How to solve overlapping?

[SjING]

Hi, i am a beginner at subnetting.

I have a subnet of 10.19.0.0/16. I have a router that is connecting two switches.

I have done interface g0/0, ip add 10.19.1.1 on the first router to switch 1. When i did interface g0/1, ip add 10.19.1.2 or 10.19.2.1 on switch 2, it says % 10.0.0.0 overlaps with GigabitEthernet0/0. How do i solve this?

[Joseph W. Doherty]

Cisco devices (on the same device) don't generally support multiple interfaces within the same network.

Or, as the old joke goes: "Patient: doctor, doctor it hurts when I do this."  "Doctor: then don't do that."

I.e. you cannot do that.

You can, use 10.19.1.2/16 or 10.19.2.1/16 on another device, or you need to split (subnet) 10.19.0.0/16 into different (smaller) networks, and if you do, often you would have such in different L2 domains (VLANs).

For example 10.19.1.1/31 and 10.19.1.2/31 could be used on the same device, or 10.19.1.1/24 and 10.19.2.1/24.

[SjING]

I am not sure if i can change the subnet because i am given a range for the private ip address of 10.19.0.0/16. I am suppose to connect 4 different country to a single router too. Each switch connects to multiple devices.

[Jitendra Kumar · Accepted solution]

See you are already given subnet mask  255.255.0.0 network you define 10.19.0.0  two octed will be utilized fully like 10.19.255.254 so your network will be the same.

here what we are trying to suggest you, user deferent network like 10.19.1.x and other interface should be 10.19.2.x keep the same mask as 255.255.0.0 that it.

Hope you understand the things.

[SjING]

Ohh i get it now thanks!

[Joseph W. Doherty]

"Hope you understand the things."

Sorry, I don't.

"here what we are trying to suggest you, user deferent network like 10.19.1.x and other interface should be 10.19.2.x keep the same mask as 255.255.0.0 that it."

Eh?  How would 10.19.1.x and 10.19.2.x be in different networks, if they use a 255.255.0.0 mask?  And if they are in the same network, how would you get a Cisco router to accept them without an overlapping network error?

[Jitendra Kumar]

waiting for @SjING to revert on this. he have done his query or not

[SjING]

Last Question

Do I use 255.0.0.0 (Default) or do i use the custom subnet mask 255.255.0.0

[Jitendra Kumar]

Use need to use separate network and subnet mask

[SjING]

So for Switch 0, i can assign 10.19.20.10 255.255.0.0 while in Switch 1 i can assign 10.19.30.10 255.255.0.0?

[Jitendra Kumar]

Nope!! the router will give you error overlaps as you need a separate network that should not fall in the same range. you have to categorized the network and mask

[SjING]

Ok so i have different subnets 900 and 150, I have to calculate them one by one to find their own respective subnets and use them in the ip add to prevent overlapping

[Joseph W. Doherty]

"I am not sure if i can change the subnet because i am given a range for the private ip address of 10.19.0.0/16."

Well, whoever provided this, find out if you can subnet.  Generally, when handed /16 networks, we don't use them as single, non-subnetted, networks.

[MHM Cisco World]

freind 
10.19.0.0/16

10.19.1.0/16 and 10.19.2.0/16 is in same subnet 
you need 
10.19.1.0/24 10.19.2.0/24

[MHM Cisco World]

I waiting to know how router will accept these prefix with this mask.
@Joseph W. Doherty You are right.