Router with DHCP help

[jfeo]

I have a router 3925 that has a public ip address on g0/1 and I am need to connect a device on G0/0 that receives and DHCP public ip address so a Vendor can vpn into with.

I tried settng up DHCP but it doesn't hand out an ip address on G0/0. Any suggestions pleaseRouting, Other Routing, WA

[balaji.bandi]

Vendor can vpn into with.

this required more information, what VPN ?

I can think of 2 Option for now  : (is this one time requirement or all time) either case.

1. you need to setup Router in bridge mode - i do not recomend this ( instead you can directly connect device to ISP - so device can get IP address with out router ?

2. you can do NAT with public IP - and allow incoming connect to VPN.

[David Ruess]

Hello,

What is the IP address of G0/0? If you configured DHCP like the following then you need to have the gig 0/0 interface in the same scope. Then you could put a default route out the g0/1 interface:

ip dhcp excluded address <range of IPs to exclude>

ip dhcp pool 

network <ip network> <mask>

default-router <ip of g0/0 on router>

Ex:

int g0/0

ip address 192.168.1.1 255.255.255.0

ip dhcp excluded address 192.168.1.1 192.168.1.10

ip dhcp pool 

network 192.168.1.0 255.255.255.0

default-router 192.168.1.1

Then configure default route:

ip route 0.0.0.0 0.0.0.0 g0/1

Secondly you mention you want the vendor to have a public IP? Do that mean you were given another public IP from the ISP since the only one you got is attached to the g0/1 interface. If that's the case you can probably just manually configure the client with that IP but you will have to do a bit more with routing and getting it out of your network.

Hope that helps

-David

[Flavio Miranda]

Hi

 If you connect this device to the Interface G0/0 of your router, this device will not receive a DHCP from outside, if thats you are trying to do.  What you can do is configure a DHCP scope on the 3925 and provide IP address to this device on the Gi0/0 but it will not be a public IP.

To configure a dhcp scope you can do this:

router(config)#ip dhcp excluded-address 192.168.0.1 192.168.0.50
router(config)#ip dhcp pool Floor1DHCP
router(dhcp-config)#network 192.168.0.0 255.255.255.0
router(dhcp-config)#default-router 192.168.0.1
router(dhcp-config)#dns-server 192.168.0.1

[MHM Cisco World]

I dont fully get your issue here,

Router have 

G0/1 have public ip

G0/0 need public ip to make vpn access to it?

Simply do NAT from g0/0 to public ip g0/1 

This make any user can vpn to public ip and nat direct traffic to g0/0

[Richard Burts]

I agree that we need a better understanding of this environment and of what they want to accomplish. The original post indicates that G0/1 connects to ISP and receives a Public IP via DHCP. The post then says that they want to connect a device to G0/0 and it should receive a Public IP via DHCP. There are multiple things that we do not know. Where would that second Public IP come from? Who would assign it?

For a device connected to G0/0 to receive a Public IP via DHCP there would need to be a subnet with at least 2 Public addresses available. You would then assign one of those Public IP to interface G0/0 and configure a DHCP scope on the router to assign the second Public IP on G0/0. Then the device connecting to G/0 would be assigned a Public IP.

I am a bit confused why there needs to be a second Public IP (which would need to be in a separate subnet) to be able to VPN. Why could you not VPN to the Public IP on G0/1?

[jfeo]

So I have a switch in between Router and ISP. G0/0 has a static ip for site to site vpn. I have this aruba device that needs to be connected via outside public ip address. I can setup the switch as a DHCP server however I will use 2 public ip address

[Richard Burts]

It is interesting that you have a switch between the ISP and the router. Does it connect G0/1 to the ISP? Does it provide any other connections?

The original post did not mention having an IP configured on G0/0. Is this a private IP or a Pubic IP?

What does G0/0 physically connect to?

As I explained in my other response to set up a DHCP scope for Public IP you would need 2 Public IPs (and since they would be part of a subnet you would also need Public IPs for the subnet address and for the subnet broadcast address.