Sub-interfaces Issue

Hello,

I started studying this month for the ccna exam and I've found answers to most questions on the oddom book, but now i'm stuck on a lab I created with packet tracer!

I have two switches linked together by trunk ports and then both of them connected to a router. I was able to create sub interfaces for de first switch but when I try to create for the second I get a message saying the subnets overlap with the previous created sub interfaces!

Both switches have the same vlans, I was trying to have them both connected to the router for redundancy.

Any help would be much appreciated. Thanks

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Comments

networker050184

You can't have two interfaces in the same subnet. Post up your configs and a diagram maybe we can show you where you went wrong.

Unidade01

I was trying replicate the fa 0/0 config on the Fa 1/0 hoping it would make redundant routes. It didn't went as expected.

When i try to assign the ip 192.168.1.2 to the sub interface fa 1/0.10 the router says the subnets overlap

FastEthernet0/0 unassigned YES unset up up

FastEthernet0/0.10 192.168.1.1 YES manual up up

FastEthernet0/0.20 192.168.2.1 YES manual up up

FastEthernet0/0.30 192.168.3.1 YES manual up up

FastEthernet1/0 unassigned YES unset administratively down down

FastEthernet1/0.10 unassigned YES unset down down

FastEthernet1/0.30 unassigned YES unset down down

Unidade01

so i gave up connecting the second switch to the router but i still can't ping between vlans. I can ping the sub-interfaces and the computers in the same vlans but not between vlans.

the port in the switch is configured as a trunk

Router config

interface FastEthernet0/0
no ip address
duplex auto
speed auto
!
interface FastEthernet0/0.10
encapsulation dot1Q 10
ip address 192.168.1.1 255.255.255.0
!
interface FastEthernet0/0.20
encapsulation dot1Q 20
ip address 192.168.2.1 255.255.255.0
!
interface FastEthernet0/0.30
encapsulation dot1Q 30
ip address 192.168.3.1 255.255.255.0
!
interface FastEthernet1/0
no ip address
duplex auto
speed auto
!
interface Serial2/0
no ip address
clock rate 2000000
shutdown
!
interface Serial3/0
no ip address
clock rate 2000000
shutdown
!
interface FastEthernet4/0
no ip address
shutdown
!
interface FastEthernet5/0
no ip address
shutdown
!
ip classless

Vask3n

Do the clients have their default gateway set to their respective subinterface?

Mrock4

Check to make sure your router has a route to the other VLAN- ie:

VLAN 10 route to VLAN 20 router:

ip route 192.168.2.0 255.255.255.0 192.168.1.1

You'll need to also ensure that your VLAN 20 router has a route back to VLAN 10.

Unidade01

Vask3n wrote: »

Do the clients have their default gateway set to their respective subinterface?

that was the problem now i can ping all computers in all vlans. Was so worried about the switch and router config that i overlooked something so simple!

This shows the importance of labs! Seems simple in the book but try to implement and there will be a rock to make trip