InterVlan Routing

[NinjaTurtle2021]

Greetings everybody

I need some help solving my Packet Tracer Networking Lab

I can't figure out how to make my DHCP work on my laptops which are on VLAN 30 (I enabled the vlan 30 interface on all routers). The laptops which are not fetching DHCP are the one in the middle (Commercial (2)) & the one on the left (Commercial (3))

You'll find attached to this post the Packet Tracer file.

Thanks in advance for your help.

[Georg Pauwen]

Hello,

the iVlan 30 interfaces on the two routers on the right have the same IP address...

[NinjaTurtle2021]

Hi thanks for your reply

Yes I noticed, even though I change it to another ip in the VLAN 30 network the laptop doesn't get any DHCP. (I also put the ip helper address of the DHCP server in the vlan 30 interface of the middle router I didn't forget that).

I wanted to put the gateway of the VLAN 30 on all the routers' VLAN 30 interfaces, that's why the duplicate address.

[Georg Pauwen]

Hello,

you cannot have the same subnet on different routers. What are the requirements of your topology ? In order for this setup to work, you need to change the IP addressing on the LAN segments completely, and assign a different DHCP pool to each segment...

[NinjaTurtle2021]

No.

You can have the same subnet but with different masks. Please check my ip addressing correctly.

My problem is linked with the encapsulation dot1Q thingy and I don't have any Gig ports on my routers available.

I cannot create sub-interfaces on Fe interfaces thats why I  created the VLAN interfaces on the routers.

But the DHCP is not dispatched through the OSPF.

[Georg Pauwen]

Hello,

--> No

No to what ?

hostname R1/1/0
!
interface Vlan30
mac-address 00d0.9704.6a03
ip address 172.16.1.62 255.255.255.192
ip helper-address 172.16.1.157

hostname R1/2/0
!
interface Vlan30
mac-address 0090.2bec.ac01
ip address 172.16.1.62 255.255.255.192
ip helper-address 172.16.1.157

hostname R1/3/0
!
interface Vlan30
mac-address 0001.97a8.0201
ip address 172.16.1.62 255.255.255.192
ip helper-address 172.16.1.157

This will never work. How is the DHCP server supposed to know which IP address/interface the request is coming from ? You need to have an IP addressing scheme that does not contain overlapping subnets. That is why I asked what the requirements are, and if you are following a set of instructions.

[NinjaTurtle2021]

No to what you've written about IP addressing.

Please forget about the duplicate address. 

Assume that both VLAN 30 interfaces on both routers don't have the exact same IP but the IP on the same network and mask.

Assuming that, I'm wondering why the DHCP is not working.

I think it's because I cannot create subinterfaces. And not that thing encapsulation.

[Georg Pauwen]

Hello,

what are you trying to accomplish ? Are you following instructions, or are you trying to practice something you have come up with yourself ? Either way, you cannot have the same subnet on different routers...

[paul driver · Accepted solution]

Hello
As noted your ip addressing isn’t correct, not only duplicate conflicts but also you have multiple opsf enabled interfaces not doing anything, you have irrelevant trunks when they should be either access or routed ports.

Regards having the same subnet ranges/addressing on differing routers this is possible but they would need be hidden and not advertised to each other which could be accomplished by Network Translation.(NAT)

You need to elaborate on what exactly your trying to accomplish, my assumption is centralised dhcp allocation?