Solved: DHCP not working?

NobleCISCO1 · ‎05-28-2017

Hello All,

Trying to work out this simple network topology with DHCP on two VLANs

Not sure what I missed?

Password to router: Cisco

Secret : Class

Thanks

Julio E. Moisa · ‎05-28-2017

Hi

No worries :-)

The wrong interface, also the interface fa0/1 from the switch connected to the router should be configured as Trunk instead access mode.

Also you need to create a trunk interface between both switches.

Attached you will find my config to be compared with yours, each computer obtained IP automatically.

Switch (connected to Router)

interface FastEthernet0/1
switchport mode trunk

interface FastEthernet0/2
switchport mode trunk

Switch 2

interface FastEthernet0/1
switchport mode trunk

>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<

View solution in original post

Julio E. Moisa · ‎05-28-2017

Hi

The reason is because the network 40.0.0.0/8 is configured under the wrong interface. It should be under the FastEthernet 0/1. Also the interface connected to the Router on the switch should be as Trunk because you are creating a dot1q connection (Router in a stick scheme). I have created the trunk between the switches as well, attached you will find the fixed Packet Tracer file. The 4 PCs are already obtaining IP address automatically.

Fixed config:

interface FastEthernet0/0

no ip address

duplex auto

speed auto

!

interface FastEthernet0/1

ip address 40.0.0.1 255.0.0.0

duplex auto

speed auto

The trunk interfaces allow the communication between multiples Vlans.

:-)

>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<

NobleCISCO1 · ‎05-28-2017

Ah, stupid mistake.

Change over the interface, still having the same issue though.

Can you see anything else?

Julio E. Moisa · ‎05-28-2017

Hi

No worries :-)

The wrong interface, also the interface fa0/1 from the switch connected to the router should be configured as Trunk instead access mode.

Also you need to create a trunk interface between both switches.

Attached you will find my config to be compared with yours, each computer obtained IP automatically.

Switch (connected to Router)

interface FastEthernet0/1
switchport mode trunk

interface FastEthernet0/2
switchport mode trunk

Switch 2

interface FastEthernet0/1
switchport mode trunk

>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<

NobleCISCO1 · ‎05-28-2017

Thank you very much Julio!

Just needed to trunk between the two switches also.

Julio E. Moisa · ‎05-28-2017

Hi

It was a pleasure my friend.

Have a great day

:-)

>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<