DHCP Problem

[dimigav1977]

Dear all,

I have a problem with DHCP. My router act as DHCP Client and Server together.

The Gi0/0.837 WAN connection configured as DHCP Client to obtain IP from ISP.

The Gi0/1.2 Data Network with IP scope 192.168.2.0/24 and Gi0/1.100 Voice Network with scope 192.168.100.0/24 assigned from DHCP Server pools.

If the DHCP pool created the Wan cannot obtain IP from WAN. If I delete the pools the WAN successfully obtain IP.

Why this?

configuration

ip dhcp pool LAN
network 192.168.2.0 255.255.255.0
default-router 192.168.2.1
dns-server 8.8.8.8 8.8.4.4

!

ip dhcp pool VOICE
network 192.168.100.0 255.255.255.0
default-router 192.168.100.1

!

interface GigabitEthernet0/0.837
description WAN
ip address dhcp
!
interface GigabitEthernet0/1.2
description LAN1
ip address 192.168.2.1 255.255.255.0

!

interface GigabitEthernet0/1.100
description VOICE1
ip address 192.168.100.1 255.255.255.0

[dimigav1977]

Yes, is a PPPoE client with PAP/CHAP authentication. But, the problem is not on Dialer interface. The problem is on Gi0/0.837 sub-interface. Sometimes cannot obtain IP address.

[paul driver · Accepted solution]

Hello

You configuration doesnt seem correct inrelation to what you have explained, please see attached file.

[dimigav1977]

I probably did not explain something correctly. Because my English is not very good either.
I need the .835 because I get data with PPPοE, but I also need the .837 because I have the telephony there.

What I do not need at the moment is .836 for IPTV, since I do not have IPTV subscription.

[paul driver]

Hello

---

@dimigav1977 wrote:

I need the .835 because I get data with PPPοE, but I also need the .837 because I have the telephony there.

---

So you are saying you should be receivingip address allocation from .835 & .837 from the ISP, but at present you only are able to receive for data?

Have you applied the suggested configuration (minus for .837 subinterface)

[dimigav1977]

Correct.

Real IP address from .835(Data) and private IP from .837(Voice).

I think I can try the solution from Mr. Giuseppe Larosa. I think I need to separate the physical connections between 835 and 835 subifs.

Many thanks!!!

[paul driver]

Hello

Your private addressing is via the lan interface gig0/0/1 not gig0/0/0, So if you need an additional vlan (837) just append it to that interface and create an addtionl dhcp scope for it.

interface GigabitEthernet0/1.837 < vlan 837
encapsulation dot1Q 837
ip address 192.168.137.254 255.255.255.0
ip nat inside

ip dhcp pool Data-Voip
network 192.168.137.0 255.255.255.0 secondary
overide-default-router 192.168.137.254

ip access-list extended lan-nat
permit ip 192.168.137.0 0.0.0.255 any

[dimigav1977]

No, no ..

ISP gives private addresses on DHCP .837. Every single time I was able to receive IP it was like 10.140.220.xxx

[paul driver]

Hello

okay apologies so you are saying the same isp provides you dual dhcp allocation with a public and private addressing all from the same single interconnect - ( to be honest i’ve never come across this so i am curious)

I understand what @Giuseppe Larosa  is saying but why do you need to do this if it was working before - what has changed physically or logically?

If nothing has changed your end have you checked with your ISP?

[dimigav1977]

Dear Mr Driver,

Firstly I would like to thank you for all your replies.

As you can see in the "Working ISP.png" file the ISP from one physical WAN port opens three possible connections together in different VLAN IDs with different connection methods.

In the "WAN.png" you can also see that two of the three connections receive IP from the ISP

The point is to replace this device with a Cisco router.

Thank you