2960XR - IP Lite- OSPF query

[Ro-Lak]

Hello Community, 

Hope you all are sound.

My question is, we are running layer 3 switches with OSPF on our network. Basically routed access layer.

And want to add a few extract switches to the network, all of them running layer 3, running OSPF as well.

We want to use the same network address ranges. e.g. 10.40.1.0/23

Vlan 20

switch 1: 10.40.1.1 - 255.255.252.0

router ospf

network 10.40.1.0.0.3.255

Vlan20

switch 2: 10.40.1.2 - 255.255.252.0

router ospf

network 10.40.1.0.0.3.255

Vlan20

switch 3: 10.40.1.3 - 255.255.252.0

router ospf

network 10.40.1.0 0.3.255

Is this even possible?

Kind Regards

[Deepak Kumar]

Hi,

OSPF network type must be broadcast and it will work. But keep in mind that if you have a bunch of routes then you must configure 2960XR area as total stub or NSSA.

Your mentioned commands are not completed but assuming that you know the basic OSPF configuration and design requirement.

router ospf 1

network 10.40.1.0.0.3.255 area X ---->OSPF area

[balaji.bandi]

one question - if all are in the same network one VLAN 20 - why do you want to run IGP OSPF  here.

or Can you explain the use case to understand better? I know you provided you already have other networks running OSPF.

but is that part of the same IP address space? and Switch has dual paths ? or single exit point to uplink?

[Ro-Lak]

Thanks for your responses. Appreciate it.

I might have not explained the scenario, for you to understand what I want to achieve.

We have a routed access layer for the access switches, each have redundant paths to the core switch.

No trunking is happening between VLAN, so this information is localised.

However, we have a massive client ranged subnet/23, e.g. 10.1.40.0/23 on one of the access switch with a DHCP helper pointing at the DC'2.

So I want the remaining access switch to share the same subnet. by configuring the same range VLAN IP 10.1.40.2 , 10.1.40.3 ... and point them to the same DHCP server..

Is this clear enought? 

[Ro-Lak]

I realize my problem is nothing to do with OSPF, but a pure subnetting consideration, where I need to effectivity subnet, where necessary.

Poor design from our end, as all our access switches are on the same area 0, will probably design this so access switch in a sub area, to limit the OSPF LSA flooding. 

This article will be guide 

https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Campus/routed-ex.html#wp998679

Thanks for your responses.

Kind Regards

[Deepak Kumar]

We glad to know that you find out the issue. It is very important to consider best design consideration.

[balaji.bandi]

sure on Layer 3 you can completely extend the whole subnet (until it is flat network), you need to make them subnet based on the requirement and announce with respected area or with peers