Vlan overlapping

[amitsharma.amit87@gmail.com]

Hi

I need to enter the config below on one of our core switches

Interface Vlan 12

IP address 10.208.75.69 255.255.255.192

ip vrf forwarding WAN

When I enter this I get the message that % 10.208.75.64 overlaps with Vlan151

Configuration of Vlan 151 is

interface Vlan151
ip vrf forwarding WAN
ip address 10.208.75.65 255.255.255.252

Any assistance would be appreciated.

Thanks

[Seb Rupik]

Hi there,

The VLAN 151 subnet 10.208.75.64 /30 occupies he same subnet as VLAN12 10.208.75.64 /26 .

Layer3 interfaces in the same VRF cannot share subnets. I suggest you adjust the VLAN12 subnet ID and mask, ie make it contiguous:

10.208.75.72 /30

...but if you need a /26 then the next usable subnet ID would be:

10.208.75.128 /26

cheers,

Seb.

[amitsharma.amit87@gmail.com]

Thanks Seb

[ssambourg]

Hello,

to make the routing decision process for the connected subnet, you can't have two interfaces in the same subnet (partially / totaly).

10.208.75.69 255.255.255.192 start from 10.208.64.0 (network address) and finish at 10.208.127.255 (broadcast).

10.208.75.65 255.255.255.252 start from 10.208.75.64 (network address) and finish to 10.208.75.67 (broadcast).

Vlan 151 network adress is included in your vlan 12 network adress.

You need to review your addressing scheme.

HTH

[amitsharma.amit87@gmail.com]

Thanks ssambourg 

[luis_cordova]

Hi amitsharma.amit87@gmail.com ,

The network you are trying to enter overlaps with the other:

Vlan12 = 10.208.75.69 255.255.255.192

Network= 10.208.75.64

First IP= 10.208.75.65

Last IP= 10.208.75.126

Broadcast= 10.208.75.127

As you can see, network vlan12  is in conflict with  the network of vlan 151.

Regards

[amitsharma.amit87@gmail.com]

thanks luis