can still assign an IP address to the router's interface from that pool. Remember, DHCP is a service that runs on your router. It does not govern how the router itself receives its IP address (unless you set the interface to receive its IP address via DHCP). HTH.

-Peanut

Thank you both for the quick reply, I wanted to keep the DHCP pool from the netgear. This would explain why on my router where I have 10.1.1.1 255.255.255.0 as the fastethernet 0/1 interface and why I cannot access.

Is there a way that I can use variations in subnet masks or would the point where I would require the cisco router with VLSM's to be enabled?

mikej412

If you don't want to reduce the size of the DHCP pool so that you could hold back some addresses for static assignment, then you may want to see if you have an option to create a reservation for specific devices so that they at least get the same IP address each time they boot up.

toe44

What would happen if I wanted to use 10.1.1.1 255.255.255.0 ?

peanutnoggin

toe44 wrote: »

What would happen if I wanted to use 10.1.1.1 255.255.255.0 ?

if you're meaning on the Cisco router's interface, you'd have to run NAT to get 10.1.1.1 network to talk to your 192.168.1.0 network... then you get into really ugly configurations and double-nat'ing. Not pretty and can be a pain to troubleshoot. I would suggest you statically assign the router's interface to an ip in the range on your dhcp server, then reserve that IP address... that way you'll have the same IP on your device everytime. HTH.

-Peanut

toe44

Thanks very much, this has now covered a big hole in my learning!