OSPF Neigbour Relationships Missing

[dmc123]

Hi All,

This is my first post on this forum, long time reader, first time poster.

I am struggling with a basic task with OSPF provision on a multi router network and am hoping for some advice and pointers so I can start to make progress.

Here is the situation - I have been given a 99.0.0.0/8 addressing scheme for a network of 9 routers, which are interconnected via four switches. For example router 1 and 2 connect to switch 1, switch one connects to switch 2 which then connects to routers 3, 4, 5 with this pattern continuing until router 9.

Each router has two interfaces, one facing out to the switch (G0/0/0) and one to the internal network (G0/0/1). I am told I can divide the 99.0.0.0/8 as I see fit, so I decide to split this down so each interface had it's own subnet, for example G0/0/0 is 99.0.0.1/9 and G0/0/1 is 99.128.0.1/10 and so on through the 9 routers.

The issue comes when I attempt to make neighbor relationships through HELLO packets, which I have done on other activities successfully previously, as no relationship is formed.

What I am trying to achieve is that - 

Router 1 - With a G0/0/0 Int of 99.0.0.1/9 and a G0/0/1 Int of 99.128.0.1/10 can say HELLO to

Router 2 - With a G0/0/0 Int of 99.192.01/11 and a G0/0/1 Int of 99.224.0.1/12 can say HELLO to

Router 3 - With a G/0/0 Int of 99.240.1/13..... and so on, based on the division of the network.

Any thoughts or pointers are greatly appreciated.

Thanks

David

[Flavio Miranda]

Hi

 Your  addressing looks not good.

99.0.0.1/9 and G0/0/1 is 99.128.0.1/10

It should be

99.0.0.1/9 and G0/0/1 is 99.128.0.2/9

You should not use the mask like this.

Or you can break in a /24

99.0.0.1/24

Then use the first 254 IP sequencially

[MHM Cisco World]

since all router connect to L2 SW then all router must share same subnet. 

friend this type of design you cannot learn anything from it, 
start simple the idea is not make our network contain many nodes, 
start simple steps by steps.
thanks 
MHM

[davidjohnson]

Hello everyone,

I'm excited to join this forum and share my first post. I've been a long-time reader and finally decided to participate.

I'm currently facing a challenge with OSPF provision on a multi-router network and would appreciate some advice and guidance to help me make progress.

Here's the situation: I have a network of 9 routers interconnected through four switches. The addressing scheme provided to me is 99.0.0.0/8. Each router has two interfaces: one facing the switch (G0/0/0) and one for the internal network (G0/0/1). I have the flexibility to divide the 99.0.0.0/8 address space as I see fit.

To simplify the network, I decided to assign each interface its own subnet. For example:
- Router 1, G0/0/0: 99.0.0.1/9 and G0/0/1: 99.128.0.1/10
- Router 2, G0/0/0: 99.192.0.1/11 and G0/0/1: 99.224.0.1/12
- Router 3, G0/0/0: 99.240.0.1/13
...and so on for the remaining routers.

The problem arises when I try to establish neighbor relationships through HELLO packets. Despite my previous successful experiences with this, no relationship is forming.

Specifically, I aim to achieve the following:

Router 1 (99.0.0.1/9 and 99.128.0.1/10) can establish a HELLO relationship with
Router 2 (99.192.0.1/11 and 99.224.0.1/12), which in turn can establish a HELLO relationship with
Router 3 (99.240.0.1/13), and so on.

I'm looking for any thoughts, insights, or pointers that can help me troubleshoot and resolve this issue. Any input is greatly appreciated. Thank you in advance.

Regards;

David Johnson.

[MHM Cisco World]

I prefer you make new post for your Q.

[Giuseppe Larosa]

Hello @davidjohnson ,

as already explained in this thread by @Flavio Miranda  and others you and the original poster are missing some basic concepts:

in IPv4 internetworks routers need to connect with shared IP subnets in order to be able to communicate and use a routing protocol like OSPF.

Your addressing plan fails to follow this basic principle and this is why you are not able to build OSPF adjacencies.

Hope to help

Giuseppe