Routing between subnets on the same VLAN

[anonomo306]

I apologize for having an elementary understanding of networking but please help me out if you get the chance.  I currently have three L2/3 Cisco 2960's in three separate data racks that are housing amplifiers and and other public address equipment.  The IP breakdown is as follows.

Switch A:

interface Vlan30
  ip address 10.170.79.1 255.255.255.240

Switch B:
interface Vlan30
  ip address 10.170.79.17 255.255.255.240

Switch C:

interface Vlan30
  ip address 10.170.79.33 255.255.255.240

Each switch is enabled with ip routing.  Additionally, there are connected in a ring topology through the gi1/0/25 and gi1/0/26 interfaces.  These interfaces are trunked and are allowing VLANs 10,20,30 and 40.  

My question is - should I be able to ping Switch C from Switch A as its currently configured or do I need to create static routes for each of the switches?  Any configuration modifications and suggestions would be appreciated.

Thank you for your help.

[Reza Sharifi]

should I be able to ping Switch C from Switch A as its currently configured or do I need to create static routes

Since they are in different subnets, you need a static route on B switch to A and C and on C you need a static route to A and B.

on A you need a static route to point to B and C.

https://www.cisco.com/c/en/us/support/docs/dial-access/floating-static-route/118263-technote-nexthop-00.html

HTH

[anonomo306]

Hi Reza,

Thanks for your reply.  Each switch is in it's own /28 subnet (A - .1, B - .17, C - .33) but are in the same VLAN.  Does your answer still hold?

[Reza Sharifi]

Hi,

So, since each switch is in a different subnet, you would need 2 static routes on each switch. In this case, since you are using one vlan (vlan 30) you can also use an access port to connect the switches together and no need for a trunk port. 

The most common way of doing this is to use a routed port on each switch and use a  /30 in between them

A-----/30-----B-----/30-----C

Between A and B

192.168.1.0/30

between B and C 

192.168.4.0/30

HTH

[anonomo306]

Thank you all for your suggestions.  Unfortunately I need to keep each switch in a separate subnet, the customer wants the equipment split based on location.  I will add static routes between all three switches to establish two-way communications.  Is this best achieved through default routes or network routes (or preference?)?  

[balaji.bandi]

No you can not ping each other, since they are not aware of any routing (if they are not configured ?)

again we need to know is connected using (layer 2 Trunk) - One should have routing information to reach each other.

[Georg Pauwen]

Hello,

since your original question is:

--> Routing between subnets on the same VLAN

I assume you want all three Vlan 30 interfaces to be in the same Vlan/Subnet ? 

If that is the case, change the subnet mask to:

Switch A:

interface Vlan30
ip address 10.170.79.1 255.255.255.192

Switch B:
interface Vlan30
ip address 10.170.79.17 255.255.255.192

Switch C:

interface Vlan30
ip address 10.170.79.33 255.255.255.192

With this addressing, you don't need any static routes.